Endocrine, Metabolic and Microbiome Influence on the Post-acute Sequelae SARS-CoV-2 (PASC): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Endocrine, Metabolic and Microbiome Influence on the Post-acute Sequelae SARS-CoV-2 (PASC) (NCT04860869), a registered phase not stated study. The primary outcome is Insulin-Like Growth Factor-1 (IGF1).

2. Clinical Question

3. Trial Design

NCT04860869 is a completed study sponsored by The University of Texas Medical Branch, Galveston. The registry lists a start date of 2021-05-12 and a primary completion date of 2022-05-31. Its stated aim is to characterize endocrine, metabolic, and microbiome features among patients with PASC and patients who recovered from COVID-19 without lingering symptoms. The listed enrollment is 23, but the registry record does not establish that every enrolled participant contributed to each outcome analysis.

The registry describes symptomatic PASC and non-symptomatic post-COVID groups. It does not describe a randomized allocation process or an assigned intervention. Allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. These features matter: any observed contrast would be a comparison between groups defined by symptom status, not a randomized estimate of a treatment effect. Differences between groups could reflect symptom status, other participant characteristics, or factors not described in the record.

The primary outcome is baseline serum IGF1, with results intended to be expressed as a mean and standard deviation. Free T4 is listed as a secondary outcome. The registry lists 31 outcome measures and 0 analyses, but it does not provide numerical primary-outcome results or explain how the outcomes relate to the analyses. A completed status indicates the registered study is marked completed; it does not, by itself, establish that every planned measurement was collected or that results were reported.

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

Reasons for not completing this period:

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 Insulin-Like Growth Factor-1 (IGF1), measured over baseline.

The primary endpoint is serum Insulin-Like Growth Factor-1 (IGF1) at baseline, measured in ng/mL. The registry specifies a mean as the summary measure and standard deviation as the measure of dispersion. A mean describes the central level of measurements within a group, while the standard deviation describes how spread out individual measurements are around that mean. Together, these summaries would help readers understand both the typical measured level and the variability in each group.

IGF1 is included as an endocrine measure within a study whose stated aim is to characterize endocrine, metabolic, and microbiome features in people with PASC and people who recovered without lingering symptoms. The registry record does not give a more specific rationale for selecting IGF1 as the primary endpoint, so its role should be read in that stated study context rather than as proof of a particular biological mechanism.

Although the measurement and intended summary are described, the registry record does not report group means, standard deviations, participant counts contributing to the endpoint, or a between-group estimate. There is therefore no reported numerical primary-endpoint result to interpret. The baseline timing also means the registered endpoint is a measurement at baseline; the record does not describe a change-from-baseline endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure: serum IGF1 at baseline, summarized as a mean and standard deviation. The interpretation of those summaries depends on the observations collected in each group and on the analysis used. The registry record does not report the group-level values or an analysis estimate, so the methods can be described in general terms, but a trial-specific effect estimate cannot be reconstructed.

What does a mean describe?

For a continuous measurement, the mean is the arithmetic average of the observed values in a group. It offers a concise description of the central level, but it does not show the full distribution. Different distributions can share a mean while differing in spread, skew, or the presence of unusual values. The registry's choice to report a standard deviation alongside the mean would describe spread around the group average, but would not, on its own, show the shape of the data or resolve concerns about unusual observations.

How should a group contrast be read?

A comparison of group means would describe the difference in average IGF1 between the symptomatic PASC and non-symptomatic post-COVID groups. In general, the point estimate conveys the size and direction of the observed contrast, while an uncertainty interval conveys the range of values compatible with the data under the model and assumptions used. A p-value addresses compatibility with a specified null hypothesis under a statistical model; it does not measure the probability that the null hypothesis is true or the clinical importance of the estimate. None of these comparison statistics is reported for the primary outcome in the registry record.

Because allocation is not stated and the registry cautions that the groups are not like-for-like controls, an unadjusted contrast would be descriptive rather than a randomized causal estimate. In general, measured and unmeasured differences between groups can influence the observed contrast. Adjustment can address some measured differences when appropriate data and a suitable analysis are available, but it cannot guarantee removal of bias from unmeasured factors. The registry record does not describe an adjusted analysis or identify covariates used for one.

Why does variability matter?

The standard deviation summarizes variability among individual measurements, whereas the uncertainty around a group mean or group contrast depends on factors including variability and the number of observations used. These are not interchangeable summaries: a standard deviation describes the spread of observations, while an uncertainty interval for a mean or contrast describes uncertainty in an estimated quantity. The record does not provide the endpoint-specific participant counts or standard deviations needed to evaluate that uncertainty for IGF1.

