Abstract

ABSTRACT Objective: To describe factors associated with failure to fill initial prescriptions for asthma-controller and dyslipidemia medications. Study Design: Retrospective cohort analysis. Methods: A total of 23,176 prescriptions were written by 507 providers between January 1, 2005, and October 31, 2006. Of these, 2243 (1182 asthma controller and 1061 dyslipidemia) were eligible for analysis (ie, not preceded by use of a clinically equivalent drug and written for a patient <65 years of age) and compared with subsequent paid pharmacy claims. If 60 days lapsed from the prescribed date without a paid pharmacy claim for a clinically equivalent drug, the prescription was deemed as unfilled. We compared selected provider, patient, and prescription benefit characteristics associated with filled and unfilled prescriptions by conducting a prescription-level logistic regression analysis. Results: Initiation failures occurred for 240 asthma-controller (20.3%) and 362 dyslipidemia (34.1%) prescriptions. Approximately 67.9% and 43.2% of the asthma-controller and dyslipidemia prescriptions, respectively, were filled on the same day as prescribed. Of those ultimately filled, 95.0% and 93.2% were filled within 2 weeks. Older age, fewer prior claims, and copayments above $10 were associated with a greater likelihood of initiation failures. Conclusions: Poor medication adherence among patients prescribed asthma-controller or dyslipidemia medications is a larger problem than can be estimated from administrative pharmacy claims alone. Adherence improvement programs should consider primary nonadherence and use the identified predictive factors to improve interventions and educational efforts. Additional research should explore other characteristics that influence primary nonadherence and the probable healthcare costs associated with initiation failures. (Am J Pharm Benefits. 2010;2(2):111-118) Medication Adherence T he full therapeutic benefit of prescription medications is realized only when the patient follows the healthcare provider's recommendations, a concept referred to as medication adherence. Premature treatment discontinuation and other forms of poor medication adherence are common and contribute to adverse drug events, worsening disease, increasing healthcare costs, and decreasing quality of life. 1-3 As a result, there is a wealth of scientific evidence documenting risk factors for poor adherence and effectiveness of interventions to improve adherence. In contrast, relatively little is known about the extent and causes of primary nonadherence, prescriptions given by a healthcare provider but never filled by the patient. Without an electronic record, connecting physicians' handwritten or oral prescriptions with medication-dispensing records is manual and resource intensive. Thus, studies of primary adherence have relied primarily on patient self-reports or on patient populations receiving prescriptions while hospitalized or receiving emergency care, where computer prescription order entry systems exist. These studies routinely report adherence rates across multiple pharmacotherapies, represent the experience of a single pharmacy, enroll only select patient populations, or report the experience of a non-US patient population. As a result, estimates of primary nonadherence vary widely, with international studies reporting rates from 2% to 30% 12-14 and US studies reporting rates from 2% to 20%.