Multiple linear regression model (second column) with length of stay (days) as the outcome and demographic variables and occurrence of postoperative AKI as covariates using data from all T&O admissions between 1 June 2020 and 31 December 2020
| Variable | Mean difference in length of stay in days (95% CI); p value | Adjusted OR for 1-year postoperative mortality (95% CI); p value |
| Age | 0.05 (0.04 to 0.07); <0.001 | 1.10 (1.07 to 1.13); <0.001 |
| Sex | ||
| Female | 0 | 1 |
| Male | −0.41 (−1.10 to 0.28); 0.246 | 3.77 (2.04 to 7.14); <0.001 |
| Type of operation | ||
| Elective | 0 | 1 |
| Emergency | 1.36 (0.61 to 2.12); <0.001 | 2.28 (0.93 to 6.34); 0.089 |
| ASA grade | ||
| 1 or 2 | 0 | 1 |
| 3 or 4 | 1.98 (1.06 to 2.89); <0.001 | 5.75 (2.75 to 13.08); <0.001 |
| AKI | ||
| Postoperative AKI did not occur | 0 | 1 |
| Postoperative AKI occurred | 7.11 (4.84 to 9.38); <0.001 | 3.22 (1.03 to 10.55); 0.046 |
| Constant | −0.63 (−1.73 to 0.47); 0.261 | 0.00001 (0.000001 to 0.0001); <0.001 |
Binary logistic regression model (third column) with 1-year postoperative mortality as the outcome and demographic variables and occurrence of postoperative AKI as covariates using the same population.
The mean difference for each included variable in the model is equivalent to the mean difference in total length of stay (days) compared with a reference category when adjusting for other included covariates. For the binary logistic regression model, adjusted ORs, relative to a reference category for each variable (except age) and adjusted for all other variables, are presented here for each category. The reference category has an OR of 1.
AKI, acute kidney injury; ASA, American Society of Anaesthesiologists; T&O, trauma and orthopaedics.