This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Peripheral Nerve Ultrasound for Diagnosis and Prognosis of Guillain-Barre Syndrome (NCT04053452), a non-randomized na study. The primary outcome is Internerve Variability of Cross-sectional Area (CSA) in Patients With GBS vs Controls.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04053452 |
| Phase | NA |
| Condition | Guillain-Barre Syndrome |
| Allocation | Non-Randomized |
| Design model | Parallel |
| Masking | Single |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Duke University |
| Results posted | Yes |
2. Clinical Question
Population
Participants with Guillain-Barre syndrome and controls. The record does not report further eligibility criteria or participant characteristics.
Intervention
Peripheral nerve ultrasound, with strength measurement also listed as a diagnostic test.
Comparator
Controls are the comparison group. Allocation was non-randomized, and the registry record does not describe the groups as matched or otherwise made comparable.
Primary question
Does internerve variability of cross-sectional area differ between participants with Guillain-Barre syndrome and controls, at Day 0 and approximately 7 days after admission?
The stated purpose is to assess whether peripheral nerve ultrasound can serve as a supplemental diagnostic tool in the acute setting and aid prognostication. The primary endpoint focuses on a quantitative ultrasound measure: variability in cross-sectional area across nerves. It is reported as a mean with standard deviation, and the listed unit is mm^2.
The comparison is observational rather than randomized. That distinction matters to the question: any difference between the groups could reflect differences in their underlying characteristics as well as differences related to Guillain-Barre syndrome. The registry record does not report the characteristics of the control group, how controls were selected, or whether the groups were comparable at enrollment.
The record also lists outcomes related to hospital stay, discharge status, intubation, strength, autonomic dysfunction, and disability. These outcomes connect the study's stated prognostic aim to clinical status, but the posted record does not provide their results or specify how ultrasound measurements would be related to those outcomes. The diagnostic and prognostic aims should therefore be understood as objectives, not as findings established by the posted results.
3. Trial Design
This is a pilot study of peripheral nerve ultrasound for diagnosis and prognosis of Guillain-Barre syndrome. The registry lists Duke University as sponsor, an enrollment of 20, and a status of terminated. The recorded start date is 2019-09-30, and the primary completion date is 2023-07-04. These registry entries describe the study record; they do not establish how many participants ultimately contributed data to each analysis.
The design is listed as parallel, with non-randomized allocation and single masking. The registry does not identify who was masked, explain how masking was implemented, or provide further details about allocation. The phase is listed as NA. The study groups are titled GBS Patients and Controls, but their arm descriptions are blank. The record does not report the control recruitment method or other details needed to assess group comparability.
Peripheral nerve ultrasound and measurement of strength are listed as diagnostic-test interventions. The primary endpoint is internerve variability of cross-sectional area in participants with Guillain-Barre syndrome compared with controls. Measurements are specified for Day 0 and approximately 7 days after admission. The stated primary population is participants with data collected at each time point, but the registry does not explain how incomplete or unavailable measurements were handled.
The record lists 10 outcome measures and 107 analyses. Secondary outcomes include length of hospital stay, ambulatory status on discharge, days intubated, strength measured by hand dynamometer and by the Medical Research Council (MRC), autonomic dysfunction, and disability measured by the Guillain-Barre Syndrome Disability Score. The record's termination status and enrollment figure do not establish why the study ended or whether the planned enrollment was reached. The reason for termination is not reported in the registry record.
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
| Stage | GBS Patients | Controls |
|---|---|---|
| STARTED | 14 | 6 |
| COMPLETED | 12 | 4 |
| NOT COMPLETED | 2 | 2 |
Reasons for not completing this period:
| Reason | GBS Patients | Controls |
|---|---|---|
| Withdrawal by Subject | 1 | 0 |
| Time restraint due to inpatient needs | 1 | 2 |
Analysis population for the primary outcome, as defined in the registry: Participants with data collected at each time point.
