The obesity paradox and mortality after pathological hip fractures: a Swedish registry study

Background and purpose - Obesity as measured by BMI has been associated with increased survival in various diseases, a phenomenon known as the "obesity paradox." It is unknown whether obesity is associated with survival after pathological fractures. We investigated the association between BMI and survival after surgery for pathological hip fracture, to improve survival prognostication, and lay grounds for further interventional nutritional studies. Patients and methods - We analyzed prospectively collected data from Swedish nationwide registry "RIKSHÖFT." The study cohort included 1,000 patients operated for a pathological hip fracture between 2014 and 2019. BMI registered on admission was available in 449 patients. Overall patient survival was measured according to the Kaplan-Meier method. Multivariable regression was used to evaluate association with other potential factors that influence patient survival. Results - Overweight and obesity were associated with an increased postoperative survival in male patients with surgically treated pathological hip fractures. Multivariable analysis considering potential confounders confirmed this finding. The association was not that strong in women and did not reach statistical significance. Interpretation - BMI, a commonly available clinical parameter, is a good predictor of overall survival for patients operated on for pathological hip fracture. Incorporation of BMI in existent survival prognostication algorithms should be considered. Treatment of malnutrition in this frail group of patients is worth studying.