Primary outcome | Day surgery (n=322 327) | Night surgery (n=27 908) | Unadjusted analysis | Adjusted analysis | ||||
Absolute difference (95% CI)* | OR (95% CI) | P value | Adjusted absolute difference (95% CI)† | ORadj (95% CI) | P value | |||
30 day mortality | 2804 (0.9%) | 940 (3.4%) | – | 2.45 (2.26 to 2.65) | <0.001 | – | 1.26 (1.15 to 1.38) | <0.001 |
Unadjusted analysis | Adjusted analysis | |||||||
Secondary outcome |
Day surgery
(n=283 185) |
Night surgery
(n=20 707) |
Absolute difference
(95% CI)* | OR (95% CI) | P value |
Adjusted absolute difference
(95% CI)† | ORadj (95% CI) | P value |
30-day morbidity | 22 919 (8.1%) | 2723 (13.2%) | 5.1% (4.6% to 5.5%) | 1.72 (1.65 to 1.79) | <0.001 | 2.1% (1.7% to 2.4%) | 1.41 (1.33 to 1.48) | <0.001 |
Cardiovascular | 6875 (2.4%) | 599 (2.9%) | 0.5% (0.2 to 0.7) | 1.2 (1.10 to 1.30) | <0.001 | 0.2% (0.0% to 0.3%) | 1.14 (1.03 to 1.27) | 0.011 |
Pulmonary | 1533 (0.5%) | 203 (1.0%) | 0.4% (0.3% to 0.6%) | 1.82 (1.57 to 2.11) | <0.001 | 0.1% (0.1% to 0.2%) | 1.46 (1.22 to 1.74) | <0.001 |
Renal | 2565 (0.9%) | 409 (2.0%) | 1.1% (0.9% to 1.3%) | 2.20 (1.98 to 2.45) | <0.001 | 0.2% (0.1% to 0.3%) | 1.42 (1.25 to 1.61) | <0.001 |
Intestinal/Digestive | 1712 (0.6%) | 113 (0.5%) | 0.1% (0.2% to 0.1%) | 0.90 (0.75 to 1.09) | 0.29 | 0.0% (0.0% to 0.0%) | 0.79 (0.62 to 1.0) | 0.051 |
Haemorrhage | 9342 (3.3%) | 1232 (5.9%) | 2.7% (2.3% to 3.5%) | 1.85 (1.74 to 1.97) | <0.001 | 1.2% (0.9 to 1.45) | 1.50 (1.39 to 1.62) | <0.001 |
Infections | 6454 (2.3%) | 1032 (5.0%) | 2.7% (2.4% to 3.0%) | 2.25 (2.10 to 2.41) | <0.001 | 0.9% (0.7% to 1.1%) | 1.59 (1.46 to 1.72) | <0.001 |
Data are expressed as frequency (prevalence in %). Statistical analyses were performed using multivariable logistic regression. OR, absolute differences and adjusted absolute differences are reported.
*Absolute difference indicates the difference in risk between compared groups, as estimated following unadjusted regression analysis.
†Adjusted absolute difference indicates the difference in risk attributable to use of night surgery, as estimated following adjusted regression analysis.