Independent validation of the Nottingham Hip Fracture Score and identification of regional variation in patient risk within England

The Nottingham Hip Fracture Score (NHFS) was developed to assess the risk of death following a fracture of the hip, based on pre-operative patient characteristics. We performed an independent validation of the NHFS, assessed the degree of geographical variation that exists between different units within the United Kingdom and attempted to define a NHFS level that is associated with high risk of mortality. The NHFS was calculated retrospectively for consecutive patients presenting with a fracture of the hip to two hospitals in England. The observed 30-day mortality for each NHFS cohort was compared with that predicted by the NHFS using the Hosmer-Lemeshow test. The distribution of NHFS in the observed group was compared with data from other hospitals in the United Kingdom. The proportion of patients identified as high risk and the mortality within the high risk group were assessed for groups defined using different thresholds for the NHFS. In all 1079 hip fractures were included in the analysis, with a mean age of 83 years (60 to 105), 284 (26%) male. Overall 30-day mortality was 7.3%. The NHFS was a significant predictor of 30-day mortality. Statistically significant differences in the distribution of the NHFS were present between different units in England (p < 0.001). A NHFS ≥ 6 appears to be an appropriate cut-point to identify patients at high risk of mortality following a fracture of the hip.