Mortality trends for ischaemic heart disease and stroke in China: an analysis of 102 continuous disease surveillance points from 1991 to 2009

Abstract

BackgroundWith rapid economic development in China, disease patterns have changed in the past two decades. This study considered mortality trends for ischaemic heart disease and stroke using data from 102 continuous disease surveillance points from 1991 to 2009. MethodsWe analysed 102 continuous disease surveillance points, covering 7·3 million people in 1991–2000 and expanded to a population of 52·0 million in the same areas in 2001–2009. The data were adjusted using garbage code redistribution and under-report rate, and mapped from the International Classification of Diseases revision 9 (ICD9) to ICD10. The mortality rates for ischaemic heart disease and stroke were further adjusted by crude death proportion multiplied by the envelope of total death, which was calculated using logrt=a+bt, where rt denotes the mortality rate at time point t. The trend b was estimated from the logarithm of the annual mortality rate (log rt) using Poisson regression. Age-standardised death rates were computed using China's 2010 census population structure. We obtained agreement from the Chinese Center for Disease Control and Prevention to use data from the Disease Surveillance Point System. Patient consent and ethics approval were not necessary because all data analysed have previously been published. FindingsIschaemic heart disease age-standardised mortality rates increased in all regions, from 38·24 per 100 000 people in 1991 to 88·72 per 100 000 people in 2009 (logrt =–94·9602+0·0495×t), especially in northeast, central, and southwest China. Before 2007, the rates for both sexes in urban areas were higher than in rural areas, but after 2007, the rates were higher in rural areas than in urban areas. For stroke, the overall age-standardised mortality rates remained stable in 1991–2009; however, the rates increased in northeast and central China but decreased in north and east China. The mortality rates in rural areas increased by 6% every year from 1991 to 2009, whereas in urban areas, mortality rates slowly rose for women (b=1·6%) and fluctuated for men. For people younger than 70 years, the proportions of deaths were 30·9% for ischaemic heart disease and 32·6% for stroke in 2006–09, which is a substantial decline from 42·7% and 40·9%, respectively, in 1991–95. InterpretationBy observing relatively unchanged areas (ie, the same surveillance points that were expanded to cover larger areas) from 1991 to 2009, the overall age-standardised mortality rate for ischaemic heart disease increased and that of stroke remained stable. These trends are likely to be a result of increased fat content in diets, blood lipid concentrations, and body weights. The different patterns of ischaemic heart disease and stroke in different geographical regions, and divergences in urban and rural areas, are an indication of varying health control strategies and health-care services. FundingChina Medical Board Grant on CMB-CP in Burden of Diseases in China (12-107).