Impact of comorbidity on the association between surgery delay and mortality in hip fracture patients: A Danish nationwide cohort study

Purpose: To examine the association between surgery delay and mortality in hip fracture patients with and without known comorbidity. Methods: We identified all patients with a first time hip fracture diagnose operated between January 1, 2010 and December 31, 2015 (n = 36,552). As a measure of comorbidity we used Charlson Comorbidity Index stratified in categories: none (no registered comorbidities prior fracture), medium (1-2 points) and high (>= 3 points). Results: No association between surgery delay, regardless of the threshold, and 30-days mortality was observed among patients with high level of comorbidity. Surgery delay of >24h vs. <= 24 h was associated with higher 0-30-days mortality in patients with medium level of comorbidity (adjusted HR: 1.12 (95% CI: 1.01; 1.24)). In addition, surgery delay was associated with up to 45% increased mortality in patients with none comorbidity prior surgery, although the confidence intervals were wide. Furthermore, surgery delay of >24 h (vs. <24 h) and >48 h (vs. <= 48 h) was associated with higher 31-90-days mortality among all patients (adjusted HR: 1.19 (95% CI: 1.10; 1.29) and 1.35 (95% CI: 1.16; 1.56), respectively), but in particular among patients with none (adjusted HR: 1.26 (95% CI: 1.08; 1.47) and 1.65 (95% CI: 1.26; 2.17), respectively) and medium (adjusted HR: 1.21 (95% CI: 1.07; 1.36) and 1.25 (95% CI: 1.00; 1.57), respectively) level of comorbidity at the time of surgery. Conclusions: There was an association between surgery delay and 30-days mortality in hip fracture surgery patients with none and medium level of comorbidity, whereas no such association was observed among hip fracture patients with a high comorbidity level. Surgery delay was associated with one year increased risk of dying in both patients with and without comorbidity prior surgery. (C) 2019 The Authors. Published by Elsevier Ltd.