Main Findings
depression, mental illness, anxiety
SENSITIVITY
In this cohort study, people who stopped smoking showed lower depression and anxiety scores 6 months after stopping smoking than people who continued smoking after adjustment for a range of possible confounding variables or with PSM. Scores were 0.40 point lower for anxiety and 0.47 point lower for depression on the HADS scale. Sensitivity analysis removing people randomly assigned to bupropion left the results unchanged. Sensitivity analyses using multiple imputation showed that effect estimates were in a similar direction of association, but point estimates were somewhat larger than in the complete case analyses. The association between smoking cessation and improvements in mental health was larger when we restricted it to those with a history of mental illness. Our IV analysis was inconclusive but lacked the power to detect an effect of smoking cessation on mental health.