Twenty-four observational studies (n=384,242 patients) were included in the review.
Persistence: In six studies (n=106,961 patients), the pooled persistence estimate from administrative database information ranged from 52% (95% confidence interval (CI):44 to 59) for treatment lasting one to six months, to 42% (95% CI: 20 to 68) for treatment lasting 13 to 24 months, after which time the rate returned to 52% (95% CI: 45 to 58). Pooled estimates from self-reported data (13 studies, n=7,230 patients) were higher, ranging from 89% (95% CI: 77 to 95%) for treatment lasting one to six months, to 68% (95% CI: 60 to 75) for treatment lasting longer than 24 months. Self reported rates were lower amongst new users, and rates increased as the gap between refills widened over a period of 30 to 120 days.
Compliance: In seven studies (n=321,734 patients) the pooled refill compliance rate was 68% at both seven to 12 months (95% CI: 63 to 72) and at 13 to 24 months (95% CI: 67 to 69). The pooled estimate from self-reported data (four studies) was 62% (95% CI: 48 to 75) of patients following the recommended instructions within six months of starting treatment.
Adherence: In six studies (n=264,432 patients), the pooled estimate of patients (achieving an medication possession ratio higher than 66% (one study) and higher than 80% (five studies) as the measure of good adherence) ranged from 53% (95% CI: 52 to 54) for treatment lasting one to six months, to 43% (95% CI: 32 to 54%) for treatment lasting 13 to 24 months. Pooled adherence rates were lower amongst new users.
Subgroup analyses showed higher rates of persistence (using various measures) arising from bone mineral density testing, use of bisphosphonates, switch or restarting medication, and weekly dosing schedules. Increased refill compliance was also noted from bone mineral density testing, switching medications, and weekly dosing schedules.