PFAS Exposure and Immune Response to Vaccination in Adults: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for PFAS Exposure and Immune Response to Vaccination in Adults (NCT06588530), a na phase 4 study. The primary outcome is Change in Tetanus-diphtheria Specific IgG by PFNA Exposure Category.

2. Clinical Question

3. Trial Design

This is a Phase 4, single-group study listed as completed. The registry lists Rutgers, The State University of New Jersey, as sponsor and an enrollment of 20. The recorded study start is 2024-11-04, and primary completion is recorded as 2025-01-08. The registry describes no masking and lists allocation as not applicable. These design details matter because participants and study staff were not masked, and the exposure categories were not formed by random assignment.

All participants were scheduled to receive TENIVAC at the first study visit. The intervention description specifies an intramuscular dose of 0.5 mL in the deltoid. Participants were scheduled for 7 visits over 30 days, with blood and saliva collected at each visit. The primary outcome uses serum samples collected before vaccination and at Day 30. PFNA levels in serum were measured before enrollment, and participants were classified into high and low exposure groups.

The registry lists one primary outcome measure and two analyses, but it does not report the results of those analyses. It also does not give the exposure cut points or a detailed description of how the analysis compared categories. Because there is no randomized control group, exposure-group differences would be observational rather than randomized treatment contrasts. Differences in antibody change could not, on the information reported, be attributed solely to PFNA exposure.

The registry record describes the study aim and procedures, but does not report a protocol-level statistical plan, sample-size justification, planned interim analyses, or methods for handling missing measurements. Those omissions limit assessment of whether the completed study followed a prespecified analysis strategy.

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.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All participants with IgG measurements at baseline and Day 30

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 Tetanus-diphtheria Specific IgG by PFNA Exposure Category, measured over 30 days.

The primary endpoint is change in tetanus- and diphtheria-specific IgG in serum from baseline, before vaccination, to Day 30 after vaccination. The registry defines the measure as log₂(day30 IgG / baseline IgG), with results expressed in log2(fold change). IgG concentrations were measured using commercially available ELISA kits according to the manufacturers’ instructions. The endpoint is described as a mean with standard deviation, and the intended population includes participants with measurements at both time points.

In general, measuring change within each participant uses that participant’s baseline value as a reference. A fold-change scale expresses the post-vaccination concentration relative to the baseline concentration; taking the logarithm transforms that ratio onto a scale suited to comparing proportional changes. On a log2 scale, a value’s direction and magnitude describe the relative change rather than the raw concentration difference. This is a general explanation of the measure, not a statement about the observed study results.

Antibody concentrations are used as a laboratory measure of the humoral immune response. The registry’s stated question concerns whether PFNA exposure is associated with a different initial IgG response after vaccination. Actual mean changes, standard deviations, and comparisons by exposure category are not reported in the registry record, so the endpoint’s observed size and precision cannot be assessed from the posted results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the outcome scale represent?

The endpoint is the log2-transformed ratio of Day 30 IgG to baseline IgG. In general, a ratio compares a follow-up measurement with a reference measurement, and logarithmic transformation expresses proportional changes on an additive scale. This can be useful when biological measurements vary multiplicatively or span a wide range. The transformation does not change which time points were measured; it changes the scale on which change is described. No raw or transformed IgG values are reported in the registry record.

The endpoint is summarized as a mean and standard deviation. In general, the mean describes the center of a set of measurements, while the standard deviation describes their spread around that center. These summaries can help describe the typical measured change and the variability among participants, but they do not alone show the uncertainty of a between-category contrast. A standard error or confidence interval for a contrast would address that inferential uncertainty. Such contrast estimates are not reported in the registry record.

How should exposure categories be understood?

The record identifies high and low PFNA exposure categories and says PFNA serum levels were measured before enrollment. It does not report the cut points, the distribution of measured PFNA levels, or the method used to assign participants to those categories. In general, grouping a continuous exposure can simplify comparisons, but it discards information about differences within each group and makes interpretation depend on how the boundaries were chosen. Since category definitions are not reported, the exact exposure contrast represented by the categories cannot be evaluated.

The categories are not randomized treatment arms. In general, randomization helps balance measured and unmeasured participant characteristics across assigned groups, whereas naturally occurring exposure groups may differ in other ways. An unadjusted comparison could therefore reflect PFNA exposure, other group differences, or a combination. The registry does not report whether covariates were included or whether the analysis adjusted for potential confounding.

What can the listed analyses establish?

