Relationship Between Altitude and the Prevalence of Hypertension in Tibet
What is the prevalence and awareness of hypertension among the inhabitants of Tibet, and what is the association with altitude?
A systematic review was conducted with electronic searches in Medline, Embase, ISI Web of Science, and Global Health. The authors assessed characteristics of studies using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) criteria. Meta-regression was used to estimate the degree of change in hypertension prevalence with increasing altitude.
Twenty-two eligible articles were identified, in which eight cross-sectional studies with a total of 16,913 participants were included. The prevalence of hypertension ranged between 23% and 56%. A scatter plot of altitude against overall prevalence revealed a statistically significant correlation (r = 0.68; p = 0.04). Meta-regression analysis revealed a 2% increase in the prevalence of hypertension with every 100 m increase in altitude (p = 0.06). The locations and socioeconomic status of subjects affected the awareness and subsequent treatment and control of hypertension.
The results from cross-sectional studies suggest that there is a significant correlation between altitude and the prevalence of hypertension among inhabitants of Tibet. The socioeconomic status of the inhabitants can influence awareness and management of hypertension.
Over 140 million people live at high altitude, defined as living at an altitude of 2400 m or more above sea level. Interestingly, subjects living chronically at high altitude appear to have a decreased frequency of obesity, diabetes, and coronary artery disease. However, these benefits on health are balanced by the frequent development of systemic and pulmonary hypertension. The average altitude in Tibet is 4500 m above sea level. Life expectancy is 67 years old, which is 8 years lower than Inland China. Tibetans consume 4-5 times the amount of salt recommended by the World Health Organization. A low-sodium and high-potassium salt substitute intervention resulted in a dramatic reduction in blood pressure in hypertensive Tibetans.
Keywords: Altitude, Blood Pressure, Diet, Sodium-Restricted, Global Health, Hypertension, Hypertension, Pulmonary, Life Expectancy, Metabolic Syndrome X, Prevalence, Primary Prevention, Social Class
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