neurofilament light chain - n.neurology.org · the longitudinal assessment of a putative biomarker...

Ching-Hua Lu MDPhD

Corrie Macdonald-WallisPhD

Elizabeth Gray PhDNeil Pearce DPhilAxel Petzold MD PhDNiklas Norgren PhDGavin Giovannoni MD

PhDPietro Fratta MD PhDKatie Sidle MD PhDMark Fish MDRichard Orrell MDRobin Howard MDKevin Talbot DPhil

FRCPLinda Greensmith PhDJens Kuhle MDMartin R Turner PhD

FRCPAndrea Malaspina MD

PhD

Correspondence toDr Malaspinaamalaspinaqmulacukor Dr Turnermartinturnerndcnoxacuk

Supplemental dataat Neurologyorg

Neurofilament light chainA prognostic biomarker in amyotrophic lateral sclerosis

ABSTRACT

Objective To test blood and CSF neurofilament light chain (NfL) levels in relation to disease pro-gression and survival in amyotrophic lateral sclerosis (ALS)

Methods Using an electrochemiluminescence immunoassay NfL levels were measured in sam-ples from 2 cohorts of patients with sporadic ALS and healthy controls recruited in London(ALScontrol plasma n 5 10342) and Oxford (ALScontrol serum n 5 6436 paired CSFn 5 3820) NfL levels in patients were measured at regular intervals for up to 3 years Changein ALS Functional Rating ScalendashRevised score was used to assess disease progression Survivalwas evaluated using Cox regression and KaplanndashMeier analysis

Results CSF serum and plasma NfL discriminated patients with ALS from healthy controlswith high sensitivity (97 89 90 respectively) and specificity (95 75 71respectively) CSF NfL was highly correlated with serum levels (r 5 078 p 00001) BloodNfL levels were approximately 4 times as high in patients with ALS compared with controls inboth cohorts and maintained a relatively constant expression during follow-up Blood NfLlevels at recruitment were strong independent predictors of survival The highest tertile ofblood NfL at baseline had a mortality hazard ratio of 391 (95 confidence interval 198ndash794 p 0001)

Conclusion Blood-derived NfL level is an easily accessible biomarker with prognostic value inALS The individually relatively stable levels longitudinally offer potential for NfL as a pharmaco-dynamic biomarker in future therapeutic trials

Classification of evidence This report provides Class III evidence that the NfL electrochemilumi-nescence immunoassay accurately distinguishes patients with sporadic ALS from healthycontrols Neurologyreg 2015842247ndash2257

GLOSSARYALS 5 amyotrophic lateral sclerosis CI 5 confidence interval Nf 5 neurofilament NfH 5 neurofilament heavy chain NfL 5neurofilament light chain PRB 5 progression rate at baseline PRL 5 progression rate at last visit

Various factors militate against the development of reliable biomarkers in amyotrophic lateralsclerosis (ALS) including clinical heterogeneity variable rate of progression and the lack of arecognizable preclinical state of this fatal neurodegenerative disorder An easily accessible andreproducible prognostic biomarker would help patient stratification improving assessment ofindividual prognosis and care-planning It might also have potential as a pharmacodynamic mea-sure of therapeutic response

These authors contributed equally to this work

From the Centre for Neuroscience amp Trauma (C-HL GG JK AM) Blizard Institute Barts and The London School of Medicine andDentistry Queen Mary University of London Sobell Department of Motor Neuroscience and Movement Disorders (C-HL LG) Departmentsof Neuroinflammation (AP) Neurodegenerative Disease (PF) Molecular Neuroscience (KS) and Clinical Neuroscience (RO) and MRCCentre for Neuromuscular Diseases (RO LG) UCL Institute of Neurology London MRC Integrative Epidemiology Unit (CM-W) Uni-versity of Bristol Nuffield Department of Clinical Neurosciences (EG KT MRT) University of Oxford Department of Medical Statistics(NP) London School of Hygiene and Tropical Medicine London UK UmanDiagnostics (NN) Umearing Sweden Medicine Clinical Trial Unit(MF) Musgrove Park Hospital Taunton UK National Hospital for Neurology and Neurosurgery (RO RH AM) London UK Neurology(JK) University Hospital Basel Switzerland North-East London and Essex MND Care and Research Centre (AM) London and Basildon andThurrock University Hospitals NHS Foundation Trust (AM) Basildon UK

Go to Neurologyorg for full disclosures Funding information and disclosures deemed relevant by the authors if any are provided at the end of the articleThe Article Processing Charge was funded by RCUK

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use distribution andreproduction in any medium provided the original work is properly cited

copy 2015 American Academy of Neurology 2247

ordf 2015 American Academy of Neurology Unauthorized reproduction of this article is prohibited

The longitudinal assessment of a putativebiomarker would allow a more reliable inter-pretation of the biomarkerrsquos behavior whenmonitoring treatment response Blood-basedbiomarkers are preferable because theyrequire minimally invasive collection com-pared to CSF sampling Neurofilaments(Nfs) the main byproducts of neuroaxonalbreakdown are potential ldquouniversalrdquo bio-markers of neurodegeneration1 Nf levels inCSF from patients with ALS increase signifi-cantly compared to other neurodegenerativedisorders2ndash4 or to ALS-mimics5 and show arobust interlaboratory reproducibility com-pared to other biomarkers6 Nf bioavailabilityand measurement depend on matrix-relatedbiological phenomena such as protein aggre-gation as recently reported78

In this study we examined the prognosticvalue in ALS of neurofilament light chain(NfL) one of the main constituents of neu-rons and axons building on previous smallcross-sectional studies9ndash11 to evaluate the tem-poral profile of NfL expression in plasmaserum and CSF from patients with ALS

METHODS Standard protocol approvals registrationsand patient consents Approvals were obtained from the East

London and the City Research Ethics Committee 1 (09

H070327) and South Central Oxford Ethics Committee B

(08H060585) All participants provided written consent (or

gave verbal permission for a carer to sign on their behalf)

Participants and sampling This study included 103 patients

with ALS and 42 healthy controls from a London cohort and 64

patients with ALS and 36 healthy controls from an Oxford

cohort Patients with ALS were diagnosed according to standard

criteria12 having been examined by experienced ALS neurologists

(London cohort AM KS RO RH MF Oxford cohort

MRT KT) Those with a family history of ALS or frontotem-

poral dementia or known to carry a genetic mutation linked to

ALS or frontotemporal dementia were excluded to minimize any

potential biases Healthy controls were typically spouses and

friends of patients Exclusion criteria included neurologic comor-

bidities likely to affect Nf bioavailability13ndash15

Baseline NfL levels were measured in plasma serum and

CSF samples Serial plasma samples and clinical information were

obtained on average every 2 to 4 months from 67 of the 103 pa-

tients with ALS recruited in London Serum and CSF samples

(where possible) were collected every 6 months from 43 and 24

of the 64 patients with ALS in Oxford No selection criteria were

applied to individuals with ALS sampled longitudinally other

than their willingness to donate further samples Symptom onset

was defined as first patient-reported weakness Progression rate

was calculated at baseline (PRB) or last visit (PRL) as 48 minus

the ALS Functional Rating ScalendashRevised score divided by the

disease duration from onset of symptoms Progression rate less

than 05 between 05 and 10 and more than 10 (pointmonth)

