Smoke-Free Home Intervention in Permanent Supportive Housing: A Cluster Randomized Clinical Trial.

Importance: Chronic diseases related to tobacco use and secondhand smoke exposure are the leading causes of death among formerly homeless adults living in permanent supportive housing (PSH) in the US. Objective: To evaluate the efficacy of a brief, smoke-free home intervention in promoting voluntary smoke-free home adoption among PSH residents. Design, Setting, and Participants: In this cluster randomized clinical trial, data collection occurred from January 11, 2022, to March 31, 2025. Participants were residents aged 18 years or older who smoked cigarettes at home in 40 multiunit PSH sites in the San Francisco Bay area, randomized to intervention or waiting list control clusters, and housing staff who worked at the study sites. Intervention: Residents in intervention sites received one-on-one in-person coaching from research staff on adopting a smoke-free home; waiting list control site residents received no interventions during the study but were offered the intervention once the intervention group completed follow-up. Staff in both intervention and control sites received training on providing brief tobacco cessation coaching. Main Outcomes and Measures: Primary outcomes were smoke-free home adoption for at least 90 days and 7-day carbon monoxide-verified point prevalence abstinence (PPA; expired carbon monoxide level ≤5 ppm) at 6 months. Secondary outcomes were any adoption (≥1 day) of a smoke-free home in the past 90 days among residents and changes in Smoking Knowledge, Attitudes, and Practices (S-KAP) scores among staff. Results: The trial enrolled 400 residents (mean [SD] age, 54.5 [10.7] years; 251 [63.1%] male), 191 in the intervention and 209 in the control cluster. At 6 months, 13 residents (6.8%) in the intervention and 10 (4.8%) in the control group adopted a smoke-free home for at least 90 days (odds ratio [OR], 1.45; 95% CI, 0.69-3.07). Few residents achieved 7-day PPA, though more intervention residents (12 [6.3%]) achieved it compared with controls (2 [1.0%]) (OR, 6.94; 95% CI, 1.69-28.45). Intervention residents had greater odds than control residents of any smoke-free home adoption of at least 1 day (121 [63.4%] vs 77 [36.8%]; adjusted OR, 3.83 [95% CI, 2.63-5.57]). Among staff, mean (SD) S-KAP scores increased at 6 months vs baseline for beliefs (by 0.21 [0.55] points) and practices (by 0.24 [0.61] points) pertaining to providing cessation treatment. Conclusions and Relevance: In this cluster randomized clinical trial, the brief intervention did not result in a significant increase in smoke-free home adoption for at least 90 days, though more residents in the intervention than the control group attempted adoption for at least 1 day. These findings support the scalability of this approach to reduce smoking in PSH, but more intensive interventions may be needed to sustain intervention effects. Trial Registration: ClinicalTrials.gov Identifier: NCT04855357.