TB Manual

2.4.1. TB infection care cascade

TB infection testing and treatment involves numerous steps (known as the care cascade), including testing, receiving a result, referral if test positive, recommendation for treatment and treatment initiation and completion.⁵⁵ Loss of individuals can occur at any step along the care cascade, and many TB infection testing and treatment programs among immigrants perform poorly due to losses throughout the care cascade.^55–59 In two systematic reviews and meta-analyses of studies of TB infection testing and treatment in immigrants after arrival, 55-69% of migrants who tested positive for TB infection initiated treatment; 73-74% of those who started treatment completed it, with higher initiation and completion in more recent years.^55,56 The overall TB infection care cascade among immigrants is weak; one review of the final steps of the care cascade found that only 52% of migrants receiving a medical evaluation initiated and completed treatment. Another review of the entire cascade found that only 14% of all migrants estimated to be positive for TB infection completed treatment.^55,56 For a strong cascade, physicians/providers need to be educated to test patients, offer treatment and encourage treatment completion, and patients need to accept and complete testing and treatment when offered.

2.4.2. Barriers to accessing TB infection testing and treatment

Immigrants and refugees may encounter significant barriers at the patient, provider and system levels when accessing TB infection testing and treatment. General barriers to accessing primary healthcare among immigrant populations in Canada have been summarized in a systematic review.⁶⁰ Several barriers mentioned in that review are relevant to TB, including cultural barriers, communication barriers (such as language discordance), socioeconomic factors (financial and work-related), concerns about confidentiality and lack of patient knowledge or trust involving the Canadian healthcare system.⁶⁰ There are also structural barriers, especially related to a lack of interpreter services in many healthcare settings, that can result in patient-provider miscommunication and compromise the quality of healthcare delivery and patient safety.⁶¹ Key additional patient, provider and system-level barriers are detailed in Table 4.

Table 4. Barriers for TB infection testing and treatment.

2.4.3. Strategies to improve TB infection testing and treatment uptake and completion

Strategies are needed to improve TB infection testing and treatment uptake and completion among at-risk foreign-born persons. Such strategies should focus on addressing context-specific barriers such as those described in the previous section (see Table 4). Facilitators of testing and treatment implementation and completion at the patient and provider level are detailed in Table 5. Engagement with community members and community-based organizations and offering services in diverse settings such as integrated care in a primary care setting or community centers have been successful. Language-concordant encounters between immigrants and health care workers, use of cultural case managers and community engagement and education are key to successful programs.^68,89–92 Programs that take a syndemics approach and provide integrated multi-disease screening of high-prevalence conditions such as TB infection, viral hepatitis and HIV have been acceptable to migrants and have led to increased detection of infections, including TB infection.^88,93–96 Several interventions have been found to improve completion of steps along the TB infection care cascade, including patient incentives, health care worker education, home visits, digital aids and patient reminders.⁹⁷ Educating primary care providers to identify, promote and deliver testing and treatment services among migrants at risk have been shown to increase screening uptake and diagnosis of active TB disease and TB infection.^84,98,99

Table 5. Facilitators and strategies to improve TB infection testing and treatment uptake and completion.

Good practice statements

• TB infection testing and treatment programs should aim to provide linguistically tailored, culturally sensitive and trauma-informed care that is sensitive to the barriers patients may face in accessing care and completing testing and treatment requirements.

• Programs able to assure a high level of provider and patient adherence and support are best placed to initiate TB infection testing and treatment activities; any such programs should carefully document both costs and clinical outcomes.

2.4.4. Travel-associated TB

Travel to TB-endemic countries poses a risk for TB infection, which is of relevance for foreign-born populations returning to their countries of birth to visit friends and relatives (VFR travelers). However, the magnitude of TB risk in this group is not precisely known. Travel-associated TB infection and active TB risk among health care workers, military personnel and general travelers/volunteers was estimated in a recent systematic review.¹⁰⁸ Among these 3 groups, the cumulative incidences of TB infection for travel durations up to 6 months were estimated at 4.3% (95% CI 2.8-6.7), 2.5% (95% CI 2.0-2.9) and 1.6% (95% CI 1.0-2.5), respectively, with health care workers having the greatest risk.¹⁰⁸ The incidence of active TB was estimated to be 120.7 cases per 100,000 travelers for all studies in the analysis reporting active TB associated with travel (ie, travel durations up to 24 months).¹⁰⁸

