Clinical subsequent fractures cluster in time after first fractures

Objectives: The risk of subsequent fractures is double the risk of having a first fracture. We analysed whether this risk is constant or not over time. Methods: A population-based study in 4140 postmenopausal women, aged between 50 and 90 years, on radiographic confirmed clinical fractures from menopause onwards analysed by Cox regression. Results: A total of 924 (22%) women had a first fracture and 243 (26% of 924) a subsequent fracture. Of all first fractures, 4% occurred in each year from menopause onwards, while after a first fracture 23% of all subsequent fractures occurred within 1 year and 54% within 5 years. When calculated from time of first fracture, the relative risk (RR) of subsequent fracture was 2.1 (95% CI 1.7 to 2.6) and remained increased over 15 years. When calculated for specific time intervals after a first fracture, the RR was 5.3 (95% CI 4.0 to 6.6) within 1 year, 2.8 (95% CI 2.0 to 3.6) within 2-5 years, 1.4 (95% CI 1.0 to 1.8) within 6-10 years and 0.41 (95% CI 0.29 to 0.53) after >10 years. Conclusions: From menopause onwards, clinical fractures cluster in time, indicating the need for early action to prevent subsequent fractures.