Lipoprotein(a) level as a predictor of cardiovascular disease and small apoliprotein(a) isoforms in dialysis patients: Assay-related differences are important

J. Craig Longenecker, Josef Coresh, Michael J. Klag, Neil R. Powe, Nancy E. Fink, Santica M. Marcovina

Research output: Contribution to journalArticlepeer-review

Abstract

Background: Lipoprotein(a) assays sensitive to apolipoprotein(a) size may underestimate associations of lipoprotein(a) with cardiovascular disease (CVD) and low molecular weight (LMW) apolipoprotein(a) isoforms. This study among 629 dialysis patients compares the value of two lipoprotein(a) assays in predicting CVD events and small isoforms. Methods: Lipoprotein(a) level was measured by an apolipoprotein(a) size-insensitive ELISA and apolipoprotein(a) size-sensitive immunoturbidometric (IT) assay; and apolipoprotein(a) size by Western blot. Positive/negative predictive values (PPV/NPV) for small isoforms were calculated, and CVD events ascertained prospectively. Results: The ELISA assay predicted CVD more strongly [Relative Hazard, RH = 1.8; p = 0.045, at the 85th Lipoprotein(a) percentile] than the IT assay (RH = 1.3; p = 0.37). The PPV for LMW isoforms using the ELISA (Whites, 98%; Blacks, 90%) were much higher than the IT assay (Whites, 75%; Blacks, 68%). Relative to the ELISA assay values, a positive bias in the IT assay values was seen for participants with larger apolipoprotein(a) isoforms, which may explain these findings. Conclusions: When measured by an apolipoprotein(a) size-insensitive ELISA assay, but not a size-sensitive IT assay, high lipoprotein(a) levels predict both incident CVD and LMW isoforms in dialysis patients. Clinicians ordering lipoprotein(a) levels and research studies of lipoprotein(a) should determine if an apolipoprotein(a)-size related bias is present in the assay they use.

Original languageEnglish (US)
Pages (from-to)36-41
Number of pages6
JournalClinica Chimica Acta
Volume397
Issue number1-2
DOIs
StatePublished - Nov 1 2008

Keywords

  • Apolipoprotein(a) isoforms size
  • Cardiovascular disease
  • Dialysis
  • Lipoprotein(a)
  • Sensitivity
  • Specificity

ASJC Scopus subject areas

  • Biochemistry
  • Clinical Biochemistry
  • Biochemistry, medical

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