Association between markers of inflammation and outcomes after hip fracture surgery: analysis of routinely collected electronic healthcare data

BACKGROUND: Risk assessment tools such as the Nottingham Hip Fracture Score (NHFS) are crucial in guiding prognostic discussions and benchmarking in hip fracture care. These scores have scope to be improved, which may help identify higher-risk patients at admission. We investigated the role of inflammatory biomarkers, which are routinely collected at admission, in predicting post-operative outcomes following hip fracture. We subsequently combined these biomarkers with the NHFS to see if we could enhance risk prediction. METHODS: We analysed data from patients admitted to a trauma unit with hip fracture between 2015 and 2020 who underwent operative management. National hip fracture database (NHFD) data, including the NHFS, were linked with admission biomarkers: albumin, C-reactive protein (CRP), neutrophil-lymphocyte ratio (NLR) and monocyte-lymphocyte ratio (MLR). Following univariate and multivariate analyses, the discrimination of the NHFS with and without each biomarker was assessed for 30-day mortality, length of stay (LOS), and failure to return home at 30 days. RESULTS: We analysed 1039 patients, 719 (69.2%) were female and the mean age was 82.5 years (SD 8.1, range 60-104). In multivariate analysis, higher CRP was associated with higher 30-day mortality (odds ratio (OR) 1.23, 95%, confidence interval (CI) 1.04-1.44, p = 0.013); higher albumin was associated with lower 30-day mortality (OR 0.86, 95%CI 0.81-0.91, p < 0.001). Independent predictors of not returning home at 30 days included albumin (OR 0.94, 95% CI 0.91-0.98) and NLR (OR 1.44, 95% CI 1.14-1.81). NLR and MLR were significantly associated with prolonged LOS but not 30-day mortality. A composite variable of NHFS and albumin had better discrimination for 30-day mortality than NHFS alone (c-statistics 0.74, 95% CI 0.68-0.80 vs. 0.68, 95% CI 0.62-0.75, respectively). CRP, NLR and MLR did not improve discrimination for any outcome when added to NHFS. CONCLUSIONS: Albumin, but not other markers of inflammation, enhances risk prediction after hip fracture when added to the NHFS. Routine recording of albumin at admission may have a future role in an enhanced risk scoring system for prognostication in hip fracture surgery.