Background: Previous studies have declared that smoking is a risk factor for postoperative delirium (POD), but others have inconsistent results. Up till now, the association between smoking and POD has not been verified. This study aims to investigate the relationship between smoking and POD in patients with pulmonary hypertension (PHTN) in the United States.Methods: This study is a secondary analysis of a retrospective cohort study completed by Aalap C. et al. Patients with PHTN who underwent

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... on-cardiac, non-obstetric surgery were enrolled in the original study. We further excluded the patients undergoing intracranial surgery and the patients with sepsis and perioperative stroke to avoid interference with POD assessment. The generalized linear model and generalized additive model were used to explore the relationship between smoking and POD.Results: After adjusting the potential confounders (age, gender, BMI, poor functional status, PHTN severity, some comorbidities such as hypertension, angina, coronary artery disease, arrhythmia, COPD, asthma, diabetes and renal failure, length of surgery, open surgical approach, intraabdominal surgery, intrathoracic surgery, vascular surgery, some medications such as anticoagulant, antiplatelet, steroids, statin, and atropine, some inhalational anesthesia agent such as isoflurane and sevoflurane), a positive relationship was found between smoking status and POD (OR=5.61, 95% CI: 1.14 to 27.51, P=0.0334). In addition, the curvilinear relationship between smoking burden (pack-years) and POD is close to a linear relationship.Conclusion: Smoking shows a positive correlation with POD in patients with PHTN. Surgical individuals need to prevent POD especially those with a heavy smoking burden.