Latent Tuberculosis Infection Screening in Immigrants to Low-Incidence Countries: A Meta-Analysis

Latent tuberculosis infection prevalence in second generation immigrants from high to low TB burden countries

BACKGROUND

Latent tuberculosis infection (LTBI) diagnosis in a country with a low tuberculosis burden is complicated. Since the prevalence of LTBI in second generation immigrants has not been well recognized, we conducted a cross-sectional study which aimed to explore the differences in LTBI prevalence between offspring of immigrants from high tuberculosis (TB) burden countries and those whose parents were born in countries with a low TB burden.

METHODS

Between May 2014 and April 2018 young native Israelis who were required to perform pre-occupational tuberculin skin tests (TST) (medical and paramedical personnel or teaching assistants of immigrants from high TB burden countries) and who had a TST result of 10mm and above were tested for QuantiFERON-TB In Tube (QFT-GIT). Statistical comparisons were made between second generation immigrants and those with both parents from a low TB burden country.

RESULTS

Of 102 patients, 71 were born to parents both of whom were from low-risk countries, 14 to one parent from a high-risk country and 17 to parents both of whom were from a high-risk country. The odds ratio for LTBI was 4.5 (95% CI, 1.2...17.2; p=0.03) if both parents were born in a high-risk country compared to both parents being from a low-risk country and 4.01 (95% CI, 1.12...14.3; p=0.03) higher compared to persons for whom at least one parent was born in a low-risk country.

CONCLUSION

The risk for latent TB is significantly higher in second generation immigrants if both parents were born in a high-risk country. IGRA should be considered before treatment to patients with a positive TST if at least one parent was born in a low-risk country in order to confirm LTBI.

Comparison of three tests for latent tuberculosis infection in high-risk people in the USA: an observational cohort study

BACKGROUND

Treatment of latent tuberculosis infection is an important strategy to prevent tuberculosis disease. In the USA, three tests are used to identify latent tuberculosis infection: the tuberculin skin test (TST) and two IFN-γ release assays (T-SPOT.TB and QuantiFERON). To our knowledge, few large studies have compared all three tests among people at high risk of latent tuberculosis infection or progression to tuberculosis disease. We aimed to assess test agreement between IFN-γ release assays and TST to provide guidance on their use in important risk groups.

METHODS

In this observational cohort study, we enrolled participants at high risk of latent tuberculosis infection or progression to tuberculosis disease at ten US sites with 18 affiliated clinics, including close contacts of infectious tuberculosis cases, people born in countries whose populations in the USA have high (≥100 cases per 100 000 people) or moderate (10-99 cases per 100 000 people) tuberculosis incidence, and people with HIV. Participants were interviewed about demographics and medical risk factors, and all three tests were administered to each participant. The primary endpoints for this study were the proportions of positive test results by test type stratified by risk group and test concordance by risk group for participants with valid results for all three test types. The study is registered at ClinicalTrials.gov, NCT01622140.

FINDINGS

Between July 12, 2012, and May 5, 2017, 26 292 people were approached and 22 131 (84·2%) were enrolled in the study. Data from 21 846 (98·7%) participants were available for analysis, including 3790 (17·3%) born in the USA and 18 023 (82·5%) born outside the USA. Among non-US-born participants overall, the RR comparing the proportions of TST-positive results (7476 [43·2%] of 17 306 participants) to QuantiFERON-positive results (4732 [26·5%] of 17 882 participants) was 1·6 (95% CI 1·6-1·7). The risk ratio (RR) for the comparison with the proportion of T-SPOT.TB-positive results (3693 [21·6%] of 17 118 participants) was 2·0 (95% CI 1·9-2·1). US-born participants had less variation in the proportions of positive results across all tests. The RRs for the proportion of TST-positive results (391 [10·9%] of 3575 participants) compared with the proportion of QuantiFERON-positive results (445 [12·0%] of 3693 participants) and T-SPOT.TB-positive results (295 [8·1%] of 3638 participants) were 0·9 (95% CI 0·8-1·0) and 1·3 (1·2-1·6), respectively. 20 149 (91·0%) of 21 846 participants had results for all three tests, including 16 712 (76%) non-US-born participants. Discordance between TST and IFN-γ release assay results varied by age among non-US-born participants and was greatest among the 848 non-US-born children younger than 5 years. 204 (87·2%) of 234 non-US-born children younger than 5 years with at least one positive test were TST-positive and IFN-γ release assay-negative. The proportion of non-US-born participants who were TST-negative but IFN-γ release assay-positive ranged from one (0·5%) of 199 children younger than 2 years to 86 (14·5%) of 594 participants aged 65 years and older (ptrend<0·0001). Test agreement was higher between the two IFN-γ release assays than between TST and either IFN-γ release assay, regardless of birthplace. κ agreement was particularly low between TST and IFN-γ release assays in non-US-born children younger than 5 years.

