Programmatic screening for latent tuberculosis in migrants
Authors: Manish Pareek, Christina Greenaway
Journal: The Lancet Public Health (2022)

WHO has set targets to eliminate tuberculosis as a public health problem globally by 2035. In settings with low tuberculosis incidence, cases have become concentrated among populations born in intermediate and high-incidence countries and susceptible populations.1Pareek M Greenaway C Noori T Munoz J Zenner D The impact of migration on tuberculosis epidemiology and control in high-income countries: a review.BMC Medicine. 2016; 14: 48Crossref PubMed Scopus (175) Google Scholar To achieve WHO targets in low-incidence countries, identification and treatment of latent tuberculosis infection (LTBI) among foreign-born individuals will be needed to reduce persistently elevated tuberculosis rates.2Greenaway C Pareek M Abou Chakra CN et al.The effectiveness and cost-effectiveness of screening for latent tuberculosis among migrants in the EU/EEA: a systematic review.Euro Surveill. 2018; 23: 17-00543Google Scholar, 3Lonnroth K Migliori GB Abubakar I et al.Towards tuberculosis elimination: an action framework for low-incidence countries.Eur Respir J. 2015; 45: 928-952Crossref PubMed Scopus (521) Google Scholar In 2016, as part of a new national Collaborative tuberculosis strategy, England implemented the first nationwide migrant LTBI screening programme. Through this initiative, migrants aged 16–35 years from high-incidence countries (tuberculosis incidence ≥150 cases per 100 000 people per year or any country in sub-Saharan Africa) who arrived in England in the previous 5 years, are offered free LTBI screening with an interferon-γ release assay (IGRA) when newly registering in primary care.4Pareek M Watson JP Ormerod LP et al.Screening of immigrants in the UK for imported latent tuberculosis: a multicentre cohort study and cost-effectiveness analysis.Lancet Infect Dis. 2011; 11: 435-444Summary Full Text Full Text PDF PubMed Scopus (161) Google Scholar If the IGRA is positive, individuals are referred, usually to specialist hospital-based tuberculosis services, for further clinical and radiological assessment to rule out active tuberculosis. Patients in this group, who do not have active tuberculosis, are offered free latent tuberculosis treatment. In this issue of The Lancet Public Health, Luis Berrocal-Almanza and colleagues provide an assessment of the real-world effectiveness of the routine migrant LTBI programme established in England.5Berrocal-Almanza LC Harris RJ Collin SM et al.Effectiveness of nationwide programmatic testing and treatment for latent tuberculosis infection in migrants in England: a retrospective, population-based cohort study.Lancet Public Health. 2022; (published online March 23.)https://doi.org/10.1016/S2468-2667(22)00031-7Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar Using a cohort of migrants registered in primary care who fulfilled the eligibility criteria for LTBI screening, they did a complex nationwide data linkage analysis to assess the effectiveness of the LTBI testing and treatment programme and to estimate the risk of future incident tuberculosis in migrants who did, and did not, commence LTBI treatment. The authors confirmed that the methods to detect and treat LTBI infection are effective. IGRA-positive migrants who did not start treatment had a 30 times higher risk of developing tuberculosis than IGRA-negative migrants (hazard ratio [HR] 31·9 [95% CI 20·4–49·8]) and IGRA-positive migrants who commenced LTBI treatment had an 85% reduced risk of developing active tuberculosis than those who did not commence treatment (HR 0·14 [0·06–0·32]). Counterintuitively, the incidence of tuberculosis was higher among individuals who were screened for LTBI than those who were not screened (incidence 204 cases [95% CI 176–238] per 100 000 person-years vs 82 cases [77–86] per 100 000 person-years), although this association varied over time, with a higher risk observed for individuals who had IGRA testing in the first 6 months of follow-up and testing was associated with a reduced risk of tuberculosis thereafter. This finding might reflect a selection bias of screening people at higher risk for developing tuberculosis or those who were symptomatic. The finding might also reflect detection of prevalent active tuberculosis soon after arrival among those who have contact with the health system and undergo an IGRA test and appropriate investigations. This risk decreased 6 months after arrival, once LTBI therapy had been started, potentially demonstrating the effectiveness of this therapy. The overall number needed to treat in this programme was relatively high (32·5 individuals to prevent one case of active tuberculosis before 2 years) and 11 (0·7%) of 1600 treated individuals