Effect of n-3 Fatty Acid Supplementation in Hyperlipidemic Patients Taking Statins
Condition: Cardiovascular Diseases; Hyperlipidemias; Dyslipidemias
MeSH terms: Cardiovascular Diseases; Dyslipidemias; Hyperlipidemias; Hyperlipoproteinemias
Study type: Interventional

Summary: 
      Epidemiological and clinical evidence suggests that high-dose intake of long-chain n-3 fatty
      acids have a favorable role in altering blood TG and non-HDL cholesterol when combined with
      statins in hyperlipidemic patients. Their efficacy in altering low density lipoprotein
      cholesterol particle size and concentration is yet to be confirmed.

      This study evaluates the effects of adding 4/day eicosapentaenoic acid (EPA) +
      docosahexaenoic acid (DHA) to stable statin therapy on blood TG, non-HDL, LDL-C as well as
      small dense (sdLDL) particle concentration in a group of hyperlipidemic patients.

      In this randomized, placebo-controlled, double-blind parallel group study, 44 subjects who
      were already on statin therapy for > 8 weeks and had non-HDL-C levels above the National
      Lipid Association Recommendations were randomized into two groups. For 8 weeks, together with
      their prescribed atorvastatin, the intervention group received 4g/day EPA+DHA (in ethyl ester
      form) while the control group received 4g/day olive oil (placebo). Baseline measurements of
      non-HDL-C, TG, TC, HDL-C, LDL-C, VLDL-C and sdLDL were repeated at week 8. Differences in
      dietary intake were assessed with a weighed 3-day food diary at week 4. Primary outcome
      measures are the percent change in non-HDL-C and sdLDL particle concentration from baseline
      to the end.
    

Detailed description: 
      This study is a parallel randomised, double-blind placebo - controlled trial which was
      conducted in Istanbul, Turkey.

      BACKGROUND

      Cardiovascular disease (CVD) has been, and still is the number 1 cause of deaths all over the
      world. According to the World Health Organisation (WHO), 1 of every 3 death was caused by CVD
      in 2012. Heart disease and stroke were the No. 1 and No. 2 killers worldwide, according to
      American Heart Association. In Turkey, it is even worse, 40% of all deaths were caused by
      CVD. Such high prevalence naturally brings a huge disease burden and in many countries there
      are ongoing research to mitigate CVD risk.

      It is essential to highlight that CVD is not a single disease, it is actually a family of
      diseases that mostly cause by a common pathology named "atherosclerosis". Atherosclerosis is
      plaque formation in artery walls which leads a reduced lumen diameter, causing organ damage
      or clinical events like myocardial infarction (MI), angina or stroke. One of the two reasons
      of atherosclerosis is hyperlipidemia, which is the theme of this study. Atherosclerosis and
      lipids are evident to be related; the elevations in circulating LDL cholesterol level plays a
      central role in atherogenesis, given the fact that they cause the formation of fatty plaque.
      Therefore, in all clinical guidelines, LDL level is the primary target to prevent
      atherosclerosis.However, more recent studies have revealed that LDL is structurally
      heterogeneous based on its size and density. There are large, buoyant LDL particles and
      small, dense LDL particles, which are believed to be more atherogenic. Individuals that have
      a large amount of small and dense LDL particles are at an increased risk of CV events,
      regardless of their total LDL level. In studies, small and dense LDL profile was associated
      with a three-fold to seven-fold increase in risk of CVD as they:1- Have the increased ability
      to penetrate arterial wall. 2- Are readily oxidized.

      The main therapeutic approach to treat small&dense LDL is using drugs that lower serum
      triglyceride (TG) levels, as they also cause a change in the LDL size profile to larger, less
      dense and, therefore, less atherogenic species. Most commonly used such drugs are statins.
      Apart from statins, there is strong evidence that omega-3 fatty acids also have a beneficial
      effect in lowering TGs. However, their effect on small, dense LDL has not been studied enough
      yet. If omega-3 fatty acids have a beneficial effect in changing LDL profile to less dense
      and larger particles, omega-3 supplementation will be quite effective for patients with
      hyperlipidemia. Given the fact that statin use is the gold standard in all clinical
      guidelines, this study will not compare statins with omega-3 fatty acids and instead, compare
      statin monotherapy to the combined use of statin and omega-3 supplements to investigate
      whether omega-3 fatty acids have a supportive role to statin.

      RECRUITMENT AND SAMPLING:

      Eligible participants were men or women from Istanbul, Turkey, aged between 50 and 79 years
      who had been receiving a stable dose of atorvastatin for the control of LDL-C levels at least
      for 8 weeks before initial screening.

      One hundred patients were selected for initial screening and 44 matched the
      inclusion/exclusion criteria and were randomized to the intervention using
      www.randomization.com.

      Participants were informed informally via telephone first, and then invited to the Clinic by
      a Patient Invitation Letter. A structured one-to-one information session was carried out with
      each participant at the Clinic, during which they were given a Participant Information Sheet.
      Participants provided written informed consent by signing the a Participant Consent Form.

