Cessation rate of anti-osteoporosis treatments and risk factors in Spanish primary care settings: a population-based cohort analysis

Among 95,057 patients ≥50 years with new anti-osteoporosis medications (AOM) (2001-2013) in primary care, 1-year cessation was 51% (28%-68%), higher in men, smokers, patients with missing lifestyle data, and out normal BMI, and lower in those aged 60-79, with recent fractures or other anti-osteoporotics, suggesting non-severe osteoporosis and less risk awareness. PURPOSE: Low compliance to anti-osteoporosis medications (AOM) has been previously reported. We aimed to estimate 1-year cessation rates of different AOMs as used in Spanish healthcare settings, and to identify associated risk factors. METHODS: A cohort study was performed using primary care records data (BIFAP). Patients entered the cohort when aged 50 years in 2001-2013, with ≥1 year of data available, and identified as incident users of AOM (1-year washout). Participants were divided into six cohorts: alendronate, other oral bisphosphonates, selective oestrogen receptor modulators, strontium ranelate, teriparatide, and denosumab. Patients were followed from therapy initiation to the earliest of cessation (90-day refill gap), switching (to alternative AOM), loss to follow-up, death, or end of 2013. One-year therapy cessation was estimated using life tables. Hazard ratios (of cessation) according to age, sex, lifestyle factors, morbidity, and co-medication were estimated after stepwise backwards selection. RESULTS: A total of 95,057 AOM users were identified (91% women; mean age 68). One-year cessation was 51% overall, highest for strontium ranelate (68%), and lowest for denosumab (28%). Cessation probability was higher in men (14% to 2.1-fold), smokers (>6%), and patients with missing BMI (19-28%) or smoking (6-20%) data, and overweight/obese/underweight (7% to 2.6-fold increase compared to normal weight). Patients aged 60-79 years, with a recent fracture or other drugs used for osteoporosis, had better persistence. CONCLUSIONS: Over half of the patients initiating AOM stopped therapy within the first year after initiation. The described risk factors for cessation could be proxies for non-severe osteoporosis, and/or disease/risk awareness, which could inform the targeting of high-risk patients for monitoring and/or interventions aimed at improving persistence