New York: Three-quarters of the world's adults with hypertension live in low- and middle-income countries and may lack access to proper care, says a study. The researchers found that more than 30 per cent of adults worldwide live with high blood pressure, and 75 per cent of those adults live in low- and middle-income countries. The findings, published in the American Heart Association's journal Circulation, are based on a 2010 data analysis involving more than 968,000 participants from 90 countries. "Ageing populations and urbanization, which is often accompanied by unhealthy lifestyle factors, such as high sodium, fat and calorie diets and lack of physical activity, may play an important role in the epidemic of hypertension in low- and middle-income countries," said senior study author Jiang He from Tulane University School of Public Health and Tropical Medicine in New Orleans, Louisiana, US. Hypertension is a major risk factor for heart disease and stroke as well as the leading preventable cause of premature death and disability worldwide. Past reports have shown that the prevalence of hypertension is increasing in low- and middle-income countries while it is steady or decreasing in high-income countries, but recent estimates of this global disparity were unknown. In this study, the researchers used sex- and age-specific high blood pressure prevalence from 131 past reports to calculate the regional and global estimates of hypertensive adults. High blood pressure prevalence decreased by 2.6 per cent in high-income countries while increasing 7.7 per cent in low- and middle-income countries between 2000 and 2010. "Healthcare systems in many low- and middle-income countries are overburdened and do not have the resources to effectively treat and control hypertension," He said. "In addition, because hypertension is symptomless and many people in low- and middle-income countries do not have access to screenings or regular preventative medical care, it is often underdiagnosed," He noted. Researchers noted that most of the world's population is represented in the study, but more than half of the countries worldwide didn't have data on hypertension prevalence, so there may be some inaccuracies in their regional and global estimates of adults living with high blood pressure.