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.
| Characteristic | Unit | GBS Patients | Controls | Total |
|---|---|---|---|---|
| Participants analysed | 14 | 6 | 20 | |
| Age, Continuous | years | 57.71 (SD 13.93) | 59.30 (SD 15.19) | 58.23 (SD 14.33) |
| Sex: Female, Male: Female | Participants | 7 | 2 | 9 |
| Sex: Female, Male: Male | Participants | 7 | 4 | 11 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 6 | 6 | 12 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 8 | 0 | 8 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): White | Participants | 13 | 5 | 18 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | Participants | 14 | 6 | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Internerve Variability of Cross-sectional Area (CSA) in Patients With GBS vs Controls, measured over Day 0 and approximately 7 days after admission.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm^2 |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is titled internerve variability of cross-sectional area (CSA) in participants with Guillain-Barre syndrome versus controls. CSA refers to the cross-sectional area measured by ultrasound. The endpoint description defines internerve variability for each participant using the maximal and minimal intranerve CSA variability, and defines intranerve variability for each nerve as maximal CSA divided by minimal CSA for the median and ulnar nerves. The stated time points are Day 0 and approximately 7 days after admission.
The registry identifies the endpoint as a continuous measure summarized by a mean and standard deviation, with the unit recorded as mm^2. Its intended role is to quantify variation in nerve measurements and compare that measure between the study groups. In general, a continuous endpoint preserves information about the measured scale rather than reducing it to categories. A mean describes the group's average, while a standard deviation describes spread among measurements around that average.
Comparing the measure between participants with Guillain-Barre syndrome and controls is relevant to the stated diagnostic aim because the study asks whether ultrasound-derived nerve measurements distinguish these groups. Repeated timing also relates to the acute and follow-up measurement objective. However, the registry record does not report the observed means, standard deviations, group contrast, confidence interval, or test result. It also does not report evidence about diagnostic accuracy or a threshold for classifying an individual participant. The endpoint definition alone therefore describes what was to be measured, not what the study found.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record states the study's aims and endpoint definitions but does not report results for the primary endpoint. No group means, standard deviations, between-group estimate, confidence interval, or p-value for internerve CSA variability are reported in the registry record. The data therefore do not establish the direction, size, or precision of a difference between GBS patients and controls.
The enrollment figure is 20. It should not be treated as the number of participants included in every analysis: the primary population is described as participants with data collected at each time point, and analysis-specific counts are not reported in the registry record. Without those counts, readers cannot assess how much information contributed to the Day 0 comparison or the measurement approximately 7 days after admission, or whether missing measurements affected the groups differently.
The design is non-randomized. In general, a non-randomized group comparison can be affected by differences between groups that are unrelated to the measurement under study. The registry record does not report participant characteristics or adjustment methods, so it is not possible to determine whether such differences were assessed or accounted for. The control arm descriptions are blank, and the record does not explain how controls were selected.
The study's stated purpose includes both diagnosis and prognosis. A group comparison in a quantitative ultrasound endpoint may address whether average measurements differ, but diagnostic use for an individual ordinarily requires information about classification performance and decision thresholds. Prognostic interpretation ordinarily requires a reported relationship between baseline measurements and later outcomes. Those results and supporting details are not reported in the registry record. The secondary outcomes are listed, but their estimates and analyses are not included in the posted record.
The registry lists 107 analyses across 10 outcome measures. That breadth makes it important to know which analyses were prespecified and how multiple comparisons were handled. The analysis plan and multiplicity approach are not reported in the registry record. Consequently, the number of listed analyses alone cannot establish which comparisons were primary, confirmatory, or exploratory.
The record lists zero participants at risk and zero affected for serious and other adverse events in both groups, with zero deaths. These are the reported registry entries; details about safety ascertainment, reporting completeness, and the meaning of zero participants at risk are not reported. They should not be taken as a substitute for a fuller account of safety monitoring.
9. Statistical Methods Explained
What does a mean and standard deviation describe?
General: A mean is a measure of the central location of continuous observations. A standard deviation describes how dispersed individual observations are around the mean. Reporting both can help readers distinguish a group average from the variability among participants. Neither quantity alone describes uncertainty in the estimated difference between groups; that is commonly conveyed with a confidence interval.
For this study, the registry identifies the primary measure as continuous and specifies mean and standard deviation. The actual means and standard deviations are not reported in the registry record, so the size and spread of the recorded CSA measure cannot be assessed from the posted results. The stated unit is mm^2, although the endpoint's ratio-based definition and the unit entry are not further reconciled in the registry record.
What does a confidence interval contribute?
General: A confidence interval gives a range of values compatible with an estimate under the assumptions of the analysis. Its width conveys precision: a narrower interval indicates more precise estimation, while a wider interval indicates greater uncertainty. Interpreting an interval requires knowing the estimate, the interval limits, the model or calculation used, and the data included.
