Risk of subsequent fracture after prior fracture among older women

Abstract

Among 377,561 female Medicare beneficiaries who sustained a fracture, 10% had another fracture within 1 year, 18% within 2 years, and 31% within 5 years. Timely management to reduce risk of subsequent fracture is warranted following all nontraumatic fractures, including nonhip nonvertebral fractures, in older women.

Introduction: Prior fracture is a strong predictor of subsequent fracture; however, postfracture treatment rates are low. Quantifying imminent (12-24 month) risk of subsequent fracture in older women may clarify the need for early postfracture management.

Methods: This retrospective cohort study used Medicare administrative claims data. Women ≥ 65 years who sustained a clinical fracture (clinical vertebral and nonvertebral fracture; index date) and were continuously enrolled for 1-year pre-index and ≥ 1-year (≥ 2 or ≥ 5 years for outcomes at those time points) post-index were included. Cumulative incidence of subsequent fracture was calculated from 30 days post-index to 1, 2, and 5 years post-index. For appendicular fractures, only those requiring hospitalization or surgical repair were counted. Death was considered a competing risk.

Results: Among 377,561 women (210,621 and 10,969 for 2- and 5-year outcomes), cumulative risk of subsequent fracture was 10%, 18%, and 31% at 1, 2, and 5 years post-index, respectively. Among women age 65-74 years with initial clinical vertebral, hip, pelvis, femur, or clavicle fractures and all women ≥ 75 years regardless of initial fracture site (except ankle and tibia/fibula), 7-14% fractured again within 1 year depending on initial fracture site; risk rose to 15-26% within 2 years and 28-42% within 5 years. Risk of subsequent hip fracture exceeded 3% within 5 years in all women studied, except those < 75 years with an initial tibia/fibula or ankle fracture.

Conclusions: We observed a high and early risk of subsequent fracture following a broad array of initial fractures. Timely management with consideration of pharmacotherapy is warranted in older women following all fracture types evaluated.

Keywords: Epidemiology; Fracture; Fracture risk assessment; Fragility; General population studies; Geriatric; Incidence; Major osteoporotic fracture; Osteoporosis; Postmenopausal; Prediction modeling; Prevalence; Refracture.

Fig. 1

Time to subsequent fracture in patients with at least 5 years of follow-up. The risk of subsequent fracture decreased over time following initial fracture

Fig. 2

Cumulative incidence of a subsequent incident fracture 1 year (a), 2 years (b), and 5 years (c) after initial fracture, by skeletal site of initial fracture and age group. The incidence of subsequent fracture differed by age group and skeletal location

Fig. 3

Calibration of different logistic regression models assessing impact of patient characteristics on risk of subsequent fracture 1 year following initial fracture. The full model included a variety of variables related to patient demographic and clinical characteristics (full list of variables shown in Table 4). The backward elimination model contained those variables retained following backward elimination of the full model. The parsimonious model contained the following variables: age group, race, skeletal site of initial fracture, single vs multiple fractures at initial, fall risk, fracture during pre-index period, chronic obstructive pulmonary disease, obesity, and glucocorticoid use. The three-variable model included age group, race, and skeletal site of initial fracture. The two-variable model included age and skeletal site of initial fracture. In some models, no patients were predicted to have a 1-year risk of subsequent fracture corresponding to the lower and/or upper ends of the distribution of risk. Thus, in these instances, there are no bars corresponding to the lowest and highest levels of risk. This corresponds with the observed distribution of 1-year risk of subsequent fracture