Dose Response Effects of Marine Omega-3 Fatty Acids on Inflammation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Dose Response Effects of Marine Omega-3 Fatty Acids on Inflammation (NCT01078909), a randomized phase 3 study. The primary outcome is Mean Concentrations of Inflammatory Markers (TNF-alpha and IL-6) Following 5 Months of Treatment.

2. Clinical Question

3. Trial Design

The registry record describes a Phase 3 randomized, double-masked, parallel-group study sponsored by Penn State University. The recorded enrollment is 125. The study began in 2011-10, reached primary completion in 2012-11, and is listed as completed. These status and timing details describe the trial record; they do not establish how many participants contributed data to each analysis.

The intervention was EPA + DHA in fish oil supplements at daily dose levels of 300, 600, 900, and 1,800 mg/day, with placebo listed as 0 mg/d EPA + DHA. A parallel design assigns participants to a study group and compares outcomes across groups, rather than having each participant receive every condition. Randomization is intended to reduce systematic differences between groups at entry, while masking is intended to limit the influence of treatment knowledge on participant experience, care, or outcome assessment. Those are general purposes of these design features, not evidence about how effectively they were implemented in this trial.

The registry record does not report the allocation ratio, sequence-generation method, concealment procedures, masking procedures, adherence information, or group enrollment at baseline. The arm descriptions are blank. It therefore does not establish whether dose groups were balanced in size or how the study supplements were administered beyond the stated fish-oil intervention.

The stated study purpose focused on inflammatory responses to in vivo and ex vivo endotoxin challenge and the production over time of several inflammatory markers. The listed primary outcome is mean TNF-alpha and IL-6 concentrations after 5 months of treatment. A secondary outcome is change in lipid mediators. The record lists 3 outcome measures, but does not provide a complete account of their definitions, analysis populations, or all time points. It also does not report a sample-size justification or a detailed protocol for the planned comparisons.

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: A computer-generated randomization scheme was developed in advance. The randomization scheme was stratified by sex and age and used a balanced block size of 5 to ensure even distribution among treatment groups. Using this randomization scheme, eligible participants were assigned to blinded treatments at the baseline visit by the study coordinator.

Overall Study

Analysis population for the primary outcome, as defined in the registry: One individual was removed from the analysis due to having very high RBC EPA+DHA content at study entry (\>8%)

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 Mean Concentrations of Inflammatory Markers (TNF-alpha and IL-6) Following 5 Months of Treatment, measured over 5 months.

The primary endpoint is described as mean concentrations of TNF-alpha and IL-6 following 5 months of treatment, measured in pg/mL. These inflammatory markers are used to quantify aspects of an inflammatory response. The study’s stated purpose relates the marker measurements to responses after in vivo and ex vivo endotoxin challenge, with marker production assessed over time. The registry description does not specify how each challenge measurement was combined or identify a single time-specific value beyond the stated primary-outcome timeframe.

A mean expresses the average measured concentration in an analysis group. It is useful for describing the typical level in that group, but it does not show how widely individual values vary. The registry lists the dispersion as a 95% confidence interval. In general, a confidence interval conveys uncertainty around an estimated quantity under the statistical method used: a narrower interval indicates greater precision than a wider interval, while neither interval width nor the mean alone establishes the clinical importance of a difference.

The registry record does not report the actual mean concentrations or confidence-interval limits for TNF-alpha or IL-6. It also does not provide a numerical comparison among dose groups and placebo. The endpoint definition therefore identifies what was intended to be measured, but the record does not contain the numerical results needed to judge the observed pattern or its precision.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies a continuous primary outcome summarized by a mean, with dispersion described as a 95% confidence interval. It does not provide numerical estimates, test statistics, or analysis details. The concepts below explain how such methods are generally interpreted; they do not describe unreported procedures in this trial.

What does a mean describe?

For a continuous measure such as a concentration in pg/mL, a mean is the sum of measured values divided by the number of observations included in the analysis. It gives a center-of-data summary, but can be influenced by unusually high or low observations. It does not describe the full distribution, variation between participants, or the number of observations without additional summaries. The registry record does not provide these supporting details for TNF-alpha or IL-6.

When comparing groups, the relevant quantity is commonly a difference between group means, or another prespecified contrast. The contrast’s interpretation depends on which groups and time points are compared and whether the analysis accounts for the study design. The record does not report a numerical contrast or specify an adjusted or unadjusted model. No such comparison should be inferred from the endpoint title alone.

How should a confidence interval be read?

In general, a confidence interval describes uncertainty in an estimate under a specified statistical procedure and its assumptions. Its endpoints indicate values compatible with the data and procedure at the stated confidence level. A wider interval reflects less precision than a narrower one. Confidence intervals are not direct probabilities that a particular fixed parameter is inside the particular interval, and they do not by themselves determine whether an effect is clinically important.

