the attention-deficit hyperactivity disorder paradox: 2. phenotypic variability in prevalence and...

22
The Attention-Deficit Hyperactivity Disorder Paradox: 2. Phenotypic Variability in Prevalence and Cost of Comorbidity Larry Burd, PhD; Marilyn Larry Burd, PhD; Marilyn G. Klug, PhD; Matthew J. G. Klug, PhD; Matthew J. Coumbe, PhD; Jacob Coumbe, PhD; Jacob Kerbeshian, MD Kerbeshian, MD

Upload: clare-ford

Post on 18-Dec-2015

219 views

Category:

Documents


1 download

TRANSCRIPT

The Attention-Deficit Hyperactivity Disorder

Paradox: 2. Phenotypic Variability in Prevalence and Cost of

Comorbidity

Larry Burd, PhD; Marilyn G. Klug, Larry Burd, PhD; Marilyn G. Klug, PhD; Matthew J. Coumbe, PhD; PhD; Matthew J. Coumbe, PhD;

Jacob Kerbeshian, MDJacob Kerbeshian, MD

Abstract The objective of this study was to use population-based data to The objective of this study was to use population-based data to

estimate the cost and phenotypic variation of conditions comorbid estimate the cost and phenotypic variation of conditions comorbid with attention-deficit hyperactivity disorder (ADHD). The case with attention-deficit hyperactivity disorder (ADHD). The case population was 7745 children. We then examined the 10 most population was 7745 children. We then examined the 10 most frequent comorbidities for a defined condition from the ICD-9. frequent comorbidities for a defined condition from the ICD-9. The observed prevalence of general health conditions was 12 to The observed prevalence of general health conditions was 12 to 70% less than expected. The presence of a comorbid condition 70% less than expected. The presence of a comorbid condition resulted in increases in costs of care of $381 to $731 per case per resulted in increases in costs of care of $381 to $731 per case per year. The observed prevalence of comorbid mental health year. The observed prevalence of comorbid mental health conditions was 97 to 5286% higher than expected. We identified conditions was 97 to 5286% higher than expected. We identified an ADHD paradox: decreased rates of comorbid general health an ADHD paradox: decreased rates of comorbid general health conditions and increased rates of comorbid mental disorders. conditions and increased rates of comorbid mental disorders. Further research on comorbidity in ADHD is required. (Further research on comorbidity in ADHD is required. (J Child J Child NeurolNeurol 2003;18:653-660). 2003;18:653-660).

Study Population

The original data set consisted of 1,509,980 visits The original data set consisted of 1,509,980 visits made by children ages 0 to 21 years in North made by children ages 0 to 21 years in North Dakota in 1996 and 1997. This included both Dakota in 1996 and 1997. This included both inpatient and outpatient visits. For the 2 years inpatient and outpatient visits. For the 2 years combined, a total of 1,473,611 visits were combined, a total of 1,473,611 visits were included in this analysis. This represented included in this analysis. This represented (averaged over 1996 and 1997) visits made by (averaged over 1996 and 1997) visits made by 197,983 uniquely identified children (88,702 in 197,983 uniquely identified children (88,702 in 1996 and 109,281 in 1997).1996 and 109,281 in 1997).

Inclusion Criteria: Cases Patients were included in the study as cases with Patients were included in the study as cases with

ADHD if at any time during either year they had an ADHD if at any time during either year they had an International Classification of Diseases,International Classification of Diseases, 9 9thth edition edition (ICD-9), code of 314.00 or (attention-deficit disorder (ICD-9), code of 314.00 or (attention-deficit disorder not otherwise specified), 314.00 or (inattentive type), not otherwise specified), 314.00 or (inattentive type), 314.01 (with hyperactivity/impulsiveness), or 314.8 314.01 (with hyperactivity/impulsiveness), or 314.8 (with other specific manifestations). The code 314.9 (with other specific manifestations). The code 314.9 (attention-deficit hyperactivity disorder not (attention-deficit hyperactivity disorder not otherwise specified) was also included to capture otherwise specified) was also included to capture cases from the cases from the Diagnostic and Statistical Manual of Diagnostic and Statistical Manual of Mental Diseases-IV Mental Diseases-IV (DSM-IV).(DSM-IV).

Inclusion Criteria: Controls

The control population consisted of all The control population consisted of all remaining subjects in the database who did remaining subjects in the database who did not have an ICD-9 code of 314.00, 314.01, not have an ICD-9 code of 314.00, 314.01, or 314.8 or the DSM-IV code of 314.9 in or 314.8 or the DSM-IV code of 314.9 in their diagnostic formulation at any time their diagnostic formulation at any time during the 2-year span of the study. There during the 2-year span of the study. There were 24.5 controls per case in this study.were 24.5 controls per case in this study.

