Explanation of inequality in utilization of ambulatory care before and after universal health insurance in Thailand

Thailand implemented a Universal Coverage Scheme (UCS) of national health insurance in April 2001 to finance equitable access to health care. This paper compares inequalities in health service use before and after the UCS, and analyses the trend and determinants of inequality. The national Health and Welfare Surveys of 2001 and 2005 are used for this study. The concentration index for use of ambulatory care among the population reporting a recent illness is used as a measure of health inequality, decomposed into contributing demographic, socio-economic, geographic and health insurance determinants. As a result of the UCS, the uninsured group fell from 24% in 2001 to 3% in 2005 and health service patterns changed. Use of public primary health care facilities such as health centres became more concentrated among the poor, while use of provincial/general hospitals became more concentrated among the better-off. Decomposition analysis shows that the increasingly common use of health centres among the poor in 2005 was substantially associated with those with lower income, residence in the rural northeast and the introduction of the UCS. The increasing use of provincial/general hospitals and private clinics among the better-off in 2005 was substantially associated with the government and private employee insurance schemes. Although the UCS scheme has achieved its objective in increasing insurance coverage and utilization of primary health services, our findings point to the need for future policies to focus on the quality of this primary care and equitable referrals to secondary and tertiary health facilities when required.