Summary of systematic reviews on the effects of smoking on TB
| Systematic reviews on effects of smoking on TB | Confounders | Multivariate analysis |
| Lin et al., 2007 [8] Effect of smoking as a risk factor for TB infection, disease and mortality Confounders: TST cut-off for LTBI Alcohol consumption SES | TST cut-off to diagnose LTBI | |
| Induration size of 5 mm | Pooled OR 2.08 (95% CI 1.53–2.83) | |
| Induration size of 10 mm | Pooled OR 1.83 (95% CI 1.49–2.23) | |
| Alcohol on risk of TB disease in current smokers | Summary estimate 1.62 (95% CI 1.15–2.29) | |
| SES on risk of TB disease in current smokers | Summary estimate 1.95 (95% CI 1.45–2.61) | |
| Alcohol on risk of TB disease in former smokers | Summary estimate 1.58 (95% CI 1.24–2.02) | |
| SES on risk of TB disease in former smokers | Summary estimate 1.54 (95% CI 1.18–2.01) | |
| Alcohol on risk of TB disease in ever-smokers | Summary estimate 2.00 (95% CI 1.55–2.57) | |
| SES on risk of TB disease in ever-smokers | Summary estimate 3.28 (95% CI 2.25–4.76) | |
| SES for risk of mortality from TB | Summary estimate 2.55 (95% CI 1.82–3.56) | |
| Slama et al., 2007 [9] Effect of smoking as a risk factor for TB infection, disease and mortality Confounders: Quality of study as rated by three independent reviewers for 25 indicators of quality regarding study population, assessment of exposure to tobacco smoke, assessment of passive smoking, assessment of TB outcome, study design, analysis and data presentation | Quality of study on risk of being infected with TB | |
| High-quality studies only | Pooled estimate 1.757 (95% CI 1.458–2.118) | |
| All studies | Pooled estimate 1.762 (95% CI 1.467–2.116) | |
| Quality of study on risk of TB disease | ||
| High-quality studies only | Pooled estimate 2.641 (95% CI 2.066–3.378) | |
| All studies | Pooled estimate 2.284 (95% CI 1.765–2.954) | |
| Quality of study on risk of TB mortality | ||
| High-quality studies only | Pooled estimate 1.347 (95% CI 1.107–1.638) | |
| All studies | Pooled estimate 2.236 (95% CI 1.340–3.732) | |
| Wagnew et al., 2018 [10] Effect of smoking on prevalence of TB Confounder: Diagnosis of diabetes | Smoking on TB among diabetes patients | OR 7.6 (95% CI 1.46–39.53) |
| Bates et al., 2007 [11] Effect of smoking on TB infection, disease and mortality Confounders: None reported | Effect of smoking on TB infection (no adjustment for confounders reported) | Summary relative risk 1.73 (95% CI 1.46–2.04) |
| Effect of smoking on TB disease (no adjustment for confounders reported) | Summary relative risk 2.29 (95% CI 1.93–2.71) | |
| Effect of smoking on TB mortality (no adjustment for confounders reported) | Summary relative risk 1.60 (95% CI 1.31–1.95) | |
| Burusie et al., 2020 [12] Effect of smoking on TB treatment outcomes Confounders: Income category of the study country's economy (not individuals’ SES) | Lower-middle income economy on effect of smoking on TB treatment outcomes | OR 1.74 (95% CI 1.31–2.30) |
| Upper-middle income economy on effect of smoking on TB treatment outcomes | OR 1.52 (95% CI 1.16–1.96) | |
| High-income economy on effect of smoking on TB treatment outcomes | OR 1.34 (95% CI 1.03–1.74) | |
| Samuels et al., 2018 [13] Effect of smoking on treatment outcomes in MDR-TB Confounders: None reported | Effect of smoking on unsuccessful treatment outcomes for MDR-TB (no adjustment for confounders reported) | Pooled relative risk 0.94 (95% CI 0.75–1.19) |
| Chaves Torres et al., 2019 [14] Effect of smoking on TB treatment outcomes Confounders: None reported | Effect of not smoking on favourable TB treatment outcomes (no adjustment for confounders reported) | OR 1.5 (95% CI 1.3–1.7) |
| Patra et al., 2015 [15] Effect of exposure to second-hand smoke on LTBI and active TB Confounders: Age Biomass fuel use SES Presence of TB patient in household | Age on effect of exposure to second-hand smoke on LTBI | |
| Children | Summary relative risk 1.64 (95% CI 1.00–2.83) | |
| Adults | Summary relative risk 1.78 (95% CI 1.19–2.68) | |
| Age on effect of exposure to second-hand smoke on active TB disease | ||
| Children | Summary relative risk 3.41 (95% CI 1.81–6.45) | |
| Adults | Summary relative risk 1.32 (95% CI 1.04–1.68) | |
| Biomass fuel use on effect of exposure to second-hand smoke on LTBI | Summary relative risk 2.66 (95% CI 1.31–5.39) | |
| Biomass fuel use on effect of exposure to second-hand smoke on active TB disease | Summary relative risk 2.03 (95% CI 1.13–3.63) | |
| Presence of a TB patient in the household on effect of exposure to second-hand smoke on LTBI | Summary relative risk 2.03 (95% CI 1.25–3.28) | |
| Presence of a TB patient in the household on effect of exposure to second-hand smoke on active TB disease | Summary relative risk 1.87 (95% CI 1.30–2.69) | |
| Combined SES and age on effect of exposure to second-hand smoke on LTBI | Summary relative risk 1.11 (95% CI 0.54–2.31) | |
| Combined SES and age on effect of exposure to second-hand smoke on active TB disease | Summary relative risk 2.13 (95% CI 1.18–3.83) | |
| Obore et al., 2020 [16] Effect of smoking and exposure to second-hand smoke on contracting TB Confounders: None reported | Effect of second-hand smoke exposure on risk of contracting TB (no adjustment for confounders reported) | Relative risk 2.15 (95% CI 1.419–3.242) |
| Effect of smoking on risk of contracting TB (no adjustment for confounders reported) | Relative risk 2.67 (95% CI 2.017–3.527) |
TB: tuberculosis; TST: tuberculin skin test; LTBI: latent tuberculosis infection; SES: socioeconomic status; OR: odds ratio; MDR: multidrug resistant.