Feasibility of and barriers to thalassemia screening in migrant populations: a cross-sectional study of Myanmar and Cambodian migrants in Thailand

Thalassemia syndromes, caused by impaired α- and/or β-globin chain synthesis, together with sickle cell disease represent the most common human Mendelian disorders. There are an estimated ~ 56,000 annual births globally with severe thalassemia (hemoglobin [Hb] Bart’s hydrops fetalis, Hb H disease, β-thalassemia major, and Hb E/β-thalassemia) [1], though the burden of all clinically significant thalassemia disease likely far exceeds this estimate. Due to increasing international migration, the epidemiology of hemoglobin disorders is changing rapidly, and the resulting new challenges posed to health services have been recognized in Europe and the United States [2‐4]. Southeast Asia (SEA) is severely affected by thalassemia syndromes [5], with high frequencies of both α- and β-thalassemia, including Hb E (β26 Glu➔Lys), a structural variant that reduces β-globin expression (Table 1).

Thailand has one of the highest burdens of thalassemia in the world, with ~ 15 million carriers and 50,000 pregnancies at risk annually for severe thalassemia [11]. Thailand is also one of the few SEA countries with effective severe thalassemia prevention and control policies, focusing on public education, prenatal screening, and prenatal diagnosis. This has led to a decreased incidence of severe thalassemia syndromes, including Hb Bart’s hydrops fetalis [11]. Concurrently, Thailand’s relatively prosperous and stable economy has encouraged increasing migration from neighboring countries, with 2.4 million migrant workers from Myanmar, Cambodia, and Laos [12, 13]. These three neighboring countries are also estimated to have a high prevalence of thalassemia and Hb E (Table 1). However, they do not have national thalassemia education, screening, or counseling programs in place, and data on the incidence of severe thalassemia syndromes are limited due to lack of routine screening [14]. With increasing intra-regional migration, the lack of access to thalassemia-related services among migrant populations in Thailand not only hinders early diagnosis and treatment but also potentially undermines the Thai thalassemia program’s long-term success. Anecdotally, a rise in the number of births affected by severe thalassemia among migrant couples has been observed (V. Viprakasit, personal communication, November 1, 2017).

Addressing the issue of thalassemia in migrant populations is therefore of utmost importance but fraught with challenges. Migrant workers are often low-skilled, enter through irregular channels, and have limited or no access to healthcare. There are also large populations of asylum seekers and refugees from Myanmar and other neighboring countries who have crossed the border into Thailand irregularly and reside in refugee camps and border towns. The lack of epidemiological data regarding disease burden in different migrant populations hinders policymakers’ abilities to weigh the social benefit and economic cost of implementing thalassemia programs. Additionally, knowledge gaps and cultural differences are known barriers to the uptake of screening and the effectiveness of thalassemia prevention efforts [15‐17], yet few studies have examined knowledge, attitudes, and health-seeking behaviors among SEA migrants. How best to engage migrants in thalassemia education and screening and whether screening is feasible and acceptable to migrant populations must be explored.

We developed demographic and knowledge, attitudes, and practices (KAP) surveys to identify potential barriers to thalassemia screening among Myanmar and Cambodian migrant workers residing in Chonburi, an industrial province within the Eastern Economic Corredor (EEC), a major growing economic region in Thailand and home to one of the largest migrant worker populations in the country. We hypothesized that migrant subjects would have less awareness of thalassemia compared to Thai subjects and that knowledge would correlate with attitudes towards thalassemia screening and prevention. Furthermore, we performed comprehensive thalassemia testing to demonstrate the disease burden and assess the feasibility and acceptability of thalassemia screening in migrants. Novel insights from this study may inform regional migrant health policy and improve thalassemia education, prevention, and care for migrant populations globally.

There were 197 Thai, 119 Myanmar, and 176 Cambodian (492 total) subjects (Fig. 1 and Table 3). The median age was similar among all groups, but the Cambodian cohort had more males. Over 70% of migrants reported some proficiency in Thai. Around 60 and 27% of Thai space obtained secondary and higher education, respectively, compared to 35 and 3% of Myanmar and 30 and 1% of Cambodians. Cambodians had the highest proportion of subjects (~ 27%) with no formal education. Migrants were more often married than Thai subjects but reported similar numbers of children (Table 3). Marriage to an individual with a different nationality was reported by ~ 5% of migrants (with 8/11 having a Thai spouse), while Thai subjects reported no inter-group marriages.

