EDN1 and chronic obstructive pulmonary disease: Elderly COPD patients had more frequent exacerbation events per year (2 vs 1, P = .06), a higher prevalence of CVD (3 vs 2, P = .04), more limited exercise tolerance (6-minute walking test distance, 343 [283–403] vs 434 [384–484]; P = .02), and mild systemic inflammation (TNF-α, 9.02 [7.08–10.96] vs 6.48 [5.21–7.76]; P = .03; ET-1, 2.24 [1.76–2.71] vs 1.67 [1.36–1.98] pg/mL; P = .04).