A new study published this week found that the proportion of American adults with high levels of low-density lipoprotein (LDL or “bad”) cholesterol fell by around one third between 1999 and 2006, but concluded that too many are still not being screened or treated for the condition. In an accompanying editorial, experts called for simpler national guidelines for cholesterol screening that are based on risk for developing coronary heart disease rather than fixed thresholds for LDL cholesterol.

The study was the work of Dr Elena V Kuklina, of the Centers for Disease Control and Prevention, Atlanta, and colleagues, and appears in the 18 November issue of JAMA, Journal of the American Medical Association.

The main public health thrust for managing cholesterol in the US is to tackle high levels of LDL cholesterol under guidelines from the National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III).

These guidelines set targets for LDL cholesterol based on the history or risk for developing coronary heart disease (CHD) in the next 10 years.

Yet, wrote the authors, not many studies have looked at the prevalence of high LDL cholesterol and the use of medication to lower it across all categories of CHD risk.

For the study, Kuklina and colleagues examined trends in LDL cholesterol prevalence, screening, and use of drugs to lower cholesterol across four time frames: 1999 to 2000, 2001 to 2002, 2003 to 2004, and 2005 to 2006.

They took their data from the National Health and Nutrition Examination Survey (NHANES), covering only participants aged 20 and above who fasted before giving samples, but leaving out groups like pregnant women, or any with missing data. The final number of participants was 7,044.

The results showed that overall prevalence for high levels of LDL cholesterol fell from 31.5 per cent in 1999-2000 to 21.2 per cent in 2005-2006.

However, this trend varied substantially by CHD risk category.

The group with the highest proportion of participants with high levels of LDL cholesterol was the ATP III risk category, with 69.4 per cent in 1999-2000 and 58.9 per cent in 2005-2006.

The ATP III risk category group included participants with a self-reported history of CHD, angina, heart attack, stroke, and diabetes mellitus or participants with a fasting blood glucose level of 126 mg/dL or greater.

The authors found no significant changes in the weighted age-standardized screening rates across the four time frames from 1999-2000 to 2005-2006.

Of the participants showing high levels of LDL cholesterol, 35.5 per cent were unscreened, 24.9 per cent were undiagnosed, and 39.6 per cent were untreated or inadequately treated in 2005-2006, wrote the authors.

Also, in the high risk CHD group, about 20 per cent were eligible for cholesterol lowering medication but were not receiving it in 2005-2006, they added.

The authors concluded that:

“Among the NHANES population aged 20 years or older, the prevalence of high LDL-C levels decreased from 1999-2000 to 2005-2006. In the most recent period, the prevalence was 21.2 per cent.”

“Self-reported use of lipid-lowering medications increased from 8.0 per cent to 13.4 per cent, but screening rates did not change significantly, remaining less than 70 per cent during the study periods,” they added.

The researchers also commented that lack of agreement about the age at which screening should start could be getting in the way of having a clear goal about how to improve screening rates.

In an accompanying editorial about how to improve the approach to managing cholesterol, JAMA contributing editor Dr J Michael Gaziano of the VA Boston Healthcare System and Brigham and Women’s Hospital, Boston, and Dr Thomas A Gaziano of Brigham and Women’s Hospital and Harvard School of Public Health, Boston, wrote that the guidelines should be simpler.

They said that even though we have got better at finding and treating patients with high cholesterol, the current guidelines are too complicated, and as the data in the study suggests, an approach based on CHD risk would be simpler.

“Abandoning the fixed LDL-C threshold and targets used in many guidelines is justified by the linear relationship of cholesterol lowering and the benefit of the intervention for preventing cardiovascular disease,” wrote the editors.

“The use of a simplified risk-based approach could increase the ease of implementation of treatment and increase the number of patients receiving beneficial lipid-lowering therapy,” they added.

“Trends in High Levels of Low-Density Lipoprotein Cholesterol in the United States, 1999-2006.”
Elena V. Kuklina, Paula W. Yoon, Nora L. Keenan.
JAMA, Vol. 302 No. 19, November 18, 2009

Source: JAMA Archives.

Written by: Catharine Paddock, PhD