Lower Fracture Rates With Gastro-Resistant Risedronate in Women With Osteoporosis

Gastro-resistant vs immediate-release risedronate or alendronate had a protective effect against fracture risk among women with osteoporosis.

Compared with immediate-release risedronate or alendronate, gastro-resistant risedronate was found to be more effective in reducing fracture rates among women with osteoporosis, according to real-world study results published in Osteoporosis International.

A retrospective cohort observational study was conducted to compare the risk for fractures between women with osteoporosis receiving gastro-resistant risedronate vs immediate-release risedronate or alendronate, using a US claims database from 2009 to 2019.  

The study included women aged 60 years and older who had been diagnosed with osteoporosis with least 2 prescriptions filled for oral bisphosphonates. Patients were followed-up with for at least 1 year after the first recorded dispensing date of their oral bisphosphonate medication.

Researchers also evaluated persistence on bisphosphonate therapy, as well as site-specific fracture rates both overall and in the subgroup of patients with high fracture risk (defined by older age, comorbidities, and concomitant medication use).

A total of 59,593 women with osteoporosis were eligible for inclusion in the study; 1080 (1.8%) received gastro-resistant risedronate, 6351 (10.7%) received immediate-release risedronate, and 42,824 (71.9%) received alendronate. The median ages of women were 66, 66, and 67 years respectively (P <.05).

[T]he current study has generated evidence suggesting that the lower fracture rates associated with GR risedronate observed in prior studies are at least partially explained by advantages of GR formulations of oral bisphosphonates relative to IR formulations.

Over a median follow-up of 29 to 32 months, unadjusted fracture rates were found to be higher among women aged 70 years and older than those aged 65 years and older in all 3 treatment cohorts. Similarly, women in all cohorts with high baseline fracture risk due to comorbidities or concomitant medications had higher fracture rates. Patients who received treatment with gastro-resistant risedronate had the lowest site-specific fracture rates, regardless of patient subgroup.

Researchers adjusted for potential confounders and observed that women receiving treatment with gastro-resistant vs immediate-release risedronate had a lower risk for fracture. In particular, gastro-resistant vs immediate-release risedronate was linked to a significantly lower risk for any fracture in women aged 65 years and older and in those aged 70 years and older (adjusted incidence rate ratios [aIRR], 0.63 and 0.69, respectively), along with a significantly lower risk for pelvic fracture overall and in the high-risk subgroups (aIRRs, ≥65 years: 0.41; ≥70 years: 0.24; high-risk: 0.34).

Gastro-resistant risedronate vs immediate-release alendronate had a substantially lower risk for any fracture among women aged 65 years and older and those aged 70 years and older (aIRRs, 0.73 and 0.72, respectively). Furthermore, the risk for pelvic fractures in the group aged 70 years and older was markedly reduced among those who received gastro-resistant risedronate compared with immediate-release alendronate, while wrist/arm fracture risks were significantly lowered among those older than 65 and 70 years.

Study limitations included the inability to make causal inferences from these association-level findings due to the retrospective design; the inclusion of only patients with commercial and Medicare Supplemental health plans; and the under- or overestimation of the accuracy of the site-specific fractures due to a claims-based algorithm.

Researchers concluded, “[T]he current study has generated evidence suggesting that the lower fracture rates associated with [gastro-resistant] risedronate observed in prior studies are at least partially explained by advantages of [gastro-resistant] formulations of oral bisphosphonates relative to [immediate-release] formulations.”

References:

Eisman JA, Cortet B, Boolell M, et al. Fracture risk in women with osteoporosis initiated on gastro‑resistant risedronate versus immediate release risedronate or alendronate: a claims data analysis in the USA. Osteoporos Int. Published online March 6, 2023. doi:10.1007/s00198-022-06627