Abstract
Introduction
A fractured hip is the commonest cause of injury related death in the UK. Prompt surgery has been found to improve pain scores and reduce the length of hospital stay, risk of decubitus ulcer formation and mortality rates. The hip fracture Best Practice Tariff (BPT) aims to improve these outcomes by financially compensating services, which deliver hip fracture surgery within 36 hours of admission. Ensuring that delays are reserved for patients with conditions which compromise survival, but are responsive to medical optimisation, would facilitate enhanced outcomes and help to achieve the 36-hour target.
We aimed to identify medical conditions associated with patients failing to achieve the 36-hour cut off, and evaluated whether these were justified by calculating their associated mortality risk.
Methods
Prospectively collected data from the National Hip Fracture Database (NHFD) and inpatient hospital records and blood results from a single major trauma centre were obtained. Complete data sets from 1361 patients were available for analysis. Medical conditions contributing to surgical delay beyond the BPPT (Best Practice Tariff Target) 36-hour cut off, were identified and analysed using univariate and multivariate regression analyses, whilst adjusting for covariates. The mortality risk associated with each factor contributing to surgical delay was then calculated using univariate and hierarchical regression techniques.
Results
A total 1,361 patients underwent hip fracture surgery, of which 537 patients (39.5%) received surgery within 36- hours of admission. The overall median time to surgery from presentation was 23 hours (range 3–36) in patients who did (group 1) and 72 hours (range 36–774) in those who did not (group 2) receive timely surgery. There was no difference between the two groups with respect to age, gender, walking ability, fracture pattern and ASA grade.
Following univariate analysis, seven variables including admission source, history of dementia, ischaemic heart disease, MI, cerebrovascular accidents (CVA), urinary tract infections and hyponatraemia met criteria for inclusion into the Cox regression model. The model thereafter revealed only hyponatraemia to be a significant determinant of delay to surgery beyond 36 hours with a covariate adjusted relative risk (RR) 1.24 (95% CI 1.06 – 1.44, p=0.006).
The overall 30- day mortality in our cohort of hip fracture patients was 9.0%. The commonest cause of death was pneumonia (37%). A second stage hierarchical cox model failed to demonstrate hyponatraemia as being a predictor of 30- day mortality after adjusting for significant co-variants (RR=0.944, CI 95% 0.616–1.447, p=0.793).
Conclusions
Hip fracture surgery should not be delayed in the presence of non-severe and isolated hyponatraemia. Instead surgical delay should be reserved for medical conditions, which contribute to mortality and are optimisable.
