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 head-to-head controlled trials.


BACKGROUND
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-naïve 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.
Mamdani
M
M
Keenan Research Centre, Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Canada.
Kopp
A
A
Hawker
G
G
D000368:Aged; D000369:Aged, 80 and over; D019386:Alendronate / Q000627:therapeutic use; D050071:Bone Density Conservation Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D004164:Diphosphonates / Q000627:therapeutic use*; D012968:Etidronic Acid / Q000031:analogs & derivatives / Q000627:therapeutic use; D005260:Female; D006620:Hip Fractures / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D009864:Ontario / Q000453:epidemiology; D015663:Osteoporosis, Postmenopausal / Q000150:complications / Q000188:drug therapy*; D012189:Retrospective Studies; D000068296:Risedronic Acid; D012923:Social Class
D050071:Bone Density Conservation Agents; D004164:Diphosphonates; D000068296:Risedronic Acid; D012968:Etidronic Acid; D019386:Alendronate