The pattern of increased odds of depression at the elevated CRP cut-point was also observed for depression among former smokers who are now exclusive e-cigarette users: OR = 2.78 (95% CI: 1.16, 6.69) and OR = 4.92 (95% CI: 0.46, 52.32), based on reference (<8 mg/L) and elevated (≥8 mg/L) CRP levels, respectively. Here, CRP is linked to major depressive disorder.