Adherence to anti-osteoporotic regimens in a Southern Taiwanese population treated according to guidelines: a hospital-based study.

Aim This study was designed to investigate adherence to anti-osteoporotic regimens in a population following therapeutic guidelines; and to assess whether this experience differs from that in other administrative surveys. Methods We reviewed an outpatient database to retrieve information on prescription of anti-osteoporotic medications at a medical centre in Taiwan from 2001 to 2007. Adherence was determined by compliance and persistence. Compliance was calculated by the medication possession ratio (MPR), and persistence by the time from treatment initiation to discontinuation. All anti-osteoporotic regimens were considered equivalent in this study. Results A total of 3589 patients (3256 women and 333 men), with a mean age of 68.6 years, were included. The median MPR at 1 year and at 2 years were 99.7% (interquartile range [IQR] 26.8–100) and 61.4% (IQR 15.3–100), respectively. Good compliance (MPR ≥ 80%) was 56% at 1 year and 43% at 2 years. Regarding the 30-day refill gap, mean duration of persistence at 1 year and at 2 years was 243 and 400 days, respectively. About 50.8% of patients continued to receive therapy at 1 year, while 36.1% at 2 years. Our findings are not different from those of other claims-based studies. The subgroup with MPR ≥ 80% had a higher persistence rate than that with MPR < 80%. Conclusion Overall adherence to anti-osteoporotic regimens based on guidelines was sub-optimal in the current study. Our results are in line with previous studies using a claims database. Non-adherence commonly occurs early after drug initiation, which indicates that efforts should be made to improve adherence as soon as possible.