Exposure to high altitude is associated with an elevated risk of hip fracture: a retrospective cohort study using data from the CHARLS

Previous investigations have suggested that high-altitude residency may increase the risk of bone loss; however, evidence on the impact of high-altitude exposure on the risk of hip fracture is lacking. Notably, hip fractures are the most serious complication of osteoporosis. We designed and conducted a retrospective cohort analysis using the China Health and Longitudinal Study data from 2011 to 2018. Participants were divided into two groups based on the altitude of their residence, with a threshold of 1500 m. Propensity score matching was used to balance covariates, including socioeconomic indicators and medical histories. Univariate Cox regression analysis was performed to evaluate the effect size of high-altitude exposure on the risk of hip fractures. To perform subgroup analysis, the participants were stratified based on sex, body mass index, smoking, and drinking. After matching, 399 participants in the high-altitude group and 3192 in the low-altitude group were enrolled. Cox regression showed that exposure to high altitude increased the risk of hip fracture (hazard ratio [HR]: 1.65, 95% confidence interval [CI]: 1.06–2.57, p = 0.03). Subgroup analysis showed that women (HR: 1.996, 95% CI: 1.142–3.491, p = 0.025) and participants with overweight (HR: 2.703, 95% CI: 1.186–6.165, p = 0.034) were vulnerable to the impact of high-altitude exposure compared with men and participants with normal weight. Exposure to high altitudes increases the risk of hip fractures, and prevention interventions should receive greater attention in these districts.