title: Vitamin D and tuberculosis: review and association in three rural provinces of Afghanistan.
abstract: OBJECTIVE
  1) To update the 2006 systematic review and meta-analysis by Nnoaham & Clarke exploring the association between serum vitamin D and risk of active tuberculosis (TB) following discrepant evidence; and 2) to identify whether TB and vitamin D are associated in rural Afghanistan.
  
  
  METHODS
  Systematic review and meta-analysis of studies published between January 1980 and June 2014 using Nnoaham & Clarke's methodology. For this case-control study, 90 age- and sex-matched pairs were recruited from rural provinces, and blood 25-hydroxyvitamin D concentrations were measured using enzyme-linked immunosorbent assay.
  
  
  RESULTS
  Sixteen studies were eligible for review. Eleven showed differences between vitamin D levels in TB patients and controls, two showed partial differences and three showed none. Studies on African and European populations show lower vitamin D levels in TB patients, but results from Asia vary. No significant differences were found in vitamin D levels in our rural Afghan population. Controls had a higher body mass index (BMI) (mean control BMI 21.50 kg/m(2), mean case BMI 18.86 kg/m(2), P < 0.001), and were more likely to have been employed (40% of controls, 15.6% of cases, P = 0.002).
  
  
  CONCLUSIONS
  Genetic differences may account for the differences among study results in the systematic review. Vitamin D levels are not associated with TB among Afghans living in these rural provinces.
authors.affiliation: College of Medical and Dental Sciences, University of Birmingham, Birmingham, UK.
authors.forename: P
authors.initials: P
authors.lastname: Sarin
authors.affiliation: Independent researcher/statistician, Edinburgh, UK.
authors.forename: J
authors.initials: J
authors.lastname: Duffy
authors.affiliation: University of Manchester, Manchester, UK.
authors.forename: Z
authors.initials: Z
authors.lastname: Mughal
authors.affiliation: Aga Khan University, Kabul, Afghanistan.
authors.forename: E
authors.initials: E
authors.lastname: Hedayat
authors.affiliation: Department of Public Health, Epidemiology and Biostatistics, School of Health and Population Sciences, College of Medical and Dental Sciences, University of Birmingham, Rm G31, Public Health Building, Edgbaston, Birmingham B15 2TT, UK. s.manasekiholland@bham.ac.uk.
authors.forename: S
authors.initials: S
authors.lastname: Manaseki-Holland
mesh_terms: D000346:Afghanistan / Q000453:epidemiology; D015992:Body Mass Index; D016208:Databases, Factual; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D015201:Meta-Analysis as Topic; D012424:Rural Population; D012959:Socioeconomic Factors; D014376:Tuberculosis / Q000097:blood* / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology
chemical_list: D014807:Vitamin D