Multivariate regression results assessing association of individual process metrics and LOS
| Covariates | Minimally invasive surgery | Open surgery | ||
| Rate ratio | 95% CI | Rate ratio | 95% CI | |
| Age group (ref ≤45) | ||||
| 46–65 years | 1.03 | 1.00 to 1.07 | 1.15 | 1.01 to 1.31 |
| >65 years | 1.09 | 1.05 to 1.13 | 1.29 | 1.11 to 1.50 |
| BMI (ref=normal) | ||||
| Overweight | 1.05 | 1.01 to 1.08 | 1.07 | 0.95 to 1.21 |
| Obese | 0.97 | 0.94 to 1.01 | 1.18 | 1.04 to 1.33 |
| ASA (ref=mild) | ||||
| Healthy | 0.97 | 0.92 to 1.02 | 0.90 | 0.67 to 1.12 |
| Severe | 1.07 | 1.02 to 1.11 | 1.12 | 0.97 to 1.29 |
| Missing | 0.97 | 0.93 to 1.02 | 1.13 | 0.99 to 1.27 |
| Has diabetic | 1.03 | 0.98 to 1.08 | 0.99 | 0.82 to 1.20 |
| Weekend (ref=weekdays) | 1.12 | 1.03 to 1.23 | 1.08 | 0.90 to 1.29 |
| Surgery year* (ref=2017) | ||||
| 2018 | 0.96 | 0.92 to 1.00 | 0.90 | 0.78 to 1.03 |
| 2019 | 0.90 | 0.87 to 0.94 | 0.91 | 0.79 to 1.05 |
| Process metrics | ||||
| Preemptive analgesia | 1.00 | 0.97 to 1.03 | 1.09 | 0.98 to 1.21 |
| Intraop <4cc/kg/hour | 1.04 | 1.01 to 1.07 | 0.91 | 0.80 to 1.04 |
| Antiemetics | 1.03 | 0.97 to 1.08 | 0.70 | 0.60 to 0.82 |
| Postop analgesia | 1.01 | 0.98 to 1.04 | 1.01 | 0.91 to 1.11 |
| Postop <1cc/kg/hour | 1.37 | 1.32 to 1.42 | 0.88 | 0.79 to 0.99 |
| Ambulation <8 hours | 0.47 | 0.45 to 0.48 | 0.92 | 0.79 to 1.07 |
| Bowel preparation | NA | 1.13 | 1.00 to 1.27 | |
| Preoperative carbohydrate drink | 1.00 | 0.96 to 1.04 | 1.08 | 0.97 to 1.21 |
| Preoperative chlorhexidine wash | 1.00 | 0.97 to 1.03 | 0.92 | 0.81 to 1.03 |
| Likelihood ratio test† | χ2(20)=2419, p<0.001 | χ2(21)=84, p<0.001 | ||
*For surgery year, data from October to December 2016 data are treated as 2017 data and January 2020 data are treated as 2019 data.
†The likelihood ratio test compares an empty model with the model specified in the table.
ASA, American Society of Anesthesia; BMI, body mass index; LOS, length of stay; NA, not availble.