Abstract
Raised blood pressure is an important risk factor for cardiovascular diseases and chronic kidney disease. We estimated worldwide trends in mean systolic and mean diastolic blood pressure, and the prevalence of, and number of people with, raised blood pressure, defi ned as systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg or higher.
Generated Summary
This research, published in The Lancet in 2017, presents a comprehensive analysis of worldwide trends in blood pressure from 1975 to 2015. The study, conducted by the NCD Risk Factor Collaboration (NCD-RisC), pooled data from 1479 population-based measurement studies, involving 19.1 million participants aged 18 years and older. The primary aim was to estimate trends in mean systolic and diastolic blood pressure, as well as the prevalence of raised blood pressure across 200 countries. Utilizing a Bayesian hierarchical model, the researchers assessed the contributions of changes in prevalence versus population growth and aging to the increase in the number of adults with raised blood pressure. The study’s scope included the analysis of data availability across different regions, highlighting the variability in data sources from high-income to low-income countries, and the statistical methods employed to handle data gaps and account for various measurement techniques. The study provided a detailed account of the global shift in blood pressure levels, indicating how the highest blood pressure levels have moved from high-income countries to low-income countries in South Asia and sub-Saharan Africa.
Key Findings & Statistics
- Global Age-Standardized Mean Blood Pressure in 2015: The age-standardized mean systolic blood pressure was 127.0 mm Hg (95% credible interval 125.7–128.3) in men and 122.3 mm Hg (121.0–123.6) in women. The age-standardized mean diastolic blood pressure was 78.7 mm Hg (77.9–79.5) for men and 76.7 mm Hg (75.9–77.6) for women.
- Prevalence of Raised Blood Pressure in 2015: The global age-standardized prevalence of raised blood pressure was 24.1% (21.4–27.1) in men and 20.1% (17.8–22.5) in women.
- Trends in Blood Pressure by Region: Mean systolic and diastolic blood pressure decreased substantially from 1975 to 2015 in high-income Western and Asia Pacific countries. Conversely, mean blood pressure might have increased in East and Southeast Asia, South Asia, Oceania, and sub-Saharan Africa.
- Highest Blood Pressure Levels in 2015: Central and Eastern Europe, sub-Saharan Africa, and South Asia had the highest blood pressure levels in 2015.
- Changes in Prevalence of Raised Blood Pressure: The prevalence of raised blood pressure decreased in high-income and some middle-income countries but remained unchanged elsewhere.
- Increase in Adults with Raised Blood Pressure: The number of adults with raised blood pressure increased from 594 million in 1975 to 1.13 billion in 2015, predominantly in low-income and middle-income countries.
- Decline in Mean Blood Pressure: The study noted a decrease of 0.47 mm Hg per decade in mean systolic blood pressure for women.
- Decreases in High-Income Regions: The largest decrease in mean systolic blood pressure, which occurred in high-income Asia Pacific, was 3.2 mm Hg per decade (95% CrI 2.4–3.9) for women and 2.4 mm Hg per decade (1.6–3.1) for men (PP>0.9999).
- Prevalence Decreases: Age-standardised prevalence of raised blood pressure from decreased globally to 2015, from 1975 29·5% (95% CrI 24·2–35·0) to 24·1% (21·4–27·1) in men (PP=0·9482) and from 26·1% (21·7–31·1) to 20·1% (17·8–22·5) in women (PP=0·9884).
- Countries with Lowest and Highest Blood Pressure: South Korea and Canada had lowest age- standardised mean systolic blood pressure in 2015. Slovenia had the highest mean systolic blood pressure in men and several countries in sub-Saharan Africa had the highest levels of mean systolic blood pressure in women.
- Correlation between Systolic and Diastolic Blood Pressure: Mean systolic and mean diastolic blood pressure were correlated across countries with correlation coeffi cients of 0·69 for men and 0·86 for women in 2015.
- Prevalence Extremes: South Korea, Canada, the USA, Peru, the UK, Singapore and Australia had the lowest prevalence of raised blood pressure in 2015 for both sexes, with an age- standardised prevalence of less than 13% in women and less than 19% in men. Age-standardised prevalence surpassed 35% in men in some countries in central and eastern Europe including Croatia, Latvia, Lithuania, Hungary, and Slovenia; prevalence was more than 33% in women in a few countries in west Africa.
Other Important Findings
- The study found that the global target of reducing raised blood pressure prevalence by 25% by 2025 is unlikely to be achieved in regions like central and eastern Europe.
- The increase in the number of people with raised blood pressure is mainly occurring in low-income and middle-income countries.
- The study highlights that population-based interventions throughout the life-course and pharmacological treatment are essential to address the global burden of non-communicable diseases.
- Mean systolic blood pressure in men was higher than in women in most countries in 2015.
- The male–female differences in blood pressure were largely due to differences in people younger than 50 years.
- The study highlights how the highest worldwide blood pressure levels have shifted from high-income countries to low-income countries in south Asia and sub-Saharan Africa due to opposite trends, while blood pressure has been persistently high in central and eastern Europe.
Limitations Noted in the Document
- Some countries had limited data sources, particularly in sub-Saharan Africa and the Caribbean, which resulted in estimates relying heavily on the statistical model and wider uncertainty intervals.
- Fewer data sources were available before 1990, leading to larger uncertainty for these years.
- The study had limited data from those older than 70 years, requiring the use of data from other sources to infer age patterns.
- Adjustments for systematic and random errors in subnational and community data were not country-specific.
- Individual participant data were inaccessible for 20% of the data sources, which increased the uncertainty of the estimates due to the need for cross-walking regressions.
- Variations in blood pressure measurement devices and protocols may have affected the estimated trends.
- Blood pressure was measured only once in some data sources, which might have led to a slight overestimation of mean blood pressure and the prevalence of raised blood pressure.
Conclusion
The research underscores a significant shift in the global landscape of hypertension, with the highest blood pressure levels now concentrated in low-income countries in South Asia and sub-Saharan Africa, while high levels persist in central and eastern Europe. The study’s findings suggest that the global target of reducing raised blood pressure by 25% by 2025 is unlikely to be met in these regions. The increasing number of adults with raised blood pressure, primarily in low-income and middle-income countries, highlights the urgent need for comprehensive interventions. The study emphasizes that addressing this global burden requires a multifaceted approach, including population-based strategies throughout the life course and individual lifestyle management, including diet and medication. The authors emphasize that governments and multinational organizations must adopt comprehensive strategies to address the inequitable burden of cardiovascular diseases and kidney disease associated with high blood pressure, focusing on both population-based and individual-level interventions.