Clinical Trial Details
— Status: Terminated
Administrative data
| NCT number |
NCT04456608 |
| Other study ID # |
SITE00000212 |
| Secondary ID |
5P01GM116691 |
| Status |
Terminated |
| Phase |
Phase 4
|
| First received |
|
| Last updated |
|
| Start date |
August 1, 2016 |
| Est. completion date |
July 31, 2023 |
Study information
| Verified date |
December 2023 |
| Source |
University of Washington |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
This study will investigate differences in platelet aggregation under basal and
aspirin-treated conditions in American Indian and Alaska Native people who have extreme
levels (low and high) of n-3 polyunsaturated fatty acids (n-3 PUFAs, EPA and DHA) in red
blood cell membranes. The study will also determine whether or not platelet aggregation under
the different conditions is modified by CYP4A11, CYP4F2, CYP4F11, PEAR1, and ACTN1 gene
variation.
Description:
Purpose: In this aim, the investigators will test the hypothesis that n-3 PUFAs modify
aspirin anti-platelet response, by measuring and comparing three different indicators of
aspirin response in individuals with extremely high and low RBC n-3 PUFA levels, under a
basal state and after 1-week of once a day aspirin treatment. The three indicators are: 1)
platelet TXB2 and 20-HETE concentrations; 2) platelet aggregation ex vivo (in response to
external stimuli); and 3) aspirin covalent adduct of COX-1. The investigators will also test
whether or not common variants in the CYP4A11, CYP4F2, CYP4F11, PEAR1 and ACTN1 genes are
associated with basal and aspirin-induced changes in platelet aggregation and, in an
exploratory analysis, modify the effects of n-3 PUFAs on aspirin response.
Procedures and Population: Investigators from the University of Montana, Southcentral
Foundation and Oregon Health & Science University will recruit a total of 150 individuals (50
at each site) to participate in the study. At each performance site, the participants
recruited will represent 25 individuals with high and 25 individuals with low RBC n-3 PUFA
concentrations. After providing written consent, each study participant will be screened for
medical history and clinical lab testing to ensure good health and good liver, kidney and
blood test parameters. If found to be eligible, each participant will provide 12-hour fasted
(overnight) blood samples for isolation of plasma, platelets, lymphocytes, and red blood
cells. A separate blood sample will be collected into a citrate treated tube for platelet
aggregation testing using the PFA-100 platform. Isolated blood fractions will be stored at
-80°C.
After baseline sampling, each participant will be given six doses of aspirin (80 mg/day for 2
days) and instructed to take one dose daily at approximately 9 am. On the day after the last
aspirin dose, the participant will provide blood samples for repeated platelet aggregation
testing, platelet lipid analysis and measurement of aspirin covalent adduct to COX-1, and a
spot urine sample to confirm aspirin consumption by testing for salicylate. For 24 hours
prior to platelet aggregation testing, study participants will be asked to avoid foods that
could lead to spurious test results (eg, chocolate, tea, coffee, cola, red wine, beer,
tomato, grapes, grape juice, orange and cranberry juices, as well as traditional wild foods
that include berries, plant roots, plant greens etc).
Analytical Methods: Whole blood, point of care, platelet aggregation testing will be
performed using the automated PFA-100 instrument. Performance by research personnel will be
compared head-head to clinical testing services at each site, as a quality control measure.
In each test setting, the investigators will obtain results in duplicate for both
collagen/epinephrine and collagen/ADP cartridges. The investigators will also measure
platelet TXB2, 20-HETE and AA concentrations, by LC-MS/MS. In addition, the investigators
will develop and employ a method to quantify theaspirin covalent adduct of COX-1 in isolated
platelets from study participants.
Statistical Methods: For each study population, and subgroups with extreme RBC n-3 PUFA
phenotypes, the investigators will use linear regression models with robust standard errors
to identify significant differences in the mean absolute platelet aggregation test results
under basal and aspirin-treated conditions (primary outcome), as well as the
post-treatment-to-baseline change in platelet aggregation. Heterogeneity between pairs of
extreme phenotypes subgroups will be accounted for by including sex, age, BMI and platelet
count as covariates in the regression model. Sample size calculation for each performance
site (n = 25 per n-3 PUFA subgroup) was based on having power of at least 0.8 for detecting a
difference in mean platelet aggregation between the two extreme (0-10 and 90-100 percentiles)
n-3 PUFA subgroups under basal conditions, at a significance level of 0.05. As a secondary
level of analysis, for each subgroup of the extreme RBC n-3 PUFA phenotypes, the
investigators will also compare mean platelet TXB2 and 20-HETE concentrations under basal and
aspirin-treated conditions, as well as the post-treatment-to-baseline change. Finally, a
third level of analysis will involve testing each study population for a difference in the
extent of aspirin adduct to COX-1 between groups with extreme RBC n-3 PUFA phenotypes. The
investigators will test for associations between platelet aggregation test results and
biochemical measures of platelet activation, each study population separately and in
aggregate.
The investigators will use linear regression models to test for an association between common
CYP4A11,CYP4F2, CYP4F11, PEAR1 and ACTN1 genotypes and the mean absolute platelet aggregation
test results under basal and aspirin-treated conditions, as well as the
post-treatment-to-baseline change in platelet aggregation. In an exploratory analysis, the
investigators will apply Linear Mixed Effects (LME) models to the combined pre- and
post-treatment dataset to test for associations with n-3 PUFAs group and drug effects, as
well as to identify any modifications of those effects by CYP4A11, CYP4F2, CYP4F11, PEAR1 and
ACTN1 variation by including and testing for significant interaction effects in the models.
The investigators will include random effects in the LME to account for potential
heterogeneity in each of the populations.
