Income-related inequity in health care access and delivery

The association between socioeconomic position, especially income gradients and morbidity/mortality has been extensively explored. However, there exist a few articles to reveal the relationship between income and horizontal inequity in health access and delivery. The current study explored the income-related horizontal inequality using Wagstaff and van Doorslaer's methods with 1998 Korea National Health Interview Survey (NHIS) and the U.S. 1998 NHIS. The study analyzed several health services including two-week ambulatory health care, hospital days and admissions, and dental care in Korea and surgical operations in the U.S. Furthermore, the study also examined the impact of several health relevant measures, such as health insurance and a usual source of care, education, race, and rurality. For statistical analyses, the study used several estimation models for count data: Poisson, negative binomial, zero-inflated model, and two-part hurdle model. To compensate for the possibility of serial correlation and heteroskedasticity, the study employed more conservative standard for statistical inference and computes robust standard errors with Kakwani's method.;Among the variables affecting health need, once the age and gender are standardized, adjusting for the illness conditions reflects relatively more objective standard than the other. On the other hand, self-assessed health status is more likely to contribute the unequal distribution of health service. The study hypothesized that the low-income groups tend to use higher amount of health care resources due to poorer ill-health status, regardless of types of health care service. As study expectation, some types of health care service are distributed favoring low-income groups, in particular hospital utilization (hospital days and admissions). However, ambulatory care and surgical operations in the U.S. and dental care in Korea were more likely positively related to income gradients, even once health status was standardized. Standardizing for insurance status (or type in Korea) and education tends to ameliorate the degree of horizontal inequalities in both countries.;Despite high cost-sharing in Korea national health insurance, universal health insurance accomplishes higher degree of horizontal equity than the U.S. does. It may confirm indirectly that social solidarity can achieve better horizontal equity than health system based on ‘entrepreneurialism’.