According to the univariate logistics regression analysis shown in Table 4, onset season (p = 0.0274), COPD history (p = 0.0207), time from onset to admission (p = 0.0029), CD4+ T lymphocyte count (p = 0.0288), CD4+ T lymphocyte percentage (p < 0.0001), CD4+/CD8+ ratio (p = 0.0142), Na+ (p = 0.0231), FCa2+ (p = 0.0206), and CRP (p = 0.0250) were regarded as potential risk factors for r-CAP, while TG (p = 0.0188) was screened out to inhibit the development of r-CAP. The gene discussed is CD4; the disease is chronic obstructive pulmonary disease.