Children and Adolescents With Attention Deficit-Hyperactivity Disorder: 1. Prevalence and Cost of Care Larry Burd, PhD; Marilyn G. Klug, PhD; Matthew J. Coumbe, PhD; Jacob Kerbeshian, MD

Abstract The objective of this study was to use population-based data to estimate the prevalence and cost of treatment for attention-deficit hyperactivity disorder (ADHD). The case population was 7745, and the mean prevalence rate was 3.9%, with a peak prevalence at 10 years of age. For children with ADHD, the annual cost of care was $649 compared with that of controls at $495. Cost of care attributable to ADHD was $694 - $495 = $154 (31%). Utilization by children with ADHD with publicly funded payers was increased 25 to 175% over that of children with privately funded coverage. In North Dakota, the annual cost of care for children with ADHD was $5.1 million, 5.6% of all health care costs for children. The annual attributable cost of care was $1.79 million. Thus, 1.9% of total health expenditures for children was attributable to ADHD. In the United States, the cost of care attributable to children with ADHD would be $2.15 billion annually. (J Child Neurol 2003;18: ). The objective of this study was to use population-based data to estimate the prevalence and cost of treatment for attention-deficit hyperactivity disorder (ADHD). The case population was 7745, and the mean prevalence rate was 3.9%, with a peak prevalence at 10 years of age. For children with ADHD, the annual cost of care was $649 compared with that of controls at $495. Cost of care attributable to ADHD was $694 - $495 = $154 (31%). Utilization by children with ADHD with publicly funded payers was increased 25 to 175% over that of children with privately funded coverage. In North Dakota, the annual cost of care for children with ADHD was $5.1 million, 5.6% of all health care costs for children. The annual attributable cost of care was $1.79 million. Thus, 1.9% of total health expenditures for children was attributable to ADHD. In the United States, the cost of care attributable to children with ADHD would be $2.15 billion annually. (J Child Neurol 2003;18: ).

Current Study In this study, we used the health claims data from the North Dakota Department of Health, to determine: 1)the administrative prevalence of ADHD in the state of North Dakota 2) differences in cost of care for children and adolescents with ADHD compared with the subjects who do not have ADHD, and 3)differences in prevalence and cost by payer type (private coverage or publicly funded health insurance).

Inclusion Criteria: Cases Patients were included in the study as cases with ADHD if at any timed during either year they had an Internal Classification of Diseases, 9 th edition (ICD-9), code of or (attention-deficit disorder not otherwise specified), (inattention type), (with hyperactivity/impulsiveness), or (with other specific manifestations). The code (attention-deficit hyperactivity disorder not otherwise specified) was also included to capture cases from the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV). This is the coding strategy used to specify children with a diagnosis of ADHD in the DSM-IV. If the codes (314.xx) were identified in any order in the diagnostic formulation in the database at any time during the year, the subject was classified as a case. Patients were included in the study as cases with ADHD if at any timed during either year they had an Internal Classification of Diseases, 9 th edition (ICD-9), code of or (attention-deficit disorder not otherwise specified), (inattention type), (with hyperactivity/impulsiveness), or (with other specific manifestations). The code (attention-deficit hyperactivity disorder not otherwise specified) was also included to capture cases from the Diagnostic and Statistical Manual of Mental Disorders-IV (DSM-IV). This is the coding strategy used to specify children with a diagnosis of ADHD in the DSM-IV. If the codes (314.xx) were identified in any order in the diagnostic formulation in the database at any time during the year, the subject was classified as a case.

Inclusion Criteria:Controls The controls were all remaining subjects 0 to 21 years of age in the database who did not have an ICD-9 code of , , or or the DSM-IV code in their diagnostic formulation. The controls were all remaining subjects 0 to 21 years of age in the database who did not have an ICD-9 code of , , or or the DSM-IV code in their diagnostic formulation. In this sample, we had 24.5 controls for each case. In this sample, we had 24.5 controls for each case.

Limitations The data are from North Dakota, a small rural state with a total population in 1997 of 650,000. The data for this study are health care claims data and might reflect coding error or bias. The data are from North Dakota, a small rural state with a total population in 1997 of 650,000. The data for this study are health care claims data and might reflect coding error or bias. Two significant populations not represented in these data were uninsured children and the Native American population. Two significant populations not represented in these data were uninsured children and the Native American population.

