EVIDENCE-BASED ANSWER
Yes, taking this step helps asthmatic children, and may even help nonasthmatic children. In families of asthmatic children, education to reduce exposure to secondhand smoke leads to fewer medical visits (strength of recommendation [SOR]: B, a single randomized, controlled trial). The effects of educating families of nonasthmatic children about secondhand smoke are not known, but parents who smoke outside expose their children to much less nicotine than parents who smoke in the house (SOR: B, cohort studies and cross-sectional surveys).
Evidence summary
Parent education reduces clinic visits for asthmatic children
A 2001 trial randomized 81 families with a smoking parent and an asthmatic child between 3 and 12 years of age to 3 sessions of behavioral and educational counseling or usual care at an outpatient asthma clinic.1 Parental education included information on second-hand smoke, basic asthma education, and feedback about urine cotinine levels (a marker of nicotine absorption). Behavioral counseling focused on reducing second-hand smoke exposure by caregivers.
The education group had a significantly reduced risk of 2 or more asthma-related clinic visits in the following 12 months compared with usual care (odds ratio=0.32; P=.03; number needed to treat=5). No significant decrease was noted in mean urine cotinine levels between groups (adjusted mean difference=-0.38 ng/mg favoring education; P=.26).
A similar trial that measured changes in urine cotinine randomized 91 families with a smoking parent and an asthmatic child into 3 groups:2
- A control group received usual care (regular office visits at an asthma clinic and medication management)
- A monitoring group used a parental smoking diary and a children’s asthma symptom diary
- A counseling group received 5 counseling sessions and also kept diaries. An environmental monitor in the home was used to assess exposure to secondhand smoke.
In the counseling group, 21.4% of patients (6 of 28) maintained 0% exposure throughout the 30-month trial period compared with 3.6% and 3.8% in the monitoring and control groups, respectively (P<.05 for comparison of counseling group to monitoring and control).
Banning indoor smoking sharply cuts nicotine exposure
No data are available on education about second-hand smoke in families with nonasthmatic children. However, strong evidence suggests that smoking outside the house reduces exposure generally.
A 2003 cross-sectional survey of 164 households in the United Kingdom with at least 1 smoking parent and 1 bottle-fed infant looked for a correlation between strategies to reduce second-hand smoke and urine cotinine-to-creatinine ratios in the infants.3 Parents were classified into 3 groups according to whether they maintained a strict ban on smoking in the home, a less strict ban (smoking at home but not near the infant), or no ban.
The mean infant urinary cotinine-to-creatinine ratio was 2.43 in the no-ban group and 2.61 in the less-strict ban group (difference not significant). The combined mean for these 2 groups—2.58—was significantly higher than the mean of 1.26 in the strictest group (P<.001).