Development and validation of a preoperative scoring system to predict 30 day mortality in patients undergoing hip fracture surgery

Background. Hip fractures are common in the elderly and have a high 30 day postoperative mortality. The ability to recognize patients at high risk of poor outcomes before operation would be an important clinical advance. This study has determined key prognostic factors predicting 30 day mortality in a hip fracture population, and incorporated them into a scoring system to be used on admission. Methods. A cohort study was conducted at the Queen's Medical Centre, Nottingham, over a period of 7 yr. Complete data were collected from 4967 patients and analysed. Forward univariate logistic regression was used to select the independent predictor variables of 30 day mortality, and then multivariate logistic regression was applied to the data to construct and validate the scoring system. Results. The variables found to be independent predictors of mortality at 30 days were: age (66-85 yr, >= 86 yr), sex (male), number of co-morbidities (>= 2), mini-mental test score (<= 6 out of 10), admission haemoglobin concentration (<= 10 g dl(-1)), living in an institution, and presence of malignant disease. These variables were subsequently incorporated into a risk score, the Nottingham Hip Fracture Score. The number of deaths observed at 30 days, and the number of deaths predicted by the scoring system, indicated good concordance (chi(2) test, P=0.79). The area (se) under the receiver operating characteristic curve was 0.719 (0.018), which demonstrated a reasonable predictive value for the score. Conclusions. We have developed and validated a scoring system that reliably predicts the probability of mortality at 30 days for patients after hip fracture.