7 katz potential harms of hiv self-testing
TRANSCRIPT
David A. Katz, PhD, MPH University of Washington
Public Health – SeaAle & King County
PotenDal Harms of HIV Self-‐TesDng
Overview
¨ PotenDal benefits vs. harms ¨ Modeling impact of self-‐tesDng on HIV prevalence
¤ Consequences of long window period ¤ Impact of delays in linkage to care
¨ Point-‐of-‐sex tesDng and condom use ¨ Future direcDons
PotenDal benefits vs. harms
↑ tesDng =
earlier diagnosis ?
test misinterpretaDon false negaDves/posiDves ↓ access to counseling ↓ linkage to care & prevenDon coerced tesDng/IPV ↓ STI screening ↓ accuracy of surveillance
Time to posiDvity for common HIV tests
Modified from Masciotra et al, J Clin Virol 2011
Days before WB positive
WB
pos
itive
APT
IMA
(-26
)
GS
1/2+
O (
-12)
Mul
ti-Sp
ot (
-7)
Rev
eal G
3 (-
6)
Viro
nost
ka (+
) 2
Ora
Qui
ck (-
1)
Uni
gold
(-2)
25 20 10 15
Arc
hite
ct C
ombo
(-2
0)
CO
MPL
ETE
HIV
-1/2
(-5
) H
IV-1
/2 S
TAT-
PAK
(-5
)
INST
I (-
9)
Bio
-Rad
Com
bo (
-19)
and Owen et al, J Clin Micro 2008
Det
erm
ine
Com
bo (
-15)
slide courtesy of Bernie Branson
5 0
¨ 3-‐month window period
¤ False-‐negaDve during acute infecDon
¨ 91.7% sensiDvity compared to 3rd gen EIA
¨ 99.98% specificity
¨ Consequences of false-‐negaDve tests:
¤ Delayed diagnosis & linkage to care
¤ Inaccurate disclosure & ineffecDve serosorDng
HIV self-‐test characterisDcs
Delayed linkage to HIV care
¨ Timely linkage necessary to: ¤ maintain health of persons living with HIV ¤ reduce ongoing transmission
¨ Persons with posiDve self-‐tests need to iniDate care on own
¨ Self-‐tests may appeal to persons experiencing barriers to care
¨ Unknown how self-‐tesDng will impact linkage
Modeling impact of self-‐tesDng
¨ Adapted a determinisDc, conDnuous-‐Dme model of HIV transmission dynamics
¨ Predict impact of replacing clinic tests with self-‐tests on HIV prevalence in SeaAle MSM ¤ Test type: sensiDvity & window period ¤ TesDng frequency ¤ Rate of iniDaDng anDretroviral therapy (ART)
Katz et al, Sex Transm Dis 2014; 41: 2-‐9.
How would replacing clinic tests with self-‐tests affect HIV prevalence?
15%
17%
19%
21%
23%
25%
27%
29%
0% 20% 40% 60% 80% 100%
Equilib
rium HIV prevalence
Propor=on of popula=on self-‐tes=ng (vs. clinic)
27.5%
18.6%
How would replacing clinic-‐based tests with self-‐tests affect HIV prevalence? ART iniDaDon
100% Clinic tes=ng
100% Self-‐tes=ng with % reduc=on in rate of ART ini=a=on among self-‐testers rela=ve to clinic testers
0% 25% 50% 75% 100%
Equilibrium HIV prevalence
18.6% 27.5% 28.1% 29.0% 30.0% 31.4%
% of MSM with diagnosed, chronic HIV infec=on on ART
72.5% 71.4% 65.2% 55.6% 38.5% 0%
Point-‐of-‐sex tesDng and condom use
29%
20% 22% 29%
39%
27% 20%
14%
0%
10%
20%
30%
40%
50%
Very unlikely Somewhat unlikely Somewhat likely Very likely
Likelihood of condomless anal sex with a new sex partner based on how HIV status was learned
Tested together at home & both HIV-‐negaDve
Partner discloses that he is HIV-‐negaDve
Katz et al, 2012 NaDonal Summit on HIV and Viral HepaDDs Diagnosis, PrevenDon, and Access to Care
Conclusions
¨ Self-‐tesDng has potenDal to increase awareness of HIV status
¨ Most potenDal for harm when: ¤ Self-‐tests replace sensiDve clinic tests ¤ Persons with reacDve tests delay medical care
¨ Need to educate potenDal users re: confirmatory tesDng, window period, and acute infecDon
¨ AddiDonal work needed to assess harms and benefits of self-‐tesDng in real world
Future direcDons
¨ iTest Study à results summer 2015 ¤ High risk MSM ¤ Impact on tesDng frequency, risk behavior, STI tesDng
¨ Assess potenDal harms in other populaDons ¨ Incorporate assessments of harms into:
