Validation of the Nottingham Hip Fracture Score (NHFS) in Patients with Hip Fracture: A Prospective Cohort Study in the Netherlands

INTRODUCTION: The Nottingham Hip Fracture Score (NHFS) was developed to predict 30-day mortality for patients with hip fracture. This study aimed to validate the NHFS in a cohort with sufficient statistical power. METHODS: Data were extracted from a prospective hip-fracture database (FAMMI). Patients were included between January 1, 2018 and January 11, 2021. All consecutively admitted patients ≥18 years of age with a hip fracture (ie, femoral neck fracture, intertrochanteric fracture, and subtrochanteric fracture) were included. Mann–Whitney’s U values were calculated to find potential miscalibration of the NHFS formula. Discrimination evaluation was performed using the concordance statistic as an equivalent to area under the receiver-operating curve. RESULTS: In total, 2,458 patients were included. Mean age was 80±12 years, and 66% were women (n=1,631). Median NHFS was 5 (4–6) and overall 30-day mortality 7.9% (n=195). Overall goodness of fit was tested with Pearson’s ?(2) (11.8, df 10; P=0.297). No statistically significant signs of miscalibration were found (Mann–Whitney U, P=0.08). Discrimination was tested with area under the receiver- operating curve, which was 72.1% (95% CI 68.7%–75.4%). However, observed 30-day mortality in our population of hip-fracture patients was slightly higher than the NHFS prediction. CONCLUSION: The NHFS seemed to predict 30-day mortality with reasonable accuracy for patients with a hip fracture in a population within the Netherlands.