1. DEPARTMENT OF INTERNAL MEDICINE,N.A.U.T.H,NNEWI
Monday Journal Club Presentation by
Dr Onwukwe Chikezie Hart.
Senior Registrar,
Endocrinology Unit.

2. Article Title: High-density lipoprotein subfractions and carotid plaque: The Northern Manhattan Study.
Authors: Tiozzo et al.
Journal: Atherosclerosis
Month and Year of Publication: November 2014
Volume: 237
Issue: 1
Pages:

3. Introduction
↓HDL-C associated with ↑risk of CV disease, stroke and carotid atherosclerosis.
Major subfractions of HDL-C:
HDL2-C (larger, less dense)
HDL3-C (smaller, more dense)
Uncertainty over the value of HDL-C subfractions in the assessment of vascular risk

4. Aim
To determine the relationship between HDL-C subfractions and carotid plaque in stroke free individuals

5. Participants, Materials & Methods
Study site: Northern Manhattan, USA (63% Hispanics) Study population: Stroke free participants from the Northern Manhattan Study (NOMAS) Participant selection: Eligibility-Absence of stroke/TIA/other neurological syndromes (aphasia, hemiparesis, weakness, coma, syncope), Age>40 years, Resident in Northern Manhattan > 3/12 in a household with a functioning telephone. Participants were identified by random-digit dialling with dual-frame sampling.

6. Participants, Materials & Methods
Ethical approval: NOMAS approved by Institutional Review Boards of Columbia University Medical Centre and the University of Miami. Consent: All participants gave written informed consent.

7. Participants, Materials & Methods
Reagents-Cholesterol/TG kits, Total HDL-C and HDL3-C kits
Equipment- Mercury sphygmomanometer, Automated spectrophotometer, Brain CT scan machine, High resolution B-mode carotid ultrasound.

8. Participants, Materials & Methods
Methods Study design: Cross-sectional observational study Clinical procedures: History, physical examination, brain CT, carotid US. Laboratory procedures: Fasting blood samples drawn for Plasma Cholesterol/TG (enzymatic methods), Total HDL-C/HDL3-C (Dual precipitation)

9. Participants, Materials & Methods
Statistical analysis:
Done with SAS version 9.1
Continuous variables presented as means + SD
Categorical variables presented as proportions (%)
Comparison between groups of continuous variables done using t-test or ANOVA
Quantile regression used to examine plaque phenotypes (thickness and area) as continuous outcomes
Logistic regression used to determine association between HDL-C subfractions and plaque presence
p<0.05 defined statistical significance

10. Participants, Materials & Methods
Definition of terms/Criteria
HTN: BP>140/90mmHg (average of 2 measurements in 1 sitting), patient’s self reported HTN, or use of anti-BP medications
DM: Fasting glucose >126mg/dL, patient’s self reported DM, use of anti-diabetic medications
Smoking: Never, Former, Current (within past year)
Alcohol use: Mild/Moderate
Physical activity: Frequency and duration of 14 recreational activities during the 2 week period b4 the interview
Carotid plaque: Focal wall thickening or protrusion from lumen >50% of surrounding thickness
Maximal plaque thickness: The greater of the highest plaque prominence at the lumina-intima and the meia-adventitia

11. Results
988 persons with complete data for analyses (3298 persons were enrolled)
Mean age 66+8 years
60% women
Mean + SD of total-HDL, HDL2-C and HDL3-C were 46+14, 14+8 & 32+8 mg/dL respectively.
Strong positive correlation between total HDL-C and subfractions (HDL-C: HDL2-C; r=0.81, p< and HDL-C: HDL3-C; r=0.75, p< respectively)
Weak positive correlation between HDL-C subfractions (r=0.34, p<0.0001)
Plaque occurred in 56% of population
Mean plaque area and thickness mm2 and mm respectively.

12. Results
No statistically significant difference between total HDL-C and plaque measurements
HDL3-C showed significant inverse association with 75th and 90th percentiles of plaque area
Association of HDL3-C with 75th percentile of plaque area was stronger among those with ↓HDL-C compared to those with ↑HDL-C (β=-0.38, p=0.02 vs β=-0.17,p=0.19)
Similar findings with 90th percentile of PA (β=-0.38, p=0.12 vs β=-0.20,p=0.43)
Positive association of HDL2-C with 90th percentile of PT (p=0.003)
None of the HDL-C variables were significantly associated with plaque presence

13. Results
Among Hispanics, HDL3-C was inversely associated with the 90th percentile of PA (p=0.03).
Total HDL-C was only significantly associated with plaque area in Hispanics (90th percentile; p=0.01)

14. Discussion
There was a negative association between HDL3-C and plaque area while HDL2-C had a positive association with plaque thickness
No significant associations of total HDL-C with plaque measurements except in hispanics in which total HDL-C had a negative association with PA
Other studies have shown significant association of HDL-C variables with CV risk despite various methods of assessment of these variables

15. Conclusion and Recommendations
HDL3-C is inversely associated with carotid plaque area as a marker of subclinical atherosclerosis among stroke-free persons
Findings support the role of HDL-C phenotypes in the atherosclerotic process and emphasizes on the complexity of HDL-C functions.
Future studies required to elucidate the anti-atherosclerotic functions in HDL-C and heir role among different ethnicities to improve on HDL-C directed therapies.

16. Strengths of Study Large population
Use of dual-step precipitation in HDL-C assessment (Better precision than electrophoresis)
Better understanding of the association between total HDL-C and subfractions in the development of the atherosclerotic plaque

17. Study Limitations Cross-sectional design
Inability to assess changes in the levels of HDL-C subfractions
Effect of HDL-C subfractions on progression of atherosclerosis was not studied
Subclasses of these subfractions and their biological activity not studied

18. Critique of Article
Participant flow distribution was described in methods section instead of results section
Some definitions were not indicated for some variables analyzed in results section. Example Obesity.
Discrepancies in laboratory assessment of total HDL-C and precision studies done for HDL2-C quality control
Gold standard for lipid assessment (Ultracentrifugation) not used
Non-parametric data expressed as mean+SD. Median (IQR) preferred for continuous variables
Some total sums not adding up in descriptives table (Table 1) e.g BMI status of study participants

19. Does this make any sense?

20. THANK YOU!