Liver Fibrosis Evaluation Using Ultrasound Shear Wave Imaging: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Liver Fibrosis Evaluation Using Ultrasound Shear Wave Imaging (NCT03637959), a na na study. The primary outcome is Liver Stiffness Measured by MRE.

2. Clinical Question

The study concerns non-invasive evaluation of liver fibrosis using ultrasound shear wave imaging. In the registry description, people scheduled to undergo clinically indicated magnetic resonance elastography also had mechanical vibrations with ultrasound shear wave imaging to measure liver stiffness. The primary outcome is liver stiffness measured by MRE, which the registry identifies as a benchmark reference.

Because the study has a single group and no like-for-like control comparison, it should be read as a measurement study rather than a randomized treatment comparison. The registry record does not specify a statistical question about agreement, correlation, diagnostic accuracy, or another particular relationship between the ultrasound technique and MRE. Those details are important for understanding exactly how the benchmark measurement was used.

3. Trial Design

The registry describes a completed, single-group study sponsored by Mayo Clinic. Its listed enrollment is 270, and its condition is liver fibrosis. The study dates in the record are 2017-01-26 for start and 2020-11-04 for primary completion. The phase and allocation are listed as NA, masking as none, and the study model as single group.

Participants scheduled to undergo a clinically indicated MRE also had mechanical vibrations with ultrasound shear wave imaging to measure liver stiffness. This is not a randomized comparison: the registry explicitly notes that there is no like-for-like control comparison. MRE is described as the standard-of-care benchmark reference for the primary outcome, not as a separate assigned study arm. The record does not describe random assignment, a masking procedure, or a parallel control group.

The primary outcome is a continuous measure: mean liver stiffness by MRE, reported in kilopascals. Its timeframe is baseline, approximately 1 day. The registry describes the MRE measurement as the benchmark reference used in the study. The arm description explains that the ultrasound procedure was also performed in participants scheduled for MRE, but the registry record does not report the detailed measurement sequence, the interval between measurements, or procedures for ensuring comparable measurement conditions.

The registry record does not report a phase beyond NA, a protocol rationale for the enrollment target, or detailed eligibility criteria. It also does not describe a statistical analysis plan or the populations intended for analysis. The listed enrollment should therefore not automatically be treated as the number of participants with complete primary outcome measurements. The count with observed MRE data 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

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 Liver Stiffness Measured by MRE, measured over Baseline, approximately 1 day.

The primary endpoint is liver stiffness measured by magnetic resonance elastography, expressed in kilopascals. The registry identifies the outcome as a mean with standard deviation and gives the timeframe as baseline, approximately 1 day. MRE is described as the standard-of-care benchmark reference in the study.

In general, a benchmark measurement provides a reference against which another measurement approach can be considered. Here, the study description says participants scheduled for clinically indicated MRE also had ultrasound shear wave imaging with mechanical vibrations. However, the primary outcome listed in the registry is MRE-measured stiffness; the record does not provide a numerical ultrasound outcome, a direct comparison statistic, or an explanation of the planned comparison method.

A mean describes the central value of a continuous measure across the observations included in an analysis. A standard deviation describes how dispersed those observations are around the mean. These summaries can characterize the measured stiffness, but by themselves do not establish how closely two measurement methods agree for individual participants. Agreement, association, and diagnostic performance are distinct statistical questions and require corresponding analyses.

The registry record does not report the mean, standard deviation, sample count contributing to the endpoint, or an estimate of the relationship between ultrasound imaging and MRE. Consequently, the endpoint definition and its intended benchmark role can be described, but the magnitude and precision of the observed MRE result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry defines the primary outcome as a continuous measurement summarized by a mean and standard deviation. The measure is liver stiffness by MRE in kilopascals, with a baseline timeframe of approximately 1 day. The registry identifies MRE as a benchmark reference. These registry entries describe what the outcome is; they do not describe a complete inferential analysis.

What does a mean and standard deviation describe?

General explanation: the mean is the arithmetic center of a set of continuous observations. The standard deviation describes the spread of observations around that center. Together, they can give a useful overview when the data distribution and analysis context make these summaries appropriate. They do not reveal the full shape of the data, and they do not show whether two measurement methods give similar results for each participant.

The registry record does not report the primary mean or standard deviation, nor does it identify how many observations contributed to those summaries. The number of participants with complete measurements is not reported in the registry record. Without those items, the endpoint cannot be reconstructed or its uncertainty assessed from the record.

How should a benchmark measurement be understood?

General explanation: a benchmark is a reference point for evaluating another measurement approach. Different analyses answer different questions. Correlation describes how measurements vary together, while agreement examines how close paired measurements are. A high association does not necessarily imply close agreement. A diagnostic accuracy analysis would require a defined classification target and appropriate performance measures. These are general distinctions, not analyses reported for this study.

