Hypoalbuminemia and long-term survival after coronary artery bypass: a propensity score analysis

Background: Hypoalbuminemia is associated with increased morbidity in surgical patients. The impact of low albumin level on survival in cardiac surgical patients is unknown. We hypothesized that a low preoperative albumin level negatively affects long-term survival after coronary artery bypass graft (CABG) surgery.

Methods: We reviewed prospectively gathered data from the records of 1,164 consecutive patients who underwent primary isolated CABG at our institution between 1997 and 2007. Propensity score analysis of 18 preoperative and intraoperative variables balanced potential confounding factors between the two groups of patients, so that the final study cohort consisted of 588 patients: 294 with a preoperative albumin level less than 3.5 g/dL (ie, hypoalbuminemia) and 294 patients with a preoperative albumin level of 3.5 g/dL or greater. We assessed long-term survival by using Kaplan-Meier curves generated by log rank tests.

Results: The two groups of patients were well matched in terms of preoperative and intraoperative covariates. Both groups had similar early outcomes, including 30-day mortality rates (2.0% versus 1.7%; p = 0. 76) and the incidence of major adverse cardiac events (2.7% versus 2.7%; p = 1.0). However, patients with hypoalbuminemia had a significantly worse 8-year survival rate (65% ± 7% versus 86% ± 3%; hazard ratio 2.2; 95% confidence interval: 1.4 to 3.6; p = 0.001) than patients without hypoalbuminemia.

Conclusions: Although preoperative hypoalbuminemia did not predict increased early postoperative mortality or morbidity in CABG patients, it did independently predict poor long-term survival after CABG. Identifying the mechanism that underlies this relationship is essential in improving overall survival among patients with low serum albumin levels who are undergoing surgical myocardial revascularization.