The association between osteoporosis and frailty: a cross-sectional observational study and mendelian randomization analysis

Abstract Background Osteoporosis and frailty are two common features in the elderly population. Despite many review articles mentioning the association between osteoporosis and frailty, there is a lack of original research directly investigating their relationship. Therefore, this study was conducted to examine the correlation between osteoporosis and frailty. Methods We conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey (NHANES), using logistic regression analysis to assess the association of osteoporosis with the frailty index. In addition, we further explored the causal relationship between them using Mendelian randomization (MR) study. Results In the cross-sectional study, 19,091 non-frailty participants and 5878 frailty participants were included in this study. We observed a significant positive association between osteoporosis and frailty after adjusting for demographic characteristics, body mass index (BMI), smoking, and alcohol use (OR = 1.454, 95% CI [1.142,1.851], P = 0.003). Moreover, the MR study showed a bidirectional causal relationship between osteoporosis and frailty. When osteoporosis was used as an exposure factor, the frailty pooled OR value calculated utilizing the inverse variance weighted (IVW) method was 2.81 (95% CI [1.69, 4.68], P = 6.82 × 10 − 5 ). When frailty was used as an exposure factor, the OR value calculated using the IVW method was 1.01 (95% CI [1.00,1.01], P = 3.65 × 10 − 7 ). Conclusions Osteoporosis was positively correlated with frailty, and the results remained robust after adjusting for covariates. Further, MR studies have shown a bidirectional causal relationship between osteoporosis and frailty.