China and Japan face epidemic of heart disease
Asia is facing a cardiovascular disease epidemic as a result of increases in obesity, high blood pressure, and smoking, show data analysed in the Asia Pacific cohort studies collaboration.
The findings are based on data from 600 000 people involved in 43 studies in nine places: China, Hong Kong, Thailand, Singapore, Australia, Japan, South Korea, Taiwan, and New Zealand. Whereas many western countries are grappling with rising obesity and have seen a peak in rates of smoking, in Asian countries most notably China several major risk factors are all rising.
"The pace of economic development in this part of the world is very fast, and smoking rates have increased rapidly too," said Professor T H Lam, head of the department of community medicine at the University of Hong Kong, one of the centres in the collaboration. "This has happened together with a higher fat diet, an increasingly westernised lifestyle, and a rapid decline in the level of physical activity."
The Asia Pacific cohort studies collaboration (www.apcsc.info) pools data from existing longitudinal studies and information on the regionâ€™s cardiovascular disease profile and is the largest study of its kind done in the region.
"The purpose of the collaboration is to see if the risk factors are the same, and if so whether or not they act in the same way, as they do in developed countries," explained Professor Mark Woodward, director of the project and professor of biological statistics at the University of Sydney.
"The biggest surprise was that the smoking effect is so similar. What weâ€™ve found is that smoking is just as important a risk factor for Asians as it is for Caucasians, despite a belief among some scientists that Asians have some protection against the ill effects of smoking," he said.
China and Korea have the regionâ€™s highest percentages of smokers; approximately 60% of Chinese men smoke. Previous studies on smoking and cardiovascular disease have found lower rates among some Asian populations than in the West but did not take account of the duration of smoking. "Now the smoking epidemic is beginning to mature, and the effect of smoking on disease rates, particularly heart disease, is showing in places with the longest history of smoking," said Professor Lam.
In a paper published in 2001 Professor Lam and his team concluded that smoking related mortality trends in Hong Kong were a likely indicator of future trends in China as a whole (BMJ 2001;323:361).
"What happened in Hong Kong is a good predictor of what will happen in China, where tobacco consumption is 20 years behind that of Hong Kong, and now we are starting to see that happening. The Asia Pacific cohort studies collaboration is showing increasing incidence of heart disease among younger adults, and the rate will rise faster than we expected," he said.
Obesity was shown to have at least as great an effect on Asian populations as smoking, and the dangers of raised blood pressure were also highlighted. "Blood pressure appears to be even more of a risk factor [than in the West], and this is thought to be due to high salt intake. It is more of a problem in rural areas where there is no refrigeration and salt is used to preserve food," said Professor Woodward.
The incidence of stroke in China is four times that in Western countries, and cardiovascular disease tends to strike Asians 10 years earlier than it does their Western counterparts, the data showed.
"Heart disease is striking earlier because of the rapid rate of change of lifestyle. Another hypothesis is that a sudden increase in obesity has an even greater effect on a population that was not well nourished in the first place," said Professor Lam.
"There is no sense of urgency at government level and a very low level of awareness among the public. We are not being alarmist when we say that the fattier diet, reduction in physical activity, and smoking are extraordinarily worrying."