Effectiveness of a one-year smoking cessation intervention for people with severe mental illness

This study evaluated the effectiveness of a one-year smoking cessation intervention (KISMET) for people with severe mental illness compared with treatment as usual (TAU) in outpatient mental healthcare. In a pragmatic cluster-randomized controlled trial across 21 outpatient mental healthcare teams in the Netherlands, the intervention combined cognitive-behavioral and peer support, and optional pharmacological treatment. Ten teams participated in the TAU condition. The primary outcome was self-reported smoking cessation at 12 months, verified through exhaled carbon monoxide levels below 10 parts per million. Smoking cessation rates were significantly higher in the intervention group at 3 and 12 months, but not at 6 months. No significant differences were found in secondary outcomes, including mental health, quality of life, and physical health measures. However, dropout rates were high, particularly in the intervention group. The findings suggest that the KISMET intervention shows potential for supporting smoking cessation without psychopathological complications, although results should be interpreted with caution due to the high dropout rates.