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Abstract
The elimination of health inequalities between and within countries has become a major focus of health policy at the national and international level. In order to develop sound policies for health, policy-makers in industrialized and developing countries need a clear understanding of the nature and causes of these inequalities. The following three independent essays attempt to provide insight into the determinants of health and health inequalities in different contexts. The first two essays examine social and medical determinants of health and mortality using recent data from Mexico and historical data from the U.S. The third essay focuses on a commonly used, yet poorly understood, measure of health in empirical research: self-assessed health status.
The first essay, which is joint work with Noreen Goldman, investigates the relationship between socioeconomic status (SES) and health in Mexico using data from the Mexican Health and Aging Study. This relationship has received much attention in industrialized countries, but few studies have explored socioeconomic correlates of health in developing countries. In major cities in Mexico, we find evidence of a robust positive SES gradient in health, similar to that found in industrialized countries: higher levels of education, income, and wealth are associated with better health outcomes. By contrast, we find very few significant SES-health associations in less urban areas. The relationship between SES and health behaviors is generally similar across regions in Mexico, showing “reverse” income gradients in obesity, smoking, and alcohol consumption. One important exception is the education-obesity relationship. More educated respondents are less likely to be obese in urban areas and more likely to be obese in rural areas. The results of this essay suggest that socioeconomic factors are significant correlates of health in middle-income countries such as Mexico and that further economic development in Mexico will spawn wider social inequalities in heath.
The second essay, which is joint work with Seema Jayachandran and Adriana Lleras-Muney, examines whether sulfa drugs, the first medicine effective at treating infectious diseases, were an important cause of mortality decline in the U.S. after their discovery in the 1930s. The prevailing view is that medical advances played a negligible role in the rapid decline in U.S. mortality during the first half of the 20th-century, but there is little empirical evidence on the effects of early medical innovations. Using time-series and difference-in-difference methods (with infectious diseases unaffected by sulfa drugs used as a comparison group), we find that sulfa drugs caused significant declines in maternal mortality and mortality from pneumonia/influenza and scarlet fever. We also find that sulfa drugs widened racial disparities in mortality, suggesting that sulfa drugs diffused more rapidly among whites than blacks and consistent with the hypothesis that medical innovation initially results in greater inequality across population sub-groups. This finding is especially striking because sulfa drugs were an inexpensive life-saving drug.
In the third essay, I examine the determinants of self-assessed health ratings, a widely used health indicator in studies of health inequality and the determinants of health. The subjective nature of self-assessed health has caused great debate over its validity, reliability, and comparability across populations. Using data from the Social Environment and Biomarkers of Aging Study in Taiwan—which contains extensive clinical, biomarker, and performance data—I examine self-assessed health in relation to two alternative measures of respondent health in the same survey: interviewer and physician assessments of overall health. I find a high rate of disagreement in overall health ratings across the three evaluators of respondent health, but that most health ratings differ by only one point on a five-point scale. Some of these differences can be explained by inter-evaluator differences in the significance and relative importance of health and non-health factors in overall health ratings. I also find suggestive evidence of differences in reporting styles across evaluators. I conclude that external evaluations of overall health by interviewers and/or physicians may provide important complementary information on respondent health that can be used to strengthen models and measures of health inequality.
