The AttentionDeficit Hyperactivity Disorder Paradox: 2' Phenotypic Variability in Prevalence and Cos

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The Attention-Deficit Hyperactivity Disorder
Paradox 2. Phenotypic Variability in
Prevalence and Cost of Comorbidity

• Larry Burd, PhD Marilyn G. Klug, PhD Matthew J.
  Coumbe, PhD Jacob Kerbeshian, MD

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Abstract

• The objective of this study was to use
  population-based data to estimate the cost and
  phenotypic variation of conditions comorbid with
  attention-deficit hyperactivity disorder (ADHD).
  The case population was 7745 children. We then
  examined the 10 most frequent comorbidities for a
  defined condition from the ICD-9. The observed
  prevalence of general health conditions was 12 to
  70 less than expected. The presence of a
  comorbid condition resulted in increases in costs
  of care of 381 to 731 per case per year. The
  observed prevalence of comorbid mental health
  conditions was 97 to 5286 higher than expected.
  We identified an ADHD paradox decreased rates of
  comorbid general health conditions and increased
  rates of comorbid mental disorders. Further
  research on comorbidity in ADHD is required. (J
  Child Neurol 200318653-660).

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Study Population

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

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Inclusion Criteria Cases

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

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Inclusion Criteria Controls

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

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Limitations

• The validity of the diagnosis reported needs to
  be considered.
• These data are from a single rural state, and the
  subjects are not currently traceable across years
  or type of claims.
• The data set does not include uninsured children
  or children who did not access health care in the
  2-year period included in this study.

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Prevalence of ADHD by Age Group, Gender, and
Payer Type
ADHD attention-deficit hyperactivity disorder
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Results

• Prevalence and Base Costs of ADHD
• The prevalence of ADHD in these claims data was
  3.9 or 7,745 children (4,317 in 1996 and 3,428
  in 1997).

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Prevalence and Risk of 4 Most Common General and
Neurologic Diagnoses in Children With ADHD
Compared With Children Without ADHD (Controls)
Respiratory illness 465.xx Acute pharyngitis
462.xx ADHD attention-deficit hyperactivity
disorder AR attributable risk percentage
10
Prevalence and Risk of 4 Most Common General and
Neurologic Diagnoses in Children With ADHD
Compared With Children Without ADHD (Controls)
Vision 367.xx Suppurative otitis media 382.xx
ADHD attention-deficit hyperactivity disorder
AR attributable risk percentage
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Comorbidity With General and Neurologic Diagnosis

• Prevalence
• These data identify an important association
  between a diagnosis of ADHD and a decrease in the
  total risk of these comorbid conditions. This
  suggests the possibility of a protective effect
  from ADHD for several common illnesses.

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Comparison of Mean Costs of Common General and
Neurologic Illnesses Between Children With ADHD
and Controls (Base Cost495, Cost Attributable
to ADHD154)
ADHD attention-deficit hyperactivity disorder
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Comparison of Mean Costs of Common General and
Neurologic Illnesses Between Children With ADHD
and Controls (Base Cost495, Cost Attributable
to ADHD154)
ADHD attention-deficit hyperactivity disorder
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Costs

• The cost of care for these comorbid general
  health conditions was increased.
• The equation for the total annual cost of care
  (1133) is composed of
• Base cost of care for a control child (495)
• Cost of care attributable to ADHD (154)
• Cost of care attributable to respiratory illness
  in controls without ADHD (164)
• The cost of comorbidity (1133-495-154-164320
  ).

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Comparison of Mean Costs of Common Mental
Illnesses Between Children With ADHD and Controls
(Base Cost495, Cost Attributable to ADHD154)
ADHD attention-deficit hyperactivity disorder
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Comparison of Mean Costs of Common Mental
Illnesses Between Children With ADHD and Controls
(Base Cost495, Cost Attributable to ADHD154)
ADHD attention-deficit hyperactivity disorder
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Prevalence and Risk of 4 Most Common Mental
Diagnoses in Children With ADHD Compared With
Children Without ADHD
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
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Prevalence and Risk of 4 Most Common Mental
Diagnoses in Children With ADHD Compared With
Children Without ADHD
Bipolar 296.xx Conduct disorders 312.xx ADHD
attention-deficit hyperactivity disorder AR
attributable risk percentage
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Prevalence Comorbidity With Mental and
Neurologic Disorders

• The relative risks of a child with ADHD being
  diagnosed with an additional mental disease were
  all greater than 1, ranging from 3.2
  (nondependent drug use) to 53.4 (oppositional
  defiant disorder).
• Children with ADHD were 53 times more likely to
  have oppositional defiant disorder than controls.

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Four Disorders

• Oppositional defiant disorder, conduct disorders,
  learning disabilities, and tics
• Have an attributable risk percentage above 90
• This suggests that ADHD represents an important
  risk marker for multiple mental health disorders.

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Policy Implications Costs

• Attributable costs for mental disorders ranged
  from 204 (tic disorder) to 1262 (personality
  disorder).
• The cost of care attributable to depression in a
  control child was 566 (1061-495).
• The cost of comorbidity in children with ADHD and
  depression was 115 (1330-495-154-566115).

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Clinical Implications

• We have identified an ADHD comorbidity paradox
• This was a decrease of 12 to 70 of the expected
  number of cases.
• In contrast, there were 26 to 698 additional
  cases of vision problems, epilepsy, depression,
  oppositional defiant disorder, bipolar disorder,
  conduct disorder, adjustment disorder, anxiety
  disorder, nondependent drug use, tic disorders,
  personality disorders, epilepsy, and visual
  impairment.
• For these illnesses, the number of observed cases
  was increased by 97 to 5286 over the expected
  number