The epidemiology of prescriptions abandoned at the pharmacy.

BACKGROUND: Picking up prescriptions is an essential but previously unstudied component of adherence for patients who use retail pharmacies. Understanding the epidemiology and correlates of prescription abandonment may have an important effect on health care quality.

OBJECTIVE: To evaluate the rates and correlates of prescription abandonment.

DESIGN: Cross-sectional cohort study.

SETTING: One large retail pharmacy chain and one large pharmacy benefits manager (PBM) in the United States.

MEASUREMENTS: Prescriptions bottled at the retail pharmacy chain between 1 July 2008 and 30 September 2008 by patients insured by the PBM were identified. Pharmacy data were used to identify medications that were bottled and either dispensed or returned to stock (RTS) or abandoned. Data from the PBM were used to identify previous or subsequent dispensing at any pharmacy. The first (index) prescription in a class for each patient was assigned to 1 of 3 mutually exclusive outcomes: filled, RTS, or RTS with fill (in the 30 days after abandonment, the patient purchased a prescription for a medication in the same medication class at any pharmacy). Outcome rates were assessed by drug class, and generalized estimating equations were used to assess patient, neighborhood, insurance, and prescription characteristics associated with abandonment.

RESULTS: 10 349 139 index prescriptions were filled by 5 249 380 patients. Overall, 3.27% of index prescriptions were abandoned; 1.77% were RTS and 1.50% were RTS with fill. Patients were least likely to abandon opiate prescriptions. Prescriptions with copayments of $40 to $50 and prescriptions costing more than $50 were 3.40 times and 4.68 times more likely, respectively, to be abandoned than prescriptions with no copayment (P < 0.001 for both comparisons). New users of medications had a 2.74 times greater probability of abandonment than prevalent users (P < 0.001), and prescriptions delivered electronically were 1.64 times more likely to be abandoned than those that were not electronic (P < 0.001).

LIMITATION: The study included mainly insured patients and analyzed data collected during the summer months only.

CONCLUSION: Although prescription abandonment represents a small component of medication nonadherence, the correlates to abandonment highlight important opportunities to intervene and thereby improve medication taking.

PRIMARY FUNDING SOURCE: CVS Caremark.