NPPB and chronic obstructive pulmonary disease: Subsequently, BNP (hazard ratio [HR] 1.248 [95% CI [1.155–1.348]]), albumin (HR 0.952 [95% CI [0.931–0.974]), age (HR 1.033 (95% CI [1.022–1.044])), GLB (HR 1.057 (95% CI [1.038–1.077]), smoking years (HR 1.011 (95% CI [1.006–1.015]), Pa CO2 (HR 1.012 (95% CI [1.007–1.017])), granulocyte ratio (HR 1.018 (95% CI [1.010–1.026])), and BUN (HR 1.041 (95% CI [1.017–1.066])) were identified to be independent risk factors for the prognosis of COPD patients according to multivariate Cox proportional hazards regression analysis (Fig. 2, Table 2).