China’s Silent Killer: Strokes

At the annual meeting of the American Stroke Association (ASA), held in Los Angeles in late February, Dr. Longjian Liu, associate professor of epidemiology and biostatistics at Drexel University, presented findings that show a direct correlation between air pollution and stroke risk. He examined over 1,000 U.S. cities and 120 cities in China, using air quality data from the Environmental Protection Agency (EPA).

According to Liu, the correlation between air pollution and incidents of stroke is highest in China’s midwest, followed by the northeast, then the south, and finally, the west. He adjusted for age, poverty rates, race, and temperatures in the midwestern and northeastern regions but, he told The Diplomat, not for the south or west.

Last year, the climate science non-profit organization Berkeley Earth released a study on this topic, saying that air pollution results in the death of 1.6 million people in China every year, accounting for 17 percent of all deaths in the country. That study was widely reported, but Liu’s work is the largest to date to examine the correlation between pollution and stroke risk, according to Newsweek.

Stroke is currently the leading cause of death in China. Every year, 1.6 million Chinese die from strokes, and every year, there are 2.5 million new cases. According to a special report in the journal Stroke, published in 2011, the incidence rate is 3.6 times higher in the northeastern part of the country--where pollution is at its worst--compared with southern China,

The report went on to say that, beyond this tragic loss of life, the economic impact is severe. In 2004, the average hospital fee for stroke admission was 6,356 yuan ($1,000), which is almost 2.5 times the annual net income of poor rural households. Moreover, the cost of stroke care nationwide rose from 1.17 billion yuan in 2003 to 8.19 billion yuan in 2009, an annual increase of 117 percent. By 2011, it had rocketed to 40 billion yuan.

“To reduce the devastating effects of stroke in China, people urgently need to lower the amount of salt in their diets, stop smoking, be physically active and keep alcohol within recommended levels,” advises Dr. Meilian Tang, an epidemiological research fellow at the Beijing Institute of Heart, Lung and Blood Vessel Diseases. Tang presented research last year at the 26th Great Wall International Congress of Cardiology (GW-ICC), showing that three-quarters of China’s stroke patients have hypertension.

This last detail is significant, because hypertension is the most important risk factor for stroke, causing 50 percent of ischemic strokes, which, in turn, make up 87 percent of all cases. An ischemic stroke is caused by a blood vessel blockage. The other type of stroke, hemorrhagic stroke, is caused by bleeding in or around the brain. In either case, early detection and rapid response are crucial, and detection can be made by using the acronym F.A.S.T. (which refers to Facial drooping, Arm weakness, Speech difficulties, Time to get help). But in China, even community physicians display a low awareness of stroke guidelines and a preference for Chinese herbs in treating patients, despite the fact that there’s little evidence to suggest traditional Chinese medicine can be used to effectively treat stroke patients.

If there’s anything we might regard as “good news” in all of this, it’s that higher rates of stroke in China are the consequence of a phenomenon known as “epidemiological transition.” First put forward by Abdel R. Omran in his seminal 1971 essay, the theory of epidemiological transition, according to Omran, “focuses on the complex change in patterns of health and disease and on the interactions between these patterns and their demographic, economic and sociologic determinants and consequences.”

For instance, Michael Pollan, author of The Botany of Desire and The Omnivore’s Dilemma, has written about the fact that type 2 diabetes, formerly known as adult onset diabetes, is increasingly diagnosed in children. In the 1980s, it was unheard of for a child to have the disorder. But dietary changes, brought on by the availability of sugary processed foods, have changed all that.

As for China, a 2008 study analyzed results from the Sino-MONICA-Beijing stroke study and found “marked changes” in stroke incidents over a 20-year period. These changes, the report said, were caused by socioeconomic development, which triggered changes in the pattern of disease occurrence. Poorer communities generally have to contend with malnutrition, bacterial infections, viruses and parasites. But, as they continue to develop, they gradually overcome these challenges and attain longer life expectancies. At that point, they begin to die more frequently from chronic, non-infectious diseases such as diabetes, heart disease and cancer.

Thankfully, Chinese stroke patients are in good hands. According to a presentation delivered on February 16 by Xichenhui Qiu at the annual Nursing Symposium of the ASA’s International Stroke Conference, 64 percent of Chinese caregivers embrace their roles as such, and 92 percent of spouses consider it their moral duty. Hopefully, there will one day be a cure. In the meantime, it warms the soul to learn that Chinese are facing this problem with open hearts.