Background: Individuals who sustain a low-energy fracture are at increased risk of sustaining a subsequent low-energy fracture. The incidence of these refractures may be reduced by secondary preventative measures, although justifying such interventions and evaluating their impact is difficult without substantive evidence of the severity of the refracture risk. The aim of this study was to quantify the risk of sustaining another fracture following a low-energy fracture compared with the risk in an age and sex-matched reference population.
Methods: During the twelve-year period between January 1988 and December 1999, all inpatient and outpatient fracture-treatment events were prospectively audited in a trauma unit that is the sole source of fracture treatment for a well-defined local catchment population. During this time, 22,060 patients at least forty-five years of age who had sustained a total of 22,494 low-energy fractures of the hip, wrist, proximal part of the humerus, or ankle were identified. All refracture events were linked to the index fracture in the database during the twelve-year period. The incidence of refracture in the cohort of patients who had sustained a previous fracture was divided by the "background" incidence of index fractures within the same local population to obtain the relative risk of refracture. Person-years at-risk methodology was used to control for the effect of the expected increase in mortality with advancing age.
Results: Within the cohort, 2913 patients (13.2%) subsequently sustained a total of 3024 refractures during the twelve-year period. Patients with a previous low-energy fracture had a relative risk of 3.89 of sustaining a subsequent low-energy fracture. The relative risk was significantly increased for both sexes, but it was greater for men (relative risk = 5.55) than it was for women (relative risk = 2.94). The relative risk was 5.23 in the youngest age cohort (patients between forty-five and forty-nine years of age), and it decreased with increasing age to 1.20 in the oldest cohort (patients at least eighty-five years of age).
Conclusions: Individuals who sustain a low-energy fracture between the ages of forty-five and eighty-four years have an increased relative risk of sustaining another low-energy fracture. This increased risk was greater when the index fracture occurred earlier in life; the risk decreased with advancing age. Secondary preventative measures designed to reduce the risk of refracture following a low-energy fracture are likely to have a greater impact on younger individuals.