Income-related inequality and its effect on depression prevalence in China: a longitudinal,population study

Background

Depression is an important mental health disorder, which is facing a serious problem of inequality. However, compared with the field of physical health, there is not as much research into the fairness of mental health. Moreover, the research mainly focuses on cross-sectional studies. Vertical comparison is missing. Therefore, we aimed to measure the income-related inequality of depressive symptoms and its trends among elderly people in China.

Methods

We extracted data from the 2011 baseline and 2015 follow-up of the China Health and Retirement Longitudinal Study (CHARLS), which is a nationally representative survey for elderly people aged 45 years and more in China. Depressive symptoms were evaluated with the Chinese version of the ten-item Center for Epidemiologic Studies-Depression Scale (CES-D). Participants were considered to have depressive symptoms once the CES-D score was 10 or more. We used five relative income levels derived from ratios between the participants' annual per capita household expenditure (PCE), excluding medical expenditure, and the median PCE of their cities. The concentration curve and index were used to measure and compare the magnitude of income-related inequality of depressive symptoms between 2011 and 2015. A logistic regression model was used to explore the crux of the inequality issue. Several confounding factors were controlled for in this model, including age, sex, marital status, and educational level.

Findings

The prevalence of depression among the elderly in China decreased from 37·0% (5540 of 14?956 participants) in 2011 to 32·7% (5606 of 17?165) in 2015. However, the absolute value of the standardised concentration index increased from 0·005 in 2011 to 0·028 in 2015. The prevalence of depression in the lowest-income group had the weakest improvement of 2·4% points compared with the other four groups. In the logistic regression model, being a part of the population with the lowest income level in 2015 was a significant risk factor for depression compared with the other income groups.

Interpretation

The prevalence of depression in people aged 45 years and more in China is declining, but the issue of income-related inequality has been exacerbated. The lowest-income group is the main factor contributing to the inequality. Policy analysis pointed out that China's current policy on equalisation of public health services has not specifically mentioned the issue of mental health. However, under the requirement of the Healthy China strategy, the fairness of mental health deserves attention.

Funding

None.