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Meta-Analysis
. 2020 Sep 17;15(9):e0239333.
doi: 10.1371/journal.pone.0239333. eCollection 2020.

Effect of smoking on tuberculosis treatment outcomes: A systematic review and meta-analysis

Abay Burusie  1 , Fikre Enquesilassie  2 , Adamu Addissie  2 , Berhe Dessalegn  3 , Tafesse Lamaro  4
Affiliations
Meta-Analysis

Effect of smoking on tuberculosis treatment outcomes: A systematic review and meta-analysis

Abay Burusie et al. PLoS One. .

Abstract

Introduction: Numerous studies have explored an effect of cigarette smoking on tuberculosis treatment outcomes but with dissimilar conclusions.

Objective: To determine the effect of cigarette smoking on tuberculosis treatment outcomes.

Methods: PubMed, Cochrane library and Google scholar databases were searched last on February 27, 2019. We applied the random-effects model for the analysis. Publication bias was assessed using funnel plot and Egger's regression. Furthermore, we performed Orwin's Fail-Safe N and cumulative meta-analysis to check for small studies' effect.

Results: Out of 22 studies we included in the qualitative synthesis, 12 studies reported p-values less than 0.05 where smoking significantly favored poor treatment outcomes. The remaining 10 studies reported p-values larger than 0.05 implying that smoking does not affect the treatment outcomes. Twenty studies met the criteria for inclusion in a meta-analysis. The meta-analysis found that smoking significantly increased the likelihood of poor tuberculosis treatment outcomes by 51% (OR = 1.51; 95% CI = 1.30 to 1.75 and I-square = 75.1%). In a sub-group analysis, the effect was higher for low- and middle-income countries (OR = 1.74; 95% CI = 1.31 to 2.30) and upper-middle-income economies (OR = 1.52; 95% CI = 1.16 to 1.98) than for high-income ones (OR = 1.34; 95% CI = 1.03 to 1.75) even though the differences in the effects among the strata were not statistically significant as demonstrated by overlapping of confidence intervals of the effects. Meta-regression analysis, adjusted for income economies, found the effect of smoking has not significantly improved over the years (p = 0.92) and thus implying neither of the covariates were source of the heterogeneity. Egger's regression test indicated that publication bias is unlikely (p = 0.403).

Conclusion: Cigarette smoking is significantly linked with poor tuberculosis treatment outcomes.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Flow chart for selecting studies for the systematic review and meta-analysis.
Fig 2
Fig 2. A forest plot displaying the effect of smoking on TB treatment outcomes.
Fig 3
Fig 3. Influential analysis for studies included in the meta-analysis.
Fig 4
Fig 4. Subgroup meta-analysis for the effect of smoking on TB treatment outcomes by income economies.
Fig 5
Fig 5. Sub-group analysis for the effect of smoking on TB treatment outcomes according to study timing.
Fig 6
Fig 6. Sub-group analysis according to the proportion of study participants living with HIV.
Fig 7
Fig 7. Funnel plot of the studies of the effect of smoking on TB treatment outcomes.
Fig 8
Fig 8. Contour enhanced funnel plot of studies of effect of smoking on TB treatment outcomes.
Fig 9
Fig 9. Cumulative meta-analysis of the effect of smoking on TB treatment outcomes.
See this image and copyright information in PMC

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