Myanmar subjects reported residing in Thailand for longer than Cambodians. Nevertheless, transience was surprisingly low, with the majority having never moved within Thailand. Within work sectors (Table 3), more Thai subjects reported holding white-collar jobs (e.g., managerial or sales), while migrants largely held blue-collar or informal sector jobs. Three-quarters of migrant workers had previously undergone health registration, while one-quarter reported registering for the first time (i.e., were likely undocumented or “unregistered”).

This is the first study characterizing thalassemia knowledge, attitudes, and health-related behaviors of migrant populations in Thailand and one of few studies examining beliefs and perceptions surrounding thalassemia in SEA. Through comprehensive thalassemia testing, we identified a higher proportion of thalassemia carriers and higher allele frequencies of some globin variants in a migrant cohort compared to a Thai cohort. Furthermore, using prevalence estimates, we found a higher projected rate of births affected by severe thalassemia in the migrant cohort compared to the Thai cohort, highlighting the significant disease burden in migrants that needs to be addressed.

We hypothesized existence of a significant gap in thalassemia awareness between Thai and migrant subjects; indeed, only 4% of migrants vs. 80% of Thai subjects had heard of thalassemia. Thalassemia awareness was associated with female gender and achieving secondary education in the Thai cohort. Our migrant cohort, on average, was more male and less educated. Consistent with migrants’ length of residence in Thailand being a proxy for linguistic integration and exposure to mass media, migrants aware of thalassemia had resided in Thailand longer. Additional potential factors leading to increased awareness in long-term migrant residents include increased likelihood of interaction with the healthcare system and larger social networks, in which knowledge of thalassemia may spread by word of mouth.

A study of thalassemia awareness among Italians vs. Italian-Americans also found a large knowledge gap (85% vs. 19%), attributed to exposure to thalassemia education and screening in Italy and the lack of such programs in the United States [23]. A similar disparity in exposure may underlie our findings, as Thailand’s thalassemia prevention and control programs only offer education, outreach, and free prenatal screening to Thai citizens and are not accessible to migrants. Education is an effective approach to lowering the burden of thalassemia [23, 32], and as such, bolstering education efforts in migrant communities could be a rational initial approach to addressing this awareness gap. However, educational efforts may be hindered by sociocultural barriers.

Education level and literacy were lower for migrant than Thai subjects in this study. Awareness of thalassemia was correlated with attainment of secondary education, as well as with awareness of hematological disorders in general, a measure of health literacy. Migrants also demonstrated a lower understanding of the genetic inheritance of thalassemia. A study in Yangon, Myanmar, found that even among mothers of children receiving regular care for thalassemia, only 18–28% had an understanding of genetic inheritance [19]. Therefore, effective thalassemia programs for migrant populations should also emphasize genetic education and counseling. In addition, Thai females were more aware of thalassemia than males, possibly related to Thailand’s prenatal approach to thalassemia prevention, providing women with more exposure through antenatal care clinics. For male migrant workers, alternative settings for screening and education should be explored.

Our study also highlights the significant structural barriers faced by migrant populations. One-quarter of our migrant cohort was unregistered, i.e., without legal documentation or access to public health insurance, potentially influencing their health seeking behaviors. Migrants were more likely to pay for healthcare with cash and less likely to have multiple types of insurance compared to Thai subjects, likely leading to higher out-of-pocket costs and lower healthcare utilization. Cost of thalassemia testing was a commonly raised concern among migrants, underscoring the need for a government-sponsored program for thalassemia prevention for migrants, similar to that for Thai citizens.

Other structural barriers related to employment, transportation, and lack of interpreters for migrants were frequently encountered during this study. Subjects undergoing thalassemia testing were offered a return of results through either domestic mail or in-person pick-up at LCH, as well as free thalassemia genetic counseling at LCH. The vast majority of migrants expressed interest in learning their thalassemia carrier status and requested the return of results but declined to return for counseling due to concerns over missing work or finding transportation. Despite having translated study documents to Thai, Burmese, and Khmer, we faced tremendous language barriers due to poor literacy among migrants, as well as the limited availability and quality of interpreters, which likely impacted subjects’ comprehension of more complex or inverted survey items (e.g., Questions 19 and 22, Table 5). Addressing structural barriers hindering the delivery of thalassemia prevention and care to migrants may require concurrent changes in immigration and employment policies, particularly as half of the migrant population in Thailand may be unregistered [33].

Additionally, the KAP survey revealed important misconceptions and beliefs that may reduce the acceptance of thalassemia screening. A large percentage of migrants believed thalassemia to be an infectious disease; correction of this and other misconceptions is required to prevent stigmatization of patients and carriers. Most migrants failed to identify thalassemia as a serious chronic condition and a common disease in Asia, which may detract from the perceived importance and urgency of screening. The fact that many Thai subjects held these same misconceptions highlights existing gaps in Thailand’s thalassemia education program that should be addressed.