INTERPRETATION

Our findings support the preferential use of IFN-γ release assays for the diagnosis of latent tuberculosis in high-risk populations, especially in very young and older people born outside the USA.

FUNDING

US Centers for Disease Control and Prevention.

A Pilot TB Screening Model in a U.S. Prison Population Using Tuberculin Skin Test and Interferon Gamma Release Assay Based on Country of Origin

The objective of this study was to compare tuberculosis (TB) screening results before and after implementation of a stratified testing strategy screening pilot study, incorporating interferon gamma release assay (IGRA) and tuberculin skin test (TST), based on country of origin. In 2015, the Washington State Department of Corrections began screening people born outside of the United States for TB with IGRA, while U.S.-born people continued screening by TST. Of 405 (75%) foreign-born men screened with IGRA, 403 had valid test results and IGRA screening positivity was 10.4% (N = 42). In contrast, among 5,940 primarily U.S-born men screened with TST, 24 (0.4%) were positive. Overall positivity was 1.05%, similar to TST-only positivity in 2013 (1.05%) and 2014 (0.85%). Incorporating IGRA screening among foreign-born persons was feasible in this state prison system.

Risk of active tuberculosis in migrants diagnosed with cancer: a retrospective cohort study in British Columbia, Canada

OBJECTIVES

To describe the association between types of cancer and active tuberculosis (TB) risk in migrants. Additionally, in order to better inform latent TB infection (LTBI) screening protocols, we assessed proportion of active TB cases potentially preventable through LTBI screening and treatment in migrants with cancer.

DESIGN

Population-based, retrospective cohort study.

SETTING

British Columbia (BC), Canada.

PARTICIPANTS

1 000 764 individuals who immigrated to Canada from 1985 to 2012 and established residency in BC at any point up to 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES

Using linked health administrative databases and disease registries, data on demographics, comorbidities, cancer type, TB exposure and active TB diagnosis were extracted. Primary outcomes included: time to first active TB diagnoses, and risks of active TB following cancer diagnoses which were estimated using Cox extended hazard regression models. Potentially preventable TB was defined as active TB diagnosed >6 months postcancer diagnoses.

RESULTS

Active TB risk was increased in migrants with cancer ((HR (95% CI)) 2.5 (2.0 to 3.1)), after adjustment for age, sex, TB incidence in country of origin, immigration classification, contact status and comorbidities. Highest risk was observed with lung cancer (HR 11.2 (7.4 to 16.9)) and sarcoma (HR 8.1 (3.3 to 19.5)), followed by leukaemia (HR 5.6 (3.1 to 10.2)), lymphoma (HR 4.9 (2.7 to 8.7)) and gastrointestinal cancers (HR 2.7 (1.7 to 4.4)). The majority (65.9%) of active TB cases were diagnosed >6 months postcancer diagnosis.

CONCLUSION

Specific cancers increase active TB risk to varying degrees in the migrant population of BC, with approximately two-thirds of active TB cases identified as potentially preventable.

Trend and treatment outcomes of latent tuberculosis infection among migrant persons in Japan: retrospective analysis of Japan tuberculosis surveillance data

BACKGROUND

Screening for latent tuberculosis infection (LTBI) among migrant population has become a critical issue for many low tuberculosis (TB) burden countries. Evidence regarding effectiveness of LTBI programs are limited, however, partly because of paucity of national data on treatment outcomes for LTBI. In Japan, notification of LTBI is mandatory, and its treatment outcome is reported as part of Japan's national TB surveillance system. We thus conducted a detailed analysis of LTBI among foreign-born persons, to update the epidemiological trend of newly notified LTBI between 2007 and 2018, and to examine the treatment regimen and outcome of those notified in 2016 and 2017, focusing specifically on the potential risk factors for lost to follow-up.

