GDF15 and chronic obstructive pulmonary disease: Similarly, GDF15 levels were significantly higher in prevalent atherosclerosis and prevalent COPD cases (n=34, median = 1224 ng/L and n=30, 1356 ng/L, respectively) compared to respective incident cases (n=357, median = 1104 ng/L, Wilcoxon rank sum test p-value = 0.02 and n=244, median = 1119 ng/L; Wilcoxon rank sum test p-value = 0.02, respectively) and healthy controls (n=6219, 784 ng/L, Wilcoxon rank sum test p-value = 4.69 x 10−13 and n=6366; 789 ng/L, Wilcoxon rank sum test p-value = 3.10 x 10−11, respectively).