Validation of the Nottingham Hip Fracture Score (NHFS) to predict 30-day mortality in patients with an intracapsular hip fracture.

Background: The Nottingham Hip Fracture Score (NHFS) was developed to predict 30-day mortality following a fracture of the hip. While the NHFS has been validated in three hip fracture populations within Great Britain, these studies make no distinction between the type of fracture and surgery. Literature 'however' shows an increased risk for mortality after a hemi-arthroplasty following an intra-capsular hip fracture. To verify whether the mortality after an intra-capsular hip fracture is higher compared to the predicted mortality score according to the NHFS, a validation of the NHFS in patients with a hemi-arthroplasty after an intra-capsular hip fracture was performed.

Methods: The NHFS was calculated for consecutive patients presenting with an intra-capsular fracture of the hip in two level II trauma teaching hospitals between 1 January 2011 and 1 May 2016. The observed 30-day mortality was compared with that predicted by the NHFS using several validation statistics.

Results: A total of 901 patients were included in the present study. Mean age in the patients was 83 years (SD 8) and 623 (68%) of the patients were female. Almost 60% of the patients had an ASA-score (American Society of Anaesthesiologists [ASA]) of≥3 and overall 30-day mortality was 9.5% (n=86). The median NHFS was 5, and there was no significant change in median NHFS over the past 5 years. The mortality rate in the studied population of hemi-arthroplasty patients was significantly higher than mortality rates predicted by the NHFS (p=0.022, Pearson's Chi-squared test).

Conclusions: Findings suggest that for a patient with a hemi-arthroplasty following an intra-capsular hip fracture, there could be an underestimation for the 30-day mortality rate following the NHFS prediction model.

Level Of Evidence: Prognostic Level III, retrospective cohort study.