Latent Tuberculosis Infection in Iqaluit, Nunavut: An Analysis of the Cascade of Care and Cost-Effectiveness of a Novel Treatment Regimen

Abstract

Background: The incidence of tuberculosis (TB) among Inuit is over 400 times that of Canadian-born non-indigenous people. To address this, more patients will need to complete preventative treatment. Methods: First, data were extracted retrospectively for all patients with a tuberculin skin test (TST) implanted in Iqaluit, Nunavut between January 2012 and March 2016 and used to identify sources of loss from the latent TB infection (LTBI) cascade of care. Associations between demographic and clinical factors and treatment non-initiation and treatment non-completion were identified using regression models. Second, using a slightly expanded version of the retrospective dataset plus other sources, a Markov model was utilized to assess the cost-effectiveness of a novel shortened regimen for LTBI (12 weeks of once weekly isoniazid and rifapentine (3HP)) compared to the current standard of care (9 months of isoniazid monotherapy (9H)). Results: Treatment non-initiation and non-completion were the largest sources of loss of TST positive patients from the cascade of care. LTBI testing via employment screening was associated with treatment non-initiation while older age was associated with both treatment noninitiation and non-completion. In cost-effectiveness analysis, 3HP was dominant over 9H: costs were lower ($835 vs $1229 per person) and health outcomes slightly improved (20.14 vs 20.13 QALYs gained per person treated), largely due to an improved treatment completion with 3HP. Conclusions: Interventions to increase LTBI treatment initiation and completion in Iqaluit are needed. This could include the use of 3HP instead of 9H for LTBI treatment which may improve treatment completion and result in cost savings and slightly improved health outcomes.