Hip fractures in users of first- vs. second-generation bisphosphonates

This study compared population hip fracture rates for women with a prior fragility fracture who were treated with first-generation versus second-generation bisphosphonate therapies. The observational study found that, relative to women treated with etidronate, a first-generation bisphosphonate, women treated with the second-generation therapies 'alendronate' or `risedronate' were equally likely to be admitted to hospital for hip fracture. Our findings must be confirmed in large randomized headtohead controlled trials. Introduction Few studies have examined hip fracture outcomes among users of first-versus second-generation bisphosphonates. We compared hip fracture rates among elderly women with a history of fracture dispensed first-and second-generation bisphosphonates, hypothesizing that hip fracture rates would be higher among users of first-versus second-generation bisphosphonates after adjusting for confounders. Methods Administrative data from Ontario, Canada from 01 April 1998 to 31 March 2002 was used to identify population-based bisphosphonate-nave cohorts of subjects age 66 years and older initiated on first- (etidronate plus calcium; n= 19,127) or second-generation (alendronate or risedronate; n= 1,460) bisphosphonates. Multivariate Cox proportional hazard models were used for analysis. Results During over 23,000 person-years of follow-up, we observed 293 hospital admissions for first hip fracture. The unadjusted event rates yielded approximately 12.5 hospital admissions for hip fracture per 1,000 person-years of follow- up in each study group. Relative to the etidronate plus calcium group, females in the alendronate or risedronate group were equally likely to be admitted for hip fracture ( adjusted rate ratio [aRR]= 1.0; 95% CI 0.6-1.6). Conclusions The findings of this study suggest similar rates of hip fracture between the first- and second- generation bisphosphonates when used continuously among elderly females with a prior history of fracture.