No confidence interval or primary effect estimate is reported in the registry record. Thus, readers cannot assess precision or determine which magnitudes of group difference remain compatible with the posted evidence. A p-value, if reported on its own, would not supply that missing information about magnitude and precision.
How should the non-randomized comparison be understood?
General: Random allocation is one way to reduce systematic differences between groups at the outset. In a non-randomized comparison, group membership may be associated with participant characteristics that also relate to outcomes. Descriptive comparisons and suitable adjusted analyses can help assess or address measured differences, but they cannot automatically remove bias from unmeasured differences.
The registry identifies allocation as non-randomized. It does not report group characteristics, a matching strategy, covariate adjustment, or the statistical model for the primary comparison. It is therefore not possible to tell whether analyses accounted for differences between GBS patients and controls. Any eventual group contrast should be interpreted in light of that design and the methods actually reported.
What is the endpoint's variability measure?
General: A ratio of a maximum to a minimum expresses how the largest observed value compares with the smallest within the defined set. Such measures can be sensitive to extreme observations and depend on how measurements are obtained and selected. Their interpretation also depends on a clear description of the units and calculation.
The registry describes intranerve CSA variability as maximal CSA divided by minimal CSA for median and ulnar nerves, and describes internerve variability using maximal and minimal intranerve CSA variability. The record does not clarify the detailed aggregation procedure across nerves or explain how measurements with zero, unavailable, or otherwise unusable values would be handled. These calculation details matter for reproducibility and for interpreting the resulting continuous measure.
Why can over-dispersion matter?
General: Over-dispersion means that observed variation exceeds what a statistical model assumes. When a model underestimates variation, standard errors may be too small and uncertainty may appear less than it is. This issue is relevant to count outcomes and some model-based analyses; it is not evidence that over-dispersion occurred in this study.
The registry lists count-like and continuous secondary outcomes, but it does not report models or distributional checks. The statistical approach to these outcomes, including whether over-dispersion was assessed where relevant, is not reported in the registry record. No conclusion about the appropriateness of a particular model can be drawn from the outcome names alone.
What does the planning illustration mean?
General: A sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, significance level, allocation, and statistical method. It describes a design scenario, not the observed strength or reliability of a completed result. An illustration based on an observed effect is especially dependent on that effect estimate and should not be confused with the study's original enrollment justification.
The registry record does not report the study's own sample-size justification or power calculation. Any planning illustration associated with the posted analysis is based on the stated assumptions of a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation, with the target effect expressed as a fraction of the observed effect. Such an illustration is not observed power and does not show that the trial was adequately designed or that its result is conclusive.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 10 outcome measures and 107 analyses. When a study examines many outcomes, time points, or comparisons, the chance of obtaining apparently notable results by chance can increase. General statistical practice may address this issue by prespecifying a primary analysis, adjusting for multiple comparisons, or distinguishing confirmatory analyses from exploratory ones. The registry record does not report whether any of these approaches were used.
The primary endpoint is defined at Day 0 and approximately 7 days after admission, but the record does not describe the analysis linking these time points or say whether the primary comparison was planned separately at each time. It also does not report which analyses among the listed set were prespecified, whether any were added later, or whether multiplicity adjustments were applied. These details are important when interpreting any isolated result from a broad set of analyses.
The primary population is described as participants with data collected at each time point. The record does not report participant flow, missing-data counts, reasons measurements were unavailable, or how incomplete observations were handled. It therefore cannot be determined whether the reported analysis population differed from the enrolled group or whether missingness could have influenced estimates.
Analysis populations for the secondary outcomes are also not reported in the registry record. There is no description of exclusions, imputation, sensitivity analyses, or methods for repeated measurements. These omissions limit assessment of how robust the findings are to incomplete data and analytical choices. They do not establish that a particular method was or was not used; the information is simply not reported in the registry record.
11. What the Result Does, and Does Not, Mean
The registry record supports a description of the study's purpose, design, endpoint, and planned outcome domains. It does not report the primary endpoint results or the estimates needed to judge the size and precision of a group difference. Accordingly, the posted record does not show whether internerve CSA variability differed between GBS patients and controls.
The study's stated aims concern supplemental diagnosis and prognosis. These are distinct forms of evidence. A diagnostic claim concerns how a measurement classifies or distinguishes individuals, while prognostic evidence concerns how a measurement relates to later outcomes. General: both require appropriate analyses and enough detail to assess uncertainty, not merely a stated objective or endpoint definition. The registry record does not report diagnostic performance, classification thresholds, or results linking ultrasound measurements to later clinical outcomes.
