Health inequality among middle-aged and older people aged 45 years and older in China: a systematic analysis of the China Health and Retirement Longitudinal Study 2011–16

Background China has a history of promoting measures to achieve equity in health, including efforts to encourage the prevention and control of infectious diseases. However, there are no comprehensive assessments of health inequality for chronic diseases in China. This study aimed to estimate health inequalities for chronic diseases in China and to investigate health system factors that might be correlated with these inequalities. Methods Data for this study were obtained from the China Health and Retirement Longitudinal Study from 2011 to 2016. A total of 50 244 middle-aged and older Chinese adults, aged 45 years and older, were included (16 128 in 2011, 16 646 in 2013, and 17 470 in 2015). Principal component analysis was used to obtain a comprehensive index of socioeconomic status. We calculated concentration indices and corresponding CIs for 14 chronic diseases and comorbidities. We then estimated the Kendall rank correlation coefficient for inequalities and GDP per capita among provinces. Findings For ten of the 14 chronic diseases (hypertension, chronic lung disease, heart disease, stroke, kidney disease, stomach and other digestive diseases, emotional or psychiatric problems, memory-related disorders, arthritis or rheumatism, and asthma), prevalences were higher for the poorest tertiles than the richest tertiles. The concentration indices of dyslipidaemia (0·1256 [95% CI 0·1052–0·151]), diabetes or high blood sugar (0·098 [0·0704–0·1244]), and cancer or malignant tumour (0·1305 [0·0528–0·215]) in 2015–2016 were indicative of higher prevalence in people with higher income. Health inequality for chronic lung diseases and eight other diseases grew markedly from 2011 to 2016. Overall, health inequality was lower for urban residents (−0·035 in 2011–2012, −0·036 in 2013–2014, and −0·05 in 2015–2016) than rural residents (−0·053, −0·064, −0·08), and healthy inequality was twice as high among women (−0·051, −0·05, −0·072) than among men (−0·023, −0·02, −0·032). There was a significant inverse association between per capita GDP among provinces and the concentration indices of dyslipidaemia (Kendall's τ=−0·2328, p=0·015), kidney disease (τ=−0·3545, p=0·0077), and asthma (τ=−0·2646, p=0·0079). Interpretation For many chronic diseases in China, prevalences are higher for people with lower income, and this health inequality is considerable and growing. Policies associated with health equity need to be facilitated to achieve the UN Sustainable Development Goals. Funding This study was funded by the National Natural Science Foundation of China (81402761), the Foundation Research Project of Jiangsu Province (BK20140361), and the Suzhou Xiangcheng district people's livelihood science and technology project (XJ201655, XJ201706).