title: Contact investigation outcomes of Canadian-born adults with tuberculosis in Indigenous and non-Indigenous populations in Alberta.
abstract: Contact investigations are a critical component of tuberculosis control in high-income countries. However, the relative success of conventional methods by population group and place of residence is unknown. This study compares outcomes of contact investigations of Canadian-born Indigenous tuberculosis cases living on- and off-reserve with other Canadian-born cases.
  
  
  
  In a retrospective analysis, Canadian-born adult culture-positive pulmonary TB cases (2001-2010) were identified. Characteristics of source cases and their contacts were compared by population group. Outcomes of contact investigations, including completion of recommended investigations and preventive therapy, were compared in multivariable analysis.
  
  
  
  Of 171 cases of tuberculosis identified, 49 (29%) were Indigenous on-reserve, 62 (36%) Indigenous off-reserve, and 60 (35%) non-Indigenous or Canadian-born, "other". Indigenous people had more contacts identified per case compared to non-Indigenous patients. Case population group and smear status were the main predictors of the success of contact investigations. Of those recommended preventive therapy, close contacts of Indigenous cases on-reserve had the highest rate of completion, at 54%, vs. 41% and 37% for close contacts of Indigenous living off-reserve and Canadian-born "other" respectively (p = 0.02). Contacts of Indigenous cases living off-reserve had the greatest delay in assessment and the lowest rates of completion of assessment and preventive therapy. In multivariable analysis, population group, smear status of source case and proximity of contact were predictors of preventive therapy acceptance and/or completion.
  
  
  
  Significant differences in outcomes of contact investigations were observed between population groups. The higher priority of contacts of smear-positive cases appears to influence efficiency of service delivery, regardless of population group. Jurisdictional differences in program delivery, resource availability and perceived risk of transmission likely influence outcomes of contact investigations.
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Lisa
authors.initials: L
authors.lastname: Eisenbeis
authors.affiliation: Department of Medicine, Memorial University of Newfoundland, St. John's, NL, Canada.
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Courtney
authors.initials: C
authors.lastname: Heffernan
authors.affiliation: First Nations Inuit Health Branch, Health Canada, Alberta Region, Canada.
authors.forename: Wadieh
authors.initials: W
authors.lastname: Yacoub
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, AB, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Long
authors.affiliation: Department of Medicine, University of Alberta, Edmonton, AB, Canada. gverma@ualberta.ca.
authors.forename: Geetika
authors.initials: G
authors.lastname: Verma
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000416:Alberta / Q000453:epidemiology; D016358:Contact Tracing; D005260:Female; D006801:Humans; D007198:Indians, North American / Q000706:statistics & numerical data*; D004930:Inuit / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D044382:Population Groups / Q000706:statistics & numerical data*; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012189:Retrospective Studies; D014397:Tuberculosis, Pulmonary / Q000453:epidemiology* / Q000517:prevention & control; D055815:Young Adult