title: Alcohol use as a risk factor for tuberculosis - a systematic review.
abstract: BACKGROUND
  It has long been evident that there is an association between alcohol use and risk of tuberculosis. It has not been established to what extent this association is confounded by social and other factors related to alcohol use. Nor has the strength of the association been established. The objective of this study was to systematically review the available evidence on the association between alcohol use and the risk of tuberculosis.
  
  
  METHODS
  Based on a systematic literature review, we identified 3 cohort and 18 case control studies. These were further categorized according to definition of exposure, type of tuberculosis used as study outcome, and confounders controlled for. Pooled effect sizes were obtained for each sub-category of studies.
  
  
  RESULTS
  The pooled relative risk across all studies that used an exposure cut-off level set at 40 g alcohol per day or above, or defined exposure as a clinical diagnosis of an alcohol use disorder, was 3.50 (95% CI: 2.01-5.93). After exclusion of small studies, because of suspected publication bias, the pooled relative risk was 2.94 (95% CI: 1.89-4.59). Subgroup analyses of studies that had controlled for various sets of confounders did not give significantly different results and did not explain the significant heterogeneity that was found across the studies.
  
  
  CONCLUSIONS
  The risk of active tuberculosis is substantially elevated in people who drink more than 40 g alcohol per day, and/or have an alcohol use disorder. This may be due to both increased risk of infection related to specific social mixing patterns associated with alcohol use, as well as influence on the immune system of alcohol itself and of alcohol related conditions.
authors.affiliation: Stop TB Department, World Health Organization, Geneva, Switzerland. lonnrothk@who.int
authors.forename: Knut
authors.initials: K
authors.lastname: Lönnroth
authors.forename: Brian G
authors.initials: BG
authors.lastname: Williams
authors.forename: Stephanie
authors.initials: S
authors.lastname: Stadlin
authors.forename: Ernesto
authors.initials: E
authors.lastname: Jaramillo
authors.forename: Christopher
authors.initials: C
authors.lastname: Dye
mesh_terms: D000428:Alcohol Drinking / Q000009:adverse effects*; D019973:Alcohol-Related Disorders / Q000150:complications*; D016022:Case-Control Studies; D015331:Cohort Studies; D016001:Confidence Intervals; D006801:Humans; D016017:Odds Ratio; D012307:Risk Factors; D014376:Tuberculosis / Q000209:etiology*