      SAMPLE-SIZE

      Total sample size was 44, consisting of two 22-subject groups (control and intervention
      group).

      A targeted sample size of 36 subjects (18 per arm) was expected to provide at least 80% power
      to detect a difference of 5% or above in primary outcome non-HDL-C and LDL-C III particle
      concentration when compared with placebo (α=0.05) . Sample size was assigned as 44 to allow
      for subject attrition and other potential causes of study withdrawal up to 20%.

      The power calculation was based on the mean changes in non-HDL-C measurement of the previous
      COMBOS trial which is a largest randomized placebo controlled trial that has the same design
      with this study. Data from COMBOS trial is summarized as follows:

      Intervention Group:

      baseline non-HDL mean + standard deviation (SD): 135.8 mg/dL + 24.5 mg/dL final non-HDL mean
      + SD: 124.1 mg/dL + 24.7 mg/dL Percent change: -7.9%

      Placebo Group:

      baseline non-HDL mean +SD: 141.3 mg/dL + 29.3 mg/dL final non-HDL mean + SD: 138.8 mg/dL +
      32.0 mg/dL Percent change: -1.5%

      METHODS

      A randomized, double-blind, placebo controlled, parallel groups study was carried out. Before
      entry into the intervention phase of the study, 8-weeks of dietary lead-in was carried out.
      Study participants received dietary counselling for the 8 weeks before the intervention,
      based on the heart-healthy diet structured in the United Kingdom (UK) National Institute of
      Health Care Excellence (NICE) guidelines (2014) and were instructed to maintain this diet
      throughout the study. Adherence to dietary advice was also measured by a 3-day weighed intake
      food diary at Week 4. Household measures were used to assess the food intake. Nutrient
      content of the diet was estimated using Nutritics software (Nutritics Ltd, Ireland) using UK:
      Scientific Advisory Committee on Nutrition (SACN) 2015 food composition tables.

      After the dietary lead-in, baseline measurements of fasting blood Triglycerides (TG), Total
      Cholesterol (TC), High-density Lipoprotein cholesterol (HDL-C), Low-density Lipoprotein
      cholesterol (LDL-C), and LDL-C sub groups (LDL-C I, LDL-C II, LDL-C III, LDL-C IV, LDL-C V)
      were carried out for all subjects at 2 clinics separated by 1 week, and the means were used
      as baseline values. Non-High-density Lipoprotein cholesterol (non-HDL-C) was calculated by
      subtracting HDL-C from TC.

      After baseline measurements, all participants were randomized in equal numbers to receive
      either 4g/day EPA (75%) & DHA (25%) ethyl esters or 4g/day olive oil (placebo) for 8 weeks in
      combination with the same dose of atorvastatin they had been prescribed. For all subjects,
      atorvastatin dosage was kept constant throughout the trial.

      Both groups consumed four 1000mg capsules orally 4 times daily and compliance was measured by
      the number of capsules consumed relative to the number estimated to be consumed.

      Baseline measurements were repeated at the end of week 8. Study participants and
      investigators remained blinded to all laboratory results until completion of analysis.

      BIOCHEMICAL MEASUREMENTS

      Laboratory analyses were performed by e-Lab Laboratories (Istanbul, Turkey) on the serum or
      plasma of 12 hours fasting blood samples. LDL-C, VLDL-C and HDL-C was measured with
      homogeneous enzymatic colorimetric assay of Roche Diagnostics (USA). TG and TC was measured
      with enzymatic colorimetric assay of Roche Diagnostics (USA). LDL-C subgroups were analyzed
      with electrophoresis by Lipoprint (Quantimetrix, USA).

      STATISTICAL ANALYSIS

      Statistical analyses was be performed with Statistical Package for the Social Sciences (SPSS)
      version 24 (IBM, USA).

      Demographic and baseline analysis was performed for all study participants, while efficacy
      analysis was performed only on subjects that successfully completed the 8-week study
      protocol. The primary efficacy end points are non-HDL and LDL-C III particle concentration
      percentage change from baseline; secondary efficacy end points are changes in TG, TC, LDL-C,
      VLDL-C and HDL-C.

      Normal distribution of the sample was checked with Shapiro-Wilk's test. Mixed model ANOVA
      test was carried out to compare changes in outcome parameters from baseline to
      end-of-treatment between the intervention and control groups.

      Paired t-tests were performed to analyze the changes from baseline to Week 8 for each outcome
      parameter, and multiple Independent t-tests were performed to analyze significant differences
      between groups across time points. A P-value < 0.05 determined statistical significance.
    

Intervention name(s): EPA+DHA; Placebo
Intervention type(s): Dietary Supplement; Other
Intervention description(s): 4 g/day EPA+DHA in tablets of 1g, 4 tablets daily, over 8 weeks (56 days); 4 g/day olive oil placebo in tablets of 1g, 4 tablets daily, over 8 weeks (56 days).
Other intervention name(s): marine omega-3; fish oil; Non-active ingredient
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Double (Participant, Investigator)
Primary purpose: Prevention
Keywords: omega-3; EPA; DHA; sdLDL; cardiovascular disease; hyperlipidemia; dyslipidemia