In general, continuous outcomes may have distributions that are asymmetric or contain influential observations. The appropriateness of a mean-based comparison depends on the data and analysis assumptions. Alternative summaries or models may be useful in some settings, but the registry record does not state whether distributional checks, transformations, robust methods, or alternative analyses were used. No particular method should be inferred from the outcome's stated summary format.

What does the planning illustration represent?

The registry describes a planning illustration computed from an observed effect, using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The illustration is described as targeting a stated fraction of the observed effect. For non-time-to-event outcomes, the described sample-size quantities are participants per arm. These are planning assumptions, not a report of the study's original sample-size justification. The registry record does not report the original design justification, the observed IGF1 effect used for the illustration, or numerical planning results.

General sample-size planning asks how many participants would be needed under a chosen effect, variability, significance level, and power target. An illustration based on an observed effect is retrospective and depends on that chosen effect; it does not measure the probability that the completed study detected a true effect. Such a calculation must not be read as observed power. Since the primary outcome estimate is not reported in the registry record, the numerical basis for the described illustration cannot be evaluated from this record.

Finally, the registry lists 0 analyses. That listing does not specify a model, standard-error method, confidence-interval procedure, hypothesis test, or handling of any departures from assumptions. The record also does not state an analysis population or identify whether outcome summaries would be adjusted. Those omissions prevent a trial-specific appraisal of the analysis method, beyond the intended continuous outcome summary stated for IGF1.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Symptomatic Post-COVID", "Non-symptomatic Post-COVID")
n   <- c(10, 13)
m   <- c(142.8, 137.6)
sp  <- c(41.6, 56.7)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Symptomatic Post-COVID  10  142.800  41.600  113.041  172.559
CARM  Non-symptomatic Post-COVID  13  137.600  56.700  103.337  171.863

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 31 outcome measures, names Free T4 as a secondary outcome, and records 0 analyses. It does not report a multiplicity strategy, such as a prespecified hierarchy of outcomes or an adjustment for multiple comparisons. With multiple outcomes, repeatedly testing hypotheses can increase the chance of at least one apparently noteworthy finding by chance. General approaches to this issue include defining a primary hypothesis in advance, adjusting the testing threshold, or treating secondary findings as exploratory. The registry record does not say which, if any, approach was used.

The record does not describe missing-data handling. It does not state whether outcome values were missing, how missing observations were addressed, or whether any sensitivity analyses were conducted. Missingness can matter when the availability of a measurement is related to participant characteristics or outcome values. Complete-case summaries, imputation, and model-based approaches rely on different assumptions; no specific approach should be attributed to this study from the information recorded.

The analysis population is also not reported in the registry record. The listed enrollment is 23, but the record does not give outcome-specific participant counts or explain which participants were included in any analysis. Enrollment should therefore not be treated as the denominator for the primary endpoint or for every listed outcome.

These gaps limit assessment of selective reporting, precision, and the robustness of findings. The registry provides outcome descriptions but does not report numerical results or the analysis details needed to determine how the outcomes were handled.

12. 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 records safety counts separately for symptomatic Post-COVID (PASC) and non-symptomatic Post-COVID (nPASC). For the symptomatic group, the serious-event at-risk count is 10 and the serious-event count is 0; the other-adverse-event at-risk count is 10 and the other-adverse-event count is 0; deaths are recorded as 0. For the non-symptomatic group, the serious-event at-risk count is 13 and the serious-event count is 0; the other-adverse-event at-risk count is 13 and the other-adverse-event count is 0; deaths are recorded as 0.

These are the registry's reported counts, not estimates of comparative risk. The record does not list serious adverse-event terms, and it does not provide additional timing or event-detail information in the safety fields described. Zero recorded events in these entries should be read as the reported count, not as a guarantee that no event occurred outside the reporting captured by the registry.

The groups are not a randomized treatment comparison, and no treatment assignment is described. The figures therefore should not be interpreted as evidence that one treatment is safer than another. They are safety counts attached to the listed groups, and they do not establish the completeness of event ascertainment beyond what the registry record reports.

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

The record supports a limited description of the study: it was designed to characterize endocrine, metabolic, and microbiome features in people with PASC and people who recovered from COVID-19 without lingering symptoms. It identifies baseline serum IGF1 as the primary outcome and specifies a mean and standard deviation as the intended summary. It also identifies Free T4 as a secondary outcome and reports safety counts for the listed groups.