¤ Self-‐tesDng studies & programs ¤ HIV surveillance
¨ Develop methods to miDgate idenDfied harms
Acknowledgments
¨ Model co-‐authors ¤ Joanne Stekler ¤ Susan Cassels
¨ iTest Study staff ¤ Joanne Stekler (PI) ¤ Sarah McDougal ¤ Lark Ballinger ¤ BriAany Walsh ¤ Tia Farrell ¤ Genya Shimkin
Funded by NIMH R01 MH086360 Supported by UW CFAR, NIH P30 AI027757
¨ Other colleagues ¤ Bernard Branson ¤ Aditya Khanna ¤ Steven Goodreau ¤ MaAhew Golden ¤ Carey Farquhar ¤ Julie Dombrowski
ADDITIONAL SLIDES
Methods
¨ Adapted a determinisDc, conDnuous-‐Dme model of HIV transmission dynamics
¨ Parameterized using 2003 RDD of SeaAle MSM ¨ Prevalence at 100% clinic tesDng: 18.6% Window period Clinic test 15 days
Self-‐test 90 days
TesDng frequency High acDvity men 2 per year
Low acDvity men 1 per year % of men with diagnosed infecDon on ART Primary infecDon 20%
Chronic infecDon or AIDS 74%
↑ in likelihood of transmission during primary infecDon (v. chronic) 6-‐10 fold
How would replacing clinic tests with self-‐tests affect HIV prevalence? TesDng frequency
15%
17%
19%
21%
23%
25%
27%
29%
0% 20% 40% 60% 80% 100%
Equilib
rium HIV prevalence
Propor=on of popula=on tes=ng self-‐tes=ng (vs. clinic)
1
1.5
2
3
27.5%
22.4%
Fold increase in tes=ng frequency among self-‐testers
18.6%
How much would a self-‐test need to increase tesDng to maintain stable prevalence?
0%
5%
10%
15%
20%
25%
30%
1 2 3 4 5 6
Equilib
rium HIV prevalence
Fold increase in tes=ng frequency among men tes=ng at home
90
60
42
15
2.5 1.6
Window period of self-‐test 1.1
27.2% 27.5%
28.0% 28.5%
26.5%
27.0%
27.5%
28.0%
28.5%
29.0%
95%CI upper bound: 96%
Point esDmate: 92%
95%CI lower bound: 84%
75%
Equilib
rium HIV prevalence
Sensi=vity of self-‐test aWer window period
OraQuick In-‐Home HIV Test
How would replacing clinic-‐based tests with self-‐tests affect HIV prevalence? SensiDvity
How would replacing clinic tests with self-‐tests affect HIV prevalence in different populaDons?
0%
2%
4%
6%
8%
10%
12%
14%
16%
0.5; 0.5 0.5; 1 1; 1 1; 2 1; 4
Increase in HIV prevalence
Tests per year (low-‐ac=vity; high-‐ac=vity)
15
28
42
Window period of clinic test (in days)
Model flowchart
Model limitaDons
¨ Does not include MSM who test at home AND clinics ¨ Does not explicitly account for MSM who would never test at a clinic choosing to test at home
¨ Assumes tesDng occurs at random with respect to Dme of infecDon
¨ Does not address differences in receipt of test results or Dme to test results
¨ Does not address tesDng with sex partners before sex or differences in sexual behavior
¨ May not be generalizable to other seqngs and populaDons
ImplicaDons for SeaAle
¨ ConDnue focus on clinic-‐based tesDng ¨ Messaging re: home-‐use tests should:
¤ Encourage supplementaDon, not replacement ¤ Highlight limitaDons of test
¨ Explore whether home-‐use tests can be used to: ¤ Reach MSM who would not otherwise test ¤ Increase tesDng in HIV/STD partner services
ImplicaDons for other seqngs
¨ Self-‐tesDng programs should consider: ¤ Tests available in clinical or outreach seqngs ¤ TesDng coverage and frequency ¤ Rates of ART use
¤ How to ensure linkage to care ¤ PopulaDons most likely to benefit
¨ Consider whether clinic tests w/ shorter window periods or ↑ clinic tesDng may have greater impact
Future direcDons
¨ Determine how and where home-‐use tests can be used safely and effecDvely to increase: ¤ awareness of HIV status ¤ proporDon of PLWHA in care ¤ accuracy of serosorDng
¨ Future studies ¤ Impact on tesDng, risk behavior, and linkage to care ¤ Methods for miDgaDng idenDfied risks ¤ Predict impact to inform tesDng strategies