COST-EFFECTIVENESS OF CANADA'S TUBERCULOSIS SCREENING AND SURVEILLANCE PROGRAM FOR NEW IMMIGRANTS

Purpose:

   All immigrants to Canada are screened for active pulmonary tuberculosis (TB) before immigration due to its high prevalence in developing countries, communicability, and high burden of morbidity and mortality. Recent data indicate that Canada's current mass screening and surveillance program may be inefficient (Khan 2015), warranting an evaluation of its cost-effectiveness.

Method:

   We performed a cost-utility analysis using a Markov model to compare the current mass screening strategy to alternative screening strategies from a governmental perspective. We used 2D microsimulation to account for patient variability and parameter uncertainty. Quality-adjusted life years (QALYs), costs in Canadian dollars (CAD), and the net health benefit (NHB) were predicted over a lifetime time horizon. Costs and QALYs were discounted at a rate of 3%. Data on probabilities, costs, and utilities were primarily obtained from the literature—with most data coming from a recent Ontario study (Khan 2015).

Result:

   The total costs, total QALYs, and net health benefits (NHB) of each strategy are presented in Table 1. Based on the 2014 cohort size of 260,404 Canadian immigration applicants, our model predicts that: mass screening of all applicants results in a NHB of 6,156,162 QALYs; targeted screening of countries with an active TB prevalence above 20/100,000 results in a NHB of 6,156,058 QALYs; targeted screening of countries with an active TB prevalence above 50/100,000 results in a NHB of 6,156,173 QALYs; targeted screening of countries with an active TB prevalence above 100/100,000 results in a NHB of 6,156,164 QALYs; and no screening results in a NHB of 6,155,367 QALYs at a cost-effectiveness threshold of $50,000/QALY. Therefore, targeted screening of immigrants from countries with an active TB prevalence above 50/100,000 is the most cost-effective strategy at the commonly used cost-effectiveness threshold of $50,000/QALY.

Conclusion:

   Canada currently performs equally rigorous tuberculosis screening and surveillance for high and low-risk immigrants, resulting in inefficient use of resources. A targeted screening program would likely be more cost-effective than the current program, offering a slightly lower benefit but at a lower cost.

   It is worth noting that the differences in costs and effects of the compared screening strategies were small, which may warrant further analysis comparing more strategies—such as strategies incorporating further risk stratification.