The study description identifies MRE as the benchmark and says participants scheduled for MRE also had ultrasound shear wave imaging. But the record does not state which statistical method was planned to compare methods, whether the comparison used paired differences, whether any thresholds were prespecified, or whether measurement error was modeled. No comparison estimates or uncertainty measures are reported in the registry record. It is therefore not possible to infer the analysis approach or its findings from the endpoint description alone.

What does the study design permit?

The study is listed as single group and not randomized. As a general matter, randomization is used to create treatment groups that can support causal comparisons by reducing systematic differences in assignment. That purpose is not relevant to a randomized contrast because no such contrast is listed. The MRE reference should not be described as a randomized control arm: it is an outcome measurement used as a benchmark.

For a method comparison, having both measurements on the same participants can be useful because each person can act as their own measurement counterpart. However, that interpretation depends on whether paired values are available and how their relationship is analyzed. The registry record does not report whether all participants had both usable measures, how missing pairs were handled, or the number of complete pairs. These are not details that can be inferred from enrollment alone.

What is and is not reported about inference?

A confidence interval is a statistical range that conveys uncertainty around an estimate under a specified model and sampling process. A p-value summarizes the compatibility of data with a stated null hypothesis under the assumptions of a test. Neither replaces the estimate itself or explains the importance of a result. The registry record lists no analysis results, so no confidence interval, p-value, or hypothesis test can be interpreted for the primary endpoint.

The registry gives the count of outcome measures as 2 and the count of analyses as 0. The primary outcome is identified, but the details of any inferential framework, including a model, covariate adjustment, or test, are not reported in the registry record. No statistical analysis plan is described. It would be inappropriate to infer a particular method from the continuous nature of the outcome or from MRE's benchmark role.

How should planning illustrations be read?

The stated sample-size assumptions describe planning illustrations computed from an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The target effect is framed as a stated fraction of the observed effect. Such calculations can illustrate how hypothetical design choices affect planned sample sizes. They do not establish the study's actual design rationale, and they are not observed power. The record does not report a sample-size justification for this single-group study.

General explanation: power is a design property calculated under assumptions about an effect, variability, analysis, and sample size. A post hoc calculation based on an observed effect does not show the probability that a finding is true, and it cannot substitute for examining estimates and uncertainty. The planning illustrations should therefore remain separate from the study's posted outcome evidence.

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("Mechanical Vibrations With Ultrasound Shear Wave I")
n   <- c(270)
m   <- c(3.07)
sp  <- c(1.36)
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  Mechanical Vibrations With Ultrasound Shear Wave I  270  3.070  1.360  2.907  3.233

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and identifies liver stiffness measured by MRE as the primary outcome. The other outcome measure is not described in the record details available for this analysis. A procedure for controlling multiplicity, such as how inference across multiple outcomes would be handled, is not reported in the registry record.

Multiplicity matters when several outcomes or statistical comparisons are tested. General explanation: testing multiple hypotheses can increase the chance of obtaining at least one apparently notable result by chance if each is assessed independently at a conventional threshold. Prespecified priorities and an explicit adjustment or hierarchical strategy can clarify how results should be interpreted. No such strategy is reported, and no analysis results are listed.

The registry record does not report a missing-data method, missingness counts for the primary endpoint, or an analysis population definition. It does not state whether analyses were intended to include all enrolled participants, only those with complete measurements, or another group. Although enrollment is listed as 270, the number with paired ultrasound and MRE data is not reported in the registry record. Enrollment should not be treated as proof that all participants contributed to every outcome.

These omissions limit assessment of selection and precision. If some participants lack one or both measurements, the analyzed set may differ from the enrolled group; the direction and magnitude of any resulting bias cannot be determined without information about missingness and the analysis approach. The registry does not provide enough detail to assess whether missing-data assumptions were plausible or whether sensitivity analyses were used.

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 0 serious adverse events among 270 participants at risk in the group titled Mechanical Vibrations With Ultrasound Shear Wave Imaging. It also records 0 other adverse events among 270 participants at risk, and 0 deaths. The record does not list any top serious adverse-event terms.

These figures describe what is entered in the registry safety summary. A count of zero means no events are recorded in that category for the listed group; it does not, by itself, establish that an intervention has no risks. Safety interpretation depends on how events were defined, collected, monitored, and attributed, as well as how completely participants were followed. Those details are not reported in the registry record.

The at-risk count is not necessarily the same as the number with complete imaging outcome data. The registry does not report additional detail about safety follow-up duration or event ascertainment. These summaries should therefore be read as registry-recorded counts, rather than as a comprehensive account of every possible adverse experience.

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

The registry record establishes that a completed, single-group study evaluated mechanical vibrations with ultrasound shear wave imaging in the context of clinically indicated MRE. It identifies liver stiffness measured by MRE as the primary outcome and describes that measure as a benchmark reference. It also records enrollment of 270 and reports zero serious adverse events, zero other adverse events, and zero deaths in the listed safety group.

