Case 2: A patient with low levels of high-density lipoprotein cholesterol

Numerous epidemiologic studies have found a strong inverse association between the level of HDL cholesterol and the risk for developing coronary heart disease (CHD). Analysis of data from 4 of the largest US epidemiologic studies suggests that each 1-mg/dl increase in HDL cholesterol reduces the risk for CHD by 2% in men and 3% in women. Although the mechanism for this cardioprotective effect has not been elucidated fully, several plausible mechanisms have been suggested by basic scientific research, including reverse cholesterol transport, antioxidant effects, and other antiatherogenic effects. The second report of the National Cholesterol Education Program (NCEP) Adult Treatment Panel recommends the measurement of HDL cholesterol at the time of initial cholesterol testing, with designation of a high HDL cholesterol level (>60 mg/dl) as a negative risk factor and a low HDL cholesterol (<35 mg/dl) as a positive risk factor. This strategy incorporates HDL cholesterol as an important aspect of risk stratification. Data from the third National Health and Nutrition Examination Survey (NHANES III) show that 11% of American men >20 years of age have low levels of HDL cholesterol (<35 mg/dl) in isolation. The incidence of isolated low HDL cholesterol levels is even higher in populationw with CHD. The second NCEP report does not provide specific recommendations for the use of drug therapy in patients with isolated low HDL cholesterol because, at the time the report was prepared, no clinical trials had assessed the clinical benefit of modifying low HDL cholesterol levels in the setting of average total cholesterol and LDL cholesterol levels. The positive results of recent prevention trials of statins (AFCAPS/TexCAPS) or fibrates (VA-HIT) to treat patients with a low baseline level of HDL cholesterol have led some investigators to call for more aggressive screening of HDL cholesterol levels in selected patients. It is important to note that in AFCAPS/TexCAPS, the main lipid effect of lovastatin treatment was a reduction in LDL cholesterol, while in VA-HIT, the main effects of gemfibrozil were in raising HDL cholesterol and lowering triglycerides.