Calculation of Costs Two types of costs were defined: base cost and attributable cost. The base cost was the cost a control child generated on average during the year. Attributable costs were costs added to the base cost for a specific illness. The cost and group (ADHD or control) interactions were examined by a linear equation with two cost elements. This database does not include the cost of medication. Two types of costs were defined: base cost and attributable cost. The base cost was the cost a control child generated on average during the year. Attributable costs were costs added to the base cost for a specific illness. The cost and group (ADHD or control) interactions were examined by a linear equation with two cost elements. This database does not include the cost of medication.

Graph of prevalence by age and gender (male, female, and total group).

Graph of prevalence rate in percentage by age of cohort and payer type (public, private, or total group).

Comparison of Mean ( ) Costs Between Children With ADHD and Without (Controls) by Payment Method HCFA AnnualMean Mean Cost per NCostVisit Total98,991 ADHD ADHD3872$648.55*$158.59* Controls Controls95,119$494.53$ Private80,819 ADHD ADHD2801$568.79*$155.79* Controls Controls78,018$503.11$ Public18,172 ADHD ADHD1071$856.03*$166.37* Controls Controls17,101$480.07$ *Mean costs of children with ADHD significantly higher than those of controls (P<.01) ADHD = attention-deficit hyperactivity disorder; HFCA = Health Care Financing Administration

Comparison of Mean ( ) Costs Between Children With ADHD and Without (Controls) by Gender HFCA AnnualMean Mean Cost per NCostVisit Male48,760 ADHD ADHD2908$612.36*$ Controls Controls45,852$491.81$ Female50,231 ADHD ADHD964$757.92*$163.66* Controls Controls49,267$497.12$ *Mean costs of children with ADHD significantly higher than those of controls (P<.01) ADHD = attention-deficit hyperactivity disorder; HFCA = Health Care Financing Administration

Comparison of Mean ( ) Costs Between Children With ADHD and Without (Controls) by Payment Method InpatientOutpatient AnnualMeanAnnualMean Mean Cost per Mean CostVisitNCostVisit Total25,553 ADHD ADHD$ *$ *613$ $577.98* Controls Controls$ $ ,920$644.29$ Private11,872 ADHD ADHD$ $ $ *$879.29* Controls Controls$ $ ,730$766.21$ Public13,661 ADHD ADHD$ $ $ *$497.48* Controls Controls$ $ ,190$553.78$ *Mean cost of children with ADHD significantly higher than those of controls (P<.01) ADHD = attention-deficit hyperactivity disorder; HFCA = Health Care Financing Administration

Comparison of Mean ( ) Costs Between Children With ADHD and Without (Controls) by Gender Inpatient Outpatien t AnnualMeanAnnualMean Mean Cost per Mean CostVisitNCostVisit Male12,617 ADHD ADHD$ $ $ *$ Controls Controls$ $ ,149$642.20$ Female12,916 ADHD ADHD$ *$ *145$ *$ Controls Controls$ $ ,771$646.30$ *Mean cost of children with ADHD significantly higher than those of controls (P<.01) ADHD = attention-deficit hyperactivity disorder; HFCA = Health Care Financing Administration

Results The prevalence of ADHD increases slowly from birth until 2 years of age, when the prevalence is 0.3%. From 3 through 10 years of age, the prevalence has a mean increase of 1.1% per year. Prevalence peaks at 10.3% at 10 years of age and then decreases at a mean rate of about 1.0% per year until 18 years of age. After 18 years of age, ADHD is diagnosed in 2% of the population. The prevalence of ADHD increases slowly from birth until 2 years of age, when the prevalence is 0.3%. From 3 through 10 years of age, the prevalence has a mean increase of 1.1% per year. Prevalence peaks at 10.3% at 10 years of age and then decreases at a mean rate of about 1.0% per year until 18 years of age. After 18 years of age, ADHD is diagnosed in 2% of the population.

Mean Cost Comparisons The mean annual cost of care for children with ADHD in the Health Care Financing Administration data was $649 per case or 31% more than controls. The annual cost of attributable to ADHD was $154 ($649- $495) per case. The mean annual cost of care for children with ADHD in the Health Care Financing Administration data was $649 per case or 31% more than controls. The annual cost of attributable to ADHD was $154 ($649- $495) per case.