METHODS

We extracted and analyzed the data of newly notified LTBI patients from the Japan Tuberculosis Surveillance System to examine the overall trend of notification and by age groups and modes of detection between 2007 and 2018, and the cohort data for treatment regimen and outcomes of foreign-born persons notified with LTBI in 2016 and 2017. Trends and proportions were summarized descriptively, and logistic regression analysis was conducted to identify potential risk factors for lost to follow-up. Comparisons were made with the Japan-born patients where appropriate, using chi-squared tests.

RESULTS

Both the number and proportion of LTBI among foreign-born persons have been constantly increasing, reaching 963 cases in 2018. Cohort analysis of the surveillance data indicated that the proportion of those on shorter regimen was higher among the foreign- than Japan-born patients (5.5% vs. 1.8%, p < 0.001). The proportion of those who have been lost to follow-up and transferred outside of Japan combined was higher among the foreign- than Japan-born patients (12.0% vs, 8.2%, p < 0.001). Risk factors for lost to follow-up were being employed on a temporal basis, and job status unknown (adjusted odds ratios 3.11 and 4.09, 95% confidence intervals 1.34-7.26 and 1.60-10.48, respectively).

CONCLUSIONS

Migrant population face greater risk of interrupting LTBI treatment, and interventions to improve adherence are a critical component of programmatic management of LTBI. Further studies are needed to explore the cultural and socioeconomic situation in which foreign-born persons undergo LTBI treatment in Japan.

Health assessment for migrants and asylum seekers upon arrival and while hosted in reception centres: Italian guidelines

BACKGROUND

During 2016-17, national guidelines were developed in order to provide evidence-based recommendations on health assessments for migrants and asylum seekers upon their arrival in Italy.

METHODS

Scientific literature published between 2005 and 2016 was searched in different databases. A free search was also performed on international organizations' websites in order to identify additional relevant documents. A multidisciplinary panel discussed the resulting evidence and formulated recommendations.

RESULTS

Evidence-based recommendations were formulated: signs and symptoms of specific diseases should to be actively searched for active TB, malaria, STI, intestinal parasites, diabetes, anaemia. In case of other health conditions (latent TB, HIV, HBV, HCV, STI, strongyloides, schistosoma, diabetes), testing should be offered to asymptomatic subjects coming from endemic areas or exposed to risk factors. Mass screening is recommended for anaemia and hypertension; a pregnancy test should be considered, while inclusion in cervical cancer screening and vaccination programs is recommended. A modulated, progressive approach was developed, covering an initial evaluation during rescue operations, a full medical examination at first line reception stage and the referral to national health services during second line reception.

CONCLUSIONS

It is important to produce and periodically update guidelines on these issues and local peculiarities should be taken into account in their design and implementation. Guidelines can not only support economic sustainability, but also counteract stigmatization dynamics.

[Recommendations for the screening for infectious diseases, mental health, and female genital mutilation in immigrant patients seen in Primary Care]

Immigrant health status may be improved if certain health conditions are identified early through the implementation of a screening program. This document presents the recommendations resulting from the Screening in immigrant population project (CRIBMI) aimed at implementing a screening program for infectious diseases (HIV, HBV, HCV, tuberculosis, strongyloidiasis, schistosomiasis and Chagas disease), as well as female genital mutilation and mental health (MH) in migrant population at Primary Care level. Screening recommendations were based on: coming from an endemic country for strongyloidiasis, schistosomiasis, and Chagas diseases; on a threshold level of prevalence for HIV (> 1%), HBV (> 2%), and HCV (> 2%), and on incidence (> 50 cases/100,000-inhabitants) for active tuberculosis in immigrants with < 5 years in Europe. Exploring the risk of FGM is recommended in women from countries where this practice is prevalent. Evaluation of MH status is recommended for people from areas of conflict and violence.