was defined as slow (ALS-slow) intermediate (ALS-intermedi-

ate) and fast progressing ALS (ALS-fast) respectively Use of

riluzole (or not) at the time of sampling was recorded

Sample analysis Plasma serum and CSF samples were pro-

cessed and aliquoted within 1 hour from collection and frozen

at 280degC following standard consensus procedures16 An elec-

trochemiluminescence immunoassay was used to quantify NfL as

previously described9 the investigators were blinded to clinical

data ALS and control samples were evenly distributed on each

plate and measured in duplicate at the same dilution Each plate

contained calibrators (0ndash10000 pgmL) and quality controls

The interassay coefficients of variance were mostly below 10

and the mean intraassay coefficients of variance were below 10

Linearity of the NfL assay was established (0ndash50000 pgmL) as

previously reported9

Statistical analysis Continuous variables were summarized in

median (interquartile range) hence nonparametric analysis for

group comparisons and correlation analysis Receiver operating

characteristic curve analysis was used to assess assay sensitivity

specificity We used log rank analysis to compare survival (fixed

date was used to censor data for survival analysis) and multilevel

random intercept models with a linear slope to examine NfL lon-

gitudinal trajectories (MLwiN version 230 from Stata version

131 runmlwin command)17 for the first 15 months of the

follow-up period in 3 ALS progression subgroups slow

intermediate and fast progressors A natural log transformation

was used to normalize the measurements Each ALS progression

group was included as a categorical fixed effect we also included

an interaction between the ALS progression categories and time

to assess whether the rate of change in NfL differed by ALS

progression rate NfL change was jointly modeled with the time

to death within the 15-month follow-up period to account for

any informative dropout18 Cox regression analysis of survival by

NfL at baseline and other covariates was tested in the London and

Oxford cohorts separately and then combined (adjusting for

study center) The matched serum and plasma NfL levels from

healthy controls in a previous study showed high correlation (n5

25 Spearman r5 093 p 00001) and strong agreement using

Bland-Altman method comparison (bias 392 serum-plasma

95 confidence interval [CI] 2241 1025 95 limits of

agreement 22615 3399 Kuhle et al unpublished data)

We conducted analyses of the 2 cohorts combined using the

corresponding NfL data (serum or plasma) from each cohort

However in recognition that NfL data from the 2 cohorts were

different (albeit highly correlated) measures we used cohort-

specific tertile cutoff levels and we adjusted Cox regression and

KaplanndashMeier survival analyses by center A p value of less than

005 was considered statistically significant

RESULTS Demographic and clinical characteristicsof the London and Oxford cohorts are summarizedin table e-1 on the Neurologyreg Web site atNeurologyorg Table 1 reports the baseline bloodand CSF NfL levels along with the demographicand clinic characteristics of the cohorts

Cross-sectional analyses NfL levels in CSF (Oxford cohort)

serum (Oxford cohort) and plasma (London cohort)NfL lev-els were higher in patients with ALS than in controls inall biofluids measured (p 00001 figure 1 AndashCleft) Receiver operating characteristic analysis showed

2248 Neurology 84 June 2 2015


Table 1 Summary of blood NfL levels (London Oxford and combined cohorts) and of CSF NfL levels (Oxford) used for cross-sectional analysis

ALS NfL levels Controls NfL levels

London (plasma)(n 5 103)

Oxford (serum)(n 5 64)

Combined (blood)(n 5 67)

Oxford (CSF)(n 5 38)





Sex

Male 823 (465 150)Ref 90 (53 146) 849 (508 1463)Ref 8948 (4651 12315) 306 (22 869) 23 (12 46) 299 (159 495) 6148 (4949 1101)

Female 1429 (761 2188)a 90 (59 183) 1257 (62 2147)b 4630 (3406 10247) 252 (167 287) 20 (105 375) 232 (142 380) 4265 (2753 4674)

Age of sampling at baseline y

lt60 929 (403 158) 69 (40 116) 78 (402 146) 7570 (4630 9483) 279 (192 622) 14 (9 33) 219 (12 384) 4607 (2906 5544)

60ndash69 997 (575 1561) 113 (62 215) 999 (576 167) 7993 (3950 14409) 22 (132 344) 31 (22 1025) 27 (188 429) 8841 (4433 1603)

70ndash79 1116 (616 1576) 105 (715 1333) 105 (617 154) 5897 (4284 10202) 257 (184 387) 28 (23 33) 257 (207 359) 1098 (1098 1098)

Dagger80 1172 (576 2317) 1225 (39 206) 1172 (549 2167) 10558 (10558 10558) 823 (823 823) mdash 823 (823 823) mdash

Age at onset y

lt60 929 (4025 158) 69 (40 116)Ref 76 (402 146) 7570 (4474 9284)

60ndash69 1001 (561 1525) 113 (79 215)b 1061 (576 1574) 5505 (3388 13954)

70ndash79 953 (617 158) 103 (39 129) 992 (617 1545) 9189 (5481 11732)

Dagger80 1985 (59 2661) 206 (206 206) 2023 (668 2546) 10558 (10558 10558)

Site of symptom onset

Limb 943 (537 1599) 86 (42 151) 901 (531 1543) 7037 (4154 10558)

Bulbar 1425 (5513 2007) 113 (75 282) 132 (615 2309) 9189 (4673 13954)

Bothc 1185 (953 1416) mdash 1185 (953 1416) mdash

Duration to baseline mo

lt12 1482 (7298 217)a 155 (103 2555)a 150 (9523 2146)d 10949 (7210 13852)a

12ndash24 1215 (6453 2148)b 1225 (863 1518)b 1215 (702 2105)d 9284 (5245 9189)a

25ndash36 823 (574 1556) 79 (415 1048) 82 (559 1165) 4154 (3388 9189)

gt36 523 (271 988)Ref 55 (265 1055)Ref 534 (273 989)Ref 4093 (2767 4785)Ref

ALSFRS-R score

47ndash40 669 (389 1436) 94 (505 1085) 816 (399 1326) 6289 (5050 9535)

39ndash26 1044 (624 1586) 90 (54 1515) 997 (60 1573) 8259 (4108 12607)

pound25 1477 (489 2539) 1715 (38 305) 1477 (484 2618) 23286 (23286 23286)

Progression rate at baseline

Slow lt05 669 (465 1173)Ref 645 (38 106)Ref 669 (395 107)Ref 4489 (3245 5701)Ref

Intermediate 05ndash10 1137 (598 1514) 116 (795 485)b 116 (62 150)b 9189 (4640 13985)e

Fast gt10 1801 (1159 2774)d 156 (99 271)d 1617 (1106 2686)f 11340 (8607 15625)g

Continued

Neurology

84

June22

015

2249


an area under the curve for CSF of 09987 for serum08626 and 08687 for plasma (p 00001 figure 1AndashC right) Cutoff levels provided clear separation ofpatients with ALS from controls in all biofluids tested(figure 1 AndashC right)

Correlation between CSF and serum NfL levelsNfL lev-els in matched CSF and serum samples were highlycorrelated (ALS r 5 078 p 00001 controlsr 5 057 p 5 0008 figure 1D) CSF NfL valueswere 738-fold (interquartile range 519ndash915) and346-fold (170ndash420) higher than serum levels inALS and controls respectively (p 00001)

Blood NfL levels vs disease progression and duration in

ALS In both London and Oxford cohorts blood NfLlevels in ALS-fast were significantly higher than inALS-slow (London p 5 00002 Oxford p 5

00007) but not in ALS-intermediate (p 5 00616and 04809 respectively) (table 1) The higherexpression of NfL in patients with ALS-fast was con-firmed by the strong correlation between blood NfLlevels at baseline and PRB in London (Spearman r5

047 p 00001) and Oxford (r 5 051 p

00001) cohorts (figure 1E) as well as with PRL inLondon (r 5 048 p 00001) and Oxford (r 5053 p 00001) PRB was strongly correlated withPRL in both cohorts (LondonOxford r 5

093095 p 00001 for both) There was a nega-tive correlation between blood NfL levels anddisease duration to baseline (LondonOxford r 5

20362050 p5 00002p 00001) while dura-tion to baseline was also negatively correlated withdisease progression (LondonOxford for PRB r 520622086 for PRL r 5 20672087 p

00001 for both)

