Association between bisphosphonate therapy and outcomes from rehabilitation in older people

Abstract

Background  Bisphosphonate therapy may have actions beyond bone, including effects on cardiovascular, immune and muscle function. We tested whether bisphosphonate treatment is associated with improved outcomes in older people undergoing inpatient rehabilitation.  Methods  Analysis of prospectively collected, linked routine clinical datasets. Participants were divided into never users of bisphosphonates, use prior to rehabilitation only, use after rehabilitation only, and current users (use before and after rehabilitation). We calculated change in 20-point Barthel scores during rehabilitation, adjusting for comorbid disease and laboratory data using multivariable regression analysis. Cox regression analyses were performed to analyse the association between bisphosphonate use and time to death or hospitalisation.  Results  2797 patients were included in the analysis. Current bisphosphonate users showed greater improvement in Barthel score during rehabilitation than non-users (5.0 points [95%CI 4.3–5.7] vs 3.8 [95%CI 3.6–3.9]), but no difference compared to those receiving bisphosphonates only after discharge (5.1 [95%CI 4.6–5.5]). Previous bisphosphonate use was significantly associated with time to death (adjusted hazard ratio 1.41 [95%CI 1.15–1.73]) but less strongly with time to combined endpoint of hospitalisation or death (adjusted hazard ratio 1.18 [95%CI 0.98–1.48]). Use after discharge from rehabilitation was associated with reduced risk of death (adjusted hazard ratio 0.64 [95%CI 0.55–0.73]; hazard ratio per year of bisphosphonate prescription 0.98 [95%CI 0.97–0.99]).  Conclusion  Bisphosphonate use is unlikely to be causally associated with improved physical function in older people, but continuing use may be associated with lower risk of death.