Evaluating the post-landing tuberculosis surveillance process for people migrating to British Columbia (2020–2022)

Background: People migrating to Canada face a disproportionately higher burden of tuberculosis (TB) disease. To address this, Immigration, Refugees, and Citizenship Canada (IRCC) mandates an Immigration Medical Exam (IME) for all permanent and select temporary residents before their arrival. This screening aims to identify TB disease, with individuals considered at high risk subsequently referred for post-landing surveillance. Despite its critical role, this process has remained largely unchanged for over four decades, prompting a comprehensive review. Methods: We conducted a retrospective cohort study of individuals referred for post-landing TB surveillance in British Columbia (BC) between January 1, 2020, and December 31, 2022. We described cohort characteristics, surveillance timelines, and TB incidence. Clinical and demographic data were extracted through chart review from IME records and the provincial TB registry. Participants were followed for up to two years from the date of IME referral. Additionally, we performed a comprehensive risk factor analysis using univariate and multivariate models, including Cox regression, to identify variables associated with TB disease and evaluate the effectiveness of current screening and surveillance criteria. Results: Of 2,895 people referred for post-landing surveillance, 31 (1.1%) were diagnosed with TB after arrival in BC. The surveillance process, while achieving high adherence with over 80% of people completing their workup, was characterized by significant delays, with a median time of 190 days from arrival to treatment initiation for those diagnosed. Abnormal chest x-ray findings were strongly associated with subsequent TB disease, present in 96.8% of people with TB disease. People with abnormal chest x-ray and those from high TB incidence countries had significantly higher hazards of developing TB disease, with adjusted hazard ratios of 9.14 (95% CI: 1.2-67.1) and 4.82 (95% CI: 1.46-15.87), respectively. Conclusion: Chest x-ray abnormalities and TB incidence in the country of origin were strongly associated with TB disease. Given the low diagnostic yield and significant delays in follow-up, post-landing surveillance efforts should prioritize individuals with radiographic abnormalities and those from high-incidence countries.