Introduction: Bisphosphonate therapy may have biological effects beyond bone health, including effects on cardiovascular, immune and muscle function. We examined the association between bisphosphonate use and functional outcomes in the rehabilitation of older people.
Methods: This was a retrospective cohort analysis of routine data collected from the Dundee Medicine for the Elderly Service between 1999 and 2011. Data on admission and discharge 20-point Barthel score was combined with comorbid disease, biochemistry, haematology and community prescribing data. The cohort was split into four groups: current bisphosphonate users, previous users (prescribed prior to admission); subsequent users (prescribed only after admission); and never users. Difference in Barthel between admission and discharge was analysed, adjusting for baseline Barthel score, age, sex, comorbid disease, medication burden, recent hip fracture, baseline albumin, calcium, renal function and haemoglobin.
Results: 2797 patients were included in this analysis. Mean age was 84.1 (SD 7.5); 1153 (41%) were male, and the mean baseline admission Barthel score was 10.5 (SD 3.8). After adjustment for the above covariates, current bisphosphonate therapy was associated with a greater improvement in Barthel score (5.0 points, 95% CI 4.3 to 5.7) compared to the never users (3.8 points, 95% CI 3.6 to 3.9, p < 0.001) and previous users (3.4 points, 95% CI 2.8 to 4.0, p < 0.001) groups. However, there was no difference from those not taking bisphosphonates, but who started use after discharge from rehabilitation (5.1 points, 95% CI 4.6 to 5.5, p = 0.82).
Conclusion: Bisphosphonate therapy is not causally associated with improved functional outcomes from inpatient rehabilitation.