New Multi-City Cohort Study Examines Elderly Health Across China

China has unveiled the extraordinary scale of one of the world’s largest prospective studies of aging, with the publication of a cohort profile describing the Multi-city Elderly Health Examination Cohort Study, or MEHECS, in the European Journal of Epidemiology. Since baseline data collection began in 2012, the study has enrolled 3,716,364 older adults with a mean age of 70.9 years, drawing on an annual free health examination program offered through China’s national Basic Public Health Services Project. By the end of 2023, researchers had documented 412,869 deaths among participants over a median follow-up of 4.44 years, and both recruitment and follow-up continue today.

The scale alone sets MEHECS apart. Most well-known aging cohorts, from the United States to Europe and elsewhere in Asia, enroll thousands to tens of thousands of participants. MEHECS enrolls millions, spanning multiple cities across China’s diverse geographic and economic landscape, from coastal megacities to inland urban centers. Ten percent of participants are over 80 years old, and men make up 46.8 percent of the cohort, giving researchers enough statistical power to examine even rare causes of death and health outcomes in the very old, a group often too small in conventional studies for robust analysis.

The study’s architecture is as notable as its size. Rather than building an entirely new data collection infrastructure, investigators led by Lin Yang, Peng Yin, Maigeng Zhou and colleagues at the Chinese Center for Disease Control and Prevention linked two existing national systems: the elderly health management records generated by the Basic Public Health Services Project and mortality registration data from the China Population Death Information Registration System. This record-linkage approach allows near-complete ascertainment of vital status without depending solely on participants’ continued participation, a perennial weakness of long-term cohort studies.

Each participant is entitled to an annual health examination structured into three components. The first is a face-to-face questionnaire interview using a standardized instrument covering demographics, lifestyles, current health problems, physical symptoms, healthcare utilization, current medications, and history of non-programmatic immunization. The second is a medical examination encompassing general condition, anthropometric measurements such as height, weight and waist circumference, physical examination findings, functional capacity assessments, and auxiliary examinations including laboratory and imaging tests. The third is a health assessment summary that integrates these findings for clinical management. Repeating this battery yearly, rather than at multi-year intervals, gives the study unusually fine temporal resolution for tracking how health trajectories evolve in late life.

Technically, the linkage design converts routine public health service data into a research-grade resource. Mortality follow-up is anchored in a national death registration system that has undergone substantial modernization and validation in recent decades, improving the accuracy of both all-cause and cause-specific mortality ascertainment. Because examinations are standardized across participating sites through the national platform, exposure and outcome variables are captured with common protocols, mitigating the heterogeneity that often complicates multicenter studies. The cohort profile reports that the study is an ongoing multicenter, multistage prospective design, with yearly data available between 2012 and 2023.

The scientific payoff is already visible in the broader literature the profile situates itself within. Prior analyses from related Chinese cohorts have tackled contentious questions such as the obesity paradox in the oldest old, the relationship between body mass index and mortality, associations of low-density lipoprotein cholesterol with all-cause and cause-specific death, and the interaction between residential greenness and air pollution in shaping mortality risk. Other work has linked fine particulate matter exposure to cause-specific mortality in large Chinese cohorts, and examined how air pollution elevates frailty risk among older adults. With millions of participants and annual measurements of weight, blood pressure, physical function and chronic disease status, MEHECS is positioned to test such hypotheses with a precision and generalizability that smaller cohorts cannot match.

The timing matters. China is aging faster than almost any large nation in history, with hundreds of millions of people projected to be over 60 in the coming decades, and non-communicable diseases already imposing a mounting burden on healthcare delivery and long-term care systems. Policymakers operating under the Healthy China 2030 framework need granular, nationally grounded evidence about which risk factors, from hypertension and dyslipidemia to sedentary lifestyles and inadequate vaccination coverage, drive disability and death among the elderly. MEHECS was explicitly designed to supply that evidence, with results intended to inform policies promoting healthy aging.

Ethically, the study was conducted in accordance with the Declaration of Helsinki and approved by the Ethics Committee of the National Center for Chronic and Noncommunicable Disease Control and Prevention of the Chinese CDC. The authors declare no competing interests, and the work was supported by the National Key Research and Development Program and the Elderly and Major NCD Research Program of the Chinese Preventive Medicine Association.

For the international research community, the profile also serves as an invitation. Cohort profiles of this kind typically precede waves of collaborative analyses, data-sharing agreements and replication studies. Given the unique features of MEHECS, its sheer size, its annual examination cadence, its geographic breadth across cities with sharply different environments and lifestyles, and its linkage to validated mortality registries, epidemiologists studying aging, cardiometabolic disease, environmental health and geriatric medicine will likely scrutinize its findings closely in the years ahead.

As baseline collection and follow-up continue, MEHECS is set to grow into one of the defining data resources for the science of healthy aging, offering a longitudinal window into how hundreds of millions of years of lived experience among China’s elderly translate into health, disability and death.