title: What is the best predictor of the atherogenic LDL subclass phenotype 'pattern B' in patients with type 2 diabetes mellitus?
abstract: BACKGROUND
  The atherogenic lipoprotein phenotype 'pattern B' comprises a predominance of small-dense low-density lipoprotein (sdLDL). Gradient gel electrophoresis (GGE) is considered a 'gold standard' method for identifying this phenotype, but is impractical for routine laboratory use. The low-density lipoprotein cholesterol:apolipoprotein-B (LDL-C:Apo-B) ratio has been advocated as a surrogate marker for sdLDL and a direct assay for sdLDL has recently become available. We compared the sdLDL assay and LDL-C:Apo-B with more established lipid parameters to predict the presence of 'pattern B' phenotype.
  
  
  METHODS
  Blood was collected from 97 fasted subjects on three separate occasions. Total cholesterol, triglyceride, Apo-B and sdLDL were measured; LDL- and HDL-cholesterol were determined after ultracentrifugation. The predominant LDL particle size and phenotype were assigned by GGE.
  
  
  RESULTS
  'Pattern B' phenotype was identified in 36% of samples. Peak particle size showed a positive correlation with HDL-cholesterol and a negative correlation with triglyceride and Apo-B. Receiver operating curve (ROC) analysis showed triglyceride:HDL-C ratio and triglyceride alone to be the best predictors of 'pattern B' phenotype, with area under the curve (AUC) being 0.87 and 0.84, respectively. AUCs for sdLDL (0.74) and LDL-C:Apo-B (0.71) were significantly lower (P < 0.05). A high sdLDL concentration had the greatest specificity (95%) and positive predictive value (74%) for 'pattern B' phenotype, but low sensitivity (43%).
  
  
  CONCLUSIONS
  Direct measurement of sdLDL provided the most specific predictor of 'pattern B' phenotype, whereas triglyceride:HDL-C ratio or triglycerides alone, parameters readily available in most laboratories, were the best predictors by ROC analysis.
authors.affiliation: Clinical Biochemistry, Canterbury Health Laboratories, Christchurch, New Zealand. richard.king@cdhb.govt.nz
authors.forename: R I
authors.initials: RI
authors.lastname: King
authors.forename: C M
authors.initials: CM
authors.lastname: Florkowski
authors.forename: J
authors.initials: J
authors.lastname: Yeo
authors.forename: T A
authors.initials: TA
authors.lastname: Walmsley
authors.forename: B I
authors.initials: BI
authors.lastname: Shand
authors.forename: R S
authors.initials: RS
authors.lastname: Scott
authors.forename: P M
authors.initials: PM
authors.lastname: George
mesh_terms: D001055:Apolipoproteins B / Q000097:blood; D019540:Area Under Curve; D050197:Atherosclerosis / Q000097:blood / Q000150:complications*; D008078:Cholesterol, LDL / Q000097:blood; D003924:Diabetes Mellitus, Type 2 / Q000097:blood* / Q000150:complications*; D005215:Fasting; D005260:Female; D006801:Humans; D008077:Lipoproteins, LDL / Q000097:blood* / Q000737:chemistry*; D008297:Male; D010316:Particle Size; D010641:Phenotype; D012372:ROC Curve; D014280:Triglycerides / Q000097:blood
chemical_list: D001055:Apolipoproteins B; D008078:Cholesterol, LDL; D008077:Lipoproteins, LDL; D014280:Triglycerides