Decades of declines in LDL cholesterol blood levels, a key marker of death risk from heart disease, ended suddenly in 2008, and may have stalled since. Those are conclusions of a multi-year, national study conducted by researchers at Quest Diagnostics and recently published in the open access journal PLOS ONE.
The study examined low-density lipoprotein, or LDL, blood-serum cholesterol test results of nearly 105 million adult Americans of both genders in all 50 states and the District of Columbia from 2001 to 2011. This study of LDL cholesterol levels in an American population is the first large-scale analysis to include data from recent years 2009-2011.
Researchers found a net 13% decline in the annual mean LDL cholesterol level of the study population over the 11-year period. Between 2001 and 2008, the average age-adjusted mean LDL levels declined from about 120 mg/dL to 104.7 mg/dL, but plateaued at that level for the remainder of the study period. LDL levels of 100 mg/dL or lower are considered optimal by the American Heart Association. By 2011, about 46% of patients had achieved LDL levels lower than 100 mg/dL, while 6% of patients had LDL levels in the high-risk category of 160 mg/dL or higher.
The study did not identify a cause for the trends, although investigators suggest several hypotheses. One is that the economic recession that began in 2008 affected Americans’ access to healthcare or their levels of compliance. Another is that users of statins may have reached the maximum therapeutic-threshold level in about 2008. Read the study.