Cost-effectiveness of Latent Tuberculosis Infection Screening before Immigration to Low-Incidence Countries

Prospective migrants to countries where the incidence of tuberculosis (TB) is low (low-incidence countries) receive TB screening; however, screening for latent TB infection (LTBI) before immigration is rare. We evaluated the cost-effectiveness of mandated and sponsored preimmigration LTBI screening for migrants to low-incidence countries. We used discrete event simulation to model preimmigration LTBI screening coupled with postarrival follow-up and treatment for those who test positive. Preimmigration interferon-gamma release assay screening and postarrival rifampin treatment was preferred in deterministic analysis. We calculated cost per quality-adjusted life-year gained for migrants from countries with different TB incidences. Our analysis provides evidence of the cost-effectiveness of preimmigration LTBI screening for migrants to low-incidence countries. Coupled with research on sustainability, acceptability, and program implementation, these results can inform policy decisions.

The effectiveness and cost-effectiveness of screening for latent tuberculosis among migrants in the EU/EEA: a systematic review

Migrants account for a large and growing proportion of tuberculosis (TB) cases in low-incidence countries in the European Union/European Economic Area (EU/EEA) which are primarily due to reactivation of latent TB infection (LTBI). Addressing LTBI among migrants will be critical to achieve TB elimination. Methods: We conducted a systematic review to determine effectiveness (performance of diagnostic tests, efficacy of treatment, uptake and completion of screening and treatment) and a second systematic review on cost-effectiveness of LTBI screening programmes for migrants living in the EU/EEA. Results: We identified seven systematic reviews and 16 individual studies that addressed our aims. Tuberculin skin tests and interferon gamma release assays had high sensitivity (79%) but when positive, both tests poorly predicted the development of active TB (incidence rate ratio: 2.07 and 2.40, respectively). Different LTBI treatment regimens had low to moderate efficacy but were equivalent in preventing active TB. Rifampicin-based regimens may be preferred because of lower hepatotoxicity (risk ratio = 0.15) and higher completion rates (82% vs 69%) compared with isoniazid. Only 14.3% of migrants eligible for screening completed treatment because of losses along all steps of the LTBI care cascade. Limited economic analyses suggest that the most cost-effective approach may be targeting young migrants from high TB incidence countries. Discussion: The effectiveness of LTBI programmes is limited by the large pool of migrants with LTBI, poorly predictive tests, long treatments and a weak care cascade. Targeted LTBI programmes that ensure high screening uptake and treatment completion will have greatest individual and public health benefit.

Effectiveness of interventions for reducing TB incidence in countries with low TB incidence: a systematic review of reviews

AIMS

What is the evidence base for the effectiveness of interventions to reduce tuberculosis (TB) incidence in countries which have low TB incidence?

METHODS

We conducted a systematic review of interventions for TB control and prevention relevant to low TB incidence settings (<10 cases per 100 000 population). Our analysis was stratified according to "direct" or "indirect" effects on TB incidence. Review quality was assessed using AMSTAR2 criteria. We summarised the strength of review level evidence for interventions as "sufficient", "tentative", "insufficient" or "no" using a framework based on the consistency of evidence within and between reviews.

RESULTS

We found sufficient review level evidence for direct effects on TB incidence/case prevention of vaccination and treatment of latent TB infection. We also found sufficient evidence of beneficial indirect effects attributable to drug susceptibility testing and adverse indirect effects (measured as sub-optimal treatment outcomes) in relation to use of standardised first-line drug regimens for isoniazid-resistant TB and intermittent dosing regimens. We found insufficient review level evidence for direct or indirect effects of interventions in other areas, including screening, adherence, multidrug-resistant TB, and healthcare-associated infection.

DISCUSSION

Our review has shown a need for stronger evidence to support expert opinion and country experience when formulating TB control policy.

The role of tuberculosis control institutes in delivering tuberculosis information to domestic migrants in China: A multi-level analysis of a nationwide cross-sectional survey

OBJECTIVES

The aim of this study was to understand how tuberculosis (TB) control institutes raise awareness of TB among domestic migrants in China, specifically whether migrants have received TB information and how they received it.

METHODS

This multi-level analysis included both county-level data and individual-level data covering 31 provinces in mainland China. Multi-level logistic models were used to explore the factors associated with receiving TB information.

