MB and chronic obstructive pulmonary disease: Baseline serum concentrations of creatine kinase-muscle/brain (creatine kinase-MB), myoglobin, and apolipoprotein A1 were significantly (FDR < 0.05) but modestly inversely correlated with baseline percent-predicted FEV1 in both the BioServe and the T54 COPD cohorts (Spearman's r = -0.22 to -0.27).