More importantly, this large-scale underdiagnosis of hypertension suggests a major health system gap in China, say the study researchers.

Yang Gonghuan, professor of epidemiology at the Chinese Academy of Medical Sciences and one of the study’s principal investigators, says the pattern of disease in China has changed. Non-communicable diseases such as hypertension and diabetes have overtaken infectious diseases as the major disease burden. “But China’s healthcare system lags behind,” she said.

Professor James P. Smith, the Distinguished Chair in Labour Markets and Demographic Studies at the Rand Corporation and another of the study’s researchers, said countries like the US and England had similar rates of undiagnosed hypertension 40 or 50 years ago.

Health campaigns have helped reduced the rate to 15 per cent in the US. “It’s part of the process that higher income countries have to go through,” said Smith, “and China is now going through it.”

Xiao has been diagnosed. But she also has diabetes and spends 1,000 yuan (HK$1,250) a month, almost half of her monthly pension, on treatment drugs.

She says her illness deprives her of “all interesting things” in life, affecting her mood. “I can’t eat delicious food or go out with my friends. I can’t walk for long.”

One in three of China’s elderly report themselves to be in poor health. The study, by an international research team led by Peking University, surveyed 17,708 individuals from a nationally representative sample of China on topics ranging from socioeconomics to health. It’s designed to provide researchers and policymakers with a broad range of data on the world’s most rapidly ageing population. Participants will be tracked every two years.

The study found that across all health measures women fared worse than men. Apart from a higher prevalence of hypertension (59 per cent vs 49 per cent for men), women were also more likely to report higher levels of depression (47 per cent versus 32 per cent), need help with basic daily activities (28 per cent verses 20 per cent), experience body pain (39 versus 28 per cent) and be overweight (32 versus 24 per cent).

Elderly women also fared worse in cognition. In a test of word memory, they recalled only 2.73 words out of 10 on average, compared with 3.09 for men. “In Western countries, it’s always the opposite,” says Smith. “It’s partly because education in China is very restricted for Chinese women historically.”

In general, better education was linked with better health outcomes in the study. However, the influence of community was highly important, much more so than other countries, Smith says. This is because provision of health care in China is done at the community level, but also because of aspects such as inherent healthiness of the community, social interaction and diet preferences.

The poor or those living alone were more likely to face health limitations, but they have lower health insurance coverage rates, the study showed.

Coverage rates among elderly have generally improved in China – 92 per cent with urban hukou (household registration) and 94 per cent with rural hukou report having had health insurance of some type due to the government’s expansion of health care insurance programmes since the mid-2000s. Low premiums which range from zero to 138 yuan per year at the median, also encourage a broad take-up rate.

But the financial burden of medical costs can still be very high. Under the most common programme, the rural-based New Co-operative Medical Scheme, those aged 45 and older who sought inpatient care spent an average 39.7 per cent of their total yearly expenditure on such care, at the median. More than one in three adults who had inpatient care spent over half their per capita expenditure on this medical care.

Professor Yu Wei, a medical insurance expert from Shanghai University of Finance and Economics, said China’s medical insurance network did not seem ready for the ageing society.

Further, benefit generosity varies considerably across programmes and regions. The programmes are also highly segmented by population groups and offer poor transferability for migrants.

“For poor provinces, the central government may need to take a leading role in terms of financial and policy support in order to improve health care utilisation among the elderly,” said Li Xin, assistant professor of applied economics at Antai College of Economics and Management, Shanghai Jiao Tong University.

Another solution for keeping medical costs low is disease prevention. For hypertension, consuming less salt, eating a balanced diet, exercising regularly, quitting smoking and not drinking too much use, and regular monitoring can cut one’s risk.

Many of these simple steps cost nothing. “The main ingredients that lead to good health is not healthcare provisions,” says Smith. “It’s good behaviours.”

Additional reporting by Alice Yan