Chin-on-Chest in Neck of Femur Fracture (COCNOF) sign: A simple radiographic predictor of frailty and mortality in hip fracture patients.

Abstract

Fragility fractures are a significant public health challenge often occurring as a result of frailty. Identifying patients who have increased risk of adverse outcomes can aid treating teams in managing these patients appropriately. We hypothesise that the appearance of the patient's head overlapping the lung fields (named Chin on Chest in Neck of Femur sign (COCNOF)) in the admission chest radiograph was a predictor of increased mortality at 3, 6 and 12 months. All consecutive patients admitted with hip fracture between 1st January - 31st December 2019 were analysed. We collected patient characteristics, AMTS score, ASA grade, length of stay, place of discharge, Nottingham Hip Fracture Score, Rockwood Frailty score, Charlson Comorbidity Index and presence of COCNOF sign. The main outcome measures were mortality at 90 days, six months and 12 months following admission. 469 patients with a mean age of 81.9 (SD 8.4) were included. 18% of patients were COCNOF positive. Univariate analysis showed positive COCNOF sign to be associated with higher mortality at 90 days (19.1 vs 10.8%; RR 1.95, 95%CI 1.05 - 3.63,p=0.03), six months (31.5% vs 14.2%; RR 2.77, 95%CI 1.62 - 4.72, p<0.001) and twelve months (41.6% vs 17.1%; RR 3.45, 95%CI 1.62-4.72, p<0.001). In the multivariate regression models the strongest predictors of mortality were age, gender and CCI it is therefore likely that the COCNOF sign is acting as a surrogate marker of these variables within the univariate models. Our results suggest that COCNOF sign is a simple radiographic marker which can be used to identify patients with higher levels of frailty and increased risk of mortality following hip fracture.