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.