A randomized controlled trial of a family intervention in reducing secondhand smoke exposure to infants under 18-months

Abstract

Background: Secondhand smoke exposure (SHS) causes many fatal diseases to children and there is no safe level of exposure. In Hong Kong, around 41%of infants are exposed to household SHS and leading to the additional hospital admissions of the infants.

Objectives: To study the effectiveness of a theory-based family intervention delivered by the smoking cessation counselor (SCCs) which aims to reduce household SHS exposure to infants under 18-months, by helping fathers to quit smoking and motivating mothers to establish a smoke-free home .

Methods: Families with a smoking father, non-smoking mother and an infant attended the Maternal and Child Health Centres (MCHCs) were invited to join this randomized controlled trial. The family (mother and father) was randomized after the completion of mother’s baseline questionnaire and the collection of saliva samples from mothers and infants. Father was then contacted for telephone baseline interview. Individual interventions were provided to both mothers and fathers at baseline, 1-week and 1-month, and a family session involving both parents was offered to the intervention group. The control group received information on the hazards of SHS and the benefits of smoking cessation. The intervention and control groups were followed-up at 6-and 12-monthsto assess father’s smoking behavior and the execution of a complete no-smoking policy at home. Chi-squares and independent t-tests were used to assess the group differences in father’s smoking behavior and the initiation of a smoke-free home. Generalized estimating equations were used to examine the group changes of mothers’ and infants’ saliva cotinine levels from baseline to 12-month. Logistic regressions were performed to identify the predictors on father’s smoking behavior and the initiation of a smoke-free home.

Results: There were 1,158 families randomized. Significantly more fathers in the intervention groupattainedhigher7-day point prevalence quit rate at 6-(8.0% vs 4.1%, p= .007)and 12-months (13.7% vs 8.0%, p= .002)respectively, stopped smoking at home at 12-month (35.7% vs 28.8%, p= .023), higher continuous quit rates at 6-(3.3% vs 0.7%, p= .002) and 12-month (1.8% vs 0.2%, p= .006), reduction of daily cigarette consumption over 50% at 12-month (33.4% vs 23.9%, p= .006), improvement in the stage of readiness to quit smoking at 6-month (13.0% vs 8.9%, p= .04) and more quit attempts (30.9% vs 24.1%, p=.015). No group differences were found in the establishment of the smoke-free home and the changes of saliva cotinine levels of infants and mothers from baseline to follow-ups.

Discussion: This theory-based family intervention is effective in reducing household SHS exposure to infants by helping fathers to quit and stopped them to smoking at home, but it is less effective in motivating the mothers to initiate a smoke-free home.

Significance: This is the first study testing a theory-based family intervention in reducing household SHS exposure to healthy infants. The family intervention provides a new insight in using ‘family’ as a unit for the intervention to reduce household SHS exposure to healthy infants by improving fathers' household smoking behavior and helping them to quit smoking.