Who benefits from fixed‐dose combinations? Two‐year statin adherence trajectories in initiators of combined amlodipine/atorvastatin therapy. Issue 12 (25th October 2017)

• Record Type: Journal Article
• Authors: Schaffer, Andrea L.; Buckley, Nicholas A.; Pearson, Sallie‐Anne
• Is Part Of: Pharmacoepidemiology and drug safety. Volume 26:Issue 12(2017)
• Page Start: 1465
• Page End: 1473
• Publication Date: 2017-10-25
• Subjects: cardiovascular diseases -- compliance -- hydroxymethylglutaryl‐CoA reductase inhibitors -- pharmacoepidemiology; Pharmacoepidemiology -- Periodicals; Chemotherapy -- Periodicals; Epidemiology -- Periodicals; 615.705
• DOI: 10.1002/pds.4342
• Languages: English
• ISSNs: 1053-8569

Abstract

Abstract: Purpose: We compared statin adherence in individuals initiating combined amlodipine/atorvastatin therapy as a fixed‐dose (FDC) or free combination and identified subgroups benefiting most from FDCs. Methods: We used a 10% sample of Australian Pharmaceutical Benefits Scheme dispensing data (2005‐2015) to identify individuals initiating amlodipine and atorvastatin as an FDC (n = 3996) or free combination (n = 5434), with or without prior statin dispensing. We measured the proportion of days covered in each 30‐day period over 24 months and classified patterns of statin adherence using group‐based trajectory models. We identified predictors of adherence trajectories using logistic regression. Results: The median age was 71 years, and 53% were female. We identified 4 patterns of statin adherence: near‐perfect adherence (n = 5383), good adherence (n = 1893), declining adherence (n = 1247), and early nonadherence (n = 907). Compared with the free combination, FDC initiators were more likely to have near‐perfect adherence if they were previously statin adherent irrespective of amlodipine dose (amlodipine 5 mg: OR = 1.61, 95% CI 1.38‐1.87; amlodipine 10 mg: OR = 2.39, 95% CI 1.63‐3.51) or they were previously statin nonadherent and initiated on the 5 mg amlodipine dose (OR = 1.87, 95% CI 1.50‐2.32). Statin‐naïve individuals initiating on the FDC with 10 mg amlodipine were less likely to have near‐perfect adherence (OR = 0.60, 95% CI 0.41‐0.88) and more likely to have early nonadherence (OR = 1.73, 95% CI 1.17‐2.55). Conclusions: The amlodipine/atorvastatin FDC was associated with greater statin adherence among prevalent statin users, and individuals who initiated on lower amlodipine doses. The FDCs did not improve adherence in statin‐naïve individuals and in some cases resulted in poorer adherence.