External validation of a prognostic model for one-year survival after fragility hip fracture: A retrospective cohort study

Abstract

Purpose To scientifically manage fragility hip fracture patients, we have developed a survival prediction model for predicting 1-year survival after fragility hip fracture (SFHF). This study aims to validate the model. Methods This was a retrospective cohort study conducted in the orthopaedics department at a regional medical centre in central China. Fragility hip fracture patients who were consecutively admitted to the orthopaedics department from January 2016 to October 31, 2021. We evaluated the performance of an SFHF model (including the full model and the simplified model) from the following three aspects: (1) Discrimination. We presented the concordance (c) index of the model, including Harrell's c-index and Uno's c-value. Overall performance was measured using Nagelkerke R2 values. (2) Calibration. The calibration plot method was used to evaluate the calibration of the model. (3) Decision curve analysis (DCA) was used to judge whether the model had clinical value in the validation population. Results A total of 877 (≥ 50 years) (out of 1132) eligible fragility hip fracture patients were included in this study. Among them, 47 patients were lost to follow-up. Among the patients who were successfully followed up, 87 died within 1 year of the fracture. After applying simple imputation to deal with missing values, the final effective sample size was 93 cases. The 1-year mortality rate after fracture was 10.6%. The Harrell’s c-index values of the full and simple SFHF models were 0.764 (standard error, 0.024) and 0.763 (0.024), respectively. Uno’s c-values were 0.765 (0.024) and 0.763 (0.024), respectively. The Nagelkerke R2 values were 0.144 and 0.144, respectively. The calibration plot showed that the model had good calibration between predicted and actual values. DCA showed that the model was clinically useful within a threshold range of risk of death of 0.03–0.38. Conclusion Our study preliminarily confirmed that the SFHF model has good accuracy and generalizability in predicting the one-year survival rate of fragility hip fracture patients, and that it has good clinical value. This predictive model may be considered for clinical practice.