The registry specifies 95% confidence intervals as the dispersion measure for the primary outcome, but gives no interval bounds. It also does not explain whether the interval is attached to each group mean or to a between-group contrast. Without that distinction and the numerical results, precision cannot be evaluated or compared across doses.

Why can dose groups require more than a single comparison?

A dose-ranging study can raise several questions: whether any dose differs from placebo, whether there is a pattern across increasing doses, and whether a particular dose is associated with a change in a marker. These are distinct statistical questions. Multiple tests can increase the chance of at least one apparently notable finding when all comparisons are treated as if they were the only test. General approaches to this issue include defining a primary contrast in advance, adjusting inferential thresholds, or presenting estimates and intervals with a clear account of the comparisons. The registry record does not report a multiplicity strategy, so none should be attributed to this study.

Measurements over time or following different challenge procedures can also create multiple potential comparisons. The study purpose refers to responses to in vivo and ex vivo endotoxin challenge and marker production over time, but the record does not specify the full analysis structure. In general, repeated observations on the same participant are correlated, so treating them as independent can understate uncertainty. Appropriate repeated-measures methods account for within-participant dependence, but the registry record does not identify whether such a method was used.

What does over-dispersion mean in general?

Over-dispersion occurs when observed variation exceeds what a chosen statistical model assumes. It is especially relevant to count outcomes, where a model may assume a particular relationship between the mean and variance. In general, unmodeled over-dispersion can make standard errors too small and statistical evidence appear stronger than warranted. The primary outcome in this record is continuous, and no model details or variance diagnostics are reported. Over-dispersion should therefore be understood as a general statistical issue, not a documented feature of this analysis.

What do the planning illustrations mean?

Planning illustrations based on an observed effect are hypothetical calculations, not evidence about how many participants were actually required or whether a trial had adequate power. The stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the target effect is expressed as a fraction of the observed effect. For non-time-to-event outcomes, the illustrations are expressed as participants per arm. These assumptions describe the illustrations, not the trial’s original design justification. The sample-size justification is not reported in the registry record. An illustration based on the observed effect must not be interpreted as observed power, and the record does not report numerical illustration results.

10. Multiplicity, Missing Data and Analysis Populations

The record lists 3 outcome measures, names mean concentrations of TNF-alpha and IL-6 after 5 months as the primary outcome, and identifies change in lipid mediators as a secondary outcome. The study purpose also refers to inflammatory-marker production over time after in vivo and ex vivo endotoxin challenge. This combination raises general multiplicity questions because several markers, doses, challenge settings, and potentially time points may yield multiple comparisons. The registry record does not report how those comparisons were prioritized or whether any adjustment for multiplicity was planned or used.

Missing-data handling is not reported in the registry record. It does not state how incomplete measurements were treated, whether participants were analyzed according to assigned groups, or whether sensitivity analyses were conducted. The record notes that one individual was removed from the analysis because RBC EPA+DHA content at study entry exceeded 8%, but does not say whether this was the only exclusion or how the rule was established.

The record lists enrollment as 125 but does not give outcome-specific analysis denominators or group counts for the primary endpoint. The number of analyses is recorded as 0. It therefore does not support conclusions about adherence to an intention-to-treat or per-protocol population, the extent of missingness, or the robustness of results to different analysis choices. These details are important because analytic populations and missing-data assumptions can affect both estimates and uncertainty.

11. 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 0% reporting threshold.

The adverse-event information lists 0 serious events and 0 other events in each reported group. The at-risk counts are 23 for 300 mg/d EPA + DHA, 21 for 600 mg/d, 24 for 900 mg/d, 24 for 1,800 mg/d, and 23 for placebo. These are the denominators attached to the event summaries in the registry record; they should not automatically be treated as the primary-outcome analysis counts.

A zero count means that no events of the listed type were recorded in the stated group within the registry summary. It does not prove that the underlying event risk is zero, particularly when group sizes are limited, and it does not describe events that were not captured or reported. The record does not list serious adverse-event terms. Death counts are null rather than numerical, so deaths are not reported in the registry record; null should not be read as a confirmed zero. The time period and detailed ascertainment procedures for these safety summaries are not reported in the registry record.

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

The registry record establishes that the study was designed to compare several daily doses of EPA + DHA with placebo and to assess inflammatory markers after 5 months of treatment. It also establishes that the study was randomized, double-masked, and parallel-group, with enrollment recorded as 125. The primary outcome was mean TNF-alpha and IL-6 concentrations, with 95% confidence intervals specified as the dispersion measure.