All nationalities, in particular Cambodians, expressed a strong interest in the concept of thalassemia screening. However, migrants expressed more negative attitudes towards pregnancy termination, which might preclude the prenatal approach to thalassemia prevention in migrants. The surveys were not designed to elucidate reasons underlying migrants’ attitudes towards pregnancy termination; these themes should be explored in greater depth using qualitative methods, such as in-depth interviews and focus group discussions. On the other hand, our study had extremely high uptake (96.9%) of thalassemia screening by healthy migrant subjects, strongly suggesting that carrier screening would be acceptable to migrants.

Our health registration-based approach to thalassemia screening represents a unique and particularly efficient means of recruiting both documented and undocumented migrants. We found that public hospitals were a feasible, convenient setting for performing thalassemia screening but not for the return of results. An alternative setting that overcomes some structural barriers is the workplace, though privacy concerns and the willingness of employers to participate would need to be considered. Our study design has some limitations; survey results and thalassemia allele frequencies obtained from migrant workers presenting to LCH may not be representative of other migrant populations in Thailand. Indeed, we previously demonstrated spatial specificity in the gene frequency of ⍺-thalassemia in Thailand [27]. A similar geographic limitation may exist for the Thai community cohort undergoing thalassemia testing. The Thai cohort presenting to LCH is likely representative of the majority of the Thai population, which utilizes public health services due to the availability of universal health coverage in Thailand. However, individuals using the private health sector may differ in socioeconomic status and may not be represented in our cohorts. Additionally, due to the extremely low level of thalassemia awareness among migrants, only 11 migrant subjects completed the KAP survey, compared to 155 Thai subjects. The limited KAP survey data from migrants made drawing comparisons challenging and further subset analyses impossible. Ideally, our findings would be confirmed using a larger representative sample of migrants, employing either a multicenter approach or with comparisons to SEA migrant populations residing in other host countries.

Nevertheless, this study highlights the dramatic gap in thalassemia awareness between Thai citizens and migrants and the urgent need for public educational interventions accessible to migrants. Furthermore, we developed a multilingual KAP survey with face validity and acceptable reliability for assessing thalassemia knowledge and attitudes across three different nationalities (see Additional file 1). This thalassemia-specific KAP survey should be further validated in future studies for use as a multinational tool in SEA populations worldwide.

Finally, our data confirm the high prevalence of thalassemia among migrants in Thailand, laying the foundation for additional epidemiological and cost-effectiveness studies needed to inform future policy decisions surrounding thalassemia prevention and control. The projected annual number of migrant newborns affected by severe thalassemia is likely an underestimate, due to unregistered migrant populations being unaccounted for in official migration statistics, demonstrating the need for regularization of the migrant workforce to create effective public health policies.

In this study, we developed a knowledge, attitudes, and practices (KAP) survey focused on thalassemia screening and validated the survey in healthy Myanmar, Cambodian, and Thai populations. We also offered comprehensive thalassemia testing to all migrant subjects and found that thalassemia is prevalent among Myanmar and Cambodian migrants and that nearly all migrants were willing to undergo thalassemia screening. However, we identified an extreme lack of awareness and understanding of thalassemia in migrant compared to Thai populations, as well as identified key misconceptions in both migrant and Thai populations that need to be addressed. Based on the KAP survey results, we conclude that lack of awareness of thalassemia is a prominent obstacle to thalassemia screening in migrant populations in Thailand and that public education efforts tailored to migrant populations are desperately needed. The negative attitudes towards termination of pregnancy among migrants suggest that Thailand’s prenatal approach to thalassemia screening may not be optimal for migrant populations and that other potential screening approaches should be explored. Indeed, we found carrier screening among migrant workers to be highly feasible and acceptable. Furthermore, the high frequencies of thalassemia variants identified in our migrant cohort argue strongly for the inclusion of migrant populations in thalassemia prevention and control policies in Thailand as well as regionally.

With increasing economic integration and cooperation among the ASEAN (Association of Southeast Asian Nations) member countries, intra-regional migration will continue to grow. The scientific community, healthcare providers, and policymakers must recognize the challenges posed by migration to regional thalassemia prevention and control and respond accordingly. Concerted efforts should be made not only to establish regional thalassemia screening programs and registries but also to extend thalassemia services to migrants within the region. With continued investigation into knowledge, cultural, and structural barriers to thalassemia prevention in migrant populations, we may begin to create a global solution for the growing public health problem of thalassemia.