Impact of body mass index on surgical case durations in an academic medical center

Abstract

Study objectiveTo investigate the association between patient body mass index (BMI) and operating room duration. DesignRetrospective cohort analysis. SettingDemographic data and anesthesia/surgical times for adult surgical patients at University of Virginia Health between August 2017 and February 2019 were collected and analyzed. PatientsA total of 31,548 cases were included in the final analysis. 55% of patients were female, and 51% were classified as ASA Physical Status 2. The mean operating room (OR) duration was 144.2 min ± 112.7 (median = 118, IQR = 121). Orthopedic surgery (32%) was the most common surgery. MeasurementsLinear mixed effects models were used to examine whether procedure intervals differed across three BMI categories (BMI < 30, 30 ≤ BMI < 40, BMI ≥ 40), considering within-surgeon correlations. Surgical times were log-transformed to correct for positive skewness. Main resultsThe average time in the operating room was longer for patients with higher BMI (mean ± SD [median, IQR] = 139.5 ± 111.2 [113.0, IQR = 114], 150.2 ± 115.4 [125, IQR = 127], and 153.1 ± 111.1 [130, IQR = 134] for BMI < 30, 30 ≤ BMI < 40, and BMI ≥ 40), respectively. We found a 2% [95% CI = 1–3%] and 3% [95% CI = 1–5%] increase in OR time for 30 ≤ BMI < 40 and BMI ≥ 40, respectively, compared to BMI < 30, after controlling for within-surgeon correlations and covariates. The excess time was primarily determined by anesthesia times. ConclusionIn an academic hospital, patients with BMI ≥ 30 required more time in the operating room than patients with BMI < 30, when controlling for confounders. This information can be incorporated into modern-day OR scheduling software, potentially resulting in more accurate case duration estimates that reduce waiting and improve OR efficiency.