Pilot Placebo Controlled Study With Lovaza in Cardiovascular Disease: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot Placebo Controlled Study With Lovaza in Cardiovascular Disease (NCT01001767), a randomized phase 2 study. The primary outcome is Change in Flow Mediated Dilation (FMD) of the Brachial Artery.

2. Clinical Question

The registry describes the trial as a prospective randomized placebo-controlled study intended to examine whether omega-3 fatty acids modulate cardiovascular risk in people with HIV. Its brief summary identifies endothelial function and inflammation as areas of interest and also mentions studies of coagulation and inflammation markers. The posted primary result concerns FMD; the record does not post secondary outcome analyses.

The statistical question is about the difference in mean change between the randomized groups, not whether either group changed from its own baseline in isolation. The reported mean difference is Lovaza minus placebo. The estimate is negative, with an interval that includes zero, so the posted results leave uncertainty about the direction and size of the between-group difference. They do not establish a treatment effect or its absence.

3. Trial Design

The registry identifies NCT01001767 as a phase 2, randomized, triple-masked, parallel-group study. Its title is “Pilot Placebo Controlled Study With Lovaza in Cardiovascular Disease,” and the official title describes a prospective randomized placebo-controlled trial of omega-3 fatty acids in HIV-infected subjects to modulate cardiovascular risk. The sponsor is University Hospitals Cleveland Medical Center. The status is completed.

The registry reports enrollment of 35. The listed conditions are HIV infections and heart disease. The start is recorded as 2009-04 and primary completion as 2010-03. These registry dates describe the study record and do not provide additional information about follow-up, recruitment pace, or the timing of individual assessments.

Participants were assigned to Lovaza or placebo. The Lovaza description specifies 1 gram by mouth twice a day for 24 weeks; the placebo description specifies a capsule by mouth twice a day for 24 weeks. The planned outcome population is described as randomized to have equal numbers in both groups. The outcome results list 14 participants for Lovaza and 17 for placebo. The registry does not explain the relationship between the enrollment figure, the planned allocation description, and the outcome group counts.

The primary outcome is change in brachial artery FMD, measured at baseline and week 24. The record reports one outcome measure and one posted outcome result, but no analyses are listed. A separate sponsor statistical analysis plan, details of sequence generation or concealment, and the trial's original sample-size justification are not reported in the registry record. The listed masking category is triple, but the record does not specify which roles were masked.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: No wash out, run-in or transition period required for this study.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Randomized to have equal number in both groups

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

6. Primary Endpoint

The registry lists the primary outcome as Change in Flow Mediated Dilation (FMD) of the Brachial Artery, measured over baseline and week 24.

The primary endpoint is change in flow-mediated dilation of the brachial artery, measured by ultrasound at baseline and week 24. FMD is expressed as percent change from the baseline brachial artery diameter to the diameter after reactive hyperemia. In the registry description, this measure represents endothelium-dependent endothelial cell function.

The endpoint is relevant to the trial's stated aim because the brief summary identifies endothelial function as a focus in studying cardiovascular risk among people with HIV. The record also describes interest in inflammation, coagulation, and related markers, but it posts no secondary outcome analyses. The primary result therefore addresses FMD specifically; it does not directly report results for the other areas mentioned in the study summary.

The posted group values are means for the continuous endpoint, accompanied by standard deviations. The comparison is the difference between the Lovaza and placebo mean changes. This between-group contrast is the central quantity for assessing how the groups differed in their reported average change. It should not be read as a direct measure of clinical events or as a complete account of cardiovascular risk. The registry record does not report a threshold for what size of FMD change would be clinically important, nor does it report additional endpoint measurement details such as assessor procedures.

7. Results Posted in the Registry

• Lovaza: mean -0.13 versus 1.47 on control; difference -1.60 (95% CI -3.96 to 0.76), standardized effect d = -0.46; z-test p = 0.184.

8. Statistical Interpretation

9. Statistical Methods Explained

The main statistical result is a comparison of means for a continuous outcome. FMD change is reported as a mean and standard deviation within each group, and the primary contrast is the difference between those means. The posted contrast is Lovaza minus placebo, so a negative estimate indicates that the Lovaza group mean was lower than the placebo group mean in the reported change measure. The sign describes the direction of the contrast as defined; it does not, by itself, imply clinical benefit or harm.

What does the mean difference represent?

The mean difference puts the groups on the same outcome scale and expresses how far apart their reported average changes were. The registry reports -0.13 for Lovaza and 1.47 for placebo, with a mean difference of -1.6. The group standard deviations, 2.6 and 4.05, describe variation among outcome values within each group. They are not uncertainty intervals for the group means, and they should not be confused with the interval around the between-group estimate.