The record lists two analyses, but does not describe their statistical methods or report their estimates. It is therefore not possible to identify whether the analyses used a paired model, a direct comparison of category-specific changes, or another approach. A paired analysis uses the relationship between measurements from the same participant; a comparison between exposure categories instead asks whether average changes differ between categories. These are general methodological distinctions, not claims about the study’s actual analysis.

In general, the choice of model should match the outcome scale, study design, and analysis question. Model assumptions may include an appropriate representation of the distribution of residuals and independence between participants. If measurements are more variable than a model allows, over-dispersion can make standard errors too small and uncertainty appear narrower than warranted. This general issue cannot be assessed for the study because outcome distributions, model details, and diagnostic results are not reported in the registry record.

How should statistical uncertainty be read?

In general, a confidence interval gives a range of estimates compatible with the observed data and stated model. Its width reflects both data variability and information available for the estimate. A p-value is a measure of how incompatible the data are with a specified null model; it is not a measure of effect magnitude or clinical importance. Neither confidence intervals nor p-values for the primary outcome are reported in the registry record. No inferential conclusion should be inferred from the study aim or the number of analyses listed.

The registry includes a planning illustration based on a fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. This is a planning framework rather than a report of the original study’s design justification. Any sample-size values associated with such planning are illustrations, not observed power. The registry does not report the trial’s own sample-size justification. In general, observed power calculated from an observed effect is not a substitute for reporting an estimate and its confidence interval.

What is not specified?

The analysis population is described as participants with IgG measurements at baseline and Day 30, but the number with paired measurements is not reported. Statistical methods for missing data, the handling of measurements outside assay limits, transformations beyond the stated log2 fold change, model diagnostics, covariate adjustment, and the exact definitions of the two analyses are not reported in the registry record. These details are important for evaluating reproducibility and the assumptions behind any estimate. Their absence means that the statistical analysis cannot be independently reconstructed from the registry description.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and two analyses. It does not describe the questions addressed by each analysis, identify which analysis is primary, or state whether either was prespecified. Methods for controlling multiplicity, such as adjustment across multiple comparisons or outcomes, are not reported in the registry record. Without those details, it is not possible to determine how the analyses relate to one another or how any reported inferential results would account for multiple testing. No analysis results are reported in any case.

The stated outcome population includes participants with IgG measurements at baseline and Day 30. That definition indicates that paired measurements are needed for the primary endpoint, but the number of participants with complete measurements is not reported. Although the enrollment is listed as 20, enrollment alone does not establish how many participants contributed to the outcome analysis. Reasons for unavailable measurements, withdrawals, or exclusions are not reported in the registry record.

Methods for handling missing outcome data are not reported. In general, excluding participants without paired measurements may reduce the analyzed sample and can introduce bias if missingness is related to exposure or immune response. Other methods make assumptions about the missing values and should be described to assess their suitability. No such method or missingness assumption is documented in the registry record.

The record does not report interim analyses or stopping rules. It also does not report a prespecified statistical analysis plan, details of protocol deviations, or sensitivity analyses addressing missing data or analytic choices. These omissions do not establish that such procedures were absent; they mean that they are not reported in the registry record and cannot be evaluated from the posted results.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports adverse-event counts separately for the high and low PFNA exposure categories. Each category lists 10 participants at risk for serious adverse events and 0 participants affected by serious adverse events; deaths are listed as 0 in both categories. The record also lists 10 participants at risk in the other adverse-event category and 0 affected in each category. These are the counts posted for the study, not estimates of the risk of an event beyond this enrolled group.

Zero recorded events should be read as a count, not as proof that an event is impossible or that the study can rule out uncommon harms. In general, a small study may provide limited information about events that occur infrequently, and the absence of an observed event does not establish the absence of risk. The registry does not report event terms in the serious-event listing, and the specific non-serious event terms and collection details are not reported in the registry record.

The two exposure categories are not randomized safety comparisons. The counts therefore should not be interpreted as a causal comparison between PFNA exposure levels. The registry’s safety figures are descriptive; no comparative safety estimate or uncertainty interval is reported.

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

The registry record supports a description of the study question, procedures, and intended antibody endpoint. It reports a community-based adult study in which all participants received TENIVAC and serum IgG was to be assessed before vaccination and at Day 30. Participants were categorized by PFNA exposure, measured before enrollment. The study therefore addresses a question about exposure category and post-vaccination antibody change in the enrolled community sample.

What the posted results do not establish is whether the high- and low-exposure categories had different IgG changes. Numerical endpoint results and inferential comparisons are not reported in the registry record. There is no reported estimate of the size or direction of a difference, and no confidence interval or p-value from which its precision could be assessed. The aim stated in the brief summary is not evidence that a particular result was observed.