RESULTS

This analysis included 205 990 migrants from 31 provinces and municipalities. Only 77 460 (37.60%) migrants reportedly received any TB information in mainland China. The center for disease control and prevention (CDC), the center for tuberculosis control (CTC), and the center for prevention and treatment of chronic diseases (CPTCD) were the most likely to provide TB information for migrants in comparison to other types of TB control institutes, such as general hospitals, specialized hospitals, and community healthcare centers. The odds ratios were calculated as: 1.563 (95% confidence interval (CI) 1.246-1.959) for CDCs, 1.385 (95% CI 1.063-1.804) for CTCs, and 1.723 (95% CI 1.424-2.085) for CPTCDs.

CONCLUSIONS

China has not achieved universal coverage of TB awareness. TB awareness levels are higher in regions with CDC, CTC, and CPTCD institutes. Domestic migrants who have moved to western areas are more likely to have received TB information.

Screening for Latent Tuberculosis Infection in Migrants With CKD: A Cost-effectiveness Analysis

RATIONALE & OBJECTIVE

In countries with a low tuberculosis (TB) incidence, TB disproportionately affects populations born abroad. TB persists in these populations through reactivation of latent TB infection (LTBI) acquired before immigration. Those with chronic kidney disease (CKD) are at increased risk for reactivation and may benefit from LTBI screening and treatment.

STUDY DESIGN

Health administrative data from British Columbia, Canada, were used to inform a cost-effectiveness analysis evaluating LTBI screening in those diagnosed with stage 4 or 5 CKD not requiring dialysis (late-stage CKD) and those who began dialysis therapy.

SETTING & POPULATION

Permanent residents establishing residency in British Columbia, Canada, between 1985 and 2012 who had late-stage CKD diagnosed or began dialysis therapy.

INTERVENTIONS

Screening with the tuberculin skin test or interferon-gamma release assay (IGRA) compared to no LTBI screening at the time of late-stage CKD diagnosis and time of dialysis therapy initiation. Treatment for those who tested positive was isoniazid for 9 months.

OUTCOMES

Costs (2016 Can $), TB cases, and quality-adjusted life-years (QALYs). The incremental cost-effectiveness ratio for QALYs gained was calculated.

MODEL, PERSPECTIVE, & TIMEFRAME

Discrete event simulation model using a health care system perspective, 1.5% discount rate, and 5-year time horizon.

RESULTS

Screening with IGRA was superior to the tuberculin skin test in all situations. Screening with IGRA was less expensive and resulted in better outcomes compared to no screening in those initiating dialysis therapy from countries with an elevated TB incidence. In individuals with late-stage CKD, screening with IGRA was only cost-effective in those 60 years or older (cost per QALY gained, <$48,000) from countries with an elevated TB incidence.

LIMITATIONS

This study has limitations in generalizability to different epidemiologic settings and in modeling complicated clinical decisions.

CONCLUSIONS

LTBI screening should be considered in non-Canadian-born residents initiating dialysis therapy and those with late stage CKD who are older.

Risk Factors for Indeterminate Outcome on Interferon Gamma Release Assay in Non-US-Born Persons Screened for Latent Tuberculosis Infection

BACKGROUND

Non-US-born individuals account for the majority of active tuberculosis (TB) in the United States. Interferon gamma release assay (IGRA) is the preferred diagnostic test for latent TB but can produce an indeterminate result. We investigated the prevalence and predictors of an indeterminate IGRA (IND-IGRA) in a diverse cohort of non-US-born individuals and evaluated outcomes after IND-IGRA.

METHODS

We identified patient age ≥18 years who had an outpatient IGRA between 2010 and 2017 in our health system and whose primary language was not English. We used univariate and multivariable logistic regression to examine the association of IND-IGRA with a variety of clinical factors.