A mean summarizes the center of a distribution, while a standard deviation describes how spread out individual values are around that center. In clinical data, the mean can be informative when the outcome scale and distribution make an average meaningful. The registry record does not describe the shape of the outcome distributions or report individual participant values, so their distribution cannot be assessed from these summaries alone.

How should the interval and p-value be read?

The reported interval for the mean difference is -3.958 to 0.758. A confidence interval is a range of values that reflects statistical uncertainty in an estimate under the assumptions of the analysis. In general, narrower intervals indicate more precise estimates and wider intervals indicate less precision. Because this interval crosses zero, it contains values representing no difference as well as values indicating either direction of difference. The record does not state the confidence level for this interval, so no confidence level should be assigned based on the registry entry alone.

The unadjusted p-value is 0.184. In general, a p-value measures how unusual data at least as incompatible with a null hypothesis would be if that hypothesis and the model assumptions were true. It is not the probability that the null hypothesis is true, nor is it a measure of the size or clinical importance of a difference. The record labels the value unadjusted; it does not report an adjusted p-value or a multiplicity strategy. The interval and p-value are complementary summaries of uncertainty, but neither resolves limitations in the underlying data or analysis reporting.

What role do the group counts and variability play?

The outcome summaries list 14 participants in the Lovaza group and 17 in the placebo group. The standard deviations are 2.6 and 4.05, respectively. In general, uncertainty in a mean comparison depends on the amount of information in each group and the variability of the outcome. Greater variability makes a mean difference harder to estimate precisely, while more observations can improve precision when other conditions are comparable. These principles explain why a small pilot result may have considerable uncertainty, but they do not support calculating a new result beyond the statistics posted in the registry.

The comparison record also reports a pooled standard deviation of 3.476 and a standardized difference of -0.460. A standardized difference expresses a mean contrast relative to a measure of outcome spread, which can make results on different scales easier to compare in some settings. It is not a replacement for the original-scale estimate, and it does not establish clinical importance. The posted primary estimate remains the mean difference on the endpoint's reported scale.

What can be inferred about the analysis approach?

The record reports a mean difference, standard deviations, an interval, and an unadjusted p-value. It does not describe the detailed statistical model or test used to produce the sponsor's primary analysis, and it lists no analyses. The reported summary does not establish whether covariates were included, whether the analysis used only participants with observed measurements, or how any missing values were handled. Those details are not reported in the registry record.

The randomized, parallel-group structure supports interpreting the intended comparison as one between assigned groups. However, the registry's summary does not establish whether the posted analysis followed intention-to-treat principles, used a per-protocol population, or applied another population definition. Randomization describes assignment, while the analysis population describes whose data were included in the outcome comparison; the latter is not specified.

In general, a reported statistical estimate depends on both the outcome data and the analytical choices. An unadjusted result refers to the displayed p-value, not necessarily to every aspect of the underlying model. Without a posted analysis plan and full methods, readers cannot determine whether other prespecified analyses were intended or whether the reported comparison was the sole planned analysis. The record does not report interim analyses, covariate adjustment, or a detailed approach to missing data.

How should the planning illustrations be understood?

The sample-size planning values use the observed effect as a reference and consider smaller fractions of that effect. Such calculations illustrate how participant requirements can change under specified planning assumptions. They are not evidence about the probability that this completed trial detected an effect, and they do not explain the trial's original design. In general, a smaller target effect requires more participants to distinguish it from random variation at a chosen significance level and power, assuming the other planning conditions remain the same.

The registry supplies planning assumptions for those illustrations: a two-sided significance level of 0.05, equal allocation, and a normal approximation. The trial's own design assumptions and sample-size justification are not reported in the registry record. The planning values therefore should be interpreted as prospective illustrations based on the observed effect, rather than as a reconstruction of the study's original planning or as an observed-power analysis.

10. Confidence Intervals and Precision

The estimate of the mean difference is -1.6, and its reported interval extends from -3.958 to 0.758. The interval is the clearest summary of the uncertainty around the estimated contrast. It includes zero, so the posted data do not sharply distinguish a negative mean difference from no mean difference or a positive one. The record does not state the confidence level attached to this interval.

Precision is limited by the information available in the outcome groups and the amount of variation in the endpoint. The reported outcome counts are 14 for Lovaza and 17 for placebo, with standard deviations of 2.6 and 4.05. In general, more outcome variability and fewer observations tend to make estimates less precise. The interval's span illustrates that the estimate remains uncertain, but the registry record does not report further diagnostics or participant-level information to assess the sources of that uncertainty.