Limitations

The validity of the diagnosis reported needs to be The validity of the diagnosis reported needs to be considered.considered. These data are from a single rural state, and the These data are from a single rural state, and the

subjects are not currently traceable across years subjects are not currently traceable across years or type of claims.or type of claims.

The data set does not include uninsured The data set does not include uninsured children or children who did not access health children or children who did not access health care in the 2-year period included in this study.care in the 2-year period included in this study.

Prevalence of ADHD by Age Group, Gender, and Payer Type

19961996 19971997 MeanMean

N (%)N (%) N (%)N (%) N (%)N (%)

Age GroupAge Group

Infant to 5 yrInfant to 5 yr 334 (1.2)334 (1.2) 190 (0.6)190 (0.6) 262 (0.9)262 (0.9)

6 to 13 yr6 to 13 yr 2952 (10.8)2952 (10.8) 2387 (6.7)2387 (6.7) 2669 (8.7)2669 (8.7)

14 to 21 yr14 to 21 yr 1031 (3.1)1031 (3.1) 851 (2.1)851 (2.1) 941 (2.6)941 (2.6)

GenderGender

MaleMale 3247 (7.5)3247 (7.5) 2570 (4.8)2570 (4.8) 2908 (6.1)2908 (6.1)

FemaleFemale 1070 (2.4)1070 (2.4) 858 (1.6)858 (1.6) 964 (2.0)964 (2.0)

Payer TypePayer Type

PublicPublic 1233 (5.8)1233 (5.8) 909 (6.0)909 (6.0) 1071 (5.9)1071 (5.9)

PrivatePrivate 3084 (4.6)3084 (4.6) 2519 (2.7)2519 (2.7) 2801 (3.6)2801 (3.6)ADHD = attention-deficit hyperactivity disorder

Results

Prevalence and Base Costs of ADHDPrevalence and Base Costs of ADHD The prevalence of ADHD in these claims The prevalence of ADHD in these claims

data was 3.9% or 7,745 children (4,317 in data was 3.9% or 7,745 children (4,317 in 1996 and 3,428 in 1997).1996 and 3,428 in 1997).

Prevalence and Risk of 4 Most Common General and Neurologic Diagnoses in Children With ADHD Compared

With Children Without ADHD (Controls)ObservedObserved ExpectedExpected AddedAdded

DiagnosisDiagnosis N (%)N (%) NN CasesCases AR%AR%

Respiratory illnessRespiratory illness

19961996 ADHDADHD

ControlControl

312 (7.2)312 (7.2)

18,672 (22.1)18,672 (22.1)

955955 -643-643 -206.2-206.2

19971997 ADHDADHD

ControlControl

267 (7.8)267 (7.8)

19,513 (18.4)19,513 (18.4)

632632 -365-365 -136.7-136.7

Acute pharyngitisAcute pharyngitis

19961996 ADHDADHD

ControlControl

271 (6.3)271 (6.3)

16,422 (19.5)16,422 (19.5)

840840 -569-569 -210.0-210.0

19971997 ADHD ADHD

ControlControl

318 (9.3)318 (9.3)

17,374 (16.4)17,374 (16.4)

563563 -245-245 -76.9-76.9

Respiratory illness: 465.xx; Acute pharyngitis: 462.xx

ADHD = attention-deficit hyperactivity disorder; AR% = attributable risk percentage

Prevalence and Risk of 4 Most Common General and Neurologic Diagnoses in Children With ADHD Compared

With Children Without ADHD (Controls)

ObservedObserved ExpectedExpected AddedAdded

DiagnosisDiagnosis N (%)N (%) NN CasesCases AR%AR%

VisionVision

1996 1996 ADHD ADHD

ControlControl

368 (8.5)368 (8.5)

5146 (6.1)5146 (6.1)

263263 105105 28.528.5

19971997 ADHD ADHD

ControlControl

181 (5.3)181 (5.3)

30,006 (2.8)30,006 (2.8)

9797 8484 46.246.2

Suppurative otitis mediaSuppurative otitis media

19961996 ADHD ADHD

ControlControl

259 (6.0)259 (6.0)

15,717 (18.6)15,717 (18.6)

804804 -545-545 -210.4-210.4

19971997 ADHD ADHD

ControlControl

235 (6.9)235 (6.9)

16,449 (15.5)16,449 (15.5)

533533 -298-298 -126.7-126.7

Vision: 367.xx; Suppurative otitis media: 382.xx

ADHD = attention-deficit hyperactivity disorder; AR% = attributable risk percentage

Comorbidity With General and Neurologic Diagnosis

PrevalencePrevalence These data identify an important These data identify an important

association between a diagnosis of association between a diagnosis of ADHD and a decrease in the total risk of ADHD and a decrease in the total risk of these comorbid conditions. This suggests these comorbid conditions. This suggests the possibility of a protective effect from the possibility of a protective effect from ADHD for several common illnesses.ADHD for several common illnesses.

