The Implications of Therapeutic Complexity on Adherence to Cardiovascular Medications

Study Questions:

What is the extent of prescribing and filling complexity in patients who are prescribed a cardiovascular medication, and its association with adherence?


The study population was comprised of individuals prescribed a statin (n = 1,827,395) or an angiotensin-converting enzyme inhibitor (ACEI) or renin angiotensin-receptor blocker (ARB) (n = 1,480,304) between June 1, 2006, and May 30, 2007. The authors estimated complexity by measuring the number of medications, prescribers, pharmacies, pharmacy visits, and refill consolidation (a measure of the number of visits per fill) during the 3 months from the first prescription. The number of daily doses was also measured in ACEI/ARB users. After this period, adherence was evaluated over the subsequent year. The relationship between complexity and adherence was assessed with multivariable linear regression.


The statin cohort had a mean age of 63 years and 49% were male. On average, during the 3-month complexity assessment period, statin users filled 11.4 prescriptions for 6.3 different medications, had prescriptions written by two prescribers, and made 5.0 visits to the pharmacy. Results for ACEI/ARB users were similar. Greater prescribing and filling complexity was associated with lower levels of adherence. In adjusted models, patients with the least refill consolidation had adherence rates that were 8% lower over the subsequent year than patients with the greatest refill consolidation.


The authors concluded that medication use and prescription filling for patients with cardiovascular disease is complex, and strategies to reduce this complexity may help improve medication adherence.


This analysis of patients filling prescriptions for two common cardiovascular medication classes demonstrates the substantial complexity that health system factors contribute to medication use by patients with chronic disease, and the negative impact of this complexity on medication adherence. These results suggest the potential for novel adherence improvement interventions aimed at improving refill consolidation at individual pharmacies and on individual visits. Such interventions would need to be prospectively and rigorously evaluated and could include providing financial incentives for patients to fill at a single pharmacy, or altering pharmacy benefits to facilitate refill consolidation, for example, by authorizing early renewals for a short period or providing patients with longer supplies of medications so that subsequent refills could all occur at the same visit.

Keywords: Medication Adherence, Cardiovascular Agents, Chronic Disease, Cardiovascular Diseases, Pharmacies

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