It does not report numerical IGF1 results. Consequently, the record cannot establish whether the group means differed, the direction or magnitude of any difference, or the precision of an estimate. The absence of an outcome estimate is not evidence that the groups were the same. Nor does the completed status replace a reported analysis.

The comparison is observational in the sense that the registry describes symptom-defined groups and does not describe random assignment. This does not invalidate descriptive comparison, but it means that group differences cannot automatically be attributed to symptom status. The record cautions that the arms are not like-for-like controls, while providing no participant-characteristic or adjustment information with which to assess comparability.

The planning illustration described in the registry should also be kept separate from evidence of an outcome. It uses an observed effect and stated planning assumptions, but the primary estimate and numerical illustration results are not reported in the record. Sample-size planning quantities are not observed power and do not show that an effect was present or absent.

Thus, the main statistical conclusion from the registry record is about reporting: the endpoint is defined, but its numerical result and analysis details are not reported. The safety entries record zero events in the listed categories for the stated groups, while providing limited event detail. Neither the endpoint description nor the safety counts answer the broader biological questions motivating the study.

14. Why This Trial Matters Statistically

This study is statistically interesting because it frames a comparison around persistent symptoms after COVID-19 rather than around an assigned treatment. Such comparisons can help describe how measured features vary across clinically relevant groups. Their interpretation depends on clearly defining the groups, reporting the measurements, and making transparent how differences between groups were addressed. The registry identifies the symptom-based groups and warns that they are not like-for-like controls, a caveat central to reading any future contrast.

The primary outcome is a continuous serum measure with an intended mean-and-standard-deviation summary. That choice makes the distinction between a group average, individual variability, and uncertainty in a contrast important. A useful report would need to communicate the estimate and its precision, not merely the endpoint name or a significance judgment. The registry record does not report those numerical results for IGF1.

The record also illustrates why outcome and analysis reporting are separate. It lists 31 outcome measures and 0 analyses, yet identifies no multiplicity plan, missing-data approach, or analysis population. These details affect how readers judge precision and whether emphasis on a particular result was planned. Their absence does not establish that the study lacked a plan; it means the plan is not reported in the registry record.

Finally, the stated planning illustration should not be confused with observed power or a prospective sample-size rationale. Keeping planning assumptions distinct from observed findings is essential to avoid interpreting a calculation as evidence. The available record therefore offers a clear study question and endpoint definition, but not the results needed to quantify the primary comparison.

15. 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 main trial-specific limitation for interpreting the primary question is that the registry record does not report numerical IGF1 results. Without group summaries or an estimated contrast, its magnitude, direction, and precision cannot be assessed. The record also does not report endpoint-specific participant counts, so the listed enrollment cannot be used as the analysis denominator.

Group comparability is another limitation. The registry does not state allocation and explicitly cautions that the arms are not a like-for-like control comparison. It does not provide further participant characteristics or an adjustment strategy. Any descriptive difference would therefore need to be interpreted with caution, and the record does not support a causal conclusion about symptom status.

The registry lists 31 outcome measures but provides no multiplicity strategy, missing-data method, or analysis-population definition. It lists Free T4 as a secondary outcome, but the analysis details and numerical results are not reported. These gaps prevent assessment of how outcome selection, missing measurements, or analysis choices may affect interpretation.

The primary endpoint is specified at baseline, but the record does not describe a change-over-time analysis. It also does not provide detailed measurement procedures beyond serum measurement and the intended unit. The safety entries include zero recorded events in the listed categories, but serious-event terms and further event details are not listed. These limitations describe what the registry record leaves unreported; they do not establish what procedures may have been performed outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Endocrine, Metabolic and Microbiome Influence on the Post-acute Sequelae SARS-CoV-2 (PASC) — NCT04860869.
• Registry record last updated 2024-10-28; status last verified 2024-08.
• Results first posted 2024-10-28.
• 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.

19. Record Summary

NCT04860869 is marked completed and is sponsored by The University of Texas Medical Branch, Galveston. The registry lists enrollment of 23, a start date of 2021-05-12, and a primary completion date of 2022-05-31. Its aim is to characterize endocrine, metabolic, and microbiome features in patients with PASC and patients who recovered from COVID-19 without lingering symptoms.

The primary outcome is baseline serum IGF1, intended to be summarized as a mean and standard deviation in ng/mL. Free T4 is listed as a secondary outcome. The record lists 31 outcome measures and 0 analyses, but does not report numerical primary-outcome results, an analysis plan, or outcome-specific participant counts. It cautions that the symptom-defined arms are not like-for-like control groups. Safety fields record zero serious adverse events, zero other adverse events, and zero deaths for the listed groups.