The record does not report numerical primary outcome results or any statistical analyses. It therefore does not show the observed mean MRE stiffness, the variability of that measure, or how ultrasound measurements compared with MRE. No estimate of agreement, association, diagnostic performance, or precision is reported. The purpose described in the registry should not be mistaken for a demonstrated result.

General explanation: a measurement study needs estimates that address the specific intended use. For example, an analysis of association and an analysis of agreement answer different questions. Even a clear statistical relationship would need to be interpreted in light of the measurement context and the range of values studied. The registry record does not report these analyses, so it cannot establish the scope of any such relationship.

The single-group design also means there is no randomized control comparison from which to estimate a treatment contrast. MRE serves as the stated benchmark, not as an assigned control intervention. The design and posted details therefore support describing the study's measurement setup, but not a causal claim or a conclusion about treatment benefit.

The sample-size illustrations are planning calculations under stated assumptions, not observed power and not the study's own sample-size justification. The registry record does not report the rationale for its listed enrollment or the number of participants contributing complete primary endpoint data. Readers should distinguish those uncertainties from the recorded safety counts and from the study's stated objective.

14. Why This Trial Matters Statistically

This study is statistically notable for its measurement question rather than for a randomized treatment comparison. The registry describes an ultrasound shear wave imaging procedure conducted in participants already scheduled for clinically indicated MRE, and identifies MRE as a benchmark reference. That setup makes clear why the distinction between a reference measurement and a control arm matters.

General explanation: measurement methods can be related without being interchangeable. Association asks whether values tend to move together; agreement asks whether values are sufficiently close for a specified purpose. A method-comparison study needs to report the appropriate estimates and uncertainty for the question being asked. The registry record does not report those analyses, making it impossible to assess the statistical evidence about the relationship between ultrasound imaging and MRE.

The record also illustrates the importance of separating study design details from statistical evidence. A listed enrollment of 270 is not a substitute for the number with complete paired measurements, and an outcome definition is not an outcome result. The count of analyses is 0, and no numerical primary findings are reported. This means the registry entry supports a transparent description of the study framework while leaving its central quantitative measurement question unresolved in the posted information.

Finally, planning illustrations can help readers understand how assumptions affect hypothetical sample sizes, but they do not explain the actual enrollment target or establish observed power. Keeping planning calculations, observed results, and safety summaries conceptually separate is essential for a careful reading of this record.

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 limitation for statistical interpretation is that the registry record does not report numerical primary outcome results or analyses. The mean and standard deviation for MRE-measured liver stiffness, endpoint-specific sample size, comparison estimates, and measures of uncertainty are not reported in the registry record. Consequently, the measurement performance of ultrasound shear wave imaging cannot be quantified from the posted information.

The study is single group and has no like-for-like randomized control comparison. MRE is specified as a benchmark reference measurement, but the registry does not state the planned method for assessing agreement or another relationship between the modalities. It also does not report measurement thresholds, repeatability procedures, or the timing details beyond baseline, approximately 1 day.

Eligibility criteria and details about the enrolled population are not reported in the registry record beyond the condition and arm description. The analysis population, number with complete measurements, missing-data handling, and reasons for missing values are also not reported. Thus, the listed enrollment cannot establish how representative the analyzed measurements were or how much information contributed to the primary outcome.

The record lists two outcome measures but does not report a multiplicity strategy. No statistical analysis plan or sample-size justification is described. These gaps prevent assessment of whether the reported analyses, if any, followed prespecified methods. The stated planning illustrations use hypothetical two-arm assumptions and should not be read as the rationale for this single-group study.

The safety summary is limited to registry-recorded event counts; event definitions, ascertainment procedures, and follow-up details are not reported. These limitations concern what can be established from the registry record and do not determine what may be available in other study materials.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Liver Fibrosis Evaluation Using Ultrasound Shear Wave Imaging — NCT03637959.
• Registry record last updated 2021-12-13; status last verified 2021-12.
• Results first posted 2021-12-13.
• 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

NCT03637959 is a completed, single-group study titled Liver Fibrosis Evaluation Using Ultrasound Shear Wave Imaging, sponsored by Mayo Clinic. The registry lists liver fibrosis as the condition, enrollment of 270, and the dates 2017-01-26 to 2020-11-04 for start and primary completion.

Participants scheduled for clinically indicated MRE also had mechanical vibrations with ultrasound shear wave imaging. The primary outcome is mean liver stiffness measured by MRE in kilopascals, with standard deviation and a baseline timeframe of approximately 1 day. MRE is identified as the benchmark reference. The record lists no randomized comparison and no statistical analyses.

Numerical primary outcome results, the analysis population, missing-data methods, and a multiplicity strategy are not reported in the registry record. The safety summary records 0 serious adverse events, 0 other adverse events, and 0 deaths among 270 participants at risk.