Elevated blood pressure is a widespread condition that leads to stroke, cardiovascular, and renal disease. Worldwide, approximately 9.4 million deaths are attributable to hypertension each year. This makes hypertension one of the most important modifiable risk factors for mortality.
The burden of hypertension is disproportionately high in low- and middle-income countries (LMICs): Two-thirds of people with hypertension live in LMICs, and this number is projected to increase substantially by 2050. In middle-income countries (MICs) in particular, the population is expected to age significantly in the coming decades, so there is likely to be an increase in the number of people requiring treatment for hypertension.
For this reason, the Assistant Professorship of Behavioral Science for Disease Prevention and Health Care of Prof. Dr. Nikkil Sudharsanan conducted a longitudinal study to investigate how successful the long-term treatment of hypertension is in several MICs. They selected four countries (China, Indonesia, Mexico and South Africa) representing three continents and covering about a quarter of the world's population. The prevalence of hypertension in these countries is between 19 and 24 percent.
The results of the study were published under the title "Longitudinal evidence on treatment discontinuation, adherence, and loss of hypertension control in four middle-income countries" in the journal “Science Translational Medicine”. This journal has an impact factor of 17.956.
For each country, the team analyzed how a total of 8,527 individuals aged 40 years or older with hypertension moved through treatment stages over a period of five to nine years. The team examined not only how individuals moved forward through care stages, but also whether those with hypertension were moving “backward” by losing blood pressure control or discontinuing treatment.
The research team led by Prof. Sudharsanan found that only 30 percent of patients who were previous undiagnosed became diagnosed over the five-to-nine-year period. In South Africa, the figure was as high as 36 percent. In addition, only one in four people who had not previously received treatment was subsequently treated. Here again, South Africa was above the average at 33 percent. One of their main important findings was that a significant proportion of participants discontinued hypertension treatment completely – in Indonesia this was as high as 70 percent of all individuals who started the study on treatment, with lower figures in China (36%), Mexico (34%) and South Africa (20%). Last but not least, almost all patients lost control of their blood pressure by the time of follow-up. At 92 percent, the value was highest in Indonesia, followed by Mexico with 77 percent, China with 76 percent and South Africa with 45 percent.
They also found that in two of the four countries, women sought treatment significantly more frequently and consistently than men. This is in line with previous studies, which generally find that females have better control over their high blood pressure compared to men.
The findings highlight that interventions aimed solely at improving diagnosis or initiating treatment may not lead to long-term improvement in hypertension control in middle-income countries.
"With our study, we were able to show that evaluating treatment of hypertension cannot be based on a snapshot in time. Hypertension must be controlled throughout the lifespan and we need to consider this long-term perspective when deciding where to intervene to improve hypertension control," explains Prof. Sudharsanan. "In particular, we found that many people discontinued treatment in just a five to seven years period in the countries studied. These results are remarkable in themselves, which is why we recommended a shift in focus from just diagnosis and treatment initiation to long-term adherence and blood pressure control."
Prof. Dr. Nikkil Sudharsanan
Rudolf Mößbauer Assistant Professorship of Behavioral Science for Disease Prevention and Health Care
phon: 089 289 24990
Text: Romy Schwaiger
Photos: “Science Translational Medicine”/private