Those design and endpoint details do not establish what the results were. The record contains no primary-outcome means, confidence-interval limits, or reported statistical analyses. It therefore does not show whether marker values differed between any dose group and placebo, whether any pattern followed dose level, or how precise an estimated difference might be. It also cannot establish a lowest effective dose: that would require interpretable results for the relevant comparisons and a defined criterion for what counts as effective, neither of which is reported in the registry record.

The safety summary records zero serious and zero other events in each group, with the stated at-risk counts. These summaries describe recorded events and do not establish that no events could occur or that all possible harms were assessed. Death counts are not reported in the registry record.

More broadly, a trial’s design can support careful comparisons only when outcome definitions, participant flow, analysis methods, and numerical findings are available. The registry information identifies the research question and some design features, but leaves the essential numerical efficacy results and several analysis details unreported. No conclusion about treatment benefit or lack of benefit follows from the absence of those results.

13. Why This Trial Matters Statistically

This trial is statistically interesting because it frames inflammation as a dose-ranging question rather than a simple comparison of one intervention with placebo. Multiple EPA + DHA dose levels make it possible in principle to examine whether the observed response changes across doses, while placebo provides a comparison condition. However, each dose-related question needs a clearly defined contrast and an account of uncertainty; dose ordering alone does not establish a trend or identify an optimal level.

The endpoint also highlights the importance of specifying what a biomarker result represents. The primary outcome names TNF-alpha and IL-6 concentrations after 5 months, while the stated purpose discusses responses after in vivo and ex vivo endotoxin challenge and marker production over time. Those descriptions point to a potentially rich measurement structure, but interpretation depends on precise timing, measurement, and analysis definitions. The registry record does not report enough detail to determine how those elements were combined.

From a reporting perspective, this record illustrates the difference between a registered research question and a report of analyzable results. It includes design characteristics, intervention levels, an endpoint description, and limited safety counts, but no primary-outcome estimates or inferential analyses. Without estimates and intervals, readers cannot assess effect magnitude or precision, and cannot distinguish an imprecise result from a result close to no difference.

The note about removing one individual because of high entry RBC EPA+DHA content also underscores why analysis-population definitions matter. A transparent explanation of exclusions, missing observations, and planned comparisons is needed to understand how the analyzed data relate to enrollment and to the randomized groups. Those details are not reported in the registry record.

14. 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 principal limitation for interpreting this trial record is that the numerical primary-outcome results are absent. Mean concentrations and 95% confidence intervals are specified, but their values are not reported. The record also lists no analyses, and the primary outcome has several categories or time points rather than a single reduced comparison. As a result, no effect estimate, uncertainty assessment, or dose-response pattern can be evaluated from the registry information.

Several features needed to understand the study population and analysis are also not reported in the registry record. Although enrollment is 125, outcome-specific denominators and group enrollment counts are absent. One individual was excluded from analysis because entry RBC EPA+DHA content exceeded 8%, but the record does not explain whether this exclusion was prespecified or whether other exclusions occurred. Missing-data procedures and analysis-population definitions are not reported.

The registry record does not provide a sample-size justification, allocation ratio, detailed randomization or masking procedures, adherence information, or a complete statistical plan. It does not report how comparisons across doses, markers, challenge conditions, or time points were handled. These omissions limit assessment of bias, precision, and multiplicity. The brief safety summaries give event counts and denominators, but do not report the observation period or detailed event-collection methods; death counts are not reported in the registry record.

These are limitations of the available registry information and should not be mistaken for evidence that the trial did or did not have methods or results beyond what is recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Dose Response Effects of Marine Omega-3 Fatty Acids on Inflammation — NCT01078909.
• Registry record last updated 2023-08-21; status last verified 2023-08.
• Results first posted 2017-06-14.
• 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.

18. Record Summary

NCT01078909 is listed as a completed Phase 3 randomized, double-masked, parallel-group study sponsored by Penn State University. The recorded enrollment is 125; the study began in 2011-10 and reached primary completion in 2012-11. It compared EPA + DHA fish oil supplement dose levels of 300, 600, 900, and 1,800 mg/day with placebo.

The primary outcome is mean TNF-alpha and IL-6 concentrations in pg/mL following 5 months of treatment, with 95% confidence intervals specified. The stated purpose concerns inflammatory responses to in vivo and ex vivo endotoxin challenge. The record also lists change in lipid mediators as a secondary outcome and identifies 3 outcome measures.

Numerical primary-outcome results and statistical analyses are not reported in the registry record. The record notes one individual removed from analysis because entry RBC EPA+DHA content exceeded 8%. Safety summaries list 0 serious and 0 other events in each group; deaths are not reported in the registry record.