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Original research
Effect of quitting smoking on health outcomes during treatment for tuberculosis: secondary analysis of the TB & Tobacco Trial
  1. Kamran Siddiqi1,2,
  2. Ada Keding1,
  3. Anna-Marie Marshall1,
  4. Omara Dogar1,
  5. Jinshuo Li1,
  6. Rumana Huque3,4,
  7. Razia Fatima5,
  8. Amina Khan6,
  9. Helen Elsey1,2,
  10. Rhian Gabe7,
  11. Daniel Kotz8,
  12. Aziz Sheikh9
  1. 1 Health Sciences, University of York, York, UK
  2. 2 Hull York Medical School, York, UK
  3. 3 Economics, Dhaka University, Dhaka, Bangladesh
  4. 4 Research and Development, ARK Foundation, Dhaka, Bangladesh
  5. 5 Common Unit (HIV,TB,Malaria), Pakistan Ministry of National Health Services, Regulation and Coordination, Islamabad, Pakistan
  6. 6 Research, The Initiative, Islamabad, Pakistan
  7. 7 Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University of London, London, UK
  8. 8 Institute of General Practice, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
  9. 9 Usher Institute of Population Health Sciences and Informatics, University of Edinburgh, Edinburgh, UK
  1. Correspondence to Professor Kamran Siddiqi, Health Sciences, University of York, York, UK; kamran.siddiqi{at}


Background Despite treatment, patients with tuberculosis (TB) who smoke have poorer outcomes compared with non-smokers. It is unknown, however, if quitting smoking during the 6 months of TB treatment improves TB outcomes.

Methods The TB & Tobacco Trial was a double-blind, placebo-controlled randomised trial of cytisine for smoking cessation in 2472 patients with pulmonary TB in Bangladesh and Pakistan. In a secondary analysis, we investigated the hypothesis that smoking cessation improves health outcomes in patients during the TB treatment course. The outcomes included an eight-point TB clinical score, sputum conversion rates, chest X-ray grades, quality of life (EQ-5D-5L), TB cure plus treatment completion rates and relapse rates. These were compared between those who stopped smoking and those who did not, using regression analysis.

Results We analysed the data of 2273 (92%) trial participants. Overall, 25% (577/2273) of participants stopped smoking. Compared with non-quitters, those who quit had better TB cure plus treatment completion rates (91% vs 80%, p<0.001) and lower TB relapse rates (6% vs 14%, p<0.001). Among quitters, a higher sputum conversion rate at week 9 (91% vs 87%, p=0.036), lower mean TB clinical scores (−0.20 points, 95% CI −0.31 to −0.08, p=0.001) and slightly better quality of life (mean EQ-5D-5L 0.86 vs 0.85, p=0.015) at 6 months were also observed. These differences, except quality of life, remained statistically significant after adjusting for baseline values, trial arm and TB treatment adherence rates.

Conclusion Patients with TB who stop smoking may have better outcomes than those who don’t. Health professionals should support patients in stopping smoking.

  • tuberculosis
  • smoking cessation
  • tobacco control
  • tobacco and the lung

Data availability statement

Data are available upon reasonable request.

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Data availability statement

Data are available upon reasonable request.

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  • Twitter @kamsid66, @DrAzizSheikh

  • Contributors KS originated the idea and drafted majority of the manuscript. AKe analysed the data and contributed in drafting the manuscript. All other authors contributed to the design and execution of the study and reviewed, revised and approved the manuscript.

  • Funding The study was funded by the European Union Horizon 2020 research and innovation programme (680995).

  • Competing interests DK reports an unrestricted grant from Pfizer in 2009 for an investigator-initiated trial on the effectiveness of practice nurse counselling and varenicline for smoking cessation in primary care. KS reports an unrestricted research grant from Pfizer to study the effects of varenicline on water pipe smoking cessation.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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