130
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: found
      • Article: not found

      Tobacco Smoke, Indoor Air Pollution and Tuberculosis: A Systematic Review and Meta-Analysis

      1 , 2 , 1 , 3 , 4 , *

      PLoS Medicine

      Public Library of Science

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          Background

          Tobacco smoking, passive smoking, and indoor air pollution from biomass fuels have been implicated as risk factors for tuberculosis (TB) infection, disease, and death. Tobacco smoking and indoor air pollution are persistent or growing exposures in regions where TB poses a major health risk. We undertook a systematic review and meta-analysis to quantitatively assess the association between these exposures and the risk of infection, disease, and death from TB.

          Methods and Findings

          We conducted a systematic review and meta-analysis of observational studies reporting effect estimates and 95% confidence intervals on how tobacco smoking, passive smoke exposure, and indoor air pollution are associated with TB. We identified 33 papers on tobacco smoking and TB, five papers on passive smoking and TB, and five on indoor air pollution and TB. We found substantial evidence that tobacco smoking is positively associated with TB, regardless of the specific TB outcomes. Compared with people who do not smoke, smokers have an increased risk of having a positive tuberculin skin test, of having active TB, and of dying from TB. Although we also found evidence that passive smoking and indoor air pollution increased the risk of TB disease, these associations are less strongly supported by the available evidence.

          Conclusions

          There is consistent evidence that tobacco smoking is associated with an increased risk of TB. The finding that passive smoking and biomass fuel combustion also increase TB risk should be substantiated with larger studies in future. TB control programs might benefit from a focus on interventions aimed at reducing tobacco and indoor air pollution exposures, especially among those at high risk for exposure to TB.

          Abstract

          Evidence from a number of studies suggest that tobacco smoking, environmental tobacco smoke, and indoor air pollution from biomass fuels is associated with an increased risk of tuberculosis.

          Editors' Summary

          Background.

          Tobacco smoking has been identified by the World Health Organization as one of the leading causes of death worldwide. Smokers are at higher risk than nonsmokers for a very wide variety of illnesses, many of which are life-threatening. Inhaling tobacco smoke, whether this is active (when an individual smokes) or passive (when an individual is exposed to cigarette smoke in their environment) has also been associated with tuberculosis (TB). Many people infected with the TB bacterium never develop disease, but it is thought that people infected with TB who also smoke are far more likely to develop the symptoms of disease, and to have worse outcomes when they do.

          Why Was This Study Done?

          The researchers were specifically interested in the link between smoking and TB. They wanted to try to work out the overall increase in risk for getting TB in people who smoke, as compared with people who do not smoke. In this study, the researchers wanted to separately study the risks for different types of exposure to smoke, so, for example, what the risks were for people who actively smoke as distinct from people who are exposed to smoke from others. The researchers also wanted to calculate the association between TB and exposure to indoor pollution from burning fuels such as wood and charcoal.

          What Did the Researchers Do and Find?

          In carrying out this study, the researchers wanted to base their conclusions on all the relevant information that was already available worldwide. Therefore they carried out a systematic review. A systematic review involves setting out the research question that is being asked and then developing a search strategy to find all the meaningful evidence relating to the particular question under study. For this systematic review, the researchers wanted to find all published research in the biomedical literature that looked at human participants and dealt with the association between active smoking, passive smoking, indoor air pollution and TB. Studies were included if they were published in English, Russian, or Chinese, and included enough data for the researchers to calculate a number for the increase in TB risk. The researchers initially found 1,397 research studies but then narrowed that down to 38 that fit their criteria. Then specific pieces of data were extracted from each of those studies and in some cases the researchers combined data to produce overall calculations for the increase in TB risk. Separate assessments were done for different aspects of “TB risk,” namely, TB infection, TB disease, and mortality from TB. The data showed an approximately 2-fold increase in risk of TB infection among smokers as compared with nonsmokers. The researchers found that all studies evaluating the link between smoking and TB disease or TB mortality showed an association, but they did not combine these data together because of wide potential differences between the studies. Finally, all studies looking at passive smoking found an association with TB, as did some of those examining the link with indoor air pollution.

          What Do These Findings Mean?

