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 Chronic Liver Disease in Urea Cycle Disorders (NCT03721367), a registered phase not stated study. The primary outcome is Liver Stiffness as Measured by Shear Wave Elastography.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03721367 |
| Phase | Phase not stated |
| Condition | Urea Cycle Disorder |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 28 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Baylor College of Medicine |
| Results posted | Yes |
2. Clinical Question
Population
People with urea cycle disorders were the study population. The registry record lists an enrollment of 28 and states that primary-outcome data were reliable for only 27 participants. The study was described as a pilot and was conducted at three UCDC sites: Baylor College of Medicine in Houston, University of California San Francisco in San Francisco, and Seattle Children's Hospital in Seattle.
Intervention
The listed intervention was Diagnostic Ultrasound, classified as “OTHER.” The study summary describes a non-invasive assessment of liver stiffness and markers of hepatic injury, function, and fibrosis. The primary measure was shear wave elastography, with one measurement made on the day of the study visit.
Comparator
No separate comparator group is listed. The registry record describes a cross-sectional study, and the listed arm is Urea Cycle Disorders. Allocation is not stated. The record therefore does not describe a randomized, like-for-like comparison between treatment groups.
Primary question
The primary outcome was liver stiffness measured by shear wave elastography, expressed in m/s and recorded as a count of participants. The registry description identifies values below 1.35 m/s as normal and values above 1.35 m/s as abnormal. The primary question is how liver stiffness was classified among participants with reliable measurements. The registry record does not report the number of participants in either category, so it does not establish the observed distribution.
3. Trial Design
This was a pilot, cross-sectional study of chronic liver disease assessment in people with urea cycle disorders. The official title describes a prospective, cross-sectional, non-invasive assessment. The study summary says it assessed liver stiffness and markers of hepatic injury, function, and fibrosis. A cross-sectional design records measurements at a particular assessment rather than following a treatment comparison over time. The primary outcome specifies one measurement on the day of the study visit.
The registry record lists an enrollment of 28 and identifies Baylor College of Medicine as the sponsor. It names three UCDC sites: Baylor College of Medicine in Houston, University of California San Francisco in San Francisco, and Seattle Children's Hospital in Seattle. The study is marked completed. The record lists its start as 2017-11-29 and primary completion as 2020-06-01.
There is one listed arm, Urea Cycle Disorders, and one listed intervention, Diagnostic Ultrasound. The intervention is categorized as “OTHER.” A separate control or comparison arm is not described, and allocation is not stated. This is not a randomized comparison, so differences between treatment groups cannot be estimated from the design as recorded.
The primary outcome is liver stiffness by shear wave elastography. Fibrotest is listed as a secondary outcome, and the registry record lists three outcome measures in total. It also lists zero analyses. The registry record does not report a protocol, a sample-size justification, an analysis plan, or details of how the additional outcome measures were assessed. These omissions mean that the design can be described from the registration, but the rationale and full analytical approach cannot be reconstructed from it.
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 | Urea Cycle Disorders |
|---|---|
| STARTED | 28 |
| COMPLETED | 28 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: The data for this outcome was reliable for only 27 participants.
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 | Urea Cycle Disorders |
|---|---|---|
| Participants analysed | 28 | |
| Age, Continuous | years | 15 (5 to 52) |
| Sex: Female, Male: Female | Participants | 16 |
| Sex: Female, Male: Male | Participants | 12 |
| Race/Ethnicity, Customized: White | Participants | 13 |
| Race/Ethnicity, Customized: Native American | Participants | 2 |
| Race/Ethnicity, Customized: Hispanic | Participants | 9 |
| Race/Ethnicity, Customized: African-American | Participants | 3 |
| Race/Ethnicity, Customized: Asian | Participants | 1 |
| Region of Enrollment: United States | participants | 28 |
| UCD diagnosis: OTC Deficiency (Male) | Participants | 3 |
| UCD diagnosis: OTC Deficiency (Female) | Participants | 7 |
| UCD diagnosis: ASS1 Deficiency | Participants | 4 |
| UCD diagnosis: ASL Deficiency | Participants | 8 |
| UCD diagnosis: ARG1 Deficiency | Participants | 6 |
| BMI: Underweight | Participants | 1 |
| BMI: Healthy | Participants | 12 |
| BMI: Overweight | Participants | 5 |
| BMI: Obese | Participants | 10 |
| History of Hyperammonemia | Participants | 16 |
6. Primary Endpoint
The registry lists the primary outcome as Liver Stiffness as Measured by Shear Wave Elastography, measured over One measurement made on the day of study visit.
