Hip fracture risk factors and the discriminability of hip fracture risk vary by age: A case–control study

Abstract

To determine the important risk factors for hip fracture and the discriminability of hip fracture risk in different age cohorts (≤80 years, >80 years). Consecutive admissions of hip fracture over 24 months in those aged >60 years, and an age- and sex-matched control derived from admissions under a medical unit were prospectively assessed. The risk factors and the discriminabilty of hip fracture risk by age were investigated for each sex in univariate and multivariate models. The area under the curve (AUC) statistics from the receiver operating characteristic curve analysis was used to estimate the ability of the independent risk factors to discriminate hip fracture risk. The important risk factors in women aged ≤80 years were lower bodyweight, previous osteoporotic fracture, hip fracture in first-degree relatives and lower plasma 25OHD, and their discriminative effect was (AUC) 0.69. Previous osteoporotic fracture and lower plasma 25OHD were the important risk factors in men aged ≤80 years, with a discriminative effect of 0.83. In the >80-year age cohorts, only falls was independently associated with hip fracture in both sexes, with discriminative effects of 0.60 and 0.62 in females and males, respectively. The overall discrimination of hip fracture risk appears less adequate in those aged >80 years when compared with those aged ≤80 years. Although skeletal factors have a greater risk association with hip fracture in patients aged ≤80 years, it is falls that is important in those aged >80 years. The relative importance of risk factors also appears to vary between the sexes in those aged ≤80 years.