Simu Huang is a PhD candidate and Chihua Li is an Assistant Professor, both are affiliated with the Institute of Chinese Medical Sciences (ICMS), University of Macau. Their recent study, "Prevalence of Sarcopenia and Individual- and Country-level Risk Factors in 36 Countries: Pooled Analysis of Nationally Representative Individual Data", has been published in Age and Ageing.
Why cross-country comparisons are difficult
Sarcopenia is an age-related condition characterised by declines in muscle strength and muscle mass. It is associated with reduced mobility, loss of independence, poorer quality of life, falls, disability, healthcare use and long-term care needs in ageing populations.
Previous studies of sarcopenia prevalence have used different study designs, sampling frames and diagnostic criteria, making direct cross-country comparisons difficult. Meta-analyses can pool prevalence estimates, but the underlying methodological differences remain. In our study, we used ageing studies with broadly similar designs and data collection protocols, and applied the same diagnostic criteria, analytical approach, and age- and gender-standardisation across countries. This allowed us to compare sarcopenia burden more consistently than is usually possible when combining published estimates from separate studies.
A cross-national view of muscle health
We pooled individual-level data from 10 ageing studies in the international Health and Retirement Study family, covering 36 high- and middle-income countries. These studies had broadly similar designs, data collection protocols, and timeframes. The analysis included more than 140,000 adults aged 50 years and older.
We defined sarcopenia using the 2019 revised European Working Group on Sarcopenia in Older People criteria. Handgrip strength was used to assess muscle strength, estimated appendicular skeletal muscle mass to assess muscle mass, and gait speed to assess physical performance. Sarcopenia was defined as low muscle strength together with low muscle mass. Participants who additionally had poor physical performance were classified as having severe sarcopenia. We also standardised prevalence estimates by age and gender to account for differences in population structure across countries.
Wide variation across countries
Standardised prevalence of sarcopenia ranged from 2.1% in Denmark to 17.4% in India. Prevalence was below 5% in 20 countries, between 5% and 10% in 13 countries, and above 10% in three countries including Cyprus, Malaysia and India. Overall, prevalence was generally higher in middle-income settings.
Combined with demographic data from the United Nations World Population Prospects, we then projected these prevalence estimates onto country-specific populations aged 50 years and older to produce rough case estimates. Across the 36 countries, approximately 92.7 million middle-aged and older adults were estimated to have sarcopenia, with around 85% from Brazil (4.8 million), the USA (5.6 million), China (25.4 million), and India (43.8 million).
What factors are linked to sarcopenia?
The study identified factors associated with sarcopenia at both the individual- and country-levels. At the individual-level, sarcopenia was associated with older age, gender (men), lower education, being unmarried or not partnered, non-full-time employment, lower household wealth, current smoking, non-recent drinking, physical inactivity and having two or more chronic diseases. At the country-level, higher gross domestic product (GDP) per capita, higher Gender Development Index and lower Labor Force Participation Rate were associated with lower sarcopenia risk.
Understanding the differences between countries
High-income countries generally had lower sarcopenia prevalence. This may reflect stronger healthcare infrastructure, healthier lifestyles, and better nutritional status, including adequate protein intake. In contrast, many middle-income countries had higher prevalence. This may be related to rapid lifestyle and nutrition transitions, with declining physical activity, poorer diet quality, rising obesity, and persistent undernutrition occurring at the same time. Health systems in some of these settings may also be less prepared for population ageing, particularly in prevention, rehabilitation, and long-term management. These differences may help explain why sarcopenia burden varies so widely across countries and points to settings where closer monitoring is needed.
What this study adds
By applying the same definition and analytical approach to individual-level data from 10 ageing studies, we were able to compare sarcopenia prevalence and rough case estimates across 36 countries on a more consistent basis. This approach also allowed us to examine individual- and country-level factors associated with sarcopenia within the same analytical framework. These findings provide a more consistent baseline for future cross-country comparisons of sarcopenia prevalence.
