The univariate logistic analyses showed that smoking, American Society of Anesthesiologist (ASA) score, chronic obstructive pulmonary disease (COPD), serum albumin level, pre-operative blood transfusion, operation procedure, extent of gastrectomy, combined multi-organ resection, operation time, amount of bleeding, intra-operative blood transfusion, tumor location, and tumor size were associated with POI (P < 0.05 for all, Table 1). This evidence concerns the gene ALB and chronic obstructive pulmonary disease.