Even if a category difference were available, the design would require cautious interpretation. Exposure was not randomly assigned, so a difference could reflect factors associated with PFNA exposure as well as PFNA itself. The registry does not report adjusted analyses or enough detail to determine which potential confounders were considered. The study’s enrollment of 20 also means that the enrolled group is the basis for any inference; the record does not describe how representative it is of other adults or communities.

In general, laboratory antibody measurements are evidence about a measured immune response, not a complete account of all immune function or clinical outcomes. The registry describes an IgG endpoint, but does not report clinical protection outcomes. The posted information therefore cannot establish whether any measured antibody change translates into a difference in health outcomes. These points define the scope of the available evidence; they do not imply a direction of effect.

13. Why This Trial Matters Statistically

This study is statistically notable because it links a pre-enrollment environmental exposure measurement with a repeated biological outcome after vaccination. Measuring IgG before vaccination and at Day 30 allows change to be defined within participants, while the exposure categories frame the central association of interest. The log2 fold-change scale also makes the outcome a relative change measure rather than a raw concentration difference. These choices determine what the primary estimate would mean.

The design highlights a distinction between an exposure comparison and a randomized intervention comparison. Participants were not randomized to PFNA exposure levels, and the study is listed as single-group. As a result, any category contrast would be observational and potentially affected by differences between participants. This is a central interpretive issue, not a technical footnote: statistical adjustment can address measured factors under suitable assumptions, but the registry does not report whether adjustment was used or what factors were considered.

The study also illustrates why outcome definitions and analysis populations matter. The endpoint requires IgG measurements at both time points, but the number of participants with paired data is not reported. Enrollment cannot be assumed to equal the number analyzed. Without the estimates, uncertainty measures, missing-data methods, and category definitions, readers cannot assess the strength or robustness of the evidence.

Finally, the registry’s stated aim should be separated from the findings. The scientific question is relevant to understanding immune responses in a community with prior PFNA exposure, but the posted record does not report the endpoint results needed to answer that question. Clear reporting of estimates, uncertainty, analysis decisions, and participant inclusion would be necessary for statistical evaluation.

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 registry record leaves important details about exposure classification unspecified. It states that serum PFNA levels were measured before enrollment and that participants were categorized as having high or low exposure, but does not report the category thresholds or the underlying PFNA measurements. This prevents assessment of how distinct the categories were or how the categorization relates to the measured exposure distribution.

The sample is described as a community-based panel study involving adults from a community with known prior PFNA exposure through contaminated drinking water. The registry does not report further details about recruitment, eligibility criteria, participant characteristics, or how representative the enrolled group is. Generalizability beyond this study population therefore cannot be assessed from the record.

Only the intended outcome definition is available; numerical IgG results are not reported. The number of participants with paired baseline and Day 30 results is also not reported, nor are reasons for missing measurements. Consequently, the extent of missing data and its possible effect on the endpoint cannot be evaluated. The registry does not report assay performance details beyond use of commercial ELISA kits according to manufacturer instructions.

The study is unmasked and has no randomized exposure assignment. Any association between exposure category and antibody change could be influenced by participant characteristics or other factors that differ between categories. The record does not report covariate adjustment or sensitivity analyses. It also does not describe the two listed analyses, multiplicity procedures, or a statistical analysis plan. These limitations concern what can be assessed from the registry record; they do not establish that unreported procedures were not conducted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: PFAS Exposure and Immune Response to Vaccination in Adults — NCT06588530.
• Registry record last updated 2025-12-30; status last verified 2025-12.
• Results first posted 2025-12-30.
• 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

The registry describes NCT06588530, titled “PFAS Exposure and Immune Response to Vaccination in Adults,” as a completed Phase 4, single-group study sponsored by Rutgers, The State University of New Jersey. Enrollment is listed as 20. The study began on 2024-11-04, with primary completion on 2025-01-08. All participants were to receive TENIVAC, and the study categorized participants by high or low PFNA exposure.

The primary outcome is the change in tetanus- and diphtheria-specific IgG from baseline to Day 30, expressed as log2 fold change. The registry lists one outcome measure and two analyses, but does not report the antibody outcome estimates, statistical comparisons, confidence intervals, or p-values. The number included in the paired-measurement analysis and methods for missing data are not reported in the registry record.

For adverse events, each exposure category lists 10 participants at risk, 0 with serious adverse events, 0 in the other adverse-event affected count, and 0 deaths. These counts are descriptive and do not provide a randomized safety comparison.