title: Epidemiology of Peripheral Lymph Node Tuberculosis and Genotyping of M. tuberculosis Strains: A Case-Control Study.
abstract: BACKGROUND
  This study examined potential risk factors of lymph node tuberculosis (LNTB), including phylogenetic lineages of Mycobacterium tuberculosis (MTB), in comparison to pulmonary tuberculosis (PTB) in a setting with an ethnically diverse population.
  
  
  METHODS
  We conducted a case-control study at a major tuberculosis clinic in Sydney, Australia, which included all patients with peripheral LNTB seen at the clinic between 2000 and 2012. Controls were randomly selected patients with PTB seen at the same clinic during the study period. Epidemiological data were extracted from the hospital electronic database and medical records. Associations between LNTB and age, sex, ethnicity, comorbidities and phylogenetic lineages of MTB in comparison to PTB were examined using logistic regression in univariate and multivariate analyses.
  
  
  RESULTS
  There were 212 cases with LNTB and 424 randomly selected controls with PTB. Among patients with LNTB, 74% were female and the mean age (standard deviation, SD) was 42 (16) years. Among patients with PTB, 43% were female and the mean age was 44 (22) years. Females, 45 to 64-year-olds and Southern Asians had an increased risk for LNTB (OR 3.13, 95% CI 2.10-4.67; OR 2.50, 95% CI 1.29-4.84; OR 3.95, 95% CI 1.54-10.12 respectively). Patients with diabetes were at a higher risk of PTB (OR 0.40, 95% CI 0.19 - 0.83 for LNTB). A subset analysis showed that patients infected with the East African Indian strain of MTB were more likely to develop LNTB (OR 10.07, 95% CI 2.37-42.77).
  
  
  CONCLUSIONS
  An increased risk for LNTB (but still lower rates than for PTB) was found among females, people aged 45 to 64 years and people born in Southern Asia. An increased risk for PTB was found among patients with diabetes. The East African Indian strain of MTB was significantly associated with a higher likelihood of LNTB compared to other MTB strains.
authors.affiliation: South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Chinmay
authors.initials: C
authors.lastname: Khandkar
authors.affiliation: South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Zinta
authors.initials: Z
authors.lastname: Harrington
authors.affiliation: NSW Mycobacterium Reference Laboratory, Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Sydney, New South Wales, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Jelfs
authors.affiliation: NSW Mycobacterium Reference Laboratory, Centre for Infectious Diseases and Microbiology Laboratory Services, Institute of Clinical Pathology and Medical Research, Westmead Hospital, Sydney, New South Wales, Australia; Marie Bashir Institute for Infectious Diseases and Biosecurity, The University of Sydney, New South Wales, Australia.
authors.forename: Vitali
authors.initials: V
authors.lastname: Sintchenko
authors.affiliation: South Western Sydney Clinical School, University of New South Wales, Sydney, New South Wales, Australia.
authors.forename: Claudia C
authors.initials: CC
authors.lastname: Dobler
mesh_terms: D000328:Adult; D001315:Australia / Q000453:epidemiology; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D015999:Multivariate Analysis; D009169:Mycobacterium tuberculosis / Q000235:genetics*; D014388:Tuberculosis, Lymph Node / Q000453:epidemiology* / Q000382:microbiology*