Associations of creatinine/cystatin C ratio and postoperative pulmonary complications in elderly patients undergoing off-pump coronary artery bypass surgery: a retrospective study

Sarcopenia along with nutritional status are associated with postoperative pulmonary complications in various surgical fields. Recently, the creatinine/cystatin C ratio and CONtrolling NUTritional status score were introduced as biochemical indicators for sarcopenia and malnutrition, respectively. We aimed to investigate the associations among these indicators and postoperative pulmonary complications in elderly patients undergoing off-pump coronary artery bypass surgery. We reviewed the medical records of 605 elderly patients (aged ≥ 65 years) who underwent off-pump coronary artery bypass surgery from January 2010 to December 2019. Postoperative pulmonary complications (pneumonia, prolonged ventilation [> 24 h], and reintubation during post-surgical hospitalisation) occurred in 80 patients. A 10-unit increase of creatinine/cystatin C ratio was associated with a reduced risk of postoperative pulmonary complications (odds ratio: 0.80, 95% confidence interval: 0.69–0.92, P = 0.001); the optimal cut-off values for predicting postoperative pulmonary complications was 89.5. Multivariable logistic regression analysis revealed that age, congestive heart failure, and creatinine/cystatin C ratio < 89.5 (odds ratio 2.36, 95% confidence interval 1.28–4.37) were independently associated with the occurrence of postoperative pulmonary complications, whereas CONtrolling NUTritional status score was not. A low creatinine/cystatin C ratio was associated with an increased risk of developing postoperative pulmonary complications after off-pump coronary artery bypass surgery.