Mortality Prediction in Hip Fracture Patients: Physician Assessment Versus Prognostic Models

Abstract

Objectives: To evaluate 2 prognostic models for mortality after a fracture of the hip, the Nottingham Hip Fracture Score and Hip Fracture Estimator of Mortality Amsterdam and to compare their predictive performance to physician assessment of mortality risk in hip fracture patients.

Design: Prospective cohort study.

Setting: Two level-2 trauma centers located in the Netherlands.

Patients: Two hundred forty-four patients admitted to the Emergency Departments of both hospitals with a fractured hip.

Intervention: Data used in both prediction models were collected at the time of admission for each individual patient, as well as predictions of mortality by treating physicians.

Main outcome measures: Predictive performances were evaluated for 30-day, 1-year, and 5-year mortality. Discrimination was assessed with the area under the curve (AUC); calibration with the Hosmer-Lemeshow goodness-of-fit test and calibration plots; clinical usefulness in terms of accuracy, sensitivity, and specificity.

Results: Mortality was 7.4% after 30 days, 22.1% after 1 year, and 59.4% after 5 years. There were no statistically significant differences in discrimination between the prediction methods (AUC 0.73-0.80). The Nottingham Hip Fracture Score demonstrated underfitting for 30-day mortality and failed to identify the majority of high-risk patients (sensitivity 33%). The Hip fracture Estimator of Mortality Amsterdam showed systematic overestimation and overfitting. Physicians were able to identify most high-risk patients for 30-day mortality (sensitivity 78%) but with some overestimation. Both risk models demonstrated a lack of fit when used for 1-year and 5-year mortality predictions.

Conclusions: In this study, prognostic models and physicians demonstrated similar discriminating abilities when predicting mortality in hip fracture patients. Although physicians overestimated mortality, they were better at identifying high-risk patients and at predicting long-term mortality.

Level of evidence: Prognostic Level II. See Instructions for Authors for a complete description of levels of evidence.