Background: In addition to lowering plasma levels of low-density lipoprotein cholesterol (LDL-C), statins also raise high-density lipoprotein cholesterol (HDL-C).
Hypothesis: Recent studies have shown that treatment with simvastatin results in larger increases in HDL-C than those seen with atorvastatin. The results of three clinical studies are analyzed, comparing the effects of simvastatin and atorvastatin on HDL-C and apolipoprotein A-I (apo A-I) in the total cohort and in several subgroups of hypercholesterolemic patients. The three studies were all multicenter, randomized clinical trials that included simvastatin (20-80 mg) and atorvastatin (10-80 mg) treatment arms. The subgroup analyses performed were gender; age (< 65 and > or = 65 years); baseline HDL-C (male: < 40 or > or = 40 mg/dl; female: < 45 or > or = 45 mg/dl), baseline LDL-C (< 160 or > or = 160 mg/dl), and baseline triglycerides (< 200 or > or = 200 mg/dl).
Results: Both drugs produced similar increases in HDL-C levels at low doses; however, at higher drug doses (40 and 80 mg), HDL-C showed a significantly greater increase with simvastatin than with atorvastatin (p < 0.05 to < 0.001). Therefore, while HDL-C remained consistently elevated across all doses of simvastatin, there appeared to be a pattern of decreasing HDL-C with an increasing dose of atorvastatin. A similar negative dose response pattern was also observed with apo A-I in atorvastatin-treated patients, suggesting a reduction in the number of circulating HDL particles at higher doses. Both drugs reduced LDL-C and triglycerides in a dose-dependent fashion, with atorvastatin showing slightly greater effects. The differential effects of atorvastatin and simvastatin on HDL-C and apo A-I were observed for both the whole study cohorts and all subgroups examined; thus, no consistent treatment-by-subgroup interactions were observed.
Conclusion: The data presented show that, across different hypercholesterolemic patient subgroups, simvastatin increases HDL-C and apo A-I more than atorvastatin at higher doses, with evidence of a negative dose response effect on HDL-C and apo A-I with atorvastatin, but not simvastatin.