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint is titled “Liver Stiffness as Measured by Shear Wave Elastography.” The measurement is expressed in m/s and described as a surrogate measure for hepatic fibrosis. In general, a surrogate is a measurable indicator used to represent a condition or process that is not directly measured by that indicator. A surrogate measure should not be treated as identical to the underlying condition.
The registry record defines normal liver stiffness as < 1.35 m/s and abnormal liver stiffness as >1.35 m/s. It does not specify how a value exactly at 1.35 m/s is classified. The endpoint is recorded in participants, with the parameter described as a count of participants. The timeframe is one measurement on the day of the study visit.
The registry record states that data for this outcome were reliable for only 27 participants. It does not report the measured values, the number classified as normal or abnormal, or a summary of the distribution. Therefore, the endpoint definition and usable-data count are available, but the observed result is not. The registry description gives the measurement's intended role; it does not by itself show how much fibrosis was present or establish a diagnosis for any participant.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies liver stiffness by shear wave elastography as the primary outcome, but it does not report a numerical primary result. It gives neither participant counts by stiffness category nor a summary of the underlying measurements. As a result, the observed distribution cannot be described from this record. The stated threshold defines how values below and above 1.35 m/s are labeled, but the record does not provide the counts in those categories or explain the treatment of a value exactly at the threshold.
The record states that primary-outcome data were reliable for only 27 participants, while enrollment was 28. These are distinct pieces of information: enrollment describes the study size, and reliability describes the subset for which the primary outcome data were considered reliable. The reason that data were not considered reliable for every enrolled participant, and the handling of that data, are not reported in the registry record.
The design is cross-sectional, and no separate comparator is listed. The results, if reported, would describe measurements made in the study population; the design as recorded would not establish whether a finding developed over time or was caused by a particular exposure or intervention. Nor does the record describe a randomized comparison. The listed Diagnostic Ultrasound is an assessment method, not evidence of a treatment contrast.
The registry record lists Fibrotest as a secondary outcome and three outcome measures in total, but does not give results for those measures. It also lists zero analyses. That registry entry does not supply inferential statistics such as confidence intervals or p-values for the primary outcome. No precision estimate can therefore be interpreted from the posted record.
In general, a confidence interval conveys uncertainty around an estimated quantity, and a wider interval indicates less precision than a narrower interval for the same quantity and method. Without a reported estimate and interval, readers cannot gauge the precision of the primary result. The available information supports a description of the study's objective, endpoint definition, and reliable-data count, but not a conclusion about the magnitude or pattern of liver stiffness in the participants.
9. Statistical Methods Explained
The registry describes a prospective, cross-sectional study. In general, “prospective” means that study procedures are planned before the measurements are collected, while “cross-sectional” means that the analysis concerns measurements taken at a particular assessment rather than change over a follow-up period. Here the primary endpoint specifies one measurement on the day of the study visit. The registry record does not describe repeated assessments or follow-up for this endpoint.
What does the endpoint measure?
Shear wave elastography is the named method for measuring liver stiffness. The registry describes stiffness, in m/s, as a surrogate measure for hepatic fibrosis. The outcome is framed as a count of participants, and the description provides threshold labels: normal is < 1.35 m/s and abnormal is >1.35 m/s. The registry record does not explain how a measurement equal to 1.35 m/s would be classified. It also does not report the participant counts in either category or the individual measurement values.
In general, categorizing a continuous measurement can make a result easier to summarize, but it discards information about how far measurements lie from a threshold. A count by category answers how many participants fall on each side of a cut point; it does not show the full spread of measurements. The continuous values and their distribution are not reported in the registry record, so no such distribution can be assessed.
What can a count-based outcome tell readers?
For a binary outcome, a participant can be classified into one of two categories, and the result can be expressed as a count in each category. Such counts describe the observed participants; they do not alone establish the precision of an estimate or whether a pattern would be similar in another sample. In general, uncertainty estimates require an analysis method and the relevant outcome data. The registry record gives neither a category count nor an interval estimate for the primary endpoint.
The record labels the outcome parameter as a participant count, but it does not provide the observed count. The phrase “data ... reliable for only 27 participants” identifies the number considered reliable for this outcome; it is not a result count for normal or abnormal stiffness. The criteria used to judge reliability are not reported in the registry record.
How should the design shape interpretation?
