Adjusted 30-day and 12 -month mortality for all variables included in Cox proportional hazards models analyses of operator volumes and potential confounders
| Factors | 30-day mortality Adjusted HR (95% CI) | 12-month mortality Adjusted HR (95% CI) |
| Low-volume operators | 1.48 (1.05 to 2.08)* | 1.26 (0.96 to 1.65) |
| Intermediate-volume operators | 1.29 (0.91 to 1.81) | 1.21 (0.93 to 1.58) |
| Out-of-hours presentation | 1.02 (0.77 to 1.35) | 1.12 (0.89 to 1.39) |
| Previous myocardial infarction | 1.48 (1.02 to 2.14)* | 1.51 (1.13 to 2.00)* |
| Hypertension | 1.09 (0.80 to 1.49) | 1.14 (0.90 to 1.46) |
| Hypercholesterolaemia | 0.79 (0.56 to 1.11) | 0.79 (0.61 to 1.03) |
| Diabetes mellitus | 1.54 (1.07 to 2.22)* | 1.64 (1.24 to 2.17)* |
| Peripheral/cerebral vascular disease | 1.44 (0.96 to 2.17) | 1.92 (1.43 to 2.57)* |
| Current/ex-smoker | 0.79 (0.57 to 1.10) | 0.91 (0.70 to 1.17) |
| Left main coronary artery culprit vessel | 7.27 (4.11 to 12.85)* | 5.00 (2.93 to 8.52)* |
| Advancing age | 1.05 (1.04 to 1.07)* | 1.06 (1.05 to 1.08)* |
| Door-to-balloon time ≥90 min | 1.46 (1.05 to 2.03)* | 1.52 (1.17 to 1.97)* |
*p≤0.05. All HRs were obtained from Cox models used to analyse operator volumes. The reference category for operator volume analysis is high-volume operators.20