Table 2.
Proportional Hazards Model of Hospital Stay after Primary Coronary Artery Bypass Graft Surgery with Preoperative and Postoperative B-type Natriuretic Peptide Measures Alone and Together in the Model (n = 1,131*)
| AIC = 4,641.79 for Clinical Model without BNP Covariates | Model Including Log10 Preoperative BNP AIC = 4,632.84 |
Model Including Log10 Peak Postoperative BNP AIC = 4,633.60 |
Model Including Both Log10 Preoperative BNP and Log10 Peak Postoperative BNP AIC = 4,630.94 |
|||
|---|---|---|---|---|---|---|
| Hazard Ratio (95% CI) | P Value | Hazard Ratio (95% CI) | P Value | Hazard Ratio (95% CI) | P Value | |
| Predictor | ||||||
| Log10 preoperative BNP | 1.13 (1.05–1.21) | 0.0007 | — | — | 1.09 (1.01–1.18) | 0.03 |
| Log10 peak postoperative BNP | — | — | 1.44 (1.15–1.81) | 0.001 | 1.28 (1.002–1.64) | 0.049 |
| Age (10-yr increment) | 1.07 (1.003–1.14) | 0.04 | 1.07 (1.003–1.14) | 0.04 | 1.06 (0.994–1.13) | 0.08 |
| Gender (female) | 1.08 (0.92–1.27) | 0.32 | 1.05 (0.89–1.24) | 0.55 | 1.05 (0.89–1.23) | 0.59 |
| Institution | 1.63 (1.40–1.90) | < 0.0001 | 1.70 (1.45–1.98) | < 0.0001 | 1.69 (1.45–1.98) | < 0.0001 |
| Ethnicity (minority) | 1.20 (1.01–1.43) | 0.04 | 1.20 (1.01–1.43) | 0.03 | 1.20 (1.01–1.43) | 0.03 |
| Preoperative nonaspirin platelet inhibitor | 1.22 (1.05–1.41) | 0.01 | 1.24 (1.07–1.44) | 0.004 | 1.23 (1.06–1.43) | 0.007 |
| Preoperative β blocker | 0.84 (0.72–0.97) | 0.02 | 0.84 (0.72–0.97) | 0.02 | 0.83 (0.72–0.96) | 0.01 |
| History of preoperative arrhythmia treatment | 1.24 (1.01–1.52) | 0.04 | 1.26 (1.02–1.55) | 0.03 | 1.24 (1.01–1.52) | 0.04 |
| Cardiopulmonary bypass time > 120 min | 1.21 (1.04–1.41) | 0.01 | 1.22 (1.05–1.42) | 0.009 | 1.21 (1.04–1.41) | 0.01 |
| Preoperative left ventricular ejection fraction (%) | 0.999 (0.994–1.004) | 0.72 | 0.998 (0.993–1.003) | 0.49 | 1.000 (0.994–1.005) | 0.88 |
| New onset postoperative atrial fibrillation | 1.81 (1.57–2.08) | < 0.0001 | 1.78 (1.54–2.04) | < 0.0001 | 1.79 (1.55–2.05) | < 0.0001 |
| Postoperative ventricular dysfunction | 2.16 (1.76–2.65) | < 0.0001 | 2.08 (1.69–2.55) | < 0.0001 | 2.09 (1.70–2.56) | < 0.0001 |
| Postoperative creatinine clearance (ml · min−1 · 1.73 m−2) | 0.988 (0.985–0.991) | < 0.0001 | 0.988 (0.985–0.991) | < 0.0001 | 0.989 (0.986–0.992) | < 0.0001 |
*
Fifty-two subjects missing one or more of the model’s predictor variables and are not included in this analysis; 18 subjects censored for hospital length of stay more than 30 days or for in-hospital death within 30 days of surgery.
AIC = Akaike information criterion; BNP = B-type natriuretic peptide; CI = confidence interval.