Effect of sex in blood NfL levelsThe male to female ratioin London Oxford and in the combined cohorts wasapproximately 21 (table e-1) In the London cohortand in the combined cohorts plasma NfL levels weresignificantly higher in female than in male participants(table 1) London female patients with ALS were olderand in a more advanced stage of the disease whileOxford female and male patients with ALS had similarage and disease severity (table e-2A)

Longitudinal analyses The average trajectories of natu-ral log NfL levels from the multilevel model analysisover the first 15 months of the follow-up period inpatients with ALS subdivided according to PRL areshown in figure 2 (solid lines) along with thetrajectories of the observed log NfL levels for eachindividual patient with ALS (dashed lines figure 2)Because PRB and PRL are highly correlated PRL waschosen for stratification of patients with ALS as morerepresentative of disease progression

A summary of the statistical analysis is shown intable e-3 Baseline natural log plasma serum and

Tab

le1

Con

tinu

ed

ALS

NfL

leve

lsCon

trols

NfL

leve

ls

Lond

on(plasm

a)(n

5103)

Oxf

ord(ser

um)

(n5

64)

Com

bined

(blood

)(n

567)

Oxf

ord(C

SF)

(n5

38)

Lond

on(plasm

a)(n

542)

Oxf

ord(ser

um)

(n5

36)

Com

bined

(blood

)(n

578)

Oxf

ord(C

SF)

(n5

20)

Rilu

zole

trea

tmen

t

Witho

ut668

(3751

392)

985

(5031

553)

83

(421

51)

mdash

With

1114

(5871

788)

885

(5751

355)

999

(591

586)

mdash

Abb

reviations

ALS

5am

yotrop

hiclaterals

cleros

isA

LSFRS-R

5ALS

Fun

ctiona

lRatingSca

lendashRev

ised

NfL

5ne

urofila

men

tlig

htch

ain

Ref

5referenc

egr

oup

Dataaremed

ian(in

terq

uartile

rang

e)

ap

001

bp

005

cOnly2

patien

tswerein

this

catego

ry

dp

0001

ep5

00138

fp

00001

gp5

0005



Figure 1 Summary of the cross-sectional analyses of NfL levels in the Oxford and London cohorts

NfL levels (median [interquartile range]) in patients with amyotrophic lateral sclerosis and controls in the cross-sectionalanalysis using (A) CSF (B) serum and (C) plasma (MannndashWhitney U test) Results of receiver operating characteristic anal-ysis are shown in the right panel (D) Matched CSF and serum NfL levels are strongly correlated in controls and in patientswith ALS (E) Blood NfL levels are strongly correlated with progression rate at baseline in both London and Oxford cohortsAUC 5 area under the curve NfL 5 neurofilament light chain

Neurology 84 June 2 2015 2251


CSF NfL levels were higher in ALS-fast than in ALS-slow (table e-3 exposure group A) in both Londonand Oxford cohorts There was little or no changein plasma NfL levels over time in any of the ALS pro-gression groups in London while in Oxford therewas a small temporal increase of serum NfL in theALS-fast group (n 5 10 increase per month 46[95 CI 16 77]) In Oxford only 22 of 38patients went on to have follow-up lumbar puncturesand the follow-up period for the ALS-fast group wasshorter Nonetheless we observed a small increase in

CSF NfL in both slow progressors (n 5 9 increaseper month 13 [95 CI 04 21]) and fastprogressors (n 5 7 increase per month 33 [95CI 08 59]) but no significant change in CSFNfL levels in the Oxford intermediate group (n 5 8table e-3)

Baseline NfL levels in our longitudinal cohortswere higher in the ALS-fast subgroup in line withfindings in the cross-sectional study The NfL bloodlevels in these patients remained stable over the15-month follow-up period Adjustment of the

Figure 2 Summary of the longitudinal analyses of NfL levels in the London and Oxford cohorts

Observed trajectories of log NfL levels in the 15-month follow-up period for individual patients with ALS (dashed lines) and the predicted average trajectories(solid lines) are shown for ALS-fast (red) ALS-intermediate (green) and ALS-slow (blue) patients in the London cohort (plasma panel A) and Oxford cohort(serum panel B CSF panel C) ALS-fast progression rate at last visit (PRL)10 ALS-intermediate PRL 05ndash10 ALS-slow PRL05 ALS 5 amyotrophiclateral sclerosis NfL 5 neurofilament light chain



multilevel study of NfL trajectories by time fromonset of symptoms to baseline producedonly minimal changes with no impact on the signif-icance of the test (table e-3)

We also used cohort-specific median cutoff forPRL to stratify patients with ALS No change inblood NfL levels over time were found in below-median and above-median groups (table e-3 expo-sure groups B) while the baseline NfL levels werehigher in the ALS above-median group in the Lon-donplasma (p 5 001) and the Oxfordserum (p 5

0004) cohorts

Survival analyses Cox regression Cox regression analysisof survival (table 2) was examined using baselineblood and CSF NfL levels In the London cohorthigh levels of blood NfL PRB and age at symptomonset were associated with poor survival In theOxford cohort (serum) only baseline NfL levelsbut not PRB were associated with poor survivalWhen the number was increased by combining theLondon and Oxford cohorts baseline NfL levels sexALS Functional Rating ScalendashRevised score at base-line and age at symptom onset were associated withpoor survival Despite the much smaller case numberCSF NfL levels were also found to be a strong inde-pendent prognostic biomarker for survival

Cox regression analysis was also performed usingthe time of ALS onset as the start point to evaluatesurvival while keeping the baseline (ie the first timepatients were sampled) as each patientrsquos entry timeinto the study (ie the time from onset to baselinewas not ldquocountedrdquo since patients had to survive fromonset to baseline to be included in the study) Find-ings using this approach were not dissimilar fromthose in which survival was calculated from baseline(table 2)

KaplanndashMeier KaplanndashMeier survival curvesshowed a clear separation of cumulative survivalsbetween subgroups of patients with ALS with differ-ent baseline NfL levels (cohort-specific tertile cutofflevels) in the London and in the Oxford cohorts sep-arately and combined (figure 3 AandashAc)

Riluzole and blood NfL levels Treatment with riluzolewas associated with increased risk of mortality in thecombined cohorts (hazard ratio 147) (table 2) Fig-ure 3 shows the KaplanndashMeier curves for London(figure 3Ba) and Oxford (figure 3Bb) cohorts sepa-rately and combined (figure 3Bc) There was no sig-nificant difference in baseline blood NfL levels(table 1) and clinical features (table e-2B) in patientswith ALS treated with riluzole in the London andOxford cohorts separately or combined In additionthere was no difference in blood NfL levels in patientswith ALS stratified according to PRB betweenriluzole-treated and untreated patients with ALS in

London and Oxford separately and combined (datanot shown)

DISCUSSION Our data support blood NfL as a bio-marker with prognostic value in ALS In 2 indepen-dent cohorts there was a striking similarity in assaysensitivity specificity and cutoff levels to distinguishpatients with ALS from healthy controls while the 2cohorts were also in agreement regarding the correla-tion between disease progression rate and baselineNfL levels in patients with ALS Both cohorts showeda steady blood NfL expression over time and levels atrecruitment predicted survival independently fromother clinical covariates The improved assay perfor-mance in blood for the analysis of clinically well-characterized cross-sectional and longitudinalcohorts of patients with ALS supports NfL as areproducible easily accessible surrogate marker ofaxonal loss In our study NfL bioavailability in thenatural history of the disease has been trulycharacterized and not predicted based on a variablebaseline measurement NfL levels in CSF were thebest at discriminating patients with ALS from controlsand for patient stratification This is not surprisingconsidering that CSF is the natural biorepository ofproducts of neuroaxonal disintegration because of itsproximity to the CNS When the total number ofALS cases from our independent cohorts wasconsidered blood NfL levels also discriminated verywell between ALS-fast ALS-intermediate and ALS-slow categories Our findings suggest that blood NfLis now a leading candidate biomarker for improvedparticipant stratification in future ALS therapeutictrials with the additional potential for assessingresponse to therapy

