The Association between Timing of Elective Surgery Scheduling and Operating Theater Utilization: A Cross-Sectional Retrospective Study

BACKGROUND: Overutilization of operating theaters (OTs) occurs when actual surgery duration exceeds scheduled duration, which could potentially result in delays or cancelations in subsequent surgeries. We investigate the association between the timing of elective surgery scheduling and OT overutilization. METHODS: A cross-sectional retrospective study was conducted using electronic health record data of 27,423 elective surgeries from July 1, 2016, to July 31, 2018, at a mid-Atlantic academic medical center with 56 OTs. The scheduling precision of each surgery is measured using the ratio of the actual (A) over the scheduled or forecast (F) length of surgery to derive the predictor variable of A/F (actual-to-forecast ratio [AF]). Student t test and χ²tests analyzed differences between OTs reserved within and over 7 days of surgery for continuous and dichotomous variables, respectively. Hierarchical regression models, controlling for potential confounds from the hospital environment, clinicians' work experience and workloads, patient factors, scheduled OT length, and operational and team factors isolated the association between OTs reserved within 7 days of the elective surgery with AF. RESULTS: The Student t test indicates that OTs reserved within 7 days of surgery had significantly higher AF (1.13 ± 0.53 vs 1.08 ± 0.41; P <.001). In-depth Student t test analyses for 4 patient groups, namely, outpatient, extended recovery, admission after surgery, and inpatient, indicate that AF was only significantly different for OTs reserved within 7 days for the admission after surgery group (1.15 ± 0.47 vs 1.09 ± 0.35; P <.001) but did not reach statistical significance among the outpatient, extended recovery, and inpatient groups. After controlling for potential confounds, hierarchical regression for the admission after surgery group reveals that OTs reserved within 7 days took 2.7% longer than the scheduled length of surgery (AF beta, 0.027; 95% CI, 0.003-0.051; P =.027). CONCLUSIONS: Elective surgeries scheduled within 7 days of surgery were associated with significantly higher likelihood of OT overutilization for surgical patients who will be admitted after surgery. Further studies at other hospitals and a longer period of time are needed to ascertain a potential "squeeze-in" effect.