title: Classification of LDL phenotypes by 4 methods of determining lipoprotein particle size.
abstract: BACKGROUND
  Low-density lipoprotein cholesterol (LDL-C) lowering is the primary objective of patient management for cardiovascular disease. However, large numbers of patients who have achieved their LDL-C goal remain at risk for cardiovascular events. Low-density lipoprotein subfractions may provide insight into this residual risk. Thus, LDL subfraction standardization and consistency are critical to these efforts.
  
  
  OBJECTIVE
  This study aimed to determine the agreement of the analytical results among 4 methods commonly used for LDL subfractionation, namely, segmented gradient gel electrophoresis (sGGE), ultracentrifugation-vertical auto profile (VAP), nuclear magnetic resonance (NMR), and ion mobility (IM).
  
  
  METHODS
  Blood samples were collected from 228 apparently healthy adults and sent to 4 clinical reference laboratories for analysis. The LDL phenotype was reported as pattern A (larger, less dense particles) or pattern B (smaller, more dense particles), respectively, and was the primary measure of comparison. An intermediate pattern (A/B) was also reported for sGGE and VAP.
  
  
  RESULTS
  We observed complete agreement in the LDL phenotype among the 4 methods in 64% of subjects and agreement among at least 3 of the 4 methods in 87% of subjects. Agreement among pairs of methods ranged from 73% to 98% depending on how differences in reporting of subjects with intermediate results were considered. When subjects having intermediate A/B pattern were excluded, sGGE and IM had the highest agreement (98%) of any pair of methods.
  
  
  CONCLUSIONS
  We found substantial agreement in the reported LDL phenotype among 4 LDL subfraction measurement technologies as performed by different clinical reference laboratories.
authors.affiliation: Celera Corporation, Alameda, CA 94502, USA. John.Sninsky@celera.com
authors.forename: John J
authors.initials: JJ
authors.lastname: Sninsky
authors.forename: Charles M
authors.initials: CM
authors.lastname: Rowland
authors.forename: Arthur M
authors.initials: AM
authors.lastname: Baca
authors.forename: Michael P
authors.initials: MP
authors.lastname: Caulfield
authors.forename: Harold Robert
authors.initials: HR
authors.lastname: Superko
mesh_terms: D000328:Adult; D000368:Aged; D008078:Cholesterol, LDL / Q000097:blood* / Q000145:classification* / Q000235:genetics; D019411:Clinical Laboratory Techniques / Q000379:methods* / Q000592:standards*; D005260:Female; D006801:Humans; D008074:Lipoproteins / Q000097:blood / Q000145:classification / Q000235:genetics; D008297:Male; D008875:Middle Aged; D010316:Particle Size; D010641:Phenotype; D055815:Young Adult
chemical_list: D008078:Cholesterol, LDL; D008074:Lipoproteins