Patients with OS had significantly lower blood oxygen pressure (PO2) and arterial oxygen saturation (SaO2) and higher BMI, partial pressure of carbon dioxide (PCO2), and serum levels of B-type natriuretic peptide (BNP) than patients with COPD or OSAS alone (all p < 0.001). This evidence concerns the gene NPPB and chronic obstructive pulmonary disease.