Odds ratio obtained from multiple logistic regression analysis for the rate of normal appendix removal in 43 061 patients undergoing primary appendicectomy in Ontario, 1989/90–1992/93
| Independent variables | Model I: Time to surgery analysed at individual level only | Model II: Time to surgery analysed at hospital level only | Model III: Time to surgery analysed at both individual and hospital level |
| Time to surgery (individual level) | 2.33 (2.20, 2.46) | NA | 2.41 (2.28, 2.56) |
| - ⩾1 day v 0 day | |||
| Time to surgery (hospital level) | NA | 0.92 (0.89, 0.96) | 0.85 (0.82, 0.88) |
| - each 10% increase in ⩾1 day of the admitted hospital | |||
| Primary appendicectomy volume | 1.01 (1.01, 1.02) | 1.01 (1.00, 1.01) | 1.01 (1.00, 1.01) |
| - 50 cases increase | |||
| Bed size | 0.99 (0.98, 0.99) | 1.00 (0.99, 1.00) | 1.00 (0.99, 1.00) |
| - 30 bed increase | |||
| Treated in teaching hospital | 1.03 (0.97, 1.09) | 1.05 (0.99, 1.11) | 1.04 (0.98, 1.10) |
| - no=0; yes=1 | |||
| Sex | 2.46 (2.33, 2.60) | 2.56 (2.42, 2.70) | 2.46 (2.33, 2.60) |
| - male=0; female=1 | |||
| Age | 1.09 (1.07, 1.10) | 1.11 (1.10, 1.13) | 1.09 (1.07, 1.10) |
| -10 year increase | |||
| Admission status | 4.37 (3.99, 4.78) | 5.76 (5.28, 6.29) | 4.43 (4.05, 4.85) |
| - emergency or urgent=0; elective=1 | |||
| Comorbidity | 1.71 (1.52, 1.91) | 1.83 (1.63, 2.04) | 1.68 (1.50, 1.88) |
| - none=0; any=1 |
Numbers in parentheses represent 95% confidence intervals; NA: not applicable.