          The findings here show that smoking is associated with an increased risk of TB infection, disease, and deaths from TB. The researchers found much more data on the risks for active smoking than on passive smoking or indoor air pollution. Tobacco smoking is increasing in many countries where TB is already a problem. These results therefore suggest that it is important for health policy makers to further develop strategies for controlling tobacco use in order to reduce the impact of TB worldwide.

          Additional Information.

          Please access these Web sites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.0040020

          Related collections

          Most cited references 70

          • Record: found
          • Abstract: found
          • Article: not found

          Emerging tobacco hazards in China: 1. Retrospective proportional mortality study of one million deaths.

          To assess the hazards at an early phase of the growing epidemic of deaths from tobacco in China. Smoking habits before 1980 (obtained from family or other informants) of 0.7 million adults who had died of neoplastic, respiratory, or vascular causes were compared with those of a reference group of 0.2 million who had died of other causes. 24 urban and 74 rural areas of China. One million people who had died during 1986-8 and whose families could be interviewed. Tobacco attributable mortality in middle or old age from neoplastic, respiratory, or vascular disease. Among male smokers aged 35-69 there was a 51% (SE 2) excess of neoplastic deaths, a 31% (2) excess of respiratory deaths, and a 15% (2) excess of vascular deaths. All three excesses were significant (P /70 there was a 39% (3) excess of neoplastic deaths, a 54% (2) excess of respiratory deaths, and a 6% (2) excess of vascular deaths. Fewer women smoked, but those who did had tobacco attributable risks of lung cancer and respiratory disease about the same as men. For both sexes, the lung cancer rates at ages 35-69 were about three times as great in smokers as in non-smokers, but because the rates among non-smokers in different parts of China varied widely the absolute excesses of lung cancer in smokers also varied. Of all deaths attributed to tobacco, 45% were due to chronic obstructive pulmonary disease and 15% to lung cancer; oesophageal cancer, stomach cancer, liver cancer, tuberculosis, stroke, and ischaemic heart disease each caused 5-8%. Tobacco caused about 0.6 million Chinese deaths in 1990 (0.5 million men). This will rise to 0.8 million in 2000 (0.4 million at ages 35-69) or to more if the tobacco attributed fractions increase. At current age specific death rates in smokers and non-smokers one in four smokers would be killed by tobacco, but as the epidemic grows this proportion will roughly double. If current smoking uptake rates persist in China (where about two thirds of men but few women become smokers) tobacco will kill about 100 million of the 0.3 billion males now aged 0-29, with half these deaths in middle age and half in old age.
            Bookmark
            • Record: found
            • Abstract: not found
            • Article: not found

            Measuring inconsistency in meta-analyses

              Bookmark
              • Record: found
              • Abstract: not found
              • Article: not found

              Measuring inconsistency in meta-analyses

                Bookmark

                Author and article information

                Contributors
                Role: Academic Editor
                Journal
                PLoS Med
                pmed
                PLoS Medicine
                Public Library of Science (San Francisco, USA )
                1549-1277
                1549-1676
                January 2007
                16 January 2007
                : 4
                : 1
                Affiliations
                [1 ] Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, United States of America
                [2 ] Department of Population and International Health and Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, United States of America
                [3 ] Division of Social Medicine and Health Inequalities, Brigham and Women's Hospital, Boston, Massachusetts, United States of America
                [4 ] Infectious Disease Unit, Massachusetts General Hospital, Boston, Massachusetts, United States of America
                Center for Tobacco Control Research and Education, United States of America
                Author notes
                * To whom correspondence should be addressed. E-mail: mmurray@ 123456hsph.harvard.edu
                Article
                06-PLME-RA-0571R3 plme-04-01-06
                10.1371/journal.pmed.0040020
                1769410
                17227135
                Copyright: © 2007 Lin et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
                Page count
                Pages: 1
                Categories
                Research Article
                Infectious Diseases
                Public Health and Epidemiology
                Public Health and Epidemiology
                Public Health
                Environmental Health
                Smoking
                Tuberculosis
                Custom metadata
                Lin HH, Ezzati M, Murray M (2007) Tobacco smoke, indoor air pollution and tuberculosis: A systematic review and meta-analysis. PLoS Med 4(1): e20. doi: 10.1371/journal.pmed.0040020

                Medicine

                Comments

                Comment on this article