Early (1-year) Discontinuation of Different Anti-osteoporosis Medications Compared: A Population-Based Cohort Study

Although a number of reports suggest very low persistence with oral bisphosphonates, there is limited data on persistence with other anti-osteoporosis medications. We compare rates of early discontinuation (in the first year) with all available outpatient anti-osteoporosis drugs in Catalonia, Spain. We conducted a population-based retrospective cohort study using data from the SIDIAP database. SIDIAP contains computerized primary care records and pharmacy dispensing data for > 80 % of the population of Catalonia (> 5 million people). All SIDIAP participants starting an anti-osteoporosis drug between 1/1/2007 and 30/06/2011 (with 2 years wash-out) were included. We modelled persistence as the time between first prescription and therapy discontinuation (refill gap of at least 6 months) using Fine and Gray survival models with competing risk for death. We identified 127,722 patients who started any anti-osteoporosis drug in the study period. The most commonly prescribed drug was weekly alendronate (N = 55,399). 1-Year persistence ranges from 40 % with monthly risedronate to 7.7 % with daily risedronate, and discontinuation was very common [from 49.5 % (monthly risedronate) to 84.4 % (daily risedronate)] as was also switching in the first year of therapy [from 2.8 % (weekly alendronate) to 10 % (daily alendronate)]. Multivariable-adjusted models showed that only monthly risedronate had better one-year persistence than weekly alendronate and teriparatide equivalent, whilst all other therapies had worse persistence. Early discontinuation with available anti-osteoporosis oral drugs is very common. Monthly risedronate, weekly alendronate, and daily teriparatide are the drugs with the best persistence, whilst daily oral drugs have 40-60 % higher first-year discontinuation rates compared to weekly alendronate.