PMH4 Comparison of Risk Adjustment Methods in Predicting Health Care Expenditure among Children with Attention Deficit/Hyperactivity Disorder

Abstract

Pediatric Attention Deficit/Hyperactivity Disorder (ADHD) is associated with substantial financial burden on families, payers, and society. This study compared different risk adjustment methods in predicting health care expenditure among children with ADHD. This study used data from 2008 Medical Expenditure Panel Survey (MEPS) involving children from 5-17 years of age with ADHD. Patients with ADHD were identified using International Classification of Diseases, ninth revision, Clinical Modification (ICD-9-CM) code of '314'. Diagnosis based (D'Hoore version of Charlson comorbidity Index (CCI), Modified Elixhauser comorbidity Index (MECI) ); pharmacy based (Chronic disease score-1 (CDS-1)); and Columbia Impairment scale (CIS) were used to risk adjust total healthcare expenditures. Performance of each of the comorbidity measures was compared after adjusting for baseline factors (age, sex, race, region, metropolitan statistical area, family income, and health insurance coverage) using regression model statistics (adjusted R2). The overall prevalence of pediatric ADHD was 2.47% (n = 5.82 million). Most of the children were boys (68%), White (84%) and had private health insurance (62%). Overall mean annual expenditure was $ 4145.87. Adjusted R2 for the baseline model was 0.1130. When different comorbidity measures were added to the baseline model the adjusted R2 increased to: 0.1230 (CIS), 0.1566 (D'Hoore version of CCI), 0.1534 (MECI), and 0.1372 (CDS-1). Among different combinations, a model consisting of patient baseline characteristics, MECI, and CIS explained the most variation in healthcare expenditure (adjusted R2 = 0.1618). Models that include comorbidity and functional status measures performs best in risk adjusting health care expenditure in pediatric ADHD. There is a greater need to evaluate the use of CIS as a potential risk adjustment tool in mental and behavioral problems.