Table 4.
Cox regression analysis of risk factors for complicated appendicitis
| Hazard ratio | P | |
|---|---|---|
| Age (years) | ||
| <45 | 1.00 (reference) | 0.004 |
| 45–60 |
1.45
(0.99, 2.12) |
0.055 |
| >60 |
1.85
(1.28, 2.66) |
0.001 |
| Pre-CT delay (h)* | ||
| <24 | 1.00 (reference) | < 0.001 |
| 24–48 |
0.97
(0.63, 1.48) |
0.877 |
| >48 |
2.05
(1.32, 3.20) |
0.001 |
| Body temperature (°C) | ||
| ≤37.0 | 1.00 (reference) | < 0.001 |
| 37.1–37.9 |
1.51
(1.04, 2.20) |
0.029 |
| ≥38.0 |
2.38
(1.56, 3.65) |
< 0.001 |
| WBC count > 13×109/l |
1.40
(1.03, 1.88) |
0.030 |
| C-reactive protein (mg/l) | ||
| ≤50 | 1.00 (reference) | 0.021 |
| 51–100 |
1.15
(0.75, 1.75) |
0.526 |
| >100 |
1.75
(1.14, 2.67) |
0.009 |
| Extraluminal free air on CT |
1.47
(0.60, 3.56) |
0.398 |
| Periappendiceal fluid on CT |
2.11
(1.39, 3.19) |
< 0.001 |
| Appendicolith on CT |
2.71
(2.01, 3.64) |
< 0.001 |
| Time from CT to antibiotics started (h) |
0.94
(0.90, 0.97) |
< 0.001 |
Values in parentheses are 95 per cent confidence intervals.
*Pre-CT delay is time from CT to start of operation; time to event is time from CT to surgery. WBC, white blood cell.