Potential biases in our investigation partly reflectthe study of a rapidly disabling and life-shorteningcondition The follow-up sampling was understand-ably more limited for the ALS-fast group in whichit was more difficult to perform repeated measure-ments and cohorts inevitably enriched for slower-progressing arguably atypical patients By using amultilevel model the analysis included all individualsrsquomeasurements under a ldquomissing at randomrdquo assump-tion19 We limited the effects of the shorter follow-uptime for fast-progressing patients by restricting anal-ysis to the first 15 months of follow-up althoughsome of the cases were monitored longitudinally forup to 3 years Also NfL change was jointly modeledwith the time to death within this 15-month periodto account for any informative dropout182021 Multi-level and Cox regression analyses showed reproduc-ible results when analyses were performed using avariable such as disease duration from either baselineor from symptom onset To better characterize thediagnostic potency of plasma NfL in ALS future



Table 2 Summary of Cox regression analysis for mortality in London Oxford and in the combined cohorts of patients with ALS

London (plasma) Oxford (serum) Combined (blood) Oxford (CSF)

No

Cox regression analysis

No


No


No


HR (95 CI) p Value HR (95 CI) p Value HR (95 CI) p Value HR (95 CI) p Value

Baseline NfL levelsa

Lowest third 35 1 (ref) mdash 22 1 (ref) mdash 57 1 (ref) mdash 13 1 (ref) mdash

Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex

Male 66 1 (ref) mdash 45 1 (ref) mdash 112 1 (ref) mdash 29 1 (ref) mdash

Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003

Age at onsetb per year 103 103 (101 106) 001 64 102 (098 107) 035 167 103 (101 105) 0001 38 104 (099 110) 011

ALSFRS-R scoreb per point 103 096 (092 100) 007 64 094 (086 103) 018 167 095 (092 099) 0005 38 095 (085 106) 040


Limb 81 1 (ref) mdash 51 1 (ref) mdash 132 1 (ref) mdash 31 1 (ref) mdash

Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087

Bothc 2 120 (024 586) 083 0 mdash mdash 2 111 (024 511) 089 0 mdash mdash


Slow lt05 51 1 (ref) mdash 36 1 (ref) mdash 87 1 (ref) mdash 18 1 (ref) mdash

Intermediate 05ndash10 30 244 (117 511) 002 17 118 (044 317) 074 47 167 (096 290) 007 11 028 (005 152) 014

Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole

Without 29 1 (ref) mdash 34 1 (ref) mdash 63 1 (ref) mdash 19 1 (ref) mdash

With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd

London mdash mdash mdash mdash mdash mdash 103 1 (ref) mdash mdash mdash mdash

Oxford mdash mdash mdash mdash mdash mdash 64 049 (029 081) 0006 mdash mdash mdash

Abbreviations ALS 5 amyotrophic lateral sclerosis ALSFRS-R 5 ALS Functional Rating ScalendashRevised NfL 5 neurofilament light chain HR 5 hazard ratio CI 5 confidence interval ref 5 referenceA global test for violation of the proportional hazards assumption gave p values of 020 021 011 and 025 for the London (plasma) Oxford (serum) combined (blood) and Oxford (CSF) cohorts respectivelyaCutoff values for tertiles are cohort-specific range of NfL levels within each tertile (pgmL) London (plasma) cohort lowest third (n 5 35) 919ndash6152 middle third (n 5 34) 6174ndash14636 highest third (n 5 34)14988ndash79828 Oxford (serum) cohort lowest third (n5 22) 11ndash68 middle third (n5 21) 69ndash129 highest third (n5 21) 130ndash812 Oxford (CSF) cohort lowest third (n5 13) 1715ndash4661 middle third (n5 13)4673ndash9483 highest third (n 5 12) 10540ndash23286b Tested as continuous variable in Cox regression analysis age at onset years ALSFRS-R score per pointcOnly 2 patients were in this categorydCohort adjustment was used in the Cox regression analysis for the combined cohort

2254

Neurology

84

June22

015


studies should include other neurodegenerative disor-ders and ALS mimics as reference while NfL meas-urements should be ideally undertaken closer to thetime of reported disease onset when ALS is suspectedor at diagnosis

NfL levels changed only minimally throughoutmost of the disease course in ALS NfL release fromaffected tissues may be a prolonged downstream effectof ALS pathology but we cannot fully comment onearlier stages of the disease in light of the diagnostic

Figure 3 Summary of survival analyses in patients with ALS from London and Oxford cohorts separately and combined

(A) Distinct curves representing cumulative survivals in patients with ALS with different baseline plasma NfL and serum NfL levels in the London cohort (Aa)Oxford cohort (Ab) and combined cohort (Ac) All 3 cohorts were divided by cohort-specific tertile cutoff values (B) KaplanndashMeier curve of patients with ALStreated with riluzole or untreated in the London cohort (Ba) Oxford cohort (Bb) and combined cohort (Bc)



latency in our cases It is possible that rising levels ofautoantibodies against NfL may have a clearing effectwhile aggregation may reduce NfL detection levelingdown the linear increase of NfL2223 Plasma levels ofaxonal injury biomarkers such as total tau and S100Bwere reported to be at their peak immediately after aconcussive injury and to slowly return to preinjurylevels thereafter24 In the more prolonged process ofneurodegeneration seen in patients with ALS theprogressive release and accumulation of Nfs may becounterbalanced by the clearing mechanisms reportedabove resulting in a flat NfL concentration profile

Blood NfL measurement appears to have advan-tage over neurofilament heavy chain (NfH)8 Theldquohook effectrdquo a potential inconsistent result due toanalyte aggregation found in measuring plasmaNfH78 was not observed in the NfL assay9 Further-more unlike the linear increase observed in animalmodels25 longitudinal NfH plasma expression in pa-tients with rapidly progressing ALS showed a steadydecline as the disease advanced8 In a clinical trialsetting a ldquonaturalrdquo reduction of the bioavailabilityof a biomarker with the disease progression may poseproblems with the overall interpretation of treatmentresponse Unlike NfH8 blood NfL levels in ALS weresignificantly higher than in controls and maintaineddistinct temporal profiles with a steady trajectory

A change in a biomarkerrsquos expression might beconsidered as supporting evidence of disease modifi-cation in ALS as shown in arimoclomol-treatedSOD1G93A mice of ALS25 allowing for the reductionof sample size and costs in clinical trials26 The anal-ysis of how riluzole treatment affected baseline NfLlevels in our cohorts was understandably inconclusivesuggesting only an indication bias for the Londoncohort Nonetheless using the same NfL assay em-ployed in this study we have recently shown a modestreduction of serum NfL concentrations at differenttime points following spinal cord injury in a subgroupof patients treated with minocycline27

Both blood and CSF NfL levels were robust inde-pendent prognostic markers Serial lumbar puncturesfor longitudinal NfL monitoring are far less practicalthan blood sampling The observed strong correlationbetween CSF and blood NfL levels suggests that bloodNfL is a surrogate marker for CSF NfL levels Thehigher blood-CSF correlation of NfL levels weobserved in patients with ALS compared with healthycontrols was puzzling A more rapid liberation of NfLprotein from affected nervous tissue and a relativelyhigher NfL concentration in CSF from patients withALS compared with healthy controls may determinea more efficient redistribution of NfL protein betweenCSF and blood through the blood-brain barrier CSFand blood matrices may act differently on NfL homeo-stasis and clearance depending on its concentration

