Health Services Research & Development

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2006 HSR&D National Meeting Abstract


3097 — Effects of Increased Copayment on Antidepressant Prescription Fill Rates in VA Patients

Author List:
Zimmer MP (Houston Center for Quality of Care and Utilization Studies, Houston VA Medical Center)
Petersen LA (Houston Center for Quality of Care and Utilization Studies, Houston VA Medical Center)
Kuebeler M (Houston Center for Quality of Care and Utilization Studies, Houston VA Medical Center)
Cully JA (Houston Center for Quality of Care and Utilization Studies, Houston VA Medical Center)

Objectives:
Depression affects 20-25% of elderly veterans and profoundly impacts healthcare outcomes and quality of life. Yet, depression is significantly under-diagnosed and under-treated. Barriers to adequate depression care include patient, physician, and system factors. The 2002 Veterans Health Care Act increased pharmacy copayments for some veterans. We examined the impact of the increased copayment on antidepressant medication use for veterans with depression.

Methods:
We studied veterans with an ICD-9 diagnosis of depression who had been prescribed an antidepressant. Using a controlled before and after study design, we assessed changes in antidepressant prescription fill patterns before (T1=10/1/00-1/31/02 N=6191) and after (T2=2/1/02-5/31/04; N=12078) an increase in the copayment from $2 to $7. Copayment-exempt veterans were used as a concurrent control group (T1 N=13578; T2 N=25428).

Results:
Mean prescription fill rates before the copayment increase were lower for the copayment-required veterans (mean, 6.31; SD 8.86) than for the copayment-exempt veterans (mean, 7.98; SD10.02). While both groups increased the number of antidepressant fills received over time, the gap between copayment-required (mean, 9.29; SD13.68) veterans and copayment-exempt (mean, 12.62, SD 16.28) fill patterns increased dramatically by 24 months after the increase in copayment.

Implications:
Our findings suggest that the increase in copayment cost from $2 to $7 affected the prescription fill rates for copayment-required veterans. The gap between the number of fills for copayment-required veterans and copayment-exempt veterans widened over time. Our data also suggest that antidepressant fill rates progressively increased across both groups over time, possibly as a reflection of improved processes of depression care.

Impacts:
Processes of depression care appear to be changing within the VA as evidenced by increased antidepressant use. However, findings from this investigation suggest that medication cost could be a prohibitive factor for veterans with copayment responsibilities. Copayment-required veterans appear to fill antidepressant prescriptions less frequently than their copayment-exempt counterparts, most notably after the recent pharmacy copayment increase. Further work should assess the effect of changes in copayments on patient outcomes and health care resource utilization.