Outcomes of interest were healthcare utilization and expenditures associated with a psychiatric diagnosis incurred by Medicaid-enrolled individuals with ASD. To identify these claims, all encounter-level claims associated with a psychiatric diagnosis (ICD-9 diagnosis codes 290–319) were extracted and categorized as inpatient, outpatient, or long term care. We did not require that claims be associated with a 299 diagnosis because children with ASD may receive care associated with other disorders, either because the disorders are truly co-occurring or because they have been assigned as a way of qualifying for services. Outpatient care was categorized as one of 10 service type categories: occupational/physical therapy, speech therapy, diagnostic assessment, case management, mental health/social skills/behavior modification, medication management, personal care/home health aide, day treatment/partial hospitalization, family therapy, and respite care. A full list of specific Current Procedure Terminology (CPT) codes and corresponding service type categorization developed by the study team can be found at http://www.paautism.org/tools.html . Psychotropic medication use was defined as any medication prescription in one of five major classes: anti-depressants, anti-psychotics, anti-anxiety agents, mood-stabilizing agents, or stimulants. Use of each category of mental health service use was dichotomously coded (used/not used). Expenditures were calculated using the amount paid for each Medicaid encounter claim. Total expenditures were defined as the sum of inpatient, outpatient, long term care and psychotropic medication expenditures.
Age in years was the primary independent variable. We examined age both as a continuous and categorical variable. For the latter, we divided patients into four groups (3–6, 7–11, 12–16 and 17–20 years of age). This categorization was chosen to compare expenditures of pre-school-age, school-age and transition-age children. Demographic characteristics included gender, race/ethnicity, and state of residence. Race/ethnicity was coded as white, black or African American, Hispanic, or other. Categories of Medicaid eligibility included foster care, poverty, disability and other. As ASDs often co-occur with other medical conditions (Levy et al. 2010 (link); Peacock et al. 2012 (link)); indicators of common comorbid psychiatric and neurological diagnoses were also included. They were identified using ICD-9 codes and included schizophrenia (295), bipolar disorder (296 excluding major depressive disorder (296.2 and 296.3)), depression (311, 296.2 and 296.3), anxiety disorders (300), attention deficit hyperactivity disorder (ADHD) (314), intellectual disabilities (317–319) and seizure disorders (345).
Age in years was the primary independent variable. We examined age both as a continuous and categorical variable. For the latter, we divided patients into four groups (3–6, 7–11, 12–16 and 17–20 years of age). This categorization was chosen to compare expenditures of pre-school-age, school-age and transition-age children. Demographic characteristics included gender, race/ethnicity, and state of residence. Race/ethnicity was coded as white, black or African American, Hispanic, or other. Categories of Medicaid eligibility included foster care, poverty, disability and other. As ASDs often co-occur with other medical conditions (Levy et al. 2010 (link); Peacock et al. 2012 (link)); indicators of common comorbid psychiatric and neurological diagnoses were also included. They were identified using ICD-9 codes and included schizophrenia (295), bipolar disorder (296 excluding major depressive disorder (296.2 and 296.3)), depression (311, 296.2 and 296.3), anxiety disorders (300), attention deficit hyperactivity disorder (ADHD) (314), intellectual disabilities (317–319) and seizure disorders (345).