Our data suggest that the measurement of bloodNfL for disease activity monitoring in an earliersymptomatic phase or at diagnosis may provide fur-ther clues on the diagnostic potency of this bio-marker particularly if other neurologic disorders orALS mimic syndromes are included as reference Incombination with biomarkers emerging from neuro-imaging28 blood NfL may improve diagnosticpotency and prognostic evaluation in ALS similarto blood markers defining the transition betweenmild cognitive impairment and Alzheimer disease2930

used in combination with Pittsburgh compound BndashPET31 An improved understanding of how NfLrelease changes in response to pathology in particularpresymptomatically32 or to factors that mitigate thedisease pathology will further strengthen the case forNfL in the diagnostic process as well as therapeutictrials in ALS

AUTHOR CONTRIBUTIONSC-HL undertook the laboratory work data analysis and interpretation

performed the statistical analysis and wrote the first draft of the paper

CM-W contributed to statistical analysis and data interpretation

EG undertook the laboratory work data analysis and review and

amendment of the manuscript NP advised on the statistical analysis

and participated in interpretation of data and review and amendment

of the manuscript NN contributed to assay materials and revised the

manuscript KT RO MF KS RH and PF contributed to

patient enrollment and data collection and revised the manuscript for

content GG participated in conceptualizing the study and revised the

manuscript for content LG and AP contributed to the conceptualiza-

tion and design of the study data interpretation and review and amend-

ment of the manuscript JK contributed to the conceptualization and

design of the study assay analysis interpretation of data and review

and amendment of the manuscript AM and MRT contributed

through the conceptualization and design of the study patient enroll-

ment data collection interpretation of the data and review and amend-

ment of the manuscript All authors reviewed the drafts and approved the

final version of the manuscript

ACKNOWLEDGMENTThe authors acknowledge the selfless effort made by all participants in the

nontherapeutic clinical research (including the carers of the patients) for

which the authors are grateful

STUDY FUNDINGThe projects were funded by the Motor Neurone Disease Association

(MalaspinaApr136097) Barts and The London Charities (468

1714) LG is the Graham Watts Senior Research Fellow funded by

the Brain Research Trust and the European Communityrsquos Seventh

Framework Programme (FP72007ndash2013) CM-W is funded by a

UK Medical Research Council research fellowship (MRJ0119321)

