Comparison of direct and indirect measurement of LDL-C in HIV-infected individuals: ACTG 5087.
BACKGROUND
Hypertriglyceridemia is common in HIV-infected individuals on antiretroviral therapy. Triglyceride (TG) levels >400 mg/dL interfere with the accurate determination of low-density lipoproteins (LDL-C) by the Friedewald equation, making it difficult to assess coronary heart disease risk.


OBJECTIVE
The objective of this study is to compare the agreement of the direct LDL-C assay and the Friedewald equation with a reference ultracentrifugation method in the estimation of LDL-C concentrations.


METHODS
Samples from ACTG 5087 were assayed by ultracentrifugation and a direct enzymatic assay and calculated using the Friedewald equation.


RESULTS
In subjects with TG <400 mg/dL (n = 271), 90% of the direct LDL-C values and Friedewald calculations were within 30 mg/dL and 32 mg/dL of the ultracentrifugation values, respectively. With TG > or = 400 mg/dL (n = 186), 90% of the direct assay and Friedewald observations were within 68 mg/dL and 120 mg/dL of the ultracentrifugation results, respectively. Only 27% of the LDL-C values were within 15 mg/dL of the ultracentrifugation LDL-C results for direct assay and 16.3% for the Friedewald equation.


CONCLUSIONS
The direct LDL-C assay and the calculated LDL-C values did not display adequate agreement with the reference ultracentrifugation method. In subjects with TG >400 mg/dL, the direct assay overestimates the actual LDL-C whereas the Friedewald calculation underestimates the actual LDL. Clinical usage of these methods may lead to misclassification of the severity of dyslipidemia, resulting in improper management.
Evans
Scott R
SR
Harvard School of Public Health, Boston, MA, USA.
Fichtenbaum
Carl J
CJ
Aberg
Judith A
JA
D002986:Clinical Trials as Topic; D011345:Fenofibrate / Q000008:administration & dosage; D006678:HIV; D015658:HIV Infections / Q000150:complications*; D006801:Humans; D006949:Hyperlipidemias / Q000175:diagnosis* / Q000188:drug therapy / Q000209:etiology*; D000960:Hypolipidemic Agents / Q000008:administration & dosage; D008077:Lipoproteins, LDL / Q000097:blood*; D011933:Reagent Kits, Diagnostic; D012680:Sensitivity and Specificity; D014280:Triglycerides / Q000097:blood*; D014461:Ultracentrifugation
D000960:Hypolipidemic Agents; D008077:Lipoproteins, LDL; D011933:Reagent Kits, Diagnostic; D014280:Triglycerides; D011345:Fenofibrate