Outcomes of tuberculosis treatment: a retrospective cohort analysis of smoking versus non-smoking patients in Penang, Malaysia

Abstract

The association between tobacco smoking and tuberculosis (TB) is increasingly coming to light and the literature is laden with the evidence of this association. However, only a few observational studies specifically investigated the association between smoking and TB treatment outcomes. The present study aims to determine the prevalence of smoking among TB patients in Penang and to compare the treatment outcomes between smoking and non-smoking TB patients. A retrospective estimate of smoking prevalence among patients with TB and a retrospective cohort study comparing smoking and non-smoking TB patients with regards to treatment outcomes was conducted. The data were extracted from medical records of newly diagnosed TB patients who registered at a chest clinic at a tertiary care hospital in the state of Penang, Malaysia from January 2006 to June 2008. The prevalence of ever-smoking among TB patients was 53.4%. Smoking was significantly associated with male gender, alcohol use, and intravenous drug use (IVDU). Ever smokers had increased likelihood of treatment failure (OR 7.48), default (OR 7.17) and were less likely to be cured (OR 0.34). After controlling for the effects of confounders using multivariate logistic regression, ever smokers were still less likely to be cured (aOR 0.31) and more likely to default treatment (aOR 3.24). Dying from TB did not reach statistical significance. Prevalence of smoking was high among TB patients in Malaysia. This study further reaffirms that smoking is an independent predictor of poor TB treatment outcomes and prognosis.