The unadjusted p-value of 0.184 is consistent with the interval crossing zero, but a p-value does not convey the range of plausible effect sizes as directly as an interval. Nor does either statistic determine whether any particular difference would matter clinically. The registry does not provide a clinically important threshold for FMD. Precision should therefore be considered in relation to both the width of the interval and the absence of a stated threshold, rather than by treating the point estimate as a definitive effect.

11. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are participants per arm, not total event counts. They are illustrations based on the observed effect, not the trial's original sample-size justification. The assumptions listed for these calculations are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set at the stated fraction of the observed effect. The original design assumptions for the trial are not reported in the registry record.

The 80% power column gives the number of participants per arm that the planning calculation indicates would be needed for an 80% chance of detecting the specified effect under those assumptions, if that effect were the true one and the model assumptions held. The 90% power column gives the corresponding per-arm planning figure for a 90% chance. Power is a property of a planned design under assumed conditions, not a measure of what happened in a completed study.

The figures consider planning for 100%, 75%, and 50% of the observed effect. The displayed requirements increase as the target effect becomes smaller: detecting a subtler difference generally calls for more participants when the other assumptions are held constant. This pattern is a general statistical principle reflected in the listed illustrations. The calculations are not observed power and do not show whether the completed trial had an adequate chance to detect a clinically meaningful effect.

12. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -1.600; pooled standard deviation σ = 3.476.
2. n = 2 × (1.96 + 0.842)² × 3.476² / -1.600² = 74.1, rounded up to 75 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -1.6                      # observed difference in means
sigma <- 3.47562943939655                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1001767)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 75 (80% power), 100 (90% power)
 75% of observed effect: n per arm = 132 (80% power), 177 (90% power)
 50% of observed effect: n per arm = 297 (80% power), 397 (90% power)
power.t.test: 75 
Simulated power at n = 75 per arm: 0.797 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

13. Multiplicity, Missing Data and Analysis Populations

The registry record posts one primary outcome measure, change in FMD, and no secondary outcome analyses. The brief summary mentions inflammation and coagulation markers, but their results are not reported in the registry record. The record lists no analyses. It does not describe a multiplicity adjustment or say whether additional outcomes or analyses were planned but not posted.

Multiplicity arises when several outcomes, comparisons, time points, or analytical choices are tested. In general, testing multiple hypotheses can increase the chance of finding an apparently notable result by chance. A prespecified analysis plan and an explicit multiplicity strategy help readers understand how results were selected and interpreted. Such a plan and strategy are not reported in the registry record. The single posted primary result should not be taken as proof that no other analyses were conducted; the record does not provide enough information to determine that.

Missing-data handling is also not reported. The outcome group counts are 14 for Lovaza and 17 for placebo, while the registry's enrollment figure is 35. The record does not explain whether every randomized participant had a week 24 measurement, whether any data were excluded, or how missing values were handled. It also does not identify the analysis population as intention-to-treat, per-protocol, or another defined set. These gaps matter because the interpretation of a randomized comparison depends in part on who contributed outcome data and how incomplete measurements were treated.

The registry does not report interim analyses, covariate adjustment, sensitivity analyses, or a detailed statistical analysis plan. In general, an analysis plan helps distinguish prespecified methods from choices made after examining results. Without those details, readers cannot evaluate whether the posted estimate reflects the intended primary analysis or assess the robustness of the result to alternative assumptions.

14. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 1% reporting threshold.

The serious adverse event figures list 18 participants at risk in the Lovaza group and 17 in the placebo group. The reported number affected by serious adverse events is 0 for each group. The registry also lists other adverse events, with 18 at risk and 0 affected in the Lovaza group, and 17 at risk and 0 affected in the placebo group. No serious adverse event terms are listed.

These are the registry's posted counts, not a detailed safety analysis. The record does not provide event-level descriptions, timing, severity categories beyond the serious-versus-other grouping, or information about how adverse events were collected. Death counts are not reported in the registry record. The at-risk counts need not be identical to the outcome group counts, and the record does not explain their relationship.

Zero reported affected participants in these entries should be read narrowly: the registry lists no affected participants for the specified categories. It does not establish the absence of all possible adverse effects or provide a basis for comparing safety comprehensively. The information reported is limited to these adverse-event summaries.

15. What the Result Does, and Does Not, Mean

The primary result is an estimate of the difference between Lovaza and placebo in mean change in brachial artery FMD from baseline to week 24. The estimated difference is -1.6, with an interval from -3.958 to 0.758 and an unadjusted p-value of 0.184. The interval includes zero, leaving uncertainty about the direction and size of the underlying group difference. The posted results do not provide a statistically clear between-group result under the conventional 0.05 reference threshold.

