Systematic review and meta-analysis of real-world adherence to drug therapy for osteoporosis.

OBJECTIVE To quantify the adherence of patients to drug therapy for osteoporosis in real-world settings via a systematic review and meta-analysis of observational studies. METHODS The PubMed and Cochrane databases were searched for English-language observational studies published from January 1, 1990, to February 15, 2006, that assessed patient adherence to drug therapy for osteoporosis using the following medical subject headings and keywords: drug therapy, medication adherence, medication persistence, medication possession ratio, patient compliance, and osteoporosis. Studies were stratified into 3 groups: persistence (how long a patient continues therapy), compliance (how correctly, in terms of dose and frequency, a patient takes the medication), and adherence (a combination of persistence and compliance). A random-effects model was used to pool results from the selected studies. RESULTS Twenty-four studies were included in the meta-analysis. The pooled database-derived persistence rate was 52% (95% confidence interval [CI], 44%-59%) for treatment lasting 1 to 6 months, 50% (95% CI, 37%-63%) for treatment lasting 7 to 12 months, 42% (95% CI, 20%-68%) for treatment lasting 13 to 24 months, returning to 52% (95% CI, 45%-58%) for treatment lasting more than 24 months. Pooled adherence rates decreased from 53% (95% CI, 52%-54%) for treatment lasting 1 to 6 months to 43% for treatment lasting 7 to 12 months (95% CI, 38%-49%) or 13 to 24 months (43%; 95% CI, 32%-54%). The pooled refill compliance estimate was 68% (95% CI, 63%-72%) for treatment lasting 7 to 12 months and 68% (95% CI, 67%-69%) for treatment lasting 13 to 24 months. The pooled self-reported compliance rate was 62% (95% CI, 48%-75%) for treatment lasting 1 to 6 months and 66% (95% CI, 45%-81%) for treatment lasting 7 to 12 months. CONCLUSION One-third to half of patients do not take their medication as directed. Nonadherence occurs shortly after treatment initiation. Terms and definitions need to be standardized to permit comparability of technologies designed to improve patient adherence. Prospective trials are needed to assess the relationship between adherence and patient outcomes.