Association between frailty index and hip fracture among Chinese middle- and old-aged adults in different glycemic status: a prospective study from the China Health and Retirement Longitudinal Study (CHARLS)

BACKGROUND: Frailty and diabetes are recognized as risk factors for hip fracture. However, the specific association between frailty and the risk of hip fracture, particularly in individuals with different glycemic statuses, remains to be explored. OBJECTIVE: This study focused on evaluating the predictive value of a 35-item frailty index (FI35) in assessing hip fracture risk under different glycemic states. METHODS: This study was a prospective cohort study, enrolled a total of 10 049 middle-aged and elderly participants from the China Health and Retirement Longitudinal Study. The primary outcome was the first occurrence of hip fracture events. Frailty status was calculated using an FI35. We used Kaplan-Meier curves, Cox proportional hazard models, and restricted cubic spline analysis to analyze the association between frailty and hip fracture risk according to gender, age, and glycemic status. RESULTS: During a follow-up of 9 years, 629 (6.26%) participants experienced a hip fracture. Our findings revealed a significant positive linear relationship between FI35 and the incidence of hip fracture. This association was similar between men and women, although the hazard ratio (HR) tended to be slightly higher in women [HR 1.59, 95% confidence interval (CI) 1.39, 1.83] than in men (HR 1.55, 95% CI 1.31, 1.85). The association was also similar between middle-aged (HR 1.44, 95% CI 1.20, 1.73) and elderly participants (HR 1.62, 95% CI 1.44, 1.85). In individuals with different glycemic statuses, higher levels of FI35 were linked to an increased risk of hip fracture in those with normal glucose regulation (HR 1.46, 95% CI 1.24, 1.71), prediabetes mellitus HR 1.60, 95% CI 1.35, 1.90), and diabetes mellitus (HR 1.90, 95% CI 1.49, 2.42). CONCLUSION: Our findings indicate a significant positive linear relationship between frailty and the occurrence of hip fracture. The association between FI and hip fracture was similar between male and female participants, and similar in middle-aged and elderly participants. In different glycemic status, the risk of hip fracture increases with worsening glycemic status.