Table 3.
Results of the Multivariate Conditional Logistic Regression Analysis Using Different Hemoglobin Values as Predictors
| Variable | Model 1b (n = 379) | Model 2c (n = 292) |
|---|---|---|
| Hemoglobin levela | OR (95% CI) | OR (95% CI) |
| A. Pre-CPB (per g/dL decrease) | 1.12 (0.99–1.27) | 1.08 (0.92–1.25) |
| pRBC quartile | 1.37 (1.01–1.84) | |
| B. Post-CPB (per g/dL decrease) | 1.41 (1.13–1.75) | 1.28 (1.00–1.64) |
| pRBC quartile | 1.37 (1.02–1.83) | |
| C. Difference (per 1 g/dL larger diff) | 0.98 (0.87–1.11) | 0.96 (0.84–1.10) |
| pRBC quartile | 1.66 (1.26–2.18) | |
| D. Post-CPB below median vs above median | 1.86 (1.17–2.96) | 1.85 (1.07–3.18) |
| pRBC quartile | 1.39 (1.05–1.86) |
(A) hemoglobin 1; (B) hemoglobin 2; (C) [hemoglobin 1 – hemoglobin 2]; and (D) post-CPB hemoglobin dichotomized at its median value (8.8 g/dL), comparing those below the median with those above the median.
Variables with p < 0.1 in stepwise logistic regression without effect of transfusion: A, B, and D: peripheral vascular disease, CPB, preoperative mean arterial pressure in mm Hg; C: same but also history of obesity.
Same variables entered into model, plus quartile of number of units of pRBC transfused as a covariate. Variables included in final models (p < 0.1 in each stepwise regression): age, squared age, CPB, history of peripheral vascular disease, preoperative mean arterial pressure.
CI = confidence interval; CPB = cardiopulmonary bypass; OR = odds ratio; pRBC = packed red blood cells.