Background The obesity paradox, which suggests that high body weight is positively associated with survival in some diseases, has not been proven in patients with hip fracture. In this study, meta-analysis of previous studies on the impacts of body weight on postoperative mortality following hip fracture surgery in older adults was conducted. Methods PubMed, Embase, and Cochrane library were searched for studies investigating the correlation between mortality after hip fracture surgery and body weight. The search main items included: (“Body mass index” OR “BMI” or “body weight”) and (“hip fracture” or “hip fractures”). Studies contained data on short-term (≤ 30-day) and long-term (≥ 1 year) mortality after hip fracture and its association with distinct body weight or BMI groups were reported as full-text articles were included in this meta-analysis. Results Eleven separate studies were included. The definitions of underweight and obesity differed among the included studies, but the majority of the enrolled studies used the average body weight definition of a BMI of 18.5 to 24.9 kg/m2; underweight referred to a BMI of < 18.5 kg/m2; and obesity pertained to a BMI of > 30 kg/m2. Based on the generalized definitions of body-weight groups from the enrolled studies, the group with obesity had lower long-term (odds ratio [OR]: 0.63, 95% CI: 0.50–0.79, P < 0.00001) and short-term (OR: 0.63, 95% CI: 0.58–0.68, P ≤ 0.00001) mortality rates after hip fracture surgery when compared with patients with average-weight group. However, compared with the average-weight group, the underweight group had higher long-term (OR: 1.51, 95% CI: 1.15-1.98, P=0.003) and short-term (OR: 1.49, 95% CI: 1.29-1.72, P<0.00001) mortality rates after hip fracture surgery. Conclusions Current evidence demonstrates an inverse relation of body weight with long-term and short-term mortality after hip fracture surgery in older adults.

Background Hip fracture is a major concern in older adults. It may result in the long-term loss of mobility and self-care ability in patients. Functional status decreases soon after hip fracture surgery but increases gradually thereafter. However, some patients may without strong physical resilience eventually exhibit functional dependence. In this study, we investigated whether short-term postoperative changes in activity of daily living (ADL) performance and quality of life (QoL) can predict the 1-year outcomes of hip fracture surgery in older Taiwanese adults. Methods This prospective cohort study included older adults (≥ 60 years) who underwent hip fracture surgery at a single tertiary medical center in Taiwan between November 2017 and March 2021. We collected baseline data, including the patients’ demographics, Charlson comorbidity index (CCI) scores, and responses to a questionnaire (Short Portable Mental State Questionnaire [SPMSQ]) for dementia screening. Moreover, their scores on the EuroQol-5D questionnaire (for evaluating QoL) and Barthel Index (for assessing ADL performance) were collected at baseline and 3 and 12 months after surgery. Changes in ADL performance and QoL 3 months after surgery were evaluated, and the associations of these parameters (and other potential factors) with 1-year surgical outcomes were investigated. Results We analyzed the data of 318 patients with hip fracture and complete follow-up data regarding ADL performance and QoL 3 and 12 months after surgery. After covariate adjustment, multivariate logistic regression revealed that changes in ADL performance and QoL 3 months after surgery were positively and significantly correlated with 1-year surgical outcomes (p < .001). Furthermore, baseline CCI and SPMSQ scores were independent predictive factors associated with 1-year ADL outcomes (p = .042 and < .001, respectively). Conclusions Short-term functional recovery may help predict long-term ADL and QoL outcomes in older adults. Thus, short-term rehabilitation programs are recommended, particularly within 3 postoperative months, to prevent long-term functional dependence. Our study may serve as a reference for future studies aimed at improving the ADL performance and QoL of older patients after hip fracture surgery.