Effectiveness of Caregiver Interventions to Reduce Household Secondhand Smoke Exposure on Pediatric Asthma Outcomes: A Systematic Review

Asthma is a common chronic condition in childhood. Household secondhand smoke exposure (SHSe) from caregiver smoking is a major, modifiable contributor to poor asthma control. Previous reviews of SHSe interventions have focused broadly on indoor environmental or health outcomes for the general population. The impact of such interventions on pediatric asthma has yet to be systematically reviewed. We aimed to synthesize evidence regarding the effectiveness of caregiver secondhand smoke interventions for improving pediatric asthma outcomes and identify gaps to guide future intervention research. Following Joanna Briggs Institute methods and Preferred Reporting Items for Systematic Reviews and Meta-Analyses standards, we systematically searched PubMed, PsycINFO, CINAHL, Web of Science, and EMBASE. Eligible studies had no publication date restrictions, tested an intervention targeting household SHSe, and reported pediatric asthma-related outcomes. Randomized and quasi-experimental designs were included. Reviewers independently screened records, extracted data, and assessed risk of bias using the Cochrane Risk of Bias tools for randomized and nonrandomized trials. Of 9,832 records screened, 14 studies spanning 13 distinct interventions met the inclusion criteria. Except for 1 study with a single-group pretest-posttest design, all studies were randomized controlled trials. Overall risk of bias was low to moderate, with only 1 study deemed to be at critical risk. Interventions were typically home-based, delivered by health professionals, and incorporated asthma or SHSe education. Nine included a behavioral counseling component, and 6 incorporated caregiver feedback on SHSe. Six interventions improved subjective asthma indicators, such as symptom control, functional status, and unscheduled health care utilization; objective lung function improvements were not found. Behaviorally focused interventions that integrated caregiver feedback with education had the greatest success in reducing short-term SHSe and improving pediatric asthma outcomes. Evidence for long-term benefits remains poor. Lack of homogeneity in intervention content, measurement, and follow-up periods limits comparability. Future longitudinal trials with standardized measurement tools and diverse racial, ethnic, and socioeconomic populations are warranted.