Predictive value of preoperative hematologic inflammation indices (NLR, PLR, SII) and clinical risk factors in predicting postoperative pulmonary complications after elective isolated on-pump coronary artery bypass grafting: a retrospective cohort study of 1034 patients.

In this single-center retrospective cohort, preoperative neutrophil-to-lymphocyte ratio, platelet-to-lymphocyte ratio and SII were associated with PPC, with neutrophil-to-lymphocyte ratio accounting for most of the predictive signal.

Because they are measured at a single preoperative timepoint, these indices reflect baseline inflammatory tone and cannot capture the acute, surgery-induced inflammatory response that drives postoperative pulmonary complications.