High total serum cholesterol, medication coverage and therapeutic control: an analysis of national health examination survey data from eight countries

Abstract

Researchers have found wide variability among countries’ efforts to control high cholesterol with medication. Many people in these countries are not aware of their high cholesterol, which significantly increases the risk of heart attack and stroke. The study, High total serum cholesterol, medication coverage and therapeutic control: an analysis of national health examination survey data from eight countries, was co-authored by Dr. Gregory A. Roth, an IHME Research Fellow and a physician in the Division of Cardiology at the University of Washington, in collaboration with researchers at IHME, the Veterans Administration Puget Sound Health Care System, Mahidol University in Bangkok, and Nippon Medical School in Tokyo.

Research findings

The researchers studied all available information on the prevalence of high cholesterol and its treatment from health surveys in England, Germany, Japan, Jordan, Mexico, Scotland, Thailand, and the United States. They discovered wide variation between the countries, including these key findings:

• The proportion of undiagnosed individuals was highest in Thailand, where 78% of individuals with high cholesterol were undiagnosed.
• In England and Jordan, about half of individuals with high cholesterol were unaware of their condition. In the United States, only 16% were unaware
• The US now has one of the lowest proportions of undiagnosed people with high cholesterol and one of the best rates of controlling cholesterol, among the countries studied.
• In England in 1993, 0.6% of men and 0.4% of women who were being treated for high cholesterol had it under control. By 2006, those percentages had increased to 35.5% in men and 25.7% in women.
• Mexico appears to be effectively delivering lipid-lowering medication to a large proportion of its high risk population, with medication coverage rates that are actually higher than the United States. This is an important observation in a middle-income country. Other middle-income countries studied, including Jordan and Thailand, had much lower rates of therapeutic control.

Gauging the progress of countries over time is difficult because of the lack of health examination surveys that inquire about medication use for chronic conditions and also incorporate lipid testing. The researchers were only able to access surveys for eight countries with the necessary data.

Analytical approach

Researchers used data from nationally representative health surveys conducted between 1998 and 2007. Overall, they were able to study a population sample that included 79,039 adults aged 40 to 79. For each country, they calculated the prevalence of high total serum cholesterol. To overcome the differences in the ways different countries determine what is considered a healthy level of cholesterol, the researchers set a bar that reflected very high cholesterol levels that would require treatment with medication in most countries, total serum cholesterol of 6.2 mmol/l or 240 mg/dl or higher. The researchers also were able to determine the fraction of individuals diagnosed, treated with cholesterol-lowering medication, and effectively controlling their cholesterol, meaning that they had lowered their total serum cholesterol to less than 6.2 mmol/l or 240 mg/dl.

Research objective

IHME studies health interventions around the world as part of its mission to track the performance of health systems. Cardiovascular disease causes nearly 20 million deaths worldwide and hits hardest in low- and middle-income countries. The World Health Organization (WHO) has set a goal of reducing the global death rate from chronic diseases — including cardiovascular disease – by 2% a year through 2015. Lowering total serum cholesterol levels is an ideal strategy for reducing the burden of cardiovascular disease. For it to work, though, people need to be properly diagnosed and offered treatment, and the treatments need to actually control their cholesterol.

Untreated high blood cholesterol represents a missed opportunity in the face of a global epidemic of chronic diseases. By examining cholesterol prevalence and the effectiveness of treatments, IHME is providing health officials and policymakers benchmarks for judging their own cholesterol reduction efforts and is encouraging more countries to include cholesterol prevalence and treatment data in national health surveys.

Policy implications

As the global health community prepares for the United Nations Summit on Non-Communicable Diseases in September 2011, the researchers recommend that governments and multilateral agencies consider:

• New programs to achieve higher detection and control of high blood cholesterol, including the use of dried blood spot technology in low-income settings.
• Improvements in chronic disease surveillance, such as the standardized chronic disease modules developed as part of WHO’s STEPwise approach to surveillance.
• Surveys conducted at regular intervals so that countries can track their progress towards achieving health goals, as is currently the practice in England and the US.

Funding

Bill & Melinda Gates Foundation – Disease Control Priorities Network (Investment # OPP51229)