effect of a dietary portfolio of cholesterol-lowering foods given at 2 levels of intensity of...

Effect of a dietary Portfolio of cholesterol-lowering foods given at 2 levels of intensity of dietary

advice on serum lipids in hyperlipidemia

Erin Woodard

September 2011

Mercer University

Overview

• Authors: David Jenkins, Peter Jones, Benoit Lamarche et al

• JAMA: Vol 306;No.8

• August 2011

Background

• Cardiovascular health stress importance of diet and lifestyle as primary means to lower lipids and CHD risk

• Specific foods (dietary portfolio) known to reduce LDL-c similarly to 1st – generation statins

• Advice to eat dietary portfolio consisting of cholesterol lowering foods– Control diet: high fiber and whole grains but lacked

portfolio components

Methods• Objective

– To assess effect of dietary portfolio at 2 levels of intensity on percentage change in LDL among participants following self-selected diets

• Trial Design– Parallel study design– 351 participants from 4 different centers across Canada– Randomized controlled trial

• Intervention– Low saturated fat (control)– Dietary portfolio:

• Routine: 2 clinic visits• Intensive: 7 clinic visits

• Recruit and randomized between June 25, 2007 – February 19,2009• Study visits at baseline, 3 months, 6 months• Follow up with labs at 6 months for all

Methods

• Primary Outcome measure– Percentage change in serum LDL adjusted for sex

• Inclusion– Men and postmenopausal women in low and intermediate

Framingham risk score– Had LDL-C 135-205 and 116 -178

• Exclusion– Hx CVD– Cancer or family hx of cancer– Untreated hypertension (>140/90)– Diabetes– Renal or liver disease – Currently taking lipid-lowering medications

Diets

• Control– Low-fat dairy and whole grain cereals – Fruit and vegetables and– Avoidance of specific portfolio components

• Routine & Intensive portfolio (2 and 7 visits)– 0.94g plant sterols from enriched margarine– 9.8g of viscous fibers from oats, barley, psyllium– 22.5g of soy protein from soy milk, tofu, soy meat– 22.5g of nuts– Encourage peas, beans, lentils

Methods - Statistics

• Randomized into groups 1, 2, 3 by blinded statistician

• Modified intent-to-treat– 345 included in primary analysis– 267 completed trial– Missing data were multiple imputed

• 95% Confidence intervals

• P-values

Methods - Statistics

• 110 participants were required per treatment group for – Power = 0.80– Alpha = 0.05

Results

LDL reductions (from overall mean 171)– 13.8% (-26mg/dL) intensive dietary portfolio

• CI [-17.2% to -10.3%]• P = <0.001

– 13.1% (-24mg/dL) routine dietary portfolio• CI [-16.7% to -9.5%]• P = <0.001

– 3.0% (-8mg/dL) control• CI [-6.1% to 1.0%]• P = 0.06

Authors Conclusion

• Use of dietary portfolio compared with the low-saturated fat dietary advice resulted in greater LDL lowering during 6 months of follow-up

Evaluation

• Validity– Randomized, controlled– Baseline treatment groups similarly distributed

• Exception of male to female (more female in all groups, esp routine dietary group)

– Intervention seems appropriate but hard to adhere to if not monitored

• Adherence was measured as 46% in intensive, 41% in routine, 8% control

• Seems unreasonable diet changes unless can maintain with monitoring

– Sample size was barely large enough to maintain power without use of multiple imputation

Evaluation Cont.

• Limitations– Complex intervention– Colinearity between diet components– Not metabolically controlled in terms of

providing food (goal was to assess effect of advice in real-world conditions)

– High drop out rate (22.6%)– Predominantly white with low to intermediate

risk of CVD and low mean BMI

Application

• Small reduction observed in dropout rate by increasing frequency of visits (2 to 7)

• No advantage observed in adherence or percent reduction

• More frequent visits unnecessary

• Could suggest to those with elevated LDL and minimal comorbidities