GDF15 and chronic obstructive pulmonary disease: Higher GDF‐15 concentrations could be shown for patients with coronary artery disease [551 ng/L (IQR 375‐720) vs 320 ng/L (IQR 120‐516)], P < .001, COPD [417 ng/L (IQR 301‐635) vs 297 ng/L (IQR 189‐499), P < .001], CKD [542 ng/L (IQR 375‐1531) vs 323 ng/L (IQR 202‐516), P < .001] or diabetes [418 ng/L (IQR 271‐620) vs 325 ng/L (IQR 198‐520), P = .017].