Relationship between antidepressant medication possession and treatment response☆☆☆
Abstract
Objective
To estimate the correlation between antidepressant medication possession ratios (MPR) measured from administrative pharmacy data and changes in self-reported depression symptoms.
Methods
The sample includes 360 primary care patients enrolled in a randomized trial of collaborative care in the Department of Veterans Affairs. Treatment response at 6 months was defined as a 50% improvement in symptoms as measured by the Hopkins Symptom Checklist (SCL-20). MPRs were calculated from administrative pharmacy data. Logistic regression analysis (controlling for intervention status and casemix) was used to test the hypothesis that MPR was significantly associated with treatment response.
Results
Seventy percent of the patients filled an antidepressant prescription and the average MPR was 0.46. A fifth (19.2%) of the patients responded to treatment. Having an MPR≥0.9 was significantly correlated with treatment response (OR=2.43, CI95=1.29–4.57, P=.006).
Conclusions
If the predictive validity of antidepressant MPR measured from administrative pharmacy data is validated in other patient populations, it could be used to estimate treatment response rates whenever it is not feasible to collect symptom data directly from patients. Thus, the effectiveness of quality improvement programs designed to increase rates of antidepressant initiation and adherence could potentially be evaluated routinely at the population or system level.
Keywords: Antidepressants, Adherence, Medication possession ratio, Primary care
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☆ Human subjects approval: The study was approved by the Research and Development Committees of the Central Arkansas Veterans Healthcare System in Little Rock, AR; the Overton Brooks VA Medical Center in Shreveport, LA; and the G.V. (Sonny) Montgomery VA Medical Center in Jackson, MS; and their affiliated institutional review boards at the University of Arkansas for Medical Sciences and the University of Louisiana Health Sciences Center at Shreveport.
☆☆ This research was supported by VA IIR 00-078-3 grant to Dr. Fortney, VA NPI-01-006-1 grant to Dr. Pyne, the VA HSR&D Center for Mental Health and Outcomes Research, and the VA South Central Mental Illness Research Education and Clinical Center. Drs. Pyne and Edlund were supported by VA HSR&D Research Career Awards. Dr. Mittal was supported by the VISN 16 South Central Network Research/Career Development Grant Program and VA South Central Mental Illness Research Education and Clinical Center.
PII: S0163-8343(10)00058-7
doi:10.1016/j.genhosppsych.2010.03.008
Published by Elsevier Inc.