Comparison of Mean Costs of Common General and Neurologic Illnesses Between Children With ADHD and Controls (Base Cost=$495, Cost Attributable to

ADHD=$154)

Mean Cost per Mean Cost per Year ($)Year ($)

ADHDADHD ControlControl

Mean CostMean Cost

Attributable ($)Attributable ($)

Mean Cost ofMean Cost of

Comorbidity ($)Comorbidity ($)

Respiratory illnessRespiratory illness

19961996

19971997

AverageAverage

14291429

837837

11331133

831831

488488

659659

222222

108108

164164

481481

159159

320320

Acute pharyngitisAcute pharyngitis

19961996

19971997

AverageAverage

13851385

789789

10871087

792792

445445

618618

183183

6565

123123

476476

153153

315315

ADHD = attention-deficit hyperactivity disorder

Comparison of Mean Costs of Common General and Neurologic Illnesses Between Children With ADHD and

Controls (Base Cost=$495, Cost Attributable to ADHD=$154)

Mean Cost perMean Cost per Year ($)Year ($)

ADHDADHD ControlControl

Mean CostMean Cost

Attributable Attributable ($)($)

Mean Cost ofMean Cost of

Comorbidity Comorbidity ($)($)

VisonVison

19961996

19971997

AverageAverage

10601060

940940

10001000

589589

402402

495495

-20-20

2222

11

354354

348348

351351

Suppurative otitis mediaSuppurative otitis media

19961996

19971997

AverageAverage

14501450

887887

11681168

838838

504504

671671

229229

124124

176176

494494

193193

343343

ADHD = attention-deficit hyperactivity disorder

Costs

The cost of care for these comorbid general health The cost of care for these comorbid general health conditions was increased.conditions was increased.

The equation for the total annual cost of care ($1133) is The equation for the total annual cost of care ($1133) is composed of:composed of: Base cost of care for a control child ($495)Base cost of care for a control child ($495) Cost of care attributable to ADHD ($154)Cost of care attributable to ADHD ($154) Cost of care attributable to respiratory illness in Cost of care attributable to respiratory illness in

controls without ADHD ($164)controls without ADHD ($164) The cost of comorbidity ($1133-$495-$154-The cost of comorbidity ($1133-$495-$154-

$164=$320).$164=$320).

Comparison of Mean Costs of Common Mental Illnesses Between Children With ADHD and Controls (Base Cost=$495, Cost Attributable to ADHD=$154)

Mean Cost Mean Cost perper

Year (%)Year (%)

ADHDADHD ControlControl

Mean CostMean Cost

Attributable (%)Attributable (%)

Mean Cost of Mean Cost of Comorbidity (%)Comorbidity (%)

DepressionDepression

19961996 15191519 10811081 586586 321321

19971997 11421142 10421042 547547 -91-91

AverageAverage 13301330 10611061 566566 115115

Oppositional Oppositional defiant disorderdefiant disorder

19961996 16641664 13661366 871871 181181

19971997 12391239 11481148 653653 -100-100

AverageAverage 14511451 12571257 762762 4040

ADHD = attention-deficit hyperactivity disorder

Comparison of Mean Costs of Common Mental Illnesses Between Children With ADHD and Controls (Base

Cost=$495, Cost Attributable to ADHD=$154)

Mean Cost Mean Cost perper

Year (%)Year (%)

ADHDADHD ControlControl

Mean CostMean Cost

Attributable (%)Attributable (%)

Mean Cost ofMean Cost of

Comorbidity (%)Comorbidity (%)

BipolarBipolar

19961996 19911991 13821382 887887 492492

19971997 14751475 12701270 775775 1515

AverageAverage 17331733 13261326 831831 253253

Conduct disordersConduct disorders

19961996 18511851 12791279 784784 454454

19971997 13021302 11401140 645645 -28-28

AverageAverage 15761576 12091209 714714 213213

ADHD = attention-deficit hyperactivity disorder

Prevalence and Risk of 4 Most Common Mental Diagnoses in Children With ADHD Compared With Children Without ADHD

DiagnosesDiagnoses

ObservedObserved

N (%)N (%)