developed hepatotoxicity—suggesting that a substantial number of migrants who are otherwise well might be given treatment without individual benefit, but with potential side-effects of treatment. This approach underlines the continuing tension between global and national guidance focused on identifying and treating LTBI to eliminate tuberculosis and individual risks and benefits of treatment. The effectiveness of a LTBI testing and treatment programme is dependent on high uptake at all steps of the care cascade including screening all individuals at risk, ensuring high levels of linkage to care and uptake, and completion of latent tuberculosis treatment for those found to be positive. Unfortunately this study was unable to provide data on attrition at each step along the LTBI care cascade, which will be required to ensure a robust and effective LTBI programme and health equity for the migrant population. However, key findings of this study were the low proportions of migrants who were screened (37 268 [10%] of 368 097 eligible individuals) and commenced LTBI treatment (1740 [26%] of 6640 IGRA-positive individuals); treatment uptake, in particular, was lower than that observed in other meta-analyses.6Alsdurf H Hill PC Matteelli A Getahun H Menzies D The cascade of care in diagnosis and treatment of latent tuberculosis infection: a systematic review and meta-analysis.Lancet Infect Dis. 2016; 16: 1269-1278Summary Full Text Full Text PDF PubMed Scopus (227) Google Scholar, 7Rustage K Lobe J Hayward SE et al.Initiation and completion of treatment for latent tuberculosis infection in migrants globally: a systematic review and meta-analysis.Lancet Infect Dis. 2021; 21: 1701-1712Summary Full Text Full Text PDF PubMed Scopus (8) Google Scholar These findings are instructive and are key to strengthening this programme in the future. It is imperative that policy makers delivering the LTBI programme urgently evaluate why and where there are barriers to accessing testing so that appropriate mechanisms can be established to allow all eligible individuals to be offered equitable access. Further studies will be needed to measure the impact of this national migrant LTBI screening programme on the overall goal of decreasing tuberculosis incidence in the UK. Perhaps more importantly, the approach to addressing migrant health disparities needs to be reimagined. Academics and policy makers need to work with communities, third-sector organisations, and migrants to redesign, and codesign, programmes that break down silos around specific diseases and develop holistic, integrated, infectious disease screening programmes in a patient centred, culturally sensitive manner, which are accessible and effective for all.8Eborall H Wobi F Ellis K et al.Integrated screening of migrants for multiple infectious diseases: Qualitative study of a city-wide programme.EClinicalMedicine. 2020; 21100315Summary Full Text Full Text PDF PubMed Scopus (7) Google Scholar, 9European Centre for Disease Prevention and ControlPublic health guidance on screening and vaccination for infectious diseases in newly arrived migrants within the EU/EEA. European Centre for Disease Prevention and Control, Stockholm2018https://www.ecdc.europa.eu/en/publications-data/public-health-guidance-screening-and-vaccination-infectious-diseases-newlyDate accessed: March 10, 2022Google Scholar This study provides insights into the potential benefit of a migrant LTBI health programme, but also highlights that much more work is needed to ensure effective screening programmes to address latent tuberculosis and other infectious diseases with the aim of decreasing health inequalities in this population. MP reports grants from Sanofi; grants and personal fees from Gilead Sciences; and personal fees from QIAGEN, outside the submitted work. CG reports an investigator-initiated grant from Gilead Sciences and consultant fees from Abbvie, outside the submitted work. The views expressed in the publication are those of the authors and not necessarily those of the National Health Service, the NIHR, or the Department of Health and Social Care. Effectiveness of nationwide programmatic testing and treatment for latent tuberculosis infection in migrants in England: a retrospective, population-based cohort studyA low proportion of eligible migrants were tested by the programme and a small proportion of those testing positive started treatment. Despite this, programmatic LTBI testing and treatment of individuals migrating to a low-incidence region is effective at diagnosing active tuberculosis earlier and lowers the long-term risk of progression to tuberculosis. Increasing programme participation and treatment rates for those testing positive could substantially impact national tuberculosis incidence. Full-Text PDF Open Access