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Payment Type HCFA Number N% Of Visits % Total98,991337,141 ADHD ADHD ,7794.1* Controls Controls95, , Private80,819274,389 ADHD ADHD Controls Controls78, , Public18,17262,752 ADHD ADHD * Controls Controls17, , *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Gender HFCA Number N% Of Visits % Male48,760159,364 ADHD ADHD Controls Controls45, , Female50,231177,777 ADHD ADHD Controls Controls49, , *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Payment Type Inpatient Number N% Of Visits % Total ADHD ADHD * Controls Controls Private ADHD ADHD Controls Controls Public ADHD ADHD * Controls Controls *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Gender Inpatient Number N% Of Visits % Male ADHD ADHD * Controls Controls Female ADHD ADHD Controls Controls *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Payment Type Outpatient Number N% Of Visits % Total25,53367,088 ADHD ADHD * Controls Controls24, , Private11,87220,370 ADHD ADHD Controls Controls11, , Public13,66146,718 ADHD ADHD * Controls Controls13, , *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Proportion of Mean ( ) Annual Number of Visits Between Children With ADHD and Without (Controls) by Gender Outpatient Number N% Of Visits % Male12,61731,811 ADHD ADHD * Controls Controls12, , Female12,91635,277 ADHD ADHD * Controls Controls12, , *Significant increase in proportion of number of visits for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Inpatient Data For inpatient data, the mean annual cost of care for children with ADHD was $8861 or 60% more than controls, with an attributable cost of $3332 ($8861-$5529). For inpatient data, the mean annual cost of care for children with ADHD was $8861 or 60% more than controls, with an attributable cost of $3332 ($8861-$5529).

Outpatient Data For outpatient data, the mean annual cost of care for children with ADHD was $1597. This produced an attributable mean annual cost of care for ADHD of $953 ($1592- $644), which was 148% greater than the cost for controls. For outpatient data, the mean annual cost of care for children with ADHD was $1597. This produced an attributable mean annual cost of care for ADHD of $953 ($1592- $644), which was 148% greater than the cost for controls.

Public Payer Type Annual mean costs for children with ADHD with public payers in the Health Care Financing Administration data set were 78% higher than controls and 59% and 176% higher than controls in the inpatients and outpatient data sets, respectively. Annual mean costs for children with ADHD with public payers in the Health Care Financing Administration data set were 78% higher than controls and 59% and 176% higher than controls in the inpatients and outpatient data sets, respectively.

Private Payer Type Annual mean costs for children with ADHD in the inpatients data set were 10% higher for those with private payers and 19% higher in the outpatients data set. In the Health Care Financing Administration data sat, children with ADHD with public payers had higher annual mean costs and mean costs per visit. Annual mean costs for children with ADHD in the inpatients data set were 10% higher for those with private payers and 19% higher in the outpatients data set. In the Health Care Financing Administration data sat, children with ADHD with public payers had higher annual mean costs and mean costs per visit.

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups HCFA N%Cost% Total98,991$48,359,948 ADHD ADHD $2,546,0245.3* Controls Controls95, $45,813, Private80,819$39,072,153 ADHD ADHD $1,609,5334.1* Controls Controls78, $37,462, Public18,172$9,287,796 ADHD ADHD $936, * Controls Controls17, $8,351, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups HCFA N%Cost% Male48,760$23,700,450 ADHD ADHD $1,803,3457.6* Controls Controls45, $21,897, Female50,231$24,659,498 ADHD ADHD9641.9$742,6793.0* Controls Controls49, $23,916, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups Inpatient N%Cost% Total4614$25,912,447 ADHD ADHD1834.0$1,628,1276.3* Controls Controls $24,284, Private2012$11,203,147 ADHD ADHD402.0$367,6483.3* Controls Controls $10,835, Public2602$14,709,301 ADHD ADHD1435.5$1,260,4798.6* Controls Controls $13,448, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups Inpatient N%Cost% Male1959$13,337,729 ADHD ADHD1346.8$1,233,7509.2* Controls Controls $12,143, Female2655$12,534,718 ADHD ADHD491.8$394, Controls Controls $12,140, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups Outpatient N%Cost% Total25,533$17,050,071 ADHD ADHD6132.4$991,1525.8* Controls Controls24, $16,058, Private11,872$8,941,555 ADHD ADHD1421.2$256,9922.9* Controls Controls11, $8,684, Public13,661$8,108,516 ADHD ADHD4713.4$734,1609.1* Controls Controls13, $7,374, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder

