GDF15 and malnutrition: The optimal cut-off value of serum GDF15 levels and serum ALB levels for predictive malnutrition in AECOOPD patients was 1,092.885 pg/mL and 36.15 g/L, respectively, with a sensitivity of 65.90 and 86.40%, respectively, as well as specificity of 89.80 and 65.00%, respectively.