Identification of an Operative Time Threshold for Substantially Increased Postoperative Complications Among Elderly Spine Surgery Patients.

Study Design: Retrospective cohort study.

Objectives: To identify whether thresholds exist beyond which operative duration or age increases risks for complications among patients ≥65 years undergoing elective spine surgery.

Methods: Elective inpatient spine procedures unrelated to infection/trauma/tumor diagnoses in patients <65 years recorded in the 2006-2019 American College of Surgeons National Surgical Quality Improvement database were identified. Univariate analyses was used to compare 30 day complication rates among 5 operative duration and age-stratified groups. To quantify the risk of prolonged operative duration on complications, multivariate analyses were performed controlling for confounders. A generalized linear model was used to assess the individual and combined effect strength of age and operative duration on complication rates.

Results: Among 87,705 patients stratified by operative duration, 30 day complication rates rose nonlinearly as operative duration increased, with a sharp rise after 4.0-4.9 hours (28.3% at 4.0-4.9 hours, 51.7% at ≥5 hours, < .001). Multivariate analysis found operative duration was independently associated with increased risk of overall complications (odds ratio 1.10→1.69, .001) and medical complications (odds ratio 1.19→1.98, < .001). Although complication rates rose by age (all < .001), age was not independently predictive of overall complications within any operative duration group on multivariate analysis. Operative duration had a greater effect (η = .067) than age (η = .003) on overall complication rates.

Conclusions: Increased operative duration was strongly associated with 30 day complication rates, particularly beyond a threshold of 5 hours. Furthermore, operative duration had a notably larger effect on overall complication rates than age.