Determining the risk of TB among migrants due to travel is a challenge, as only a minority (20-30%) seek pre-travel advice and there are no prospective pre-/post-travel screening studies that estimate this risk.^109–111 Several small observational studies suggest that VFR travel is associated with increased risk of TB and report that 15-50% of active TB cases in some foreign-born populations are due to recent return travel to their countries of origin.^112–116 This is supported by a study of ill travelers presenting to 16 European clinics (EuroTravNet) in the GeoSentinel network between 2008-2010, which found that VFR travelers had a more than 15-fold higher risk (3.67% [91/2477] vs 0.23% [33/14,140] vs 0.24% [4/1,686]) of being diagnosed with active TB after travel as compared to other short-term travelers or expatriate travelers respectively.¹¹² The risk of TB among immigrants who travel also increases with trip duration. In a case-control study in the Netherlands, the travel-associated odds ratio (OR) for active TB among Moroccan immigrants with less than three months of travel to Morocco was 3.2 (95% CI 1.3–7.7), and increased to 17.2 (95% CI 3.7–79) when the cumulative duration of travel exceeded three months.¹¹⁶ Health care practitioners should also consider the possibility of TB infection among VFR children and Canadian-born children who travel to the country of origin of their foreign-born parents. In two studies in the United States, the OR for a positive TST after travel to a TB-endemic country was 1.9 among Mexican-American children and 1.8 in a mixed cohort of children living in New York City, 78% of whom were Hispanic.^117,118

The optimal strategy to test for TB infection among VFR travelers is still to be determined. A cost-effectiveness analysis of TB infection testing among moderate and high TB-incidence countries found that the most effective (preventing the most active TB cases) and cost-effective strategy for detecting travel-associated TB infection was a single post-trip TST. Testing became more cost-effective as trip duration and the TB incidence of the country visited increased, but was reduced if there was poor treatment adherence.¹¹⁹ New TB infection should be considered among foreign-born persons who have recently traveled to an intermediate or high TB-incidence country based on their duration of travel and the TB incidence in the country visited. Those who have engaged in healthcare work are at the highest risk for TB infection.

Recommendation

• We conditionally recommend that the risks and benefits of TB infection testing and treatment be discussed with particular attention to travelers visiting friends and relatives (including Canadian-born children of foreign-born parents); people engaging in higher-risk travel such as travel for healthcare work; and/or persons born in low TB-incidence countries who have lived in moderate or high TB-incidence countries for prolonged periods of time. The following should be considered high risk when counseling travelers to moderate or high TB-incidence countries:

  • Any travel with very high-risk contact, particularly direct patient contact in a hospital or indoor setting, and also potentially work in prisons, homeless shelters, refugee camps or inner-city slums.

  • ≥3 months of travel to TB-incidence country ≥400/100,000 population^{^}

  • ≥6 months of travel to TB-incidence country 200-399/100,000 population^{^}

  • ≥12 months of travel to TB-incidence country 100-199/100,000 population^{^}

  • (poor evidence)

^For TB incidence in individual countries see the World Health Organization TB country, regional and global profiles.⁵⁴

2.4.5. Limitations of migrant testing and treatment for TB infection

Several studies have assessed the effectiveness and cost-effectiveness of TB infection testing and treatment among migrants in the pre-arrival, post-landing surveillance and post-arrival settings.^{22,53,119–123} On the one hand, widely applied post-arrival TB infection testing and treatment among immigrants is not a cost-effective strategy and could have an enormous impact on primary-care infrastructure as well as on healthcare budgets.¹²¹ On the other hand, narrowly focusing TB infection testing only on those with medical risk factors who have a high risk of developing active TB disease, such as persons with HIV infection, close TB contacts, or using tumor necrosis factor antagonists would only detect infection in a tiny minority of the migrant population, who account for a small proportion of TB disease. Among more than a million migrants who took up permanent residence in British Columbia between 1985 and 2012, only 1.5% had or developed such risk factors and this strategy would require testing 136 persons to prevent 1 case and only prevent 4.2% of all TB cases in this cohort.⁵³ Targeted testing based on TB disease incidence in migrants’ source countries, age and presence of underlying medical co-morbidities is the approach taken in this chapter and is supported by some data. In the same BC cohort of immigrants, TB infection testing of all migrants with high-risk medical co-morbidities as well as those aged less than 65 years from countries with annual TB incidence >200 per 100,000 would require testing ∼30% of the population (about 10,000 annually), amounting to testing 204 persons to prevent 1 case of TB, and would prevent 50% of potentially preventable TB disease in the cohort.⁵³