The impact of dosing frequency on compliance and persistence with bisphosphonates among postmenopausal women in the UK: evidence from three databases.

Background: Bisphosphonates are currently among the most effective therapies for the treatment of osteoporosis and provide one of the mainstays of treatment in the UK. However studies in several countries have all reported sub-optimal compliance and persistence with treatment.

Objective: To examine the impact of dosing frequency on compliance and persistence with bisphosphonates in the UK.

Methods: Three UK General Practitioner sourced databases, the General Practice Research Database (GPRD), IMS Disease Analyzer (MEDIPLUS) and the Doctors Independent Network Database (DIN-LINK) were used to identify bisphosphonate naïve postmenopausal women. In each of the three retrospective analyses women were grouped into weekly or daily cohorts and followed for 12 months from an initial prescription. Compliance was measured as a Medication Possession Ratio (MPR), defined as the proportion of days for which patients had prescription coverage. Persistence was measured as the number of continuous days of treatment from the initial prescription to the end of the last prescription issued in the follow-up period.

Results: GPRD, MEDIPLUS and DIN-LINK provided access to 7567, 5962 and 1801 women, respectively. All three analyses consistently demonstrated that those on weekly regimens had a higher MPR than those on daily regimens (GPRD 76.2%, CI(95%,) 75.4-77.0 vs. 63.5%, CI(95%) 61.2-65.8, MEDIPLUS 70.3%, CI(95%) 69.3-71.2 vs. 56.3%, CI(95%) 53.8-58.9, DIN-LINK 59.5%, CI(95%) 59.4-59.6 vs. 46.3%, CI(95%) 45.9-46.7) (p < 0.0001) and persisted longer with treatment (GPRD 249, CI(95%) 246-253 vs. 208, CI(95%) 199-217, MEDIPLUS 228, CI(95%) 224-231 vs. 186, CI(95%,) 176-196, DIN-LINK 235, CI(95%) 234-236 vs. 189, CI(95%) 187-191) days respectively), (p < 0.0001).

Conclusions: Although this study only provided an indirect measure of medication usage, it demonstrated that a less frequent dosing regimen significantly improved levels of both compliance and persistence; however, even on weekly regimens bisphosphonate usage remains sub-optimal thereby reducing the clinical benefits.