We also assessed the risk of suicidal ideation among former smokers versus nonsmokers (no figure is given). The former smokers were at higher risk for suicidal ideation. The overall estimate of OR was 1.65 (95% CI: 1.09, 2.22; 2 studies; I2 = 0.0%; P = 0.875) on the basis of cohort studies and 1.26 (95% CI: 1.06, 1.46; 5 studies; I2 = 69.1%.1%; P = 0.012) according to case-control/cross-sectional studies.
