8 years. Among new users treated with alendronate or risedronate at the index date, only 5% switched therapy Wnt inhibitor within one year and less than 10% switched over the length of follow-up. Discussion Our results are consistent with prior reports that indicate that persistence with bisphosphonate therapy is suboptimal [10–12]. Recent evidence suggests that uninterrupted bisphosphonate therapy for a minimum of 3–5 years is important to reduce fracture risk [24–27]. However,
our results show that fewer than half of patients persist with therapy for 2 years, and only 25% persist with therapy for 5 years. Even when a more lenient permissible gap of 120 days was used to identify non-persistence, our findings identify that only 40% of patients persisted with therapy for 5 years. We also note that extending
the permissible gap length from 60 to 120 days changed our estimates of persistence from 63% to 77% at 1 year, and from 25% to 43% at 5 years. These findings highlight the impact of length of follow-up and permissible gap on persistence measurement. Given the observed variation in persistence rates with different permissible gap lengths, we recommend that methodology be explicitly reported to facilitate study comparisons . Regardless of the permissible gap length used to determine length of treatment persistence, our findings identify that extended gaps in oral bisphosphonate therapy are common, and the selleck kinase inhibitor majority of patients experience more
than one extended gap between bisphosphonate prescriptions. Although it is encouraging that many patients are returning to therapy, the clinical impact of the time off drug remains unknown, and requires further investigation. In fact, experiencing a fracture after stopping VX-680 solubility dmso osteoporosis treatment has been found to be a significant predictor of reinitiating osteoporosis medication . Our results also indicate that the longer the length of follow-up, the more likely it is that a patient will switch treatments. Over the entire study period of up to 12.8 years, 37% of all users (51% of etidronate users) switched to a different oral bisphosphonate. triclocarban In Ontario, etidronate has been available without restriction through the ODB program since 1996, thus permitting greater opportunity for patients to initiate etidronate and switch to another bisphosphonate over time. Although second generation bisphosphonates have been available since 1996 (daily alendronate), the initial listing status for both alendronate and risedronate required a trial of, or documented allergy to etidronate (2000–2003), or two of the following: (i) BMD T-score ≤3.0 SD, (ii) aged 75 or more years, (iii) prior osteoporosis-related fracture (2003–2007). Since 2007, all three agents have been covered without restrictions.