Risk of low-energy hip, wrist, and upper arm fractures among current and previous users of hormone replacement therapy: The Danish Nurse Cohort Study

Objective: To examine the effect of oestrogen alone and in combination with progestin on the risk of low-energy, hip, wrist, and upper arm fractures. Additionally, to examine to what extent previous use, duration of use as well as recency of discontinuation of hormone replacement therapy (HRT) influences the fracture risk. Design: Prospective cohort study. Setting: The Danish Nurse Cohort Study Participants: 7082 female nurses aged 50-69, who completed a questionnaire on lifestyle and use of HRT in 1993. Outcome measures: Self-reported low-energy, hip, wrist, and upper arm fractures between 1993-1999 obtained at a re-examination in 1999. Results: Compared to never users, current users of HRT, either oestrogen alone or combined with progestin, had a lower risk of low-energy, hip, wrist, and upper arm fractures (hazard ratio 0.60, 0.39-0.93 and hazard ratio 0.44, 0.30-0.66, respectively). The protective effect of HRT appeared to be significantly restricted to users who used the therapy for 10 years or more (hazard ratio 0.27, 0.14-0.51). Women who previously used hormones experienced no protective effect on fracture risk regardless of duration of therapy and recency of discontinuation. Conclusion: Only long-term HRT (10 years or more) offers a protective effect against low energy, hip, wrist, and upper arm fractures. In women with risk factors or established osteoporosis, benefits and risks of this therapy should be balanced when considering its use as a first line treatment for prevention of these fractures.