Tobacco and tuberculosis: A qualitative systematic review and meta-analysis

OBJECTIVES: To assess the strength of evidence in published articles for an association between smoking and passive exposure to tobacco smoke and various manifestations and outcomes of tuberculosis (TB). Clinicians and public health workers working to fight TB may not see a role for themselves in tobacco control because the association between tobacco and TB has not been widely accepted. A qualitative review and meta-analysis was therefore undertaken. METHODS: Reference lists, PubMed, the database of the International Union Against Tuberculosis and Lung Disease and Google Scholar were searched for a final inclusion of 42 articles in English containing 53 outcomes for data extraction. A quality score was attributed to each study to classify the strength of evidence according to each TB outcome. A meta-analysis was then performed on results from included studies. RESULTS: Despite the limitations in the data available, the evidence was rated as strong for an association between smoking and TB disease, moderate for the association between second-hand smoke exposure and TB disease and between smoking and retreatment TB disease, and limited for the association between smoking and tuberculous infection and between smoking and TB mortality. There was insufficient evidence to support an association of smoking and delay, default, slower smear conversion, greater severity of disease or drug-resistant TB or of second-hand tobacco smoke exposure and infection. CONCLUSIONS: The association between smoking and TB disease appears to be causal. Smoking can have an important impact on many aspects of TB. Clinicians can confidently advise patients that quitting smoking and avoiding exposure to others' tobacco smoke are important measures in TB control.