CRP and major depressive disorder: Stratification by CRP level in the model did impact the odds of depression among e-cigarette users compared to the reference group of equivalent cut-point (simple slope models): e-cigarette users with CRP < 8 mg/L had an OR of 3.37 (95% CI: 2.06, 5.51); these odds doubled to 6.70 (95% CI: 2.48, 18.11) when CRP ≥ 8 mg/L.