Emergency department prediction model for 30-day mortality after hip fracture: the Spanish National Hip Fracture Registry (RNFC) cohort

Introduction: The aim of this study was to design and validate a predictive model for 30-day mortality in a cohort of patients from the Spanish National Hip Fracture Registry (RNFC) with variables collected at the Emergency Department.Methods: Retrospective study of a prospective database of hip fracture patients >75 years old between 1 January 2017 and 30 September 2019. Patient characteristics, type of fracture and osteoprotective medication were collected at the Emergency Department. Univariate analysis compared the results between patients alive and deceased 30 days after hospital discharge. The variables associated with 30-day mortality in the regression analysis were age >85 years, male sex, indoors pre-fracture mobility, dementia, ASA score >3, pathological fracture, and vitamin D intake. A score scale was created with these variables. Discriminative performance was assessed using the area under the curve (AUC), calibration was assessed by applying Hosmer-Lemeshow goodness-of-fit test and predicted-to-observed mortality was compared.Results: A total of 29,875 hip fracture cases were included in the study. The 30-day mortality of the overall cohort was 7.7%. A scale of 0-9 points was created, with a cut-off point of 4 points for the determination of patients at high risk of mortality. The AUC was 0.886. RNFC score presented good level of calibration (p = 0.139). The predicted-to-observed ratio was 1.09.Conclusions: The RNFC predictive model with variables collected at the Emergency Department showed an excellent predictive capacity for 30-day mortality in patients after hip fracture.