The Oxford MND Centre (MRT KT) receives funding from the

Motor Neurone Disease Association UK MRT is funded by the Med-

ical Research Council and Motor Neurone Disease Association Lady

Edith Wolfson Fellowship (G0701923 and MRK01014X1) and

EG through the PROMISES project award to MRT by the Thierry

Latran Foundation JK is funded by an ECTRIMS Research Fellowship

Programme and by the Research Funds of the University of Basel

Switzerland RO receives funding from the Motor Neurone Disease

Association UK

DISCLOSUREC Lu reports no disclosures relevant to the manuscript C Macdonald-

Wallis E Gray and N Pearce report no disclosures relevant to the



manuscript A Petzold has a patent P91964EP00 issued to VU Medical

Centre the Netherlands N Norgren is employed by UmanDiagnostics

AB Sweden G Giovannoni P Fratta K Sidle M Fish R Orrell

R Howard K Talbot L Greensmith J Kuhle M Turner and A

Malaspina report no disclosures relevant to the manuscript Go to

Neurologyorg for full disclosures

Received October 24 2014 Accepted in final form February 20 2015

REFERENCES1 Petzold A Neurofilament phosphoforms surrogate

markers for axonal injury degeneration and loss

J Neurol Sci 2005233183ndash198

2 Brettschneider J Petzold A Sussmuth SD Ludolph AC

Tumani H Axonal damage markers in cerebrospinal fluid

are increased in ALS Neurology 200666852ndash856

3 Norgren N Rosengren L Stigbrand T Elevated neuro-

filament levels in neurological diseases Brain Res 2003

98725ndash31

4 Rosengren LE Karlsson JE Karlsson JO Persson LI

Wikkelso C Patients with amyotrophic lateral sclerosis

and other neurodegenerative diseases have increased levels

of neurofilament protein in CSF J Neurochem 199667

2013ndash2018

5 Reijn TS Abdo WF Schelhaas HJ Verbeek MM CSF

neurofilament protein analysis in the differential diagnosis

of ALS J Neurol 2009256615ndash619

6 Lehnert S Costa J de Carvalho M et al Multicentre

quality control evaluation of different biomarker candi-

dates for amyotrophic lateral sclerosis Amyotroph Lateral

Scler Frontotemporal Degener 201415344ndash350

7 Lu CH Kalmar B Malaspina A Greensmith L Petzold A

A method to solubilise protein aggregates for immunoassay

quantification which overcomes the neurofilament ldquohookrdquo

effect J Neurosci Methods 2011195143ndash150

8 Lu CH Petzold A Topping J et al Plasma neurofilament

heavy chain levels and disease progression in amyotrophic

lateral sclerosis insights from a longitudinal study

J Neurol Neurosurg Psychiatry Epub 2014 Jul 9

9 Gaiottino J Norgren N Dobson R et al Increased neuro-

filament light chain blood levels in neurodegenerative neu-

rological diseases PLoS One 20138e75091

10 Tortelli R Copetti M Ruggieri M et al Cerebrospinal

fluid neurofilament light chain levels marker of progres-

sion to generalized amyotrophic lateral sclerosis Eur J

Neurol 201522215ndash218

11 Tortelli R Ruggieri M Cortese R et al Elevated cerebro-

spinal fluid neurofilament light levels in patients with amy-

otrophic lateral sclerosis a possible marker of disease

severity and progression Eur J Neurol 201219

1561ndash1567

12 Brooks BR Miller RG Swash M Munsat TL El Escorial

revisited revised criteria for the diagnosis of amyotrophic

lateral sclerosis Amyotroph Lateral Scler Other Motor

Neuron Disord 20001293ndash299

13 Petzold A Keir G Kay A Kerr M Thompson EJ Axonal

damage and outcome in subarachnoid haemorrhage

J Neurol Neurosurg Psychiatry 200677753ndash759

14 Petzold A Mondria T Kuhle J et al Evidence for acute

neurotoxicity after chemotherapy Ann Neurol 201068

806ndash815

15 Petzold A Tisdall MM Girbes AR et al In vivo moni-

toring of neuronal loss in traumatic brain injury a micro-

dialysis study Brain 2011134464ndash483

16 Teunissen CE Petzold A Bennett JL et al A consensus

protocol for the standardization of cerebrospinal fluid col-

lection and biobanking Neurology 2009731914ndash1922

17 Leckie G Charlton C Runmlwin a program to run the

MLwiN multilevel modeling software from within Stata

J Stat Softw 2013521ndash40

18 Touloumi G Pocock SJ Babiker AG Darbyshire JH

Estimation and comparison of rates of change in longitu-

dinal studies with informative drop-outs Stat Med 1999

181215ndash1233

19 Cnaan A Laird NM Slasor P Using the general linear

mixed model to analyse unbalanced repeated measures and

longitudinal data Stat Med 1997162349ndash2380

20 Berry JD Miller R Moore DH et al The Combined

Assessment of Function and Survival (CAFS) a new end-

point for ALS clinical trials Amyotroph Lateral Scler Fron-

totemporal Degener 201314162ndash168

21 Rudnicki SA Berry JD Ingersoll E et al Dexpramipexole

effects on functional decline and survival in subjects with

amyotrophic lateral sclerosis in a phase II study subgroup

analysis of demographic and clinical characteristics Amyo-

troph Lateral Scler Frontotemporal Degener 201314

44ndash51

22 Fialova L Svarcova J Bartos A et al Cerebrospinal fluid

and serum antibodies against neurofilaments in patients

with amyotrophic lateral sclerosis Eur J Neurol 2010

17562ndash566

23 Puentes F Topping J Kuhle J et al Immune reactivity to

neurofilament proteins in the clinical staging of amyotro-

phic lateral sclerosis J Neurol Neurosurg Psychiatry 2014

85274ndash278

24 Shahim P Tegner Y Wilson DH et al Blood biomarkers

for brain injury in concussed professional ice hockey play-

ers JAMA Neurol 201471684ndash692

25 Lu CH Petzold A Kalmar B Dick J Malaspina A

Greensmith L Plasma neurofilament heavy chain levels

correlate to markers of late stage disease progression and

treatment response in SOD1 G93A mice that model ALS

PLoS One 20127e40998

26 Ganesalingam J Bowser R The application of biomarkers

in clinical trials for motor neuron disease Biomark Med

20104281ndash297

27 Kuhle J Gaiottino J Leppert D et al Serum neurofila-

ment light chain is a biomarker of human spinal cord

injury severity and outcome J Neurol Neurosurg Psychi-

atry 201586273ndash279

28 Turner MR Agosta F Bede P Govind V Lule D

Verstraete E Neuroimaging in amyotrophic lateral sclero-

sis Biomark Med 20126319ndash337

29 Hye A Riddoch-Contreras J Baird AL et al Plasma pro-

teins predict conversion to dementia from prodromal dis-

ease Alzheimers Dement 201410799ndash807e2

30 Mousavi M Jonsson P Antti H et al Serum metabolomic

biomarkers of dementia Dement Geriatr Cogn Dis Extra

20144252ndash262

31 Forsberg A Almkvist O Engler H Wall A Langstrom B

Nordberg A High PIB retention in Alzheimerrsquos disease is

an early event with complex relationship with CSF bio-

markers and functional parameters Curr Alzheimer Res

2010756ndash66

32 Benatar M Wuu J Ravits J Opportunity and innovation

in studying pre-symptomatic amyotrophic lateral sclerosis

Muscle Nerve 201347629ndash631



DOI 101212WNL00000000000016422015842247-2257 Published Online before print May 1 2015Neurology

Ching-Hua Lu Corrie Macdonald-Wallis Elizabeth Gray et al Neurofilament light chain A prognostic biomarker in amyotrophic lateral sclerosis

This information is current as of May 1 2015

ServicesUpdated Information amp

httpnneurologyorgcontent84222247fullincluding high resolution figures can be found at

Supplementary Material

642DC1httpnneurologyorgcontentsuppl20150530WNL0000000000001Supplementary material can be found at

References httpnneurologyorgcontent84222247fullref-list-1

This article cites 31 articles 5 of which you can access for free at

Citations httpnneurologyorgcontent84222247fullotherarticles

This article has been cited by 17 HighWire-hosted articles

Subspecialty Collections

httpnneurologyorgcgicollectionprognosisPrognosis

httpnneurologyorgcgicollectionamyotrophic_lateral_sclerosis_Amyotrophic lateral sclerosisfollowing collection(s) This article along with others on similar topics appears in the

Errata

content85109212fullpdf or page

nextAn erratum has been published regarding this article Please see

Permissions amp Licensing

httpwwwneurologyorgaboutabout_the_journalpermissionsits entirety can be found online atInformation about reproducing this article in parts (figurestables) or in

Reprints

httpnneurologyorgsubscribersadvertiseInformation about ordering reprints can be found online

rights reserved Print ISSN 0028-3878 Online ISSN 1526-632X1951 it is now a weekly with 48 issues per year Copyright copy 2015 American Academy of Neurology All

reg is the official journal of the American Academy of Neurology Published continuously sinceNeurology

WriteClickreg

Editorrsquos Choice

Section EditorRobert C Griggs MD

Editorsrsquo Note In reference to ldquoSusceptibility-weighted MRI in

mild traumatic brain injuryrdquo Dr Wong and authors Huang and

Chen discuss the reliability of the studyrsquos CT imaging in

differentiating small microbleeds from calcifications and the

potential limitation of missing calcifications smaller than 5 mm

mdashMegan Alcauskas MD and Robert C Griggs MD

SUSCEPTIBILITY-WEIGHTED MRI IN MILDTRAUMATIC BRAIN INJURY

Peter K Wong Vancouver Canada Huang et al1

defined microbleeds as hypodense lesions less than 5mm The authors ruled out calcification using CTbut how reliable is their CT scanner in detecting cal-cification lesions smaller than 5 mm If such smalllesions are undetected on CT and detected on MRIthen it would constitute a false-positive Can the au-thors estimate what this figure might be

Author Response Yen-Lin Huang Chi-Jen ChenTaipei Taiwan We thank Dr Wong for his ques-tion As most mild traumatic brain injuryndashassociatedmicrobleeds are located at the corticalsubcorticalregion of the brain it is rare for physiologic calcifica-tions to occur at this location In addition pathologiccalcifications are excluded at the initial inclusionstage The slice thickness of our brain CT is 5 mmwithout interslice gap so partial volume effectis minimal and a calcification greater than 2 mmwould

be detectable by experienced radiologists Only calcifi-cations less than 2 mm may be undetectable on CTand constitute false-positives Even if this exists thisfalse-positive would have equally affected both groupsbecause this study is a case-control study and wouldnot cause significant difference in the results

Peter KWong Vancouver Canada I thank Huanget al1 for their reply While thorough the reply gen-erated a new question what are the voxel dimensionsof the CT scan I do not believe that blinded a lesionof 2 mm could be recognized even if the CT slicethickness is 5 mm Any missed calcification of 5 mmor less would cause a confounding effect which islikely not zero Further studies may provide the nec-essary clarification

Author Response Chi-Jen Chen Yen-Lin HuangTaipei Taiwan The voxel dimension of our CT scanwas 119 mm3 Despite slice thickness of 5 mm with-out interslice gap on our brain CT it is true that sometiny calcifications less than 5 mm can be missed andthus the false-positive rate is likely not zero as DrWong mentioned We thank Dr Wong for the com-ment and will include this factor into the limitationsection of our related future studies

copy 2015 American Academy of Neurology

1 Huang YL Kuo YS Tseng YC Chen DY Chiu WT

Chen CJ Susceptibility-weighted MRI in mild traumatic

brain injury Neurology 201584580ndash585

CORRECTIONNeurofilament light chain A prognostic biomarker in amyotrophic lateral sclerosis

In the article ldquoNeurofilament light chain A prognostic biomarker in amyotrophic lateral sclerosisrdquo by C-H Lu et al (Neurologyreg

2015842247ndash2257) there is an omission in the Study Funding section which should read ldquoAM is funded by the MedicalResearch Council (MRM0158821)rdquo The authors regret the omission

Author disclosures are available upon request (journalneurologyorg)

Neurology 85 September 8 2015 921


The longitudinal assessment of a putativebiomarker would allow a more reliable inter-pretation of the biomarkerrsquos behavior whenmonitoring treatment response Blood-basedbiomarkers are preferable because theyrequire minimally invasive collection com-pared to CSF sampling Neurofilaments(Nfs) the main byproducts of neuroaxonalbreakdown are potential ldquouniversalrdquo bio-markers of neurodegeneration1 Nf levels inCSF from patients with ALS increase signifi-cantly compared to other neurodegenerativedisorders2ndash4 or to ALS-mimics5 and show arobust interlaboratory reproducibility com-pared to other biomarkers6 Nf bioavailabilityand measurement depend on matrix-relatedbiological phenomena such as protein aggre-gation as recently reported78

In this study we examined the prognosticvalue in ALS of neurofilament light chain(NfL) one of the main constituents of neu-rons and axons building on previous smallcross-sectional studies9ndash11 to evaluate the tem-poral profile of NfL expression in plasmaserum and CSF from patients with ALS

METHODS Standard protocol approvals registrationsand patient consents Approvals were obtained from the East

London and the City Research Ethics Committee 1 (09

H070327) and South Central Oxford Ethics Committee B

(08H060585) All participants provided written consent (or

gave verbal permission for a carer to sign on their behalf)