There is one listed study arm, Urea Cycle Disorders, and no separate comparator group. Allocation is not stated. In general, a cross-sectional description can characterize measurements in its study population, but it does not by itself establish temporal order or causal effects. Without a comparison group, a difference between intervention groups is not part of the design described in the record. The Diagnostic Ultrasound entry is the listed intervention, while the study summary describes non-invasive assessment rather than a treatment comparison.
The registry names three sites and labels the project a pilot. A pilot study can be used to conduct an initial assessment, but the record does not state a specific pilot objective beyond assessing liver stiffness and markers of hepatic injury, function, and fibrosis. It does not report a sample-size justification or explain how enrollment was determined. The sample-size assumptions described for planning illustrations are not the trial's own design justification, and such illustrations are not observed power.
What statistical details are unavailable?
The record lists three outcome measures, Fibrotest as a secondary outcome, and zero analyses. It does not identify a statistical model, an estimation method, a confidence-interval method, a hypothesis test, or a plan for covariate adjustment. It also does not report an interim-analysis plan. These omissions should not be filled in by assuming standard practice; the registry record does not say which methods were used.
In general, confidence intervals express the uncertainty associated with an estimate under a specified method and assumptions. P-values, when used, address compatibility of data with a specified null model; they do not measure the size or practical importance of an effect. Neither kind of inference can be reviewed for this endpoint because no corresponding estimate, interval, or p-value is reported. Over-dispersion is a general concern when count data vary more than a chosen model expects; whether it is relevant depends on the data and model. The registry record does not report an analysis model or sufficient outcome detail to assess that issue.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists three outcome measures, names Fibrotest as a secondary outcome, and lists zero analyses. It does not describe how many hypotheses were tested, identify a prespecified testing hierarchy, or report any multiplicity adjustment. A multiplicity strategy matters in general when several outcomes or hypotheses are evaluated, because repeated testing can affect the interpretation of statistical evidence. Without an analysis plan or reported inferential results, the impact of multiplicity cannot be assessed for this study from the registry record.
The primary outcome is reported as having reliable data for only 27 participants. The record does not explain why data for the remaining enrolled participant were not considered reliable, what reliability criteria were applied, or whether any data were excluded, imputed, or otherwise handled. It also does not report missingness for Fibrotest or the other outcome measures. The distinction between unreliable data and missing data is important in general: an observation may exist but fail a quality criterion, while missing data may not have been collected or may not be available. The record does not provide enough detail to determine which situation applies.
The analysis population is not described. In general, an analysis population specifies which participants contribute to an analysis and under what rules. The registry record does not say whether analyses used all enrolled participants, only participants with reliable measurements, or another defined population. No missing-data method or sensitivity analysis is reported. These gaps limit assessment of how the reported study population relates to the data used in any analyses; the record lists zero analyses, so no analysis population can be verified.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Urea Cycle Disorders | 0 | 28 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Urea Cycle Disorders | 0 of 28 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Urea Cycle Disorders | 0 of 28 |
The registry record lists the Urea Cycle Disorders group with 28 participants at risk for serious adverse events and zero serious adverse events. It also lists 28 at risk for other adverse events and zero such events. Deaths are listed as zero, and no top serious adverse-event terms are listed.
These figures are event counts as recorded, not estimates of comparative risk. The study has one listed group and no separate comparator arm, so the record does not support a between-group safety comparison. The registry lists Diagnostic Ultrasound as the intervention, but the adverse-event information does not specify the assessment period, event-collection procedures, or attribution rules. Those details are not reported in the registry record.
In general, a reported zero means that no events of that category were recorded in the stated data; it does not prove that the event cannot occur or that the risk is absent. The listed counts should therefore be read alongside the available population and reporting details, not as a guarantee of safety. The registry record does not provide additional information about the completeness of adverse-event ascertainment or the duration over which events were monitored.
12. What the Result Does, and Does Not, Mean
The record establishes that a pilot, cross-sectional study assessed liver stiffness and markers of hepatic injury, function, and fibrosis in people with urea cycle disorders. Its primary outcome was shear wave elastography, with a stated normal threshold below 1.35 m/s and an abnormal threshold above 1.35 m/s. It also states that primary-outcome data were reliable for only 27 participants. These are design and measurement details, not a report of the primary outcome distribution.
The registry record does not report the number of participants with normal or abnormal stiffness, the underlying measurements, or a summary estimate. It therefore cannot show how common either category was among participants with reliable measurements. It also cannot show the precision of an estimate, since no confidence interval or other uncertainty measure for the primary outcome is reported. Fibrotest is listed as a secondary outcome, but results for it and the other outcome measures are not reported in the registry record.
