Excess subsequent fracture and mortality risk after ankle fractures: a relative survival analysis of the 45 and Up Study.

Ankle fractures are one of the common fractures that account for hospitalization. Ankle fractures were often thought of inconsequential as limited data on their long-term consequences. After accounting for age, sex, and time, ankle fractures were associated with increased risk of subsequent fracture and mortality.

Background: Ankle fractures are common but it is uncertain whether they are indicative of poor bone health. There are limited data about subsequent fracture and mortality risk following ankle fractures.

Objective: To determine if there is increased subsequent fracture and mortality risk after ankle fractures.

Methods: A prospective population-based cohort of 143,070 women and 123,818 men in the 45 and Up Study (NSW, Australia) had baseline questionnaire responses that were linked to Emergency Department Data Collection (EDDC), the Admitted Patient Data Collection (APDC), and the NSW Registry of Births Deaths & Marriages death registrations from 2006 to 2017. Secure data access was provided through the Sax Institute's Secure Unified Research Environment (SURE). Sex-specific excess risks of subsequent fracture and mortality following ankle fractures were quantified using relative survival analysis.

Results: During 1,490,651 person-years, women and men experienced 1379 and 579 ankle fractures and 78 deaths and 76 deaths, respectively. Ankle fractures were associated with a 5-year 5% (95% CI 3-8%) excess risk of subsequent fracture in both women and men, compared to subjects' risk of an incident fracture in the study. There was a 5-year cumulative excess mortality of 10% (95% CI 6-13%) following ankle fractures in men but no excess mortality in women compared to the overall cohort. Participants with ankle fractures who died were older (P < 0.001), more likely to have had a second fracture (P < 0.001), have had a prior fracture (P < 0.001), and have more comorbidities (P < 0.001).

Conclusion: In the 45 and Up cohort, there was a modest but significant increased risk of fracture following ankle fracture seen in both women and men. In men, but not women, ankle fractures were associated with 10% excess mortality. Ankle fractures should be considered for secondary fracture prevention in those who are older and have more comorbidities.