Biomarkers of Liver Pathology in Patients With Presumed Non-Alcoholic Steatohepatitis Following Bariatric Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Biomarkers of Liver Pathology in Patients With Presumed Non-Alcoholic Steatohepatitis Following Bariatric Surgery (NCT03294850), a non-randomized na study. The primary outcome is Percent Change in Liver Fat Between Baseline and 12 Weeks Post-surgery.

2. Clinical Question

The study’s stated purpose was to evaluate imaging and other biomarkers of non-alcoholic fatty liver disease before and after bariatric surgery. Its primary endpoint focuses on change in liver fat, rather than a randomized comparison of surgery against a control intervention. The baseline measurements in the Non-NASH group provide a different descriptive context; because that group did not have longitudinal evaluation, it cannot establish how liver fat changed over time in a comparable control group.

The registry lists an enrollment of 14. That enrollment figure does not by itself establish how many participants contributed data to the primary endpoint. The endpoint analysis population is described as the NASH group, but the number with paired baseline and follow-up MRI measurements is not reported in the registry record.

3. Trial Design

BARI was a completed, non-randomized, unmasked, single-group study sponsored by AdventHealth Translational Research Institute. The registry lists its phase as NA and enrollment as 14. The recorded start date is 2018-07-18, and the primary completion date is 2019-11-14. These dates describe the registry record; they do not supply details about recruitment pace or the timing of individual assessments.

The study enrolled a NASH group and a Non-NASH group comprising people with NAFLD or normal liver physiology. The registry describes NASH as identified by magnetic resonance elastography, with liver biopsy confirmation required for continuation in the longitudinal study. The Non-NASH group was studied up to the day of bariatric surgery and was intended as a comparator population for baseline measurements. Only the NASH group had longitudinal evaluation.

Bariatric surgery is listed as a procedure, and the HepQuant SHUNT Dual Cholate Liver Diagnostic Kit is listed as a device. The stated purpose was to evaluate imaging and other biomarkers before and after bariatric surgery. The registry does not report details of the surgical procedures, the device assessment schedule, or whether all participants underwent the same assessments.

Because allocation was non-randomized and masking was absent, the design does not support treating the groups as exchangeable by assignment. In particular, the Non-NASH group is not a longitudinal control for the NASH group’s primary outcome. The registry does not report a protocol-level rationale for the group structure, eligibility criteria beyond the group descriptions, or a sample-size justification.

The record lists 2 outcome measures and 0 analyses. It gives the primary endpoint description but does not report its numerical result. Details of any additional outcome measures are not reported in the registry record. Thus, the completed status and planned endpoint are known, but the posted record does not allow a reader to reconstruct the primary analysis or its result.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Only the NASH group had longitudinal evaluation

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 Percent Change in Liver Fat Between Baseline and 12 Weeks Post-surgery, measured over 12 weeks.

The primary endpoint is the percent change in liver fat between baseline and 12 weeks after surgery, assessed by magnetic resonance imaging proton density fat fraction, or MRI PDFF. The endpoint is defined for the NASH group, which is the only group described as having longitudinal evaluation. The registry specifies a mean as the summary measure and standard deviation as the measure of dispersion.

MRI PDFF is an imaging-based measure used to quantify the fraction of signal attributable to fat in the liver. As a general statistical point, measuring the same marker at baseline and follow-up can describe within-participant change over time. A percent-change endpoint expresses that change relative to a baseline value, while a group mean summarizes the average across participants with endpoint data. The standard deviation describes how spread out the individual measurements are around that mean; it is not the same as uncertainty in the estimated mean.

The registry record does not report the mean percent change, standard deviation, number of participants contributing endpoint data, or any confidence interval. It also does not give participant-level observations. Consequently, the endpoint’s observed direction, magnitude, variability, and precision are not reported in the registry record. The endpoint definition alone does not establish what change occurred.

The endpoint is an imaging biomarker outcome, not a direct report of every aspect of liver pathology or of a clinical outcome. The registry’s stated purpose includes evaluating biomarkers, but it does not provide enough endpoint results to compare the performance of different biomarkers.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary outcome summarized by a mean and standard deviation. It does not report the numerical outcome or an analysis. The points below explain the statistical ideas relevant to reading this endpoint in general; they are not claims about methods used by the investigators.

