Health transition of Thai migrant women in Japan: a preliminary cross-sectional study in a country with insufficient migrant health data.

Abstract

Background: Most research on the healthy migrant effect (HME) of migrants and the reduction in such health advantages due to long-term residence has been conducted in countries with a high proportion of migrants. However, in Japan, where there is a low migrant population of 2.0% and a low Migrant Integration Policy Index (MIPEX) rating, only limited health data on migrants is available from official statistics, and no residence length data is available. Therefore, health indicators in studies on the HME in Japan are limited to the cause of death or mortality, and residence length data are estimated from migration historical background or surrogates from age. The study aimed to compare the health status of Thai women residing in Japan with that of Japanese women and clarify the health transition of Thai women due to long-term residence in multiple health indicators.

Methods: We conducted a cross-sectional study using self-administered questionnaires among Thai residents in Japan aged 20 years or older, assessing their health outcomes, such as subjective symptoms, and health behaviors, such as smoking. Chi-square or binomial tests were performed to compare the health outcomes and behaviors of the Thai migrants during the early stages of migration and the subsequent long-term residence with those of the Japanese population.

Results: HME was observed only among Thai women aged 20-39 years who had resided in Japan for less than 10 years, with a lower prevalence of subjective symptoms compared to Japanese women in the same age group. HME was not observed in middle-aged women with less than 10 years of residence. Long-term residents exhibited poorer health outcomes and behaviors than Japanese women across most age-groups, despite undergoing more frequent health examinations. Statistically significant differences were particularly noted among middle-aged women.

Conclusions: These results indicate that the duration of residence is associated with migrant health, with longer stays in Japan linked to a decline in health among migrants, thereby suggesting the need to collect migrant health data in official statistics and position migrants as targets for primary and secondary prevention in public health.