Participants and sampling This study included 103 patients

with ALS and 42 healthy controls from a London cohort and 64

patients with ALS and 36 healthy controls from an Oxford

cohort Patients with ALS were diagnosed according to standard

criteria12 having been examined by experienced ALS neurologists

(London cohort AM KS RO RH MF Oxford cohort

MRT KT) Those with a family history of ALS or frontotem-

poral dementia or known to carry a genetic mutation linked to

ALS or frontotemporal dementia were excluded to minimize any

potential biases Healthy controls were typically spouses and

friends of patients Exclusion criteria included neurologic comor-

bidities likely to affect Nf bioavailability13ndash15

Baseline NfL levels were measured in plasma serum and

CSF samples Serial plasma samples and clinical information were

obtained on average every 2 to 4 months from 67 of the 103 pa-

tients with ALS recruited in London Serum and CSF samples

(where possible) were collected every 6 months from 43 and 24

of the 64 patients with ALS in Oxford No selection criteria were

applied to individuals with ALS sampled longitudinally other

than their willingness to donate further samples Symptom onset

was defined as first patient-reported weakness Progression rate

was calculated at baseline (PRB) or last visit (PRL) as 48 minus

the ALS Functional Rating ScalendashRevised score divided by the

disease duration from onset of symptoms Progression rate less

than 05 between 05 and 10 and more than 10 (pointmonth)

was defined as slow (ALS-slow) intermediate (ALS-intermedi-

ate) and fast progressing ALS (ALS-fast) respectively Use of

riluzole (or not) at the time of sampling was recorded

Sample analysis Plasma serum and CSF samples were pro-

cessed and aliquoted within 1 hour from collection and frozen

at 280degC following standard consensus procedures16 An elec-

trochemiluminescence immunoassay was used to quantify NfL as

previously described9 the investigators were blinded to clinical

data ALS and control samples were evenly distributed on each

plate and measured in duplicate at the same dilution Each plate

contained calibrators (0ndash10000 pgmL) and quality controls

The interassay coefficients of variance were mostly below 10

and the mean intraassay coefficients of variance were below 10

Linearity of the NfL assay was established (0ndash50000 pgmL) as

previously reported9

Statistical analysis Continuous variables were summarized in

median (interquartile range) hence nonparametric analysis for

group comparisons and correlation analysis Receiver operating

characteristic curve analysis was used to assess assay sensitivity

specificity We used log rank analysis to compare survival (fixed

date was used to censor data for survival analysis) and multilevel

random intercept models with a linear slope to examine NfL lon-

gitudinal trajectories (MLwiN version 230 from Stata version

131 runmlwin command)17 for the first 15 months of the

follow-up period in 3 ALS progression subgroups slow

intermediate and fast progressors A natural log transformation

was used to normalize the measurements Each ALS progression

group was included as a categorical fixed effect we also included

an interaction between the ALS progression categories and time

to assess whether the rate of change in NfL differed by ALS

progression rate NfL change was jointly modeled with the time

to death within the 15-month follow-up period to account for

any informative dropout18 Cox regression analysis of survival by

NfL at baseline and other covariates was tested in the London and

Oxford cohorts separately and then combined (adjusting for

study center) The matched serum and plasma NfL levels from

healthy controls in a previous study showed high correlation (n5

25 Spearman r5 093 p 00001) and strong agreement using

Bland-Altman method comparison (bias 392 serum-plasma

95 confidence interval [CI] 2241 1025 95 limits of

agreement 22615 3399 Kuhle et al unpublished data)

We conducted analyses of the 2 cohorts combined using the

corresponding NfL data (serum or plasma) from each cohort

However in recognition that NfL data from the 2 cohorts were

different (albeit highly correlated) measures we used cohort-

specific tertile cutoff levels and we adjusted Cox regression and

KaplanndashMeier survival analyses by center A p value of less than

005 was considered statistically significant

RESULTS Demographic and clinical characteristicsof the London and Oxford cohorts are summarizedin table e-1 on the Neurologyreg Web site atNeurologyorg Table 1 reports the baseline bloodand CSF NfL levels along with the demographicand clinic characteristics of the cohorts

Cross-sectional analyses NfL levels in CSF (Oxford cohort)

serum (Oxford cohort) and plasma (London cohort)NfL lev-els were higher in patients with ALS than in controls inall biofluids measured (p 00001 figure 1 AndashCleft) Receiver operating characteristic analysis showed













Sex

Male 823 (465 150)Ref 90 (53 146) 849 (508 1463)Ref 8948 (4651 12315) 306 (22 869) 23 (12 46) 299 (159 495) 6148 (4949 1101)

Female 1429 (761 2188)a 90 (59 183) 1257 (62 2147)b 4630 (3406 10247) 252 (167 287) 20 (105 375) 232 (142 380) 4265 (2753 4674)


lt60 929 (403 158) 69 (40 116) 78 (402 146) 7570 (4630 9483) 279 (192 622) 14 (9 33) 219 (12 384) 4607 (2906 5544)

60ndash69 997 (575 1561) 113 (62 215) 999 (576 167) 7993 (3950 14409) 22 (132 344) 31 (22 1025) 27 (188 429) 8841 (4433 1603)

70ndash79 1116 (616 1576) 105 (715 1333) 105 (617 154) 5897 (4284 10202) 257 (184 387) 28 (23 33) 257 (207 359) 1098 (1098 1098)


Age at onset y

lt60 929 (4025 158) 69 (40 116)Ref 76 (402 146) 7570 (4474 9284)

60ndash69 1001 (561 1525) 113 (79 215)b 1061 (576 1574) 5505 (3388 13954)

70ndash79 953 (617 158) 103 (39 129) 992 (617 1545) 9189 (5481 11732)

Dagger80 1985 (59 2661) 206 (206 206) 2023 (668 2546) 10558 (10558 10558)


Limb 943 (537 1599) 86 (42 151) 901 (531 1543) 7037 (4154 10558)

Bulbar 1425 (5513 2007) 113 (75 282) 132 (615 2309) 9189 (4673 13954)



lt12 1482 (7298 217)a 155 (103 2555)a 150 (9523 2146)d 10949 (7210 13852)a

12ndash24 1215 (6453 2148)b 1225 (863 1518)b 1215 (702 2105)d 9284 (5245 9189)a

25ndash36 823 (574 1556) 79 (415 1048) 82 (559 1165) 4154 (3388 9189)

gt36 523 (271 988)Ref 55 (265 1055)Ref 534 (273 989)Ref 4093 (2767 4785)Ref

ALSFRS-R score

47ndash40 669 (389 1436) 94 (505 1085) 816 (399 1326) 6289 (5050 9535)

39ndash26 1044 (624 1586) 90 (54 1515) 997 (60 1573) 8259 (4108 12607)

pound25 1477 (489 2539) 1715 (38 305) 1477 (484 2618) 23286 (23286 23286)




Fast gt10 1801 (1159 2774)d 156 (99 271)d 1617 (1106 2686)f 11340 (8607 15625)g

Continued

Neurology

84

June22

015

2249







047 p 00001) and Oxford (r 5 051 p




00001 for both)




Tab

le1

Con

tinu

ed

ALS

NfL

leve

lsCon

trols

NfL

leve

ls

Lond

on(plasm

a)(n

5103)

Oxf

ord(ser

um)

(n5

64)

Com

bined

(blood

)(n

567)

Oxf

ord(C

SF)

(n5

38)

Lond

on(plasm

a)(n

542)

Oxf

ord(ser

um)

(n5

36)

Com

bined

(blood

)(n

578)

Oxf

ord(C

SF)

(n5

20)

Rilu

zole

trea

tmen

t

Witho

ut668

(3751

392)

985

(5031

553)

