title: A meta-analysis of drug resistant tuberculosis in Sub-Saharan Africa: how strongly associated with previous treatment and HIV co-infection?
abstract: BACKGROUND
  In Sub-Saharan Africa, the fight against tuberculosis (TB) has encountered a great challenge because of the emergence of drug resistant TB strains and the high prevalence of HIV infection. The aim of this meta-analysis was to determine the association of drug-resistant TB with anti-TB drug treatment history and HIV co-infection.
  
  
  METHODS
  After electronic based literature search in the databases of Medline, HINARI, EMBASE and the Cochrane library, article selection and data extraction were carried out. HIV co-infection and previous history of TB treatment were used as predictors for the occurrence of any anti-TB drug resistant or multiple drug resistant TB (MDR-TB). The risk ratios for each included study and for the pooled sample were computed using the random-effects model. Heterogeneity test, sensitivity analyses and funnel plots were also done.
  
  
  RESULTS
  The pooled analysis showed that the risk of developing drug-resistant TB to at least one anti-TB drug was about 3 times higher in individuals who had a previous history of anti-TB treatment than new TB cases. The risk of having MDR-TB in previously anti-TB treated TB cases was more than 5-fold higher than that of new TB cases. Resistance to Ethambutol and Rifampicin was more than fivefold higher among the previously treated with anti-TB drugs. However, HIV infection was not associated with drug-resistant TB.
  
  
  CONCLUSIONS
  There was a strong association of previous anti-TB treatment with MDR-TB. Primary treatment warrants special emphasis, and screening for anti-TB drugs sensitivity has to be strengthened.
authors.affiliation: College of Medicine and Health Sciences, Hawasa Univeristy, Ethiopia.
authors.forename: Asres
authors.initials: A
authors.lastname: Berhan
authors.forename: Yifru
authors.initials: Y
authors.lastname: Berhan
authors.forename: Desalegn
authors.initials: D
authors.lastname: Yizengaw
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D000368:Aged; D000369:Aged, 80 and over; D000995:Antitubercular Agents / Q000009:adverse effects / Q000494:pharmacology*; D002648:Child; D060085:Coinfection; D004977:Ethambutol / Q000627:therapeutic use; D005260:Female; D015658:HIV Infections / Q000150:complications* / Q000188:drug therapy / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012293:Rifampin / Q000627:therapeutic use; D018088:Tuberculosis, Multidrug-Resistant / Q000150:complications* / Q000188:drug therapy* / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000995:Antitubercular Agents; D004977:Ethambutol; D012293:Rifampin
keywords: HIV; Sub-Saharan Africa; drug resistance; meta-analysis; previous treatment; tuberculosis