Transcript Effect of a dietary Portfolio of cholesterol

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
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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)
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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