Long‐Term Prognostic Value of the Prognostic Nutritional Index in Patients Undergoing Coronary Artery Bypass Grafting

Background The Prognostic Nutritional Index (PNI) as an indicator of nutritional and immunological status has been widely applied in various medical conditions. However, its prognostic role in postoperative outcomes after coronary artery bypass grafting has not been fully elucidated. This study investigated the long‐term prognostic impact of PNI for patients undergoing coronary artery bypass grafting. Methods A total of 6626 patients who underwent coronary artery bypass grafting from 2001 to 2017 were analyzed. PNI was calculated as 10×serum albumin (g/ dL )+0.005×total lymphocyte count (per mm 3 ). Results PNI is negatively correlated with age ( r =−0.24, P <0.001) and positively correlated with body mass index ( r =0.13, P <0.001). PNI was significantly associated with all‐cause mortality during a median follow‐up of 10.0 years (hazard ratio [HR], 0.96 [per 1 increase] [95% CI, 0.96–0.97]; P <0.001). The low‐PNI group (≤47, n=3956) showed a higher incidence of all‐cause mortality than those with high PNI (>47, n=2670) (64.8% versus 45.5%; adjusted HR, 1.19 [95% CI, 1.09–1.30]; P <0.001). The model including PNI showed better prognostic discrimination for predicting all‐cause mortality during long‐term follow‐up compared with the model with only clinical variables (C index, 0.733 [95% CI, 0.721–0.745] versus 0.763 [95% CI, 0.751–0.774]; integrated discrimination improvement, 0.037 [95% CI, 0.032–0.042]; net reclassification index, 0.334 [95% CI, 0.286–0.383]; P <0.001 for each comparison). Conclusions Perioperative PNI was significantly associated with long‐term mortality after coronary artery bypass grafting, and addition of PNI improved risk discrimination beyond conventional clinical models. Further prospective studies are warranted to validate these findings.