Characteristics of study patients
| Case patients | Control patients | p-value | OR (95% CI) | |
| Subjects | 177 | 177 | ||
| At ICU admission | ||||
| Age yrs | 59±16 | 60±15 | 0.891 | |
| Male | 141 (79) | 122 (68) | 0.021 | 1.7 (1–2.7) |
| SAPS II | 41±12 | 42±12 | 0.872 | |
| Transfer to ICU from ward | 137 (77) | 158 (89) | 0.002 | 1.6 (1.1–2.4) |
| Diabetes mellitus | 25 (14) | 24 (13) | 0.550 | |
| COPD | 106 (59) | 84 (47) | 0.013 | 1.2 (1–1.5) |
| Prior antibiotic treatment | 102 (57) | 111 (62) | 0.193 | |
| Surgery | 39 (22) | 39 (22) | 0.551 | |
| Failed organs | 1.4±0.6 | 1.6±0.8 | 0.575 | |
| Type of organ failure | ||||
| Cardiac | 27 (15) | 40 (22) | 0.052 | |
| Respiratory | 146 (82) | 153 (86) | 0.189 | |
| Renal | 24 (13) | 30 (16) | 0.230 | |
| Neurological | 29 (16) | 21 (11) | 0.143 | |
| Digestive | 7 (3) | 7 (3) | 0.607 | |
| During ICU stay | ||||
| Stress ulcer prophylaxis | 91 (51) | 95 (53) | 0.375 | |
| Antibiotic treatment | 106 (59) | 104 (58) | 0.457 | |
| Duration of antibiotic treatment days | 12±12 | 15±15 | 0.060 |
Data are presented as n, mean±sd or n (%), unless otherwise stated. OR: odds ratio; CI: confidence interval; ICU: intensive care unit; SAPS: simplified acute physiology score; COPD: chronic obstructive pulmonary disease.