Multivariate analysis found that smoking status [odds ratio(OR): 7.79, 95% CI: 3.05, 19.88, p < 0.001], drinking status (OR: 22.68, 95% CI: 9.29, 55.37, p < 0.001) and hypertension (OR: 2.85, 95% CI: 1.28, 6.35, p = 0.011), IL-6 on POD2 (OR: 1.01, 95% CI: 1.00, 1.01, p = 0.018), mechanical ventilation time (OR: 1.03, 95% CI: 1.00, 1.05, p = 0.040) and intensive care unit stay time (OR: 1.01, 95% CI: 1.00, 1.02, p < 0.001) were independent risk factors for postoperative pneumonia. This evidence concerns the gene IL6 and pneumonia.