RESULTS

Of 3128 outpatients with ≥1 IGRA done, 33% were Asian, 30% Hispanic, and 29% black; 44% were men, and the median age was 50 years. An initial IND-IGRA occurred in 118 (3.8%; 95% confidence interval [CI], 3.1%-4.5%); notably, Asian race (55%) and rheumatologic conditions (25%) were prevalent in this group. In multivariable analysis, Asian race was independently associated with IND-IGRA (adjusted odds ratio [aOR], 2.9; 95% CI, 1.9-4.3), in addition to the presence of anemia and hypoalbuminemia (aOR for interaction, 4.3; 95% CI, 1.3-14.3). Only 55% of patients with an initial IND-IGRA underwent repeat testing; of those who did, 66% had a determinate result.

CONCLUSIONS

Asian race and anemia/hypoalbuminemia were independent risk factors for an indeterminate IGRA outcome in foreign-born patients screened in the United States. Our study underscores the importance of following through on indeterminate results in these key subgroups.

Cost-effectiveness of post-landing latent tuberculosis infection control strategies in new migrants to Canada

BACKGROUND

The majority of tuberculosis in migrants to Canada occurs due to reactivation of latent TB infection. Risk of tuberculosis in those with latent tuberculosis infection can be significantly reduced with treatment. Presently, only 2.4% of new migrants are flagged for post-landing surveillance, which may include latent tuberculosis infection screening; no other migrants receive routine latent tuberculosis infection screening. To aid in reducing the tuberculosis burden in new migrants to Canada, we determined the cost-effectiveness of using different latent tuberculosis infection interventions in migrants under post-arrival surveillance and in all new migrants.

METHODS

A discrete event simulation model was developed that focused on a Canadian permanent resident cohort after arrival in Canada, utilizing a ten-year time horizon, healthcare system perspective, and 1.5% discount rate. Latent tuberculosis infection interventions were evaluated in the population under surveillance (N = 6100) and the total cohort (N = 260,600). In all evaluations, six different screening and treatment combinations were compared to the base case of tuberculin skin test screening followed by isoniazid treatment only in the population under surveillance. Quality adjusted life years, incident tuberculosis cases, and costs were recorded for each intervention and incremental cost-effectiveness ratios were calculated in relation to the base case.

RESULTS

In the population under surveillance (N = 6100), using an interferon-gamma release assay followed by rifampin was dominant compared to the base case, preventing 4.90 cases of tuberculosis, a 4.9% reduction, adding 4.0 quality adjusted life years, and saving $353,013 over the ensuing ten-years. Latent tuberculosis infection screening in the total population (N = 260,600) was not cost-effective when compared to the base case, however could potentially prevent 21.8% of incident tuberculosis cases.

CONCLUSIONS

Screening new migrants under surveillance with an interferon-gamma release assay and treating with rifampin is cost saving, but will not significantly impact TB incidence. Universal latent tuberculosis infection screening and treatment is cost-prohibitive. Research into using risk factors to target screening post-landing may provide alternate solutions.

Comparison of QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) for diagnosis of latent tuberculosis in haemodialysis (HD) patients: a meta-analysis of κ estimates

Diagnosis of latent tuberculosis infection (LTBI) is a concern in haemodialysis (HD) patients. Many studies have compared QuantiFERON-TB Gold In-Tube (QFT-GIT) and tuberculin skin test (TST) for detecting LTBI and reported the κ statistic of agreement between QFT-GIT and TST in HD patients. The present study aimed to systematically review this literature and conduct meta-analysis of individual studies that estimated the κ between QFT-GIT with TST among HD patients. All relevant published studies that were available as full-text were obtained by searching Medline (1950), Web of Sciences (1945), Scopus (1973) through May 2016. The κ was re-estimated from the individual studies and pooled using random effect meta-analysis. Subgroup analysis and meta-regression were applied to evaluate the effect of Bacillus Calmette-Guérin (BCG) vaccination, TST cut-off points, quality of studies, sample size and age on variation of κ estimate. Eight studies involving 901 HD patients were included in meta-analysis. The pooled κ estimate was 0·28 (I 2 = 18·4%, P = 0·239, 95% confidence intervals 0·22-0·34). The discordance of TST-/QFT-GIT+ was more than TST+/QFT-GIT-. History of BCG vaccination, TST cut-off points and age are related to variation of κ estimates. TST and QFT-GIT are not comparable in detecting LTBI in HD patients. The higher TST-/QFT-GIT+ ratio compared with TST+/QFT-GIT- ratio, may indicate the superiority of QFT-GIT over TST for detection LTBI in HD patients.