This finding concerns a specific continuous measure of endothelial function. It does not directly establish an effect on heart disease, cardiovascular events, inflammation, coagulation, or any other clinical outcome. Although those topics appear in the study summary, the registry record does not post secondary analyses for them. It also does not report a threshold for clinical importance on the FMD scale, so the estimate cannot be classified as clinically important or unimportant from the record alone.

The result does not show that the groups were exactly equivalent. An interval that includes zero can still include differences in either direction, and the posted interval reflects substantial uncertainty about the mean contrast. Conversely, the negative point estimate does not establish that Lovaza caused a lower FMD change. Interpretation depends on the analysis methods, completeness of follow-up, and population included, details that are not reported in the registry record.

The study is described as a pilot and the outcome group counts are 14 and 17. Its result is best understood as an imprecise estimate from the posted comparison rather than a definitive answer about treatment effects. The registry record does not provide the trial's original sample-size justification, a detailed analysis plan, or missing-data methods. Those limitations constrain what can be concluded from this one posted primary result.

16. Why This Trial Matters Statistically

This trial illustrates why an estimated effect and its uncertainty should be read together. The mean difference of -1.6 gives the direction and scale of the observed contrast, while the interval from -3.958 to 0.758 shows that the estimate is not precise enough to rule out values on either side of zero. The unadjusted p-value of 0.184 is another summary of the evidence against a null difference, but it does not replace the interval or describe clinical importance.

The endpoint also highlights the distinction between a biological measure and a clinical outcome. FMD is described as a measure of endothelium-dependent endothelial cell function. It is relevant to the trial's stated cardiovascular-risk question, but the posted result is not a direct comparison of cardiovascular events. Statistical interpretation should stay tied to the measure actually reported.

The record's limited analysis reporting makes transparency important. It lists a primary outcome and its result but does not report secondary analyses, missing-data methods, the analysis population, or the original sample-size rationale. These details affect reproducibility and the ability to evaluate whether a result was robust to analytical choices. Their absence is not evidence that methods were not used; it means they are not documented in the registry record.

Finally, planning calculations based on an observed effect can illustrate how the required sample size depends on the target effect, power, and other assumptions. Such calculations answer a prospective planning question, not whether this completed trial was adequately powered or whether its observed result is reliable. Keeping those questions separate is central to sound interpretation.

17. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The posted outcome data cover one primary measure, FMD change, and the registry lists no analyses. Results for inflammation and coagulation markers mentioned in the study summary are not reported in the registry record. This restricts interpretation to the primary continuous endpoint and prevents assessment of the broader set of biological questions named in the summary.

The outcome group counts are 14 for Lovaza and 17 for placebo, while enrollment is reported as 35. The registry does not explain this difference or describe participant flow, endpoint completion, exclusions, or missing measurements. It also does not identify the analysis population or state how missing data were treated. These omissions make it difficult to determine how closely the posted outcome comparison represents the randomized groups.

The record does not provide the original sample-size justification, detailed statistical analysis plan, method used to generate the reported interval, or a stated confidence level for that interval. It does not report multiplicity handling, covariate adjustment, interim analyses, or sensitivity analyses. The record also gives no clinical-importance threshold for FMD and no additional measurement details beyond ultrasound and the endpoint definition.

For safety, the registry lists zero affected participants for serious and other adverse events in both groups, but provides limited event detail. Death counts are not reported in the registry record. These limitations do not change the posted numbers, but they narrow the conclusions that can be drawn about the outcome, the analysis, and safety.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Pilot Placebo Controlled Study With Lovaza in Cardiovascular Disease — NCT01001767.
• Registry record last updated 2015-01-07; status last verified 2014-12.
• Results first posted 2012-04-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

21. Record Summary

NCT01001767 is a completed phase 2 randomized, triple-masked, parallel-group placebo-controlled trial sponsored by University Hospitals Cleveland Medical Center. The registry reports enrollment of 35 and describes Lovaza 1 gram by mouth twice a day for 24 weeks versus placebo by mouth twice a day for 24 weeks.

The primary endpoint was change in brachial artery FMD from baseline to week 24. The posted mean difference for Lovaza versus placebo was -1.6, with an interval from -3.958 to 0.758 and an unadjusted p-value of 0.184. The interval includes zero, and the registry does not report secondary outcome analyses.

The record does not report the trial's original sample-size justification, detailed analysis plan, analysis population, or missing-data methods. Serious and other adverse-event entries list zero affected participants in both groups; death counts are not reported in the registry record.