Association between wait-time and 30-day mortality in adults undergoing hip fracture surgery

Importance — Although wait-times for hip fracture surgery have been linked to mortality and are being used as quality-of-care indicators worldwide, controversy exists about the duration of the wait that leads to complications.

Objective — Use population-based wait-time data to identify the optimal time window in which to conduct hip fracture surgery before the risk of complications increases.

Design, Setting, and Participants — Population-based, retrospective cohort study of adults undergoing hip fracture surgery between April 1, 2009 and March 31, 2014 at 72 hospitals in Ontario, Canada.

Exposure — Time elapsed from hospital arrival to surgery (in hours).

Main Outcome Measure — Mortality within 30 days. Secondary outcomes included a composite of mortality or other medical complications (MI, DVT, PE, and pneumonia).

Analysis — Risk-adjusted restricted cubic splines modeled the probability of each complication according to wait-time. The inflection point (in hours) when complications began to increase was used to define ‘early’ and ‘delayed’ surgery. To evaluate the robustness of this definition, outcomes amongst propensity-score matched early and delayed patients were compared using percent absolute risk differences (% ARDs, with 95% confidence intervals [CIs]).

Results — Among 42,230 patients with hip fracture (mean [SD] age, 80.1 [10.7], 70.5% women) who met study entry criteria, overall mortality at 30 days was 7.0%. The risk of complications increased when wait-times were greater than 24 hours, irrespective of the complication considered. Compared to 13,731 propensity-score matched patients who received surgery earlier, 13,731 patients receiving surgery after 24 hours had a significantly higher risk of 30-day mortality (N=898 (6.5%) versus N=790 (5.8%), % ARD 0.79 [95% CI 0.23 to 1.35]) and the composite outcome (N=1,680 (12.2%) versus N=1,383 (10.1%), % ARD 2.16 [95% CI 1.43 to 2.89]).

Conclusions and Relevance — Among adults undergoing hip fracture surgery, increased wait-time was associated with a greater risk for 30-day mortality and other complications. A wait-time of 24 hours may represent a threshold defining higher risk.