Cholesterol levels among U.S. adults improving
CHICAGO – Between 1998 and 2010, cholesterol levels among U.S. adults improved, according to a study that appeared in the Oct. 17 issue of JAMA, a journal of the American Medical Association.
Margaret D. Carroll, of the Centers for Disease Control and Prevention and based in Hyattsville, Md., and colleagues conducted a study to examine trends in serum lipids in adults between 1988 and 2010, using three U.S. cross-sectional National Health and Nutrition Examination Surveys, 1988-1994, which included a sample size of 16,573 adults, 1999-2002 (9,471 adults), and 2007-2010 (11,766 adults). Included in the analysis were measurements of average levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), non-high density lipoprotein cholesterol, and geometric triglyceride. The researchers also examined the prevalence of lipid-lowering medication use.
The authors found average TC declined from 206 mg/dL in 1988-1994 to 203 mg/dL in 1999-2002 and to 196 mg/dL in 2007-2010. Similar trends over the 22-year period were observed in age-adjusted average TC levels for men and for women.
From 1988 to 2010, there was a decreasing linear trend in age-adjusted average LDL-C levels for all adults, from 129 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002 and to 116 mg/dL during 2007-2010.
“Although men had a higher age-adjusted mean LDL-C level than women during 1988-1994 and 1999-2002, during 2007-2010 there was no longer a sex difference,” the study said.
From 1988-1994 to 2007-2010, an increasing linear trend in age-adjusted average HDL-C levels was observed for all adults. Between 1988 and 2010, a linear decline in age-adjusted average non-HDL-C level was observed for all adults. The age-adjusted geometric average triglyceride level for all adults increased from 118 mg/dL in 1988-1994 to 123 mg/dL in 1999-2002 and then declined in 2007-2010 to 110 mg/dL.
The researchers also found that from 1988 to 2010, there was an increasing trend in the age-adjusted percentage of adults taking lipid-lowering medications, from 3.4% in 1988-1994 to 9.3% in 1999-2002 and to 15.5% in 2007-2010. Among men and women age 50 years or older, increases in use of lipid-lowering medications of up to 35% were observed.
“Among adults not receiving lipid-lowering medications, trends in lipids were similar to those reported for adults overall,” the researchers said in the study. “Among obese adults, mean TC, non-HDL-C, LDL-C, and geometric mean triglycerides declined between 1988 and 2010.”
The researchers further hypothesized, “The favorable trends in TC, non-HDL-C, and LDL-C may be due in part to a decrease in consumption of trans-fatty acids or other healthy lifestyle changes, in addition to an increase in the percentage of adults taking lipid-lowering medications. They are unlikely to be the result of changes in physical activity, obesity, or intake of saturated fat.”
The study’s authors added the intake of saturated fat as a percentage of calories did not decrease between 1999 and 2008; little progress was made from 1998 to 2008 in increasing leisure-time physical activity levels of adults; and the prevalence of obesity among adults remains high, at more than one-third of the population.
They added “although the percentage of adults receiving lipid-lowering medications continued to increase between 1999-2002 and 2007-2010, declining trends in TC, non-HDL-C, and LDL-C also occurred for adults not taking lipid-lowering medications.”