title: Risk factors for latent tuberculosis infection in close contacts of active tuberculosis patients in South Korea: a prospective cohort study.
abstract: BACKGROUND
  The diagnosis and treatment of latent tuberculosis infection (LTBI) have become mandatory to reduce the burden of tuberculosis worldwide. Close contacts of active TB patients are at high risk of both active and LTBI. The aim of this study is to identify the predominant risk factors of contracting LTBI, persons in close contact with TB patients were recruited. This study also aimed to compare the efficacy of the tuberculin skin test (TST) and QuantiFERON(®)-TB GOLD (QFT-G) to diagnose LTBI.
  
  
  METHODS
  Close contacts of active pulmonary TB patients visiting a hospital in South Korea were diagnosed for LTBI using TST and/or QFT-G. The association of positive TST and/or QFT-G with the following factors was estimated: age, gender, history of Bacillius Calmette-Guerin (BCG) vaccination, history of pulmonary TB, cohabitation status, the acid-fast bacilli smear status, and presence of cough in source cases.
  
  
  RESULTS
  Of 308 subjects, 38.0% (116/305) were TST positive and 28.6% (59/206) were QFT-G positive. TST positivity was significantly associated with male gender (OR: 1.734; 95% CI: 1.001-3.003, p =0.049), history of pulmonary TB (OR: 4.130; 95% CI: 1.441-11.835, p =0.008) and household contact (OR: 2.130; 95% CI: 1.198-3.786, p =0.01) after adjustment for confounding variables. The degree of concordance between TST and QFT-G was fair (70.4%, κ =0.392).
  
  
  CONCLUSIONS
  A prevalence of LTBI among close contacts of active pulmonary TB patients was high, and prior TB history and being a household contact were risk factors of LTBI in the study population.
authors.forename: Seung Jun
authors.initials: SJ
authors.lastname: Lee
authors.forename: Seung Hun
authors.initials: SH
authors.lastname: Lee
authors.forename: You Eun
authors.initials: YE
authors.lastname: Kim
authors.forename: Yu Ji
authors.initials: YJ
authors.lastname: Cho
authors.forename: Yi Yeong
authors.initials: YY
authors.lastname: Jeong
authors.affiliation: Department of Internal Medicine, College of Medicine, Gyeongsang National University, 90 Chilam-Dong, Jinju, Gyeongnam 660-302, South Korea. hochkim@gnu.ac.kr.
authors.forename: Ho Cheol
authors.initials: HC
authors.lastname: Kim
authors.forename: Jong Deog
authors.initials: JD
authors.lastname: Lee
authors.forename: Jang Rak
authors.initials: JR
authors.lastname: Kim
authors.forename: Young Sil
authors.initials: YS
authors.lastname: Hwang
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Kim
authors.forename: Dick
authors.initials: D
authors.lastname: Menzies
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D005260:Female; D006801:Humans; D055985:Latent Tuberculosis / Q000453:epidemiology* / Q000635:transmission; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011446:Prospective Studies; D056910:Republic of Korea / Q000453:epidemiology; D012307:Risk Factors; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000635:transmission; D055815:Young Adult