a significant trendP < 0.001
Compared to the highest quartile of pulmonary function, the risk of MCI was 1.691 (95% CI, 1.267–2.258) in quartile 1, 1.280 (95% CI, 0.979–1.674) in quartile 2 and 1.127 (95% CI, 0.881–1.441) in quartile 3, with a significant trend test ( P < 0.001) in the fully adjusted model.