- Design
- Systematic review and meta-analysis of observational studies
- Population
- 12 studies, 6411 children and adolescents aged 0–18 in low-resource settings
- Primary outcome
- TB infection or disease with versus without household second-hand smoke
- Effect
- Pooled OR 2.69 (lower 95% limit 2.38); I² = 0%
A meta-analysis in the International Journal of Tuberculosis and Lung Disease, published on 30 October, pooled 12 observational studies with 6411 children and adolescents in low-resource settings. Those exposed to second-hand smoke at home had about 2.7 times the odds of TB infection or disease. Heterogeneity was negligible, though there was a hint of publication bias.
The association is plausible, since smoke impairs airway defences, but household smoking also travels with crowding, poverty and adult TB in the home, all of which raise a child's risk. The studies were observational, so the link may be partly confounded.
In practice, this adds smoking to the questions asked during contact tracing. A child living with a smoker and an adult with TB is in a higher-risk household on two counts.
- Ask about smoking in the home during childhood TB contact tracing.
- Treat a child exposed to both household smoke and an adult TB case as higher risk.
- Counsel adult smokers in TB-affected households about their children's exposure.
- Consider indoor smoke from biomass fuel too, where relevant, though this review focused on tobacco smoke.
Why it matters
It adds a modifiable household exposure to childhood TB prevention.
Don't overread it
This is observational evidence; confounding by poverty and crowding may explain part of the link.
The statistics, in plain English
The pooled odds ratio was 2.69, with a lower confidence limit of 2.38 (the upper limit was not reported in the abstract). An I² of 0% means the studies agreed with each other, which strengthens consistency but not causation.
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