ORIGINAL ARTICLE Adherence to anti-osteoporotic regimens in a Southern Taiwanese population treated according to guidelines: a hospital-based study Shan-Fu YU, 1 Ching-Lan CHOU, 1 Han-Ming LAI, 1 Ying-Chou CHEN, 1 Chun-Kai CHIU, 1 Ming-Chun KUO, 2 Yu-Jih SU, 1 Chung-Jen CHEN 1 and Tien-Tsai CHENG 1 1 Division of Rheumatology, Allergy and Immunology and 2 Division of Metabolism Department of Internal Medicine Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan Abstract 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 cur- rent 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. Key words: adherence, compliance, osteoporosis, persistence, Taiwan. INTRODUCTION Osteoporosis and related fractures are a major public health problem. The prevalence of osteoporosis has increased worldwide during the past few decades. 1 In Taiwan, the prevalence of osteoporosis between 1999 and 2001 in those aged over 50 years was 1.6% for men and 11.4% for women. 2 The incidence rate of hip fracture in Taiwan, although similar to that in Western countries, was higher than that in other Han Chinese populations. 3–5 It has been reported that hip fractures lead to an overall 12–20% reduction in expected survival, with 5–20% excess mortality, within the first year after the fracture. 6,7 Osteoporosis has Correspondence: Asst Prof Tien-Tsai Cheng, Division of Rheu- matology, Allergy and Immunology, Department of Internal Medicine, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, No. 123, Ta-Pei Road, Kaohsiung 833, Taiwan. Email: tiantsai@ms2.hinet.net © 2012 The Authors International Journal of Rheumatic Diseases © 2012 Asia Pacific League of Associations for Rheumatology and Blackwell Publishing Asia Pty Ltd International Journal of Rheumatic Diseases 2012