Comparison of Mean ( ) Total Annual Costs Between Children With ADHD and Without (Controls) by Payment Method, Gender, and Age Groups Outpatient N%Cost% Male12,617$8,493,406 ADHD ADHD4683.7$699,2538.2* Controls Controls12, $7,794, Female12,916$8,556,554 ADHD ADHD1451.1$291,8983.4* Controls Controls12, $8,264, *Significant increase in proportion of total cost for children with ADHD compared with proportion of children with ADHD in the sample (P<.01) ADHD = attention-deficit hyperactivity disorder

Comparisons of Number of Visits The proportion of the number of visits of children with ADHD to the total number of visits in the Health Care Financing Administration data set is 4.1%, 5.9% in the inpatients data, and 4.3% in the outpatient data. These proportions are significantly greater (P<.01) than the proportion of children with ADHD in the corresponding data set. The proportion of the number of visits of children with ADHD to the total number of visits in the Health Care Financing Administration data set is 4.1%, 5.9% in the inpatients data, and 4.3% in the outpatient data. These proportions are significantly greater (P<.01) than the proportion of children with ADHD in the corresponding data set.

Comparisons of Total Cost Table 3 shows that children with ADHD accumulated costs totaling $2,546,024 + $1,618,127 + $991,152 = $5,155,303 per year on average during 1996 and Children with ADHD used 5.6% of the $91,322,466 total cost incurred by all children in the three data sets. Table 3 shows that children with ADHD accumulated costs totaling $2,546,024 + $1,618,127 + $991,152 = $5,155,303 per year on average during 1996 and Children with ADHD used 5.6% of the $91,322,466 total cost incurred by all children in the three data sets.

Mean Attributable Cost of Health Care to Children With ADHD in North Dakota for 1996 and 1997 by HCFA Dataset HFCA HFCA PayerGroupNMeanAttributableCostTotalAttributableCost Private2801$66$184,866 Public1071$376$402,969 Total3872$154$591,668 ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Mean Attributable Cost of Health Care to Children With ADHD in North Dakota for 1996 and 1997 by Inpatient Dataset Inpatient PayerGroupnMeanAttributableCostTotalAttributableCost Private40$3888$155,420 Public143$3249$464,607 Total183$3332$609,756 ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Mean Attributable Cost of Health Care to Children With ADHD in North Dakota for 1996 and 1997 by Outpatient Dataset Outpatient PayerGroupNMeanAttributableCostTotalAttributableCost Private142$1049$148,958 Public471$974$458,754 Total613$1049$584,189 ADHD = attention-deficit hyperactivity disorder; HCFA = Health Care Financing Administration

Policy Implications The total mean annual cost of care attributable to ADHD in North Dakota in 1996 and 1997 was $1.79 million. The total mean annual cost of care attributable to ADHD in North Dakota in 1996 and 1997 was $1.79 million.

Policy Implications For children with private coverage, the attributable cost of $489,344 was 27.4% of all health care costs attributable to AHDS. For children with private coverage, the attributable cost of $489,344 was 27.4% of all health care costs attributable to AHDS.

Policy Implications The attributable cost of care for children with publicly funded care was $1,326,057 or 74.3% of the total attributable costs of care attributable to ADHD in North Dakota (see Table 4). This was 1.5% of the total cost of care for all of the children in the dataset. The attributable cost of care for children with publicly funded care was $1,326,057 or 74.3% of the total attributable costs of care attributable to ADHD in North Dakota (see Table 4). This was 1.5% of the total cost of care for all of the children in the dataset.

Policy Implications Utilization measured by the number of visits per year for children in the Health Care Financing Administration data set was 3.1 visits per year for private payers versus 4.7 for public payers. Utilization measured by the number of visits per year for children in the Health Care Financing Administration data set was 3.1 visits per year for private payers versus 4.7 for public payers.

Policy Implications In 1997, the United States population of 85,091,200 children with a 3.9% prevalence rate for ADHD would produce a total population of 3,318,557 children with ADHD. The total annual cost of care would be $2.15 billion at an annual cost of $649 per child. This result is similar to the estimates from Chan of an annual cost of care of $2.5 billion. The attributable cost of care for ADHD was $154 per case for an annual cost of care of $511,000 in North Dakota. In 1997, the United States population of 85,091,200 children with a 3.9% prevalence rate for ADHD would produce a total population of 3,318,557 children with ADHD. The total annual cost of care would be $2.15 billion at an annual cost of $649 per child. This result is similar to the estimates from Chan of an annual cost of care of $2.5 billion. The attributable cost of care for ADHD was $154 per case for an annual cost of care of $511,000 in North Dakota.