In search of China’s income-health gradient: a biomarker-based analysis

Abstract

Using data from the 1991–2009 China Health and Nutrition Survey, this study investigates China’s income-health gradient by analysing the effect of both current and long-term household income on 22 blood-based biomarkers, 4 used as individual variables and all 22 assessed as a composite. We employ estimation approaches that allow for analysis ‘beyond the mean’ and accounting for individual-specific unobserved heterogeneity. After applying a two-step residual inclusion estimator, we find limited evidence of an income-health gradient irrespective of whether the income measure is current or long term. Because risky behaviour may attenuate income’s positive effects on health, we also analyse the associations between income and such health-influencing factors as alcohol consumption, smoking, diet, physical activity, and dietary knowledge. Although we find that higher incomes go hand-in-hand with some of these factors (in particular, a higher number of cigarettes smoked per day), they also promote poorer diets. However, the fact that these effects are small, dependent on income measure, and susceptible to reporting biases makes it unlikely that they are attenuating income’s potentially positive effects on health. Our findings highlight the importance of considering more accurate measures of health in assessing income-health gradients in future research.