LEP and chronic kidney disease: Compared to quartile 1 of plasma leptin (referent), the multivariable OR (95% CI) of CKD was 1.31 (0.70 to 2.44) in quartile 2, 1.22 (0.57 to 2.62) in quartile 3, and 2.72 (1.14 to 6.48) in quartile 4; P-trend = 0.0475.