83

(421

51)

mdash

With

1114

(5871

788)

885

(5751

355)

999

(591

586)

mdash

Abb

reviations

ALS

5am

yotrop

hiclaterals

cleros

isA

LSFRS-R

5ALS

Fun

ctiona

lRatingSca

lendashRev

ised

NfL

5ne

urofila

men

tlig

htch

ain

Ref

5referenc

egr

oup

Dataaremed

ian(in

terq

uartile

rang

e)

ap

001

bp

005

cOnly2

patien

tswerein

this

catego

ry

dp

0001

ep5

00138

fp

00001

gp5

0005
















0004) cohorts












No


No


No


No





Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex


Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003





Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087





Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole


With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd




2254

Neurology

84

June22

015


















































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice



































Sex

Male 823 (465 150)Ref 90 (53 146) 849 (508 1463)Ref 8948 (4651 12315) 306 (22 869) 23 (12 46) 299 (159 495) 6148 (4949 1101)

Female 1429 (761 2188)a 90 (59 183) 1257 (62 2147)b 4630 (3406 10247) 252 (167 287) 20 (105 375) 232 (142 380) 4265 (2753 4674)


lt60 929 (403 158) 69 (40 116) 78 (402 146) 7570 (4630 9483) 279 (192 622) 14 (9 33) 219 (12 384) 4607 (2906 5544)

60ndash69 997 (575 1561) 113 (62 215) 999 (576 167) 7993 (3950 14409) 22 (132 344) 31 (22 1025) 27 (188 429) 8841 (4433 1603)

70ndash79 1116 (616 1576) 105 (715 1333) 105 (617 154) 5897 (4284 10202) 257 (184 387) 28 (23 33) 257 (207 359) 1098 (1098 1098)


Age at onset y

lt60 929 (4025 158) 69 (40 116)Ref 76 (402 146) 7570 (4474 9284)

60ndash69 1001 (561 1525) 113 (79 215)b 1061 (576 1574) 5505 (3388 13954)

70ndash79 953 (617 158) 103 (39 129) 992 (617 1545) 9189 (5481 11732)

Dagger80 1985 (59 2661) 206 (206 206) 2023 (668 2546) 10558 (10558 10558)


Limb 943 (537 1599) 86 (42 151) 901 (531 1543) 7037 (4154 10558)

Bulbar 1425 (5513 2007) 113 (75 282) 132 (615 2309) 9189 (4673 13954)



lt12 1482 (7298 217)a 155 (103 2555)a 150 (9523 2146)d 10949 (7210 13852)a

12ndash24 1215 (6453 2148)b 1225 (863 1518)b 1215 (702 2105)d 9284 (5245 9189)a

25ndash36 823 (574 1556) 79 (415 1048) 82 (559 1165) 4154 (3388 9189)

gt36 523 (271 988)Ref 55 (265 1055)Ref 534 (273 989)Ref 4093 (2767 4785)Ref

ALSFRS-R score

47ndash40 669 (389 1436) 94 (505 1085) 816 (399 1326) 6289 (5050 9535)

39ndash26 1044 (624 1586) 90 (54 1515) 997 (60 1573) 8259 (4108 12607)

pound25 1477 (489 2539) 1715 (38 305) 1477 (484 2618) 23286 (23286 23286)




Fast gt10 1801 (1159 2774)d 156 (99 271)d 1617 (1106 2686)f 11340 (8607 15625)g

Continued

Neurology

84

June22

015

2249







047 p 00001) and Oxford (r 5 051 p




00001 for both)




Tab

le1

Con

tinu

ed

ALS

NfL

leve

lsCon

trols

NfL

leve

ls

Lond

on(plasm

a)(n

5103)

Oxf

ord(ser

um)

(n5

64)

Com

bined

(blood

)(n

567)

Oxf

ord(C

SF)

(n5

38)

Lond

on(plasm

a)(n

542)

Oxf

ord(ser

um)

(n5

36)

Com

bined

(blood

)(n

578)

Oxf

ord(C

SF)

(n5

20)

Rilu

zole

trea

tmen

t

Witho

ut668

(3751

392)

985

(5031

553)

83

(421

51)

mdash

With

1114

(5871

788)

885

(5751

355)

999

(591

586)

mdash

Abb

reviations

ALS

5am

yotrop

hiclaterals

cleros

isA

LSFRS-R

5ALS

Fun

ctiona

lRatingSca

lendashRev

ised

NfL

5ne

urofila

men

tlig

htch

ain

Ref

5referenc

egr

oup

Dataaremed

ian(in

terq

uartile

rang

e)

ap

001

bp

005

cOnly2

patien

tswerein

this

catego

ry

dp

0001

ep5

00138

fp

00001

gp5

0005
















0004) cohorts












No


No


No


No





Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex


Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003





Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087





Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole


With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd




2254

Neurology

84

June22

015


















































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice






























047 p 00001) and Oxford (r 5 051 p




00001 for both)




Tab

le1

Con

tinu

ed

ALS

NfL

leve

lsCon

trols

NfL

leve

ls

Lond

on(plasm

a)(n

5103)

Oxf

ord(ser

um)

(n5

64)

Com

bined

(blood

)(n

567)

Oxf

ord(C

SF)

(n5

38)

Lond

on(plasm

a)(n

542)

Oxf

ord(ser

um)

(n5

36)

Com

bined

(blood

)(n

578)

Oxf

ord(C

SF)

(n5

20)

Rilu

zole

trea

tmen

t

Witho

ut668

(3751

392)

985

(5031

553)

83

(421

51)

mdash

With

1114

(5871

788)

885

(5751

355)

999

(591

586)

mdash

Abb

reviations

ALS

5am

yotrop

hiclaterals

cleros

isA

LSFRS-R

5ALS

Fun

ctiona

lRatingSca

lendashRev

ised

NfL

5ne

urofila

men

tlig

htch

ain

Ref

5referenc

egr

oup

Dataaremed

ian(in

terq

uartile

rang

e)

ap

001

bp

005

cOnly2

patien

tswerein

this

catego

ry

dp

0001

ep5

00138

fp

00001

gp5

0005
















0004) cohorts












No


No


No


No





Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex


Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003





Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087





Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole


With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd




2254

Neurology

84

June22

015


















































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice






































0004) cohorts












No


No


No


No





Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex


Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003





Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087





Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole


With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd




2254

Neurology

84

June22

015


















































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice



























No


No


No


No





Middle third 34 191 (086 423) 011 21 268 (087 827) 009 55 208 (109 397) 003 13 364 (077 1725) 010

Highest third 34 378 (168 850) 0001 21 605 (168 2187) 0006 55 382 (198 739) 0001 12 3182 (375 26971) 0002

Sex


Female 37 141 (078 256) 026 19 189 (086 414) 011 56 167 (106 263) 003 9 798 (207 3083) 0003





Bulbar 20 073 (037 145) 037 13 041 (013 134) 014 33 066 (038 116) 015 7 113 (026 490) 087





Fast gt10 22 242 (103 569) 004 11 059 (016 214) 042 33 149 (077 289) 024 9 010 (001 066) 002

Riluzole


With 74 154 (078 303) 021 30 125 (050 309) 063 104 147 (089 241) 013 19 092 (023 367) 091

Cohortd




2254

Neurology

84

June22

015


















































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice









































































Association UK




















98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice








































98725ndash31





2013ndash2018



























1561ndash1567










806ndash815













181215ndash1233













44ndash51




17562ndash566




85274ndash278











20104281ndash297













20144252ndash262





2010756ndash66




















Errata





Reprints




WriteClickreg

Editorrsquos Choice







































Errata





Reprints




WriteClickreg

Editorrsquos Choice

























WriteClickreg

Editorrsquos Choice

























neurofilament light chain - n.neurology.org · the longitudinal assessment of a putative biomarker...

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