What does a mean describe?

For a continuous measurement, the mean is the arithmetic average of the observed values in the analysis population. For this endpoint, the registry identifies the measure as mean percent change in MRI PDFF liver fat for the NASH group. A mean gives a concise description of the average change, but it does not show whether individual participants had similar changes or widely varying changes. It can also be influenced by unusually large or small observations.

The standard deviation describes the spread of observed participant values around the mean. It is a descriptive measure of participant-to-participant variability. It does not, on its own, quantify how precisely the sample mean estimates an underlying population mean. Precision would usually be communicated with a confidence interval or another uncertainty measure, but one is not reported in the registry record.

What does a before-and-after endpoint capture?

As a general statistical point, a paired before-and-after analysis uses measurements from the same participants at both time points. The within-participant change can account for the fact that each person has their own baseline measurement. For this study, the stated endpoint compares baseline with the 12-week post-surgery assessment, and only the NASH group had longitudinal evaluation.

A paired analysis requires both measurements for each participant included in the calculation. The registry record does not report how many NASH-group participants had both measurements, how missing measurements were handled, or whether the analysis used a paired calculation. The endpoint description therefore identifies the intended time contrast but does not fully specify the statistical implementation.

A percent-change measure expresses change relative to a baseline value. As a general matter, values near zero at baseline, measurement variability, and differences in baseline values can affect the interpretation of percent change. The registry does not report baseline MRI PDFF values, the formula used for percent change, or any assessment of the distribution of the endpoint. Those details are not reported in the registry record and cannot be assumed.

What does uncertainty mean?

A confidence interval is a statistical range intended to express uncertainty around an estimate under a specified method. It helps readers distinguish a relatively precise estimate from one that is compatible with a broad range of values. A confidence interval is not a guarantee that the true value lies within the observed interval. No confidence interval for the primary endpoint is reported.

A p-value, when used, measures how incompatible data are with a specified null hypothesis under the assumptions of the test. It does not measure the size or importance of an effect, and it is not the probability that the null hypothesis is true. The registry record does not report a p-value or the hypothesis tested. No inferential analysis is listed, so statistical significance cannot be assessed from the posted record.

Why does the design affect interpretation?

Random assignment is one way to make comparison groups similar, on average, with respect to both measured and unmeasured factors at the time of assignment. BARI is described as non-randomized, so treatment assignment did not create randomized groups. Moreover, the Non-NASH group was used for baseline comparison and was not followed longitudinally for the primary outcome. It therefore cannot serve as a like-for-like control for the NASH group’s change from baseline.

Within-group change after surgery can describe what happened over time among participants with available measurements. By itself, it cannot separate the contribution of surgery from other influences that may coincide with follow-up, such as changes over time or measurement conditions. This is a general limitation of interpreting an uncontrolled before-and-after outcome, not a claim about what caused any particular result in this study.

What can sample-size planning show?

Sample-size calculations are planning illustrations based on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. They do not describe how many participants actually contributed data, and they are not observed power. The registry record does not report its own design justification or a sample-size justification. Any planning illustration based on an observed effect should be distinguished from the trial’s original planning, especially because the primary observed effect is not reported in the registry record.

More generally, planning calculations do not repair limitations in the observed data or provide evidence that an effect occurred. Their interpretation depends on the assumptions used, and the registry’s own sample-size assumptions are described as an illustration rather than the trial’s design. The study enrolled 14 participants, but that fact alone does not establish whether the primary endpoint estimate is precise.

What is not available for this endpoint?

The registry record does not report the endpoint mean, standard deviation, analysis sample size, confidence interval, p-value, or details of the statistical model. It lists 0 analyses. The record also does not report whether any covariate adjustment, sensitivity analysis, or interim analysis was undertaken. Without those details and the numerical endpoint result, the statistical evidence cannot be independently evaluated beyond the design and outcome definition.

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("NASH Group")
n   <- c(4)
m   <- c(-16.4)
sp  <- c(52.9)
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  NASH Group  4  -16.400  52.900  -100.576  67.776

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 0 analyses. The primary outcome is described as mean percent change in MRI PDFF liver fat between baseline and 12 weeks after surgery in the NASH group. Details