Predicting tuberculosis risk in the foreign-born population of British Columbia, Canada: study protocol for a retrospective population-based cohort study

INTRODUCTION

Improved understanding of risk factors for developing active tuberculosis (TB) will better inform decisions about diagnostic testing and treatment for latent TB infection (LTBI) in migrant populations in low-incidence regions. We aim to examine TB risk factors among the foreign-born population in British Columbia (BC), Canada, and to create and validate a clinically relevant multivariate risk score to predict active TB.

METHODS AND ANALYSIS

This retrospective population-based cohort study will include all foreign-born individuals who acquired permanent resident status in Canada between 1 January 1985 and 31 December 2013 and acquired healthcare coverage in BC at any point during this period. Multiple administrative databases and disease registries will be linked, including a National Immigration Database, BC Provincial Health Insurance Registration, physician billings, hospitalisations, drugs dispensed from community pharmacies, vital statistics, HIV testing and notifications, cancer, chronic kidney disease and dialysis treatment, and all TB and LTBI testing and treatment data in BC. Extended proportional hazards regression will be used to estimate risk factors for TB and to create a prognostic TB risk score.

ETHICS AND DISSEMINATION

Ethical approval for this study has been obtained from the University of British Columbia Clinical Ethics Review Board. Once completed, study findings will be presented at conferences and published in peer-reviewed journals. An online TB risk score calculator will also be created.

The impact of migration on tuberculosis epidemiology and control in high-income countries: a review

Tuberculosis (TB) causes significant morbidity and mortality in high-income countries with foreign-born individuals bearing a disproportionate burden of the overall TB case burden in these countries. In this review of tuberculosis and migration we discuss the impact of migration on the epidemiology of TB in low burden countries, describe the various screening strategies to address this issue, review the yield and cost-effectiveness of these programs and describe the gaps in knowledge as well as possible future solutions.The reasons for the TB burden in the migrant population are likely to be the reactivation of remotely-acquired latent tuberculosis infection (LTBI) following migration from low/intermediate-income high TB burden settings to high-income, low TB burden countries.TB control in high-income countries has historically focused on the early identification and treatment of active TB with accompanying contact-tracing. In the face of the TB case-load in migrant populations, however, there is ongoing discussion about how best to identify TB in migrant populations. In general, countries have generally focused on two methods: identification of active TB (either at/post-arrival or increasingly pre-arrival in countries of origin) and secondly, conditionally supported by WHO guidance, through identifying LTBI in migrants from high TB burden countries. Although health-economic analyses have shown that TB control in high income settings would benefit from providing targeted LTBI screening and treatment to certain migrants from high TB burden countries, implementation issues and barriers such as sub-optimal treatment completion will need to be addressed to ensure program efficacy.

A Step toward Tuberculosis Elimination in a Low-Incidence Country: Successful Diagnosis and Treatment of Latent Tuberculosis Infection in a Refugee Clinic

Objectives. Approximately 65 percent of tuberculosis (TB) cases in Canada each year occur from reactivation in foreign-born individuals. Refugees are at high risk after immigration. Routine screening of this population for latent TB infection (LTBI) is generally considered infeasible. We evaluated the outcome of LTBI screening and treatment amongst refugees. Methods. Government-sponsored refugees in Edmonton are seen at the New Canadians' Clinic and screened for TB and LTBI. We reviewed records of patients between 2009 and 2011. Completeness of initial assessment, diagnosis of latent infection, and completion of LTBI treatment were evaluated. Treatment for LTBI was offered when patients had a positive Tuberculin Skin Test (TST) and risk factors for progression to TB. An Interferon-Gamma Release Assay (IGRA) was performed on all other TST positives; treatment is only offered if it was positive. Results. 949 refugees were evaluated. 746 TSTs were read, with 265 positive individuals. IGRA testing was performed in 203 TST positive individuals without other TB risk factors; 110 were positive. LTBI treatment was offered to 147 of 151 eligible patients, 141 accepted, and 103 completed a treatment course. Conclusion. We observed high proportions of patient retention, completion of investigations, and treatment. This care model promises to be a component of effective TB prevention in this high-risk population.