Review question
Do treatments to help people with tuberculosis (TB) of the lungs to stop smoking also improve how they respond to treatment for their TB?
Background
Tuberculosis (TB) is a bacterial infection that can affect any organ of the human body. TB of the lungs can be transmitted from one person to another through the air when people who have TB cough, sneeze or spit. TB is a major cause of death in low- and middle-income countries. Smokers are twice as likely to become infected with TB as nonsmokers. Smoking is a common risk behaviour among people with TB. People who breathe in secondhand smoke are also more likely to be infected with TB. When people who smoke are infected with TB, they are more likely to have a more serious form of TB. They are also more likely to refuse or to stop their treatment and are less likely to respond to drug treatment.
Smoking can cause problems for the body's immune system (the system that protects a person from disease). However, research shows that most of these problems can be resolved after stopping smoking for six weeks. We therefore wanted to test whether quitting smoking can help people with TB by improving how they respond to treatment and reducing their infection levels.
Review methods
We searched various research databases that contain published and ongoing research on this topic up to the 29th of July 2015. We searched for studies written in any language, published and unpublished. We planned to include only studies that tested the success of a treatment to help someone with TB stop smoking, by comparing it to another treatment or to no treatment, using randomised controlled trials (RCTs). We considered treatments targeted at individuals (adults with TB and on TB treatment) or at whole populations. This included counselling or drug-based interventions for quitting smoking. We were interested in studies if they measured the number of people who completed the treatment for TB or the number of people cured of TB, or both.
Key results
We found no studies that met the eligibility criteria above. This is therefore an 'empty' review. However, there are studies that are currently being carried out, which may be reported in our next update of this review.
Quality of the evidence
There is as yet no high-quality evidence that can tell us whether treatments to help people with TB to stop smoking also help them to complete their TB treatment and to respond better to that treatment. There is therefore a need for good-quality research studies that test the usefulness of treatments to quit smoking in people with TB.
There is a lack of high-quality evidence, i.e. RCTs, that tests the effectiveness of cessation interventions in improving TB treatment outcomes. There is a need for good-quality randomised controlled trials that assess the effect of SCIs on TB treatment outcomes in both the short and long term. Establishing such an evidence base would be an essential step towards the implementation of SCIs in TB control programmes worldwide.
Active smoking increases the risk of tuberculosis (TB) infection 2 to 2.5 times and is significantly associated with recurrent TB and TB mortality. Observational studies have shown associations between smoking and poor TB treatment outcomes such as increased loss to follow-up rate, severity of disease, drug resistance and slow smear conversion. Since most smoking-related immunologic abnormalities are reversible within six weeks of stopping smoking, smoking cessation may have substantial positive effects on TB treatment outcomes, TB relapse and future lung disease.
To analyse the effect of tobacco smoking cessation interventions (SCIs) on the treatment outcomes of people with adult pulmonary TB.
We searched the Cochrane Tobacco Addiction Group Specialised Register using free-text and MeSH terms for TB and antitubercular treatment. We also searched MEDLINE and EMBASE using the same topic-related terms, combined with the search terms used to identify trials of tobacco cessation interventions from the Specialised Register. We also searched reference list of articles and reviews, the Conference Paper Index, clinicaltrials.gov and grey literature. The searches are current to 29th July 2015.
Individual and cluster-randomised controlled trials (RCTs), regardless of date, language and publication status, studies of adults with pulmonary TB on first-line anti-tubercular drugs, with interventions at either an individual or a population level, delivered separately or as part of a larger tobacco control package. This included any type of behavioural or pharmaceutical intervention or both for smoking cessation.
Using the eligibility criteria, two authors independently checked the abstracts of retrieved studies for relevance, and acquired full trial reports of candidates for inclusion. The authors resolved any disagreements on eligibility by mutual consent, or by recourse to a third author. Two authors intended to independently extract study data from eligible studies into a data extraction form and compare the findings, synthesise data using risk ratios, and assess risk of bias using standard Cochrane methodologies. However, we found no eligible trials.
There were no randomised controlled trials that met the eligibility criteria. A number of potentially eligible studies are underway, and we will assess them for inclusion in the next update of this review.