The non-randomized design also constrains causal interpretation. Even if a group difference were reported, it would not by itself show that the difference was caused by GBS rather than by other group differences. The registry record does not give participant characteristics or adjusted results that would permit assessment of this concern. The blank arm descriptions and absent control-selection details add uncertainty about the comparison.
The listed zeros for adverse-event fields describe what the registry record contains, but they do not provide a detailed account of safety ascertainment or reporting. Likewise, the enrollment figure does not establish the number of observations available for each outcome or time point. These limits should be kept separate from the study's intended aims: absence of reported results is not evidence for or against the diagnostic or prognostic questions.
12. Why This Trial Matters Statistically
This study raises a practical measurement question: whether peripheral nerve ultrasound can contribute information about Guillain-Barre syndrome in the acute setting and about prognosis. Statistically, it is useful to distinguish that motivating question from the endpoint actually specified. The primary endpoint is a quantitative comparison of internerve CSA variability between GBS patients and controls, measured at Day 0 and approximately 7 days after admission.
The registry record also illustrates why reporting estimates and uncertainty is essential. Naming a mean and standard deviation does not reveal the observed values, and defining a measurement does not show whether groups differed. A reader needs analysis counts, effect estimates, and measures of precision to judge how informative the data are. None of those primary results are reported in the registry record.
The non-randomized design makes transparent reporting of group characteristics and analysis methods especially important. Without those details, readers cannot judge comparability or determine whether measured differences were considered. The stated prognostic aim also requires explicit results connecting ultrasound measures to subsequent outcomes; listing outcome domains does not establish such a relationship.
Finally, the 107 analyses across 10 outcome measures make prespecification and multiplicity reporting relevant to interpretation. The registry record does not describe these methods. This does not invalidate the study's question, but it means the posted information is insufficient to evaluate the statistical evidence for its diagnostic or prognostic aims. The record is most informative about what investigators intended to measure and least informative about the results of those measurements.
13. 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 has important trial-specific reporting gaps. Although enrollment is listed as 20 and the status is terminated, the reason for termination and the number of participants contributing data to each analysis are not reported in the registry record. The primary population requires data at each time point, but the record does not state how many participants met that requirement or describe participant flow.
The group descriptions are blank. The record does not report eligibility criteria, baseline characteristics, control recruitment, or procedures used to make the groups comparable. Since allocation was non-randomized, these omissions limit assessment of potential differences between GBS patients and controls. Masking is listed as single, but the masked party and implementation are not reported.
The primary endpoint's calculation is described in terms of maxima and minima for median and ulnar nerve measurements. The record does not give further details about aggregation, measurement reliability, handling of unusable values, or the relationship between the ratio-based description and the listed mm^2 unit. Such information would be needed to reproduce and fully interpret the measure.
The posted record does not report primary or secondary outcome estimates, analysis methods, confidence intervals, p-values, missing-data procedures, or multiplicity handling. It also does not report the study's own sample-size justification. The listed adverse-event fields contain zeros, but the record does not describe safety monitoring or reporting completeness. These limitations concern what can be evaluated from the registry record; they do not establish what procedures investigators used but did not report.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Peripheral Nerve Ultrasound for Diagnosis and Prognosis of Guillain-Barre Syndrome — NCT04053452.
- Registry record last updated 2025-05-09; status last verified 2025-03.
- Results first posted 2025-05-09.
- 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.
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17. Record Summary
The registry record describes a Duke University-sponsored pilot study of peripheral nerve ultrasound for diagnosis and prognosis of Guillain-Barre syndrome. It lists enrollment of 20, non-randomized allocation, a parallel model, single masking, and terminated status. The recorded start date is 2019-09-30, and primary completion is dated 2023-07-04.
The primary endpoint is internerve variability of CSA in GBS patients compared with controls, assessed on Day 0 and approximately 7 days after admission. The record lists 10 outcome measures and 107 analyses, including outcomes related to hospitalization, discharge status, intubation, strength, autonomic dysfunction, and disability.
The posted record does not report primary or secondary outcome results, the reason for termination, detailed participant characteristics, missing-data handling, or the statistical analysis plan. Its entries list zero adverse-event counts for both groups. Those entries do not substitute for detail about safety ascertainment. Overall, the record describes the intended comparison and measures, but does not provide results with which to assess the study's diagnostic or prognostic aims.