Impact of Public Health Insurance on Reducing Out-of-Pocket Payment for Psychiatric Care Among Cross-Border Migrants in Thailand: A Two-Part Model and Machine Learning Approach

Purpose: Thailand has long implemented public insurance schemes for cross-border migrants, though psychiatric care is not explicitly included in the schemes’ benefit package. As evidence related to the association between public insurance and migrants’ out-of-pocket (OOP) expenditure for psychiatric services remains limited, this study aims to assess if and to what extent the insurance is associated with OOP spending among migrants utilizing psychiatric-related care in Thailand. Patients and Methods: A cross-sectional analysis of routine service data was applied. We analyzed nationwide service utilization data of cross-border migrants receiving psychiatric care in public hospitals between 2018 and 2022. A two-part model (TPM) with machine learning was employed. The first part used a decision tree classifier to estimate the probability of incurring OOP spending, and the second part applied a non-negative least squares ensemble to predict the magnitude of OOP spending. Results: A total of 4,559 migrant patients accounted for 13,744 visits (inpatient and outpatient care combined), of which 84.1% were uninsured. The mean OOP spending per visit was 449 Baht, ranging from zero to 109,075 Baht. Public insurance was associated with about 50% reduction in the likelihood of incurring any OOP payment. After integrating both parts of the model, the estimated mean OOP spending per visit was 471.3 Baht (95% confidence interval [CI] = 433.8– 511.3) among the uninsured, compared with 7.4 Baht (95% CI = 6.7– 8.1) among the insured—about 98% OOP spending avoidance. Conclusion: Public insurance for cross-border migrants in Thailand was associated with reduced OOP spending for psychiatric services at the point of care. Inclusion of psychiatric services in migrant health insurance benefit packages may be considered as an option to help reduce inconsistent interpretations of coverage. Further research examining the financial burden of psychiatric illnesses among migrant households would be valuable. Ongoing monitoring of migrant-related policy changes may help inform future policy decisions.