Preoperative C-reactive protein predicts long-term mortality and hospital length of stay after primary, nonemergent coronary artery bypass grafting

Abstract

Background: Preoperative C-reactive protein (CRP) levels more than 10 mg/l have been shown to be associated with increased morbidity and mortality after cardiac surgery. We examine the value of preoperative CRP levels less than 10 mg/l for predicting long-term, all-cause mortality and hospital length of stay in surgical patients undergoing primary, nonemergent coronary artery bypass graft-only surgery.

Methods: We examined the association between preoperative CRP levels stratified into four categories (< 1, 1-3, 3-10, and > 10 mg/l), and 7-yr all-cause mortality and hospital length of stay in 914 prospectively enrolled primary, nonemergent coronary artery bypass graft-only surgical patients using a proportional hazards regression model.

Results: Eighty-seven patients (9.5%) died during a mean follow-up period of 4.8 +/- 1.5 yr. After proportional hazards adjustment, the 3-10 and > 10 mg/l preoperative CRP groups were associated with long-term, all-cause mortality (hazards ratios [95% CI]: 2.50 [1.22-5.16], P = 0.01 and 2.66 [1.21-5.80], P = 0.02, respectively) and extended hospital length of stay (1.32 [1.07-1.63], P < 0.001 and 1.27 [1.02-1.62], P = 0.001, respectively).

Conclusion: We demonstrate that preoperative CRP levels as low as 3 mg/l are associated with increased long-term mortality and extended hospital length of stay in relatively lower-acuity patients undergoing primary, nonemergent coronary artery bypass graft-only surgery. These important findings may allow for more objective risk stratification of patients who present for uncomplicated surgical coronary revascularization.

Figures

Fig. 1

Perioperative C-reactive protein (CRP) levels during coronary artery bypass graft (CABG) surgery stratified by preoperative CRP risk categories. Data are represented as median and interquartile range. P values in figure represent significant differences across CRP categories. Upper limit of the CRP assay was 300 mg/l. POD = postoperative day.

Fig. 2

Survival for each C-reactive protein (CRP) category for up to 7 yr after coronary artery bypass graft surgery.

Fig. 3

Unadjusted and adjusted Cox proportional hazards ratio (HR) for all-cause mortality up to 7 yr after surgery. Data represented as HR with 95% confidence interval bars. C-reactive protein (CRP) risk category adjusted for history of myocardial infarction P ≤ 0.05 compared with preoperative CRP risk category of < 1 mg/l as reference.

Fig. 4

Unadjusted and adjusted Cox proportional hazards ratios for hospital length of stay (HLOS). Data are represented as hazards ratios with 95% confidence interval bars. C-reactive protein (CRP) risk category adjusted for preoperative left ventricular ejection fraction, preoperative serum creatinine, preoperative use of antiarrhythmic medications, digoxin, or nonaspirin platelet inhibitors, administration of perioperative blood product, cardiopulmonary bypass time, and new-onset postoperative atrial fibrillation. * P ≥ 0.05 compared with preoperative CRP risk category of < 1 mg/l as reference. HR = hazards ratio.