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Manager, Health and Outcomes Research, AstraZeneca Pharmaceuticals LP; Health Economics, AstraZeneca Pharmaceuticals LP, Wilmington, DE
Professor and Chair, Pharmaceutical Systems and Policy, School of Pharmacy, West Virginia University, Department of Pharmaceutical Systems and Policy, Robert C Byrd Health Sciences Center (North), Morgantown, WV
Assistant Professor of Pharmacy Practice, College of Pharmacy and Health Science, Butler University, Indianapolis, IN
Associate Professor, School of Pharmacy, West Virginia University, Department of Pharmaceutical Systems and Policy, Robert C Byrd Health Sciences Center (North)
Director, Global Health Economics, Biogen Idec, Cambridge, MA
Associate Professor, Department of Pharmaceutical Systems and Policy, School of Pharmacy, West Virginia University, Department of Pharmaceutical Systems and Policy, Robert C Byrd Health Sciences Center (North)
Assistant Professor, Pharmacy Care Systems, Harrison School of Pharmacy, Auburn University, Auburn, AL
Assistant Professor, School of Pharmacy, West Virginia University, Department of Pharmaceutical Systems and Policy, Robert C Byrd Health Sciences Center (North)
Reprints: Dr. Hassan, AstraZeneca Pharmaceuticals LP, Wilmington, DE, fax 302/886-5728, Mariam.Hassan{at}astrazeneca.com
BACKGROUND: Medication nonadherence is a significant problem among patients with bipolar disorder.
OBJECTIVE: To compare adherence and persistence among patients with bipolar disorder initiated on antipsychotics in a state Medicaid system over a 12 month follow-up period.
METHODS: Claims data for patients with bipolar disorder from a de-identified Medicaid database were examined. Patients were classified into 4 monotherapy treatment groups (risperidone, olanzapine, quetiapine, or typical antipsychotic) based on the first prescription filled between January 1, 1999, and December 31, 2001. Adherence and persistence were analyzed over a 12 month follow-up period. Adherence was measured using the Medication Possession Ratio (MPR). Persistence was defined as the total number of days from the initiation of treatment to therapy modification (ie, discontinuation, switching, or combination with another antipsychotic). Adjustment for confounding variables was undertaken using ordinary least-squares and Cox proportional hazard regression modeling.
RESULTS: The mean MPRs were 0.68 for risperidone (n = 231), 0.68 for olanzapine (n = 283), 0.71 for quetiapine (n = 106), and 0.46 for typical antipsychotics (n = 205). Patients initiated on typical antipsychotics were 23.6% less adherent than patients initiated on risperidone (p < 0.001). Mean persistence (days) was 194.8 for risperidone, 200.9 for olanzapine, 219.8 for quetiapine, and 179.2 for typical antipsychotics. Extended Cox regression modeling indicated no significant differences between antipsychotics in hazards of therapy modification within 250 days of initiation. However, patients initiated on typical antipsychotics were 5.2 times more likely to modify therapy compared with those initiated on risperidone after 250 days of antipsychotic therapy (p < 0.001).
CONCLUSIONS: Adherence and persistence were similar between atypical antipsychotic groups. The typical antipsychotic group, however, demonstrated lower adherence and a greater likelihood of patients modifying therapy compared with the risperidone cohort.
Key Words: adherence, antipsychotic, bipolar disorder, compliance, persistence
Published Online, October 9, 2007. www.theannals.com, DOI 10.1345/aph.1K205
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  T. Suppes, E. Vieta, S. Liu, M. Brecher, B. Paulsson, and Trial 127 Investigators Maintenance Treatment for Patients With Bipolar I Disorder: Results From a North American Study of Quetiapine in Combination With Lithium or Divalproex (Trial 127) Am J Psychiatry, April 1, 2009; 166(4): 476 - 488. [Abstract] [Full Text] [PDF]
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