In general, a surrogate measure can provide information about a related biological process without being identical to a clinical condition. The registry describes liver stiffness as a surrogate measure for hepatic fibrosis; that description does not make stiffness a direct measure of fibrosis or establish a diagnosis. The posted record does not provide enough outcome information to evaluate the relationship between stiffness and the other markers mentioned in the study summary.
The cross-sectional design describes measurements at a study visit. It does not, by itself, show how measurements change over time or demonstrate that an exposure caused a finding. The lack of a separate comparator also means that the design as recorded is not a randomized treatment comparison. These limits do not negate the study's descriptive purpose; they define what can be inferred from its design and the results recorded.
13. Why This Trial Matters Statistically
This study is statistically notable as a pilot, cross-sectional assessment of liver stiffness and related markers in people with urea cycle disorders. It focuses on measurement and description rather than a randomized comparison. That distinction is important when interpreting what the design can answer: measurements at a study visit can describe the observed sample, while they do not by themselves establish changes over time or treatment effects.
The primary endpoint is described in a way that links a continuous stiffness measurement to threshold categories and frames the result as a participant count. This makes clear the intended outcome, but the registry record does not report category counts or the underlying values. The reader can understand the measurement definition and its reliability limitation without being able to evaluate the observed pattern or its precision.
The record also identifies the limits of the available statistical reporting. It lists three outcome measures, gives Fibrotest as a secondary outcome, and lists zero analyses, but does not provide the analysis methods or outcome results. Consequently, no reported inferential result can be examined for uncertainty, multiplicity, or sensitivity to missing or unreliable data. This is a distinction between a registered study purpose and the evidence available in its registry record.
In general, transparent outcome reporting helps readers separate the question a study was designed to address from the findings that are actually available to interpret. For this study, the stated objective, sites, enrollment, endpoint definition, and reliability count are informative about design and measurement. The absent numerical primary result means that the record does not support a statistical conclusion about the distribution of liver stiffness in the study population.
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 main limitation for interpreting the primary endpoint is that the registry record does not report its observed result. Although it defines the shear wave elastography measure and its threshold categories, it gives no participant counts by category and no measurement summary. It also does not specify classification for a value exactly at 1.35 m/s. Consequently, readers cannot assess the observed distribution or its precision.
The record states that data were reliable for only 27 participants, but does not give the reliability criteria, reasons for unreliable data, or handling procedures. It does not describe the analysis population or report methods for missing or unreliable observations. These omissions prevent assessment of whether the available outcome data represent all enrolled participants or how data quality may have affected the result.
The cross-sectional design and absence of a separate comparator limit interpretation to the study's descriptive aim as recorded. The study does not provide a randomized comparison, and a measurement made on the day of a visit cannot establish change over time. The three listed sites provide the study setting, but the registry record does not report site-specific results or explain how results were combined across sites.
Further limitations are the lack of reported statistical methods, inferential results, and outcome findings for the three outcome measures. Fibrotest is identified as secondary, but no result is given. The registry record does not report a sample-size justification, multiplicity plan, interim-analysis plan, or detailed protocol. These details should be considered unavailable rather than assumed. The safety record lists zero serious adverse events and zero other adverse events, but does not describe the observation period or ascertainment procedures.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Chronic Liver Disease in Urea Cycle Disorders — NCT03721367.
- Registry record last updated 2023-02-10; status last verified 2023-02.
- Results first posted 2023-02-10.
- 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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18. Record Summary
NCT03721367, “Chronic Liver Disease in Urea Cycle Disorders,” is listed as a completed pilot, cross-sectional study sponsored by Baylor College of Medicine. The official title describes a prospective, cross-sectional, non-invasive assessment. Enrollment was 28, and the registry record lists three UCDC sites: Baylor College of Medicine, University of California San Francisco, and Seattle Children's Hospital.
The primary outcome was liver stiffness measured by shear wave elastography, with one measurement on the day of the study visit. The record defines normal as < 1.35 m/s and abnormal as >1.35 m/s, and says reliable data were available for 27 participants. It does not report the primary outcome result. Fibrotest is listed as a secondary outcome; three outcome measures and zero analyses are recorded.
The record lists one study group and no separate comparator. It reports zero serious adverse events, zero other adverse events, and zero deaths. Analysis methods, missing-data handling, and a sample-size justification are not reported in the registry record.