Cross-sectional study of prevalence and risk factors, and a cost-effectiveness evaluation of screening and preventive treatment strategies for latent tuberculosis among migrants in Singapore

Abstract

ObjectivesWHO recommends that low burden countries consider systematic screening and treatment of latent tuberculosis infection (LTBI) in migrants from high incidence countries. We aimed to determine LTBI prevalence and risk factors and evaluate cost-effectiveness of screening and treating LTBI in migrants to Singapore from a government payer perspective.DesignCross-sectional study and cost-effectiveness analysis.SettingMigrants in Singapore.Participants3618 migrants who were between 20 and 50 years old, have not worked in Singapore previously and stayed in Singapore for less than a year were recruited.Primary and secondary outcome measuresCosts, quality-adjusted life-years (QALYs), threshold length of stay, incremental cost-effectiveness ratios (ICERs), cost per active TB case averted.ResultsOf 3584 migrants surveyed, 20.4% had positive interferon-gamma release assay (IGRA) results, with the highest positivity in Filipinos (33.2%). Higher LTBI prevalence was significantly associated with age, marital status and past TB exposure. The cost-effectiveness model projected an ICER of S$57 116 per QALY and S$12 422 per active TB case averted for screening and treating LTBI with 3 months once weekly isoniazid and rifapentine combination regimen treatment compared with no screening over a 50-year time horizon. ICER was most sensitive to the cohort’s length of stay in Singapore, yearly disease progression rates from LTBI to active TB, followed by the cost of IGRA testing.ConclusionsFor LTBI screening and treatment of migrants to be cost-effective, migrants from high burden countries would have to stay in Singapore for ~50 years. Risk-stratified approaches based on projected length of stay and country of origin and/or age group can be considered.

A cost-effectiveness evaluation of latent tuberculosis infection screening of a migrant population in Malaysia

“…Based on a meta-analysis, the global prevalence of LTBI was 24.8% when using IGRAs and 21.2% when using TST 50 . However, LTBI prevalence estimates are based on diagnosis tools which are inherently uncertain and depend on a variety of factors, including on the country of origin and immigration patterns 8 , 47 . Given that it is not possible to know when an individual contracted LTBI through screening methods, the reactivation rate used in this study was estimated by extrapolating reactivation curves and did not consider other risk factors.…”

“…Other studies have estimated the cost-effectiveness of LTBI screening for migrants with varying results 6 , 8 , 12 . A similar study assessed the cost-effectiveness of QuantiFERON versus TST with different preventative treatment regimens for a migrant population in Oman and found that QuantiFERON was dominant when compared with TST across all treatment regimens 6 .…”

“…Systematic LTBI testing and treatments have been shown to be beneficial in scenarios where the likelihood of exposure to TB disease is high, for example, among recent migrants from countries with a high TB burden 7 . The cost-effectiveness of LTBI screening of migrants in low TB burden countries has also been demonstrated by numerous studies 6 , 8 – 12 . However, there is less evidence available for countries that are considered a medium TB burden.…”

Seroprevalence of IgG antibodies against diphtheria antitoxin among migrant workers in Singapore, 2016–2019

“…The survey on latent tuberculosis involved migrant workers from eight Asian countries that had large number of workers in Singapore (Bangladesh, China, India, Indonesia, Malaysia, Myanmar, the Philippines, and Vietnam) [ 16 ]. They were recruited from 27 locations around Singapore, including clinics providing health screening services for migrant workers (67%), worker dormitories (30%) and recreation centers catering to migrant workers (3%).…”

Prevalence of measles antibodies among migrant workers in Singapore: a serological study to identify susceptible population subgroups

“…The study involved residual sera collected between 2016 and 2019 from a survey on latent tuberculosis among 3584 migrant workers in Singapore from eight Asian countries with large number of migrant workers in Singapore (Bangladesh, China, India, Indonesia, Malaysia, Myanmar, the Philippines and Vietnam). They were recruited from 27 locations around Singapore [ 12 ]. About 67% were recruited from clinics providing health screening services for migrant workers, 30% from migrant worker dormitories and 3% from recreation centres catering to migrant workers.…”