Results
mental illness, Anxiety, anxiety, depression, Depression
Of the 4260 participants included (mean [SD] age, 46.5 [12.4] years; 2485 women [58.3%]; 3044 White individuals [71.5%]), 2359 (55.4%) had a history of mental illness. The mean (SD) baseline Hospital Anxiety and Depression Scale score was 4.25 (3.68) (median [IQR], 3 [1-6]) for anxiety and 2.44 (2.91) (median [IQR], 1 [0-4]) for depression. After adjustment for demographics and baseline variables, smoking cessation was associated with a decrease in scores for both anxiety (−0.40 point; 95% CI, −0.58 to −0.22 point) and depression (−0.47 point; 95% CI, −0.61 to −0.33 point) compared with continuing smoking. Similarly, propensity score–adjusted models indicated that smoking cessation was associated with reduced scores for anxiety (β = −0.32; 95% CI, −0.53 to −0.11) and depression (β = −0.42; 95% CI, −0.60 to −0.24). Instrumental variable analysis was underpowered, and estimates were imprecise. Findings were robust to planned sensitivity and subgroup analyses, with larger effect sizes in people with a history of mental illness.