Tuberculosis outcomes worse for smokers

Smoking among people with tuberculosis (TB) raises the risk of infection recurrence or relapse, as well as that of death while receiving treatment, according to the results of a systematic review and meta-analysis.

Pooled data from 15 studies showed that ever-smokers had a 78-percent higher risk of TB recurrence/relapse compared with never-smokers (risk ratio [RR], 1.78, 95 percent confidence interval [CI], 1.31–2.43; I²=85 percent). [Chest 2023;doi:10.1016/j.chest.2023.08.021]

The same was true for current smokers and past smokers, who were 84–95 percent more likely to experience recurrence/relapse than nonsmokers (RR, 1.95, 95 percent CI, 1.59–2.40; I²=72 percent and RR, 1.84, 95 percent CI, 1.21–2.80; I²=4 percent).

The meta-analysis of mortality-during-treatment outcome included 13 studies. The results followed the same pattern as that for recurrence/relapse. Specifically, the likelihood of dying while receiving treatment was high among ever-smokers (RR, 1.55, 95 percent CI, 1.32-1.81; I²=0 percent) and current smokers (RR, 1.51, 95 percent CI, 1.09–2.10; I²=87 percent) than among never-smokers and noncurrent smokers, respectively.

Heterogeneity across studies was explained by differences in study design, design, and participant characteristics. Almost all studies in the meta-analyses scored ‘high’ or ‘moderate’ on quality assessments.

On further analysis, smoking also emerged as a risk factor for other unfavourable TB treatment outcomes, such as default, failure, or unsuccessful treatment; delayed sputum conversion; and treatment nonadherence.

Smokeless tobacco

With regard to smokeless tobacco, five out of six studies showed associations with poor TB treatment outcomes, such as unsuccessful treatment, TB mortality, and treatment nonadherence.

“While evidence is limited on smokeless tobacco, it still suggests that we need to be cognisant of the risks associated with their use, especially given their disproportionately high prevalence in low-to-middle income countries (LMICs),” the investigators said. [Indian J Tuberc 2021;68S:S89-S92155]

The investigators pointed to the integration of tobacco cessation within TB services as a viable option to improve outcomes, particularly in LMICs. “A large proportion of people with TB who smoke are willing to stop, and those who stop smoking have better treatment success (91 percent vs 80 percent; p<0.001) and lower relapse rates (6 percent vs 14 percent; p<0.001).” [Int J Tuberc Lung Dis 2007;11:1049-1061; Thorax 2022;77:74-78]

Overall, the results of the meta-analysis review reinforce that smoking causes problems for people with TB and provide additional evidence to invest in smoking-reduction policies and practices in order to reduce the global TB and tobacco-related disease burden, the investigators said.