Associations with postoperative pneumonia
| Panel A | |||
|---|---|---|---|
| Marker | Pneumonia | No pneumonia | p Value |
| Preoperative leucocyte count in blood (×109/L) | 9.1 (8.4–11.2) | 7.9 (6.7–9.5) | 0.007 |
| Preoperative blood neutrophils (×109/L) | 5.8 (5.1–6.9) | 4.7 (4.1–5.7) | 0.015 |
| Preoperative BAL leucocyte count (millions/mL) | 0.14 (0.1–0.2) | 0.08 (0.0–0.1) | 0.012 |
| Serum IL-8 (48 h; pg/mL) | 17.4 (13.2–21.1) | 14.5 (10.5–16.8) | 0.031 |
| Serum TNF (48 h; pg/mL) | 6.9 (4.0–10.3) | 7.5 (5.3–9.2) | 0.023 |
| Monocyte supernatant IL-12 (preoperative; pg/mL/μg) | 0.140 (0.1–0.2) | 0.187 (0.1–0.3) | 0.008 |
| Monocyte supernatant IL-10 (24 h; pg/mL/μg) | 3.2 (2.1–4.7) | 1.4 (0.5–2.4) | 0.014 |
| Monocyte supernatant IL-6 (24 h; pg/mL/μg) | 525 (347–823) | 298 (115–532) | 0.040 |
| Monocyte supernatant IL-6 (48 h; pg/mL/μg) | 616 (397–778) | 315 (176–607) | 0.014 |
| Monocyte supernatant IL-8 (48 h; pg/mL/μg) | 2525 (2127–3448) | 2298 (1043–2719) | 0.040 |
| Panel B | |||||
|---|---|---|---|---|---|
| Biomarker | Optimum | Fisher | RR (95% CI) | Positive LR | Negative LR |
| Cut point | p Value | ||||
| Pre-op blood neutrophils (×109/L) | 5.04 | 0.02 | 3.3 (1.1 to 10.1) | 2.04 (1.17–3.57) | 0.32 (0.11–0.99) |
| Pre-op BAL white cell count (millions/mL) | 0.104 | 0.0093 | 3.4 (1.3 to 9.0) | 2.55 (1.25–5.19) | 0.40 (0.17–0.94) |
| Pre-op monocyte supernatant IL-12 (pg/mL/μg) | 0.147 | 0.0168 | 3.0 (1.2 to 7.3) | 2.78 (1.25–6.20) | 0.46 (0.22–0.96) |
| Monocyte supernatant IL-10 (24 h; pg/mL/μg) | 1.988 | 0.0072 | 4.1 (1.3 to 12.3) | 2.55 (1.35–4.83) | 0.31 (0.11–0.87) |
| Monocyte supernatant IL-6 (24 h; pg/mL/μg) | 414 | 0.02 | 3.1 (1.2 to 8.1) | 2.32 (1.19–4.51) | 0.41 (0.17–0.98) |
(A) Factors associated with postoperative pneumonia. Data are presented as medians with IQR in brackets. Statistical analysis was performed using an unpaired Student t test. Only factors that were significantly different in the two groups are shown. n=40 for all comparisons except preoperative BAL, serum and monocyte supernatant experiments at 48 h, where n=38.
(B) Predictive strength of biomarkers associated with pneumonia. The optimum cut point to dichotomise each parameter was determined by Youden's index. n=40 for all comparisons except preoperative BAL where n=38.
For both (A) and (B), monocyte supernatant values refer to monocytes stimulated ex vivo with LPS.
BAL, Bronchoalveolar lavage; LPS, lipopolysaccharide; LR, likelihood ratio; Pre-op, preoperative; RR, relative risk; TNF, tumour necrosis factor.