Fractures at various skeletal sites are dependent on different risk factors: the results from 10 years of prospective longitudinal observation in postmenopausal women from the RAC-OST-POL Study

Introduction: The aim of the study was to present data on risk factors for fractures in various parts of the skeleton in a cohort of postmenopausal women during a 10-year prospective observation period. It can be hypothesised that fracture risk factors should be different for spine, hip, and peripheral fractures. Material and methods: 640 postmenopausal women at mean baseline age was 65.0 +/- 6.9 years were enrolled into the study. The cohort was randomly selected from the population of the entire Racib & oacute;rz district. Data on the incidence of fractures and falls were updated annually during the 10-year follow-up period. Information on clinical risk factors for fractures was collected at baseline. Results: During the observation period, 190 low-traumatic fractures were recorded in 129 patients. The following number of fractures was observed: hip 15, spine 30, non-hip fractures other than spine 145 (including 81 forearm fractures). The effect of falls was insignificant in the case of spine fractures (chi-square test: 3.64; p = 0.06). For all other skeletal sites, the incidence of fractures was significantly increased by falls, with the greatest effect observed for forearm fractures and non-spine and non-hip fractures (chi-square test for hip, forearm, and all non-spine, non-hip fractures was 6.43, p < 0.05; 42.7, p < 0.0001 and 66.7, p < 0.0001, respectively). To determine the factors having a significant impact on the incidence of fractures during the observation period, logistic regression was used separately in subgroups. The following risk factors were taken into account: age, height, body weight, bone mineral density (BMD) at the femoral neck as expressed by T-score, rheumatoid arthritis, steroid use, falls reported at baseline, and the total number of risk factors. Spine fractures depended only on T-score, odds ratio (OR) = 0.42 (0.23-0.76); hip fractures depended only on age, OR = 1.15 (1.07-1.24); forearm fractures depended only on age T-score, OR = 0.69 (0.51-0.92); and non-hip, non-spine on fall rate, OR = 1.86 (1.20-2.87). Conclusions: Fractures at various skeletal sites recorded in long-term follow-up in postmenopausal women were dependent on various risk factors. Multivariate analysis identified a single, dominant risk factor for each fracture location analysed.