198656 Impact of classification methods when using Medicaid claims for mental health services research

Tuesday, November 10, 2009: 3:30 PM

Elizabeth L. Noll, MA , Center for Mental Health Policy and Services Research, University of Pennsylvania, Philadelphia, PA
Aileen Rothbard, ScD , Center for Mental Health Policy and Services Research, University of Pennsylvania, Philadelphia, PA
Cathy Bolton, PhD , Community Behavioral Health, Philadelphia Department of Behavioral Health & Intellectual Disabilities Services, Philadelphia, PA
Objective: Medicaid claims data are increasingly used for planning purposes to estimate treated prevalence of mental disorders in public sector mental health systems and to identify cohorts for mental health services research. This study investigates how different methods of estimation and identification affect case classification, prevalence rates and service cost estimates when individuals have multiple diagnoses over a study period. Methods: A cross-sectional, observational analysis of 224,654 adult Medicaid recipients in a managed care behavioral health plan was employed to identify treated individuals from 2005 claims records. ICD-9 diagnostic codes were used to classify individuals. Four classification methods were used to assign individuals to diagnostic categories of schizophrenia, major depressive disorder, bipolar disorder and other mental health disorders. Treated prevalence rates for all diagnostic categories were compared as were inpatient and emergency room costs. Results: Diagnostic group classification and cost estimates varied depending on the classification method employed. Annual treated prevalence for a mental disorder ranged from 14% to 22% of the Medicaid population. Identification of individuals with schizophrenia ranged from 2.6% to 4% depending on the method. Inpatient and emergency room costs were also affected by the method used. Conclusions: Methods chosen for identifying cohorts for mental health services research from Medicaid claims data will affect overall and diagnosis-specific treated prevalence rates and cost estimates. Researchers should be aware of the ways in which different methods of selecting cohorts may affect their findings and should make their classification procedure explicit to enhance the correct interpretation of results.

Learning Objectives:
Demonstrate the way in which methods used for classifying diagnostic cohorts from Medicaid claims data impacts treated prevalence rates and mental health services cost estimates.

Keywords: Mental Health Services, Methodology

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I have been involved in public sector research endeavors for over 15 years in the capacities of research specialist and data analyst. I have been working exclusively in mental health services research for the past five years. My work has appeared in the Journal of the American Medical Association, Evaluation Review, Preventive Medicine and Educational Psychologist among others. I am currently a candidate for PhD in Social Welfare at the University of Pennsylvania.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.