Abstract
OBJECTIVES: 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.
METHODS: 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.
RESULTS: 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 onreserve 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.
CONCLUSIONS: 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.
Key Words: Tuberculosis in Canada, tuberculosis in Indigenous peoples, contact investigations
Résumé
OBJECTIFS: Le traçage des contacts est un élément essentiel de la lutte contre la tuberculose dans les pays à revenu élevé. On ignore cependant quel est le succès relatif des méthodes classiques selon le segment démographique et le lieu de résidence. Notre étude compare les effets du traçage des contacts de cas de tuberculose autochtones nés au Canada (vivant dans des réserves et hors des réserves) avec d’autres cas nés au Canada.
MÉTHODE: Une analyse rétrospective a permis d’identifier les cas de tuberculose pulmonaire positifs par culture chez les adultes nés au Canada (2001–2010). Nous avons comparé les caractéristiques des cas sources et de leurs contacts selon le segment démographique. Les résultats du traçage des contacts, dont l’exécution des traçages recommandés et l’achèvement du traitement préventif, ont été comparés par analyse multivariée.
RÉSULTATS: Sur les 171 cas de tuberculose identifiés, 49 (29 %) étaient des Autochtones dans les réserves, 62 (36 %) étaient des Autochtones hors des réserves, et 60 (35 %) étaient des personnes non autochtones ou « autres » nées au Canada. Il y avait davantage de contacts identifiés par cas pour les patients autochtones que pour les patients non autochtones. Le segment démographique et la positivité ou non des frottis d’expectoration des cas étaient les principaux prédicteurs de succès du traçage des contacts. Parmi les contacts pour lesquels un traitement préventif était recommandé, les contacts étroits des cas autochtones dans les réserves présentaient le taux d’achèvement le plus élevé, soit 54 %, contre 41 % et 37 % pour les contacts étroits des Autochtones vivant hors des réserves et des « autres » personnes nées au Canada, respectivement (p = 0,02). Les contacts des cas autochtones vivant hors des réserves présentaient le plus long délai d’évaluation et les plus faibles taux d’exécution de l’évaluation et d’achèvement du traitement préventif. Selon l’analyse multivariée, le segment démographique, la positivité ou non des frottis d’expectoration des cas sources et la proximité du contact étaient des prédicteurs de l’acceptation et/ou de l’achèvement du traitement préventif.
CONCLUSIONS: Des écarts significatifs dans les résultats du traçage des contacts ont été observés entre les segments démographiques. La priorité plus élevée accordée aux contacts des cas dont les frottis sont positifs semble influencer l’efficience de la prestation des services, peu importe le segment démographique. Les écarts dans la prestation des programmes et la disponibilité des ressources selon la province ou le territoire et les écarts dans le risque de transmission perçu influencent probablement les résultats du traçage des contacts.
Mots Clés: tuberculose au Canada, tuberculose chez les peuples autochtones, traçage des contacts
Footnotes
Conflict of Interest: None to declare.
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