ExpectedExpected

NN

AddedAdded

CasesCases AR%AR%

DepressionDepression

19961996 ADHDADHD

ControlControl

836 (19.4)836 (19.4)

2690 (3.2)2690 (3.2)

138138 698698 83.583.5

19971997 ADHDADHD

ControlControl

655 (19.1)655 (19.1)

2139 (2.0)2139 (2.0)

6969 586586 89.489.4

Oppositional Oppositional defiant disorderdefiant disorder

19961996 ADHDADHD

ControlControl

493 (11.4)493 (11.4)

316 (0.4)316 (0.4)

1616 477477 96.796.7

19971997 ADHDADHD

ControlControl

377 (11.0)377 (11.0)

218 (0.2)218 (0.2)

77 370370 98.198.1

Depression: 293.83, 296.2x, 296.3x, 296.5x, 296.82, 298.0x, 300.4x, 301.12, 309.0x, 309.1x, 309.28, 311.xx, and 313.1x; Oppositional defiant disorder: 3131.81

ADHD = attention-deficit hyperactivity disorder; AR%= attributable risk percentage

Prevalence and Risk of 4 Most Common Mental Diagnoses in Children With ADHD Compared With Children Without ADHD

DiagnosesDiagnoses

ObservedObserved

N (%)N (%)

ExpectedExpected

NN

AddedAdded

CasesCases AR%AR%

BipolarBipolar

19961996 ADHDADHD

ControlControl

363 (8.4)363 (8.4)

1148 (1.4)1148 (1.4)

5959 304304 83.883.8

19971997 ADHDADHD

ControlControl

270 (7.9)270 (7.9)

909 (0.9)909 (0.9)

2929 241241 89.189.1

Conduct disordersConduct disorders

19961996 ADHDADHD

ControlControl

329 (7.6)329 (7.6)

437 (0.5)437 (0.5)

2222 307307 93.293.2

19971997 ADHDADHD

ControlControl

198 (5.8)198 (5.8)

305 (0.3)305 (0.3)

1010 188188 95.095.0

Bipolar: 296.xx; Conduct disorders: 312.xx

ADHD = attention-deficit hyperactivity disorder; AR% = attributable risk percentage

Prevalence: Comorbidity With Mental and Neurologic Disorders

The relative risks of a child with ADHD being The relative risks of a child with ADHD being diagnosed with an additional mental disease diagnosed with an additional mental disease were all greater than 1, ranging from 3.2 were all greater than 1, ranging from 3.2 (nondependent drug use) to 53.4 (oppositional (nondependent drug use) to 53.4 (oppositional defiant disorder). defiant disorder).

Children with ADHD were 53 times more Children with ADHD were 53 times more likely to have oppositional defiant disorder likely to have oppositional defiant disorder than controls.than controls.

Four Disorders

Oppositional defiant disorder, conduct Oppositional defiant disorder, conduct disorders, learning disabilities, and ticsdisorders, learning disabilities, and tics Have an attributable risk percentage Have an attributable risk percentage

above 90%above 90% This suggests that ADHD represents an This suggests that ADHD represents an

important risk marker for multiple mental important risk marker for multiple mental health disorders.health disorders.

Policy Implications: Costs Attributable costs for mental disorders Attributable costs for mental disorders

ranged from $204 (tic disorder) to $1262 ranged from $204 (tic disorder) to $1262 (personality disorder).(personality disorder).

The cost of care attributable to depression The cost of care attributable to depression in a control child was $566 ($1061-$495).in a control child was $566 ($1061-$495).

The cost of comorbidity in children with The cost of comorbidity in children with ADHD and depression was $115 ($1330-ADHD and depression was $115 ($1330-$495-$154-$566=$115).$495-$154-$566=$115).

Clinical Implications

We have identified an ADHD comorbidity paradoxWe have identified an ADHD comorbidity paradox This was a decrease of 12 to 70% of the expected number This was a decrease of 12 to 70% of the expected number

of cases.of cases. In contrast, there were 26 to 698 additional cases of vision In contrast, there were 26 to 698 additional cases of vision

problems, epilepsy, depression, oppositional defiant problems, epilepsy, depression, oppositional defiant disorder, bipolar disorder, conduct disorder, adjustment disorder, bipolar disorder, conduct disorder, adjustment disorder, anxiety disorder, nondependent drug use, tic disorder, anxiety disorder, nondependent drug use, tic disorders, personality disorders, epilepsy, and visual disorders, personality disorders, epilepsy, and visual impairment.impairment.

For these illnesses, the number of observed cases was For these illnesses, the number of observed cases was increased by 97 to 5286% over the expected numberincreased by 97 to 5286% over the expected number