Abstract
Background: Many older individuals have concomitant hypertension and dyslipidaemia — two conditions that, together with age, increase the risk of adverse cardiovascular events. Adherence to antihypertensive (AH) and lipid-lowering (LL) therapy is therefore particularly important in older patients with concomitant hypertension and dyslipidaemia.
Objective: To determine patterns and predictors of adherence to concomitant AH and LL therapy among an older Medicare-eligible population.
Methods: Enrolees (n = 4052) aged ≥65 years who initiated treatment with both AH and LL therapy within a 90-day period were studied in this retrospective cohort study conducted in a US managed care organization. Adherence to AH and LL medications was measured as the proportion of days covered by any AH and/or LL medication in each 3-month interval, from the start of concomitant therapy for up to 36 months (mean follow-up 19.5 months). In each interval, patients were considered ‘adherent’ to AH and LL therapy if they had filled prescriptions sufficient to cover ≥80% of days with both medication classes. A multivariable regression model evaluated potential predictors of adherence to concomitant therapy, including patient demographics, clinical characteristics and health services use patterns at baseline.
Results: The percentage of patients adherent to both AH and LL therapy declined rapidly, before stabilizing, with 40.5%, 32.7% and 32.9% adherent at 3, 6 and 12 months, respectively. At each timepoint, an additional 27.8–35.0% of patients were adherent to either AH or LL therapy, but not both. Adherence was on average greater to AH than LL therapy. After adjusting for age, sex and other potential predictors, patients were more likely to be adherent if AH/LL therapies were initiated closer together in time (adjusted odds ratio [AOR] 1.13 for 0–30 days vs 61–90 days, p = 0.0563), had a history of cardiovascular disease (AOR 1.27, p = 0.0004), took fewer additional medications (AOR 0.43 for six or more medications vs zero or one medication, p < 0.0001) or had more outpatient physician visits in the prior year (AOR 1.26 for four to six visits vs zero to one visit, p < 0.0027).
Conclusion: Adherence to concomitant AH and LL therapy among older adults is poor. Modifiable factors that may improve adherence in Medicare-eligible patients include initiating therapy concurrently and reducing patients’ overall pill burden.
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Acknowledgements
This study was sponsored by a grant from Pfizer Inc., New York, NY, USA (ValueMedics Research, LLC). Editorial support was provided by Karen Burrows of Envision Pharma and funded by Pfizer Inc.
ValueMedics Research, LLC (now IMS Health, US Health Economics & Outcomes Research; Drs Chapman, Petrilla and Benner) has received payments for research and consulting from Pfizer Inc. in connection with the development of this manuscript. Dr Schwartz has received unrestricted research support for this and related research from the National Institute on Aging and Pfizer Inc.; serves on scientific advisory boards and/or as a scientific consultant for Abbott, Amgen, Berlex, Eli Lilly, General Electric, Pfizer Inc., sanofi-aventis, Schering-Plough and United BioSource Corporation; and is a member of the Agency for Health Research and Quality U.S. Preventive Services Task Force, the Blue Cross and Blue Cross Shield Associations Technology Evaluation Center Medical Advisory Panel, the Centers for Medicare and Medicaid Services Medical Coverage Advisory Committee, and the National Heart, Lung and Blood Institute National Cholesterol Education Project Adult Treatment Panel III. Mr Tang is an employee of Pfizer Inc. and holds stock and stock options in that company.
The sponsor of this study approved the study protocol, and an employee of the sponsor contributed to the interpretation of data as a co-author of the paper.
The authors would like to thank Cindy Eisenschenk for assisting in the preparation of this manuscript, and Dr David Battleman for his comments on the draft manuscript.
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Chapman, R.H., Petrilla, A.A., Benner, J.S. et al. Predictors of Adherence to Concomitant Antihypertensive and Lipid-Lowering Medications in Older Adults. Drugs Aging 25, 885–892 (2008). https://doi.org/10.2165/00002512-200825100-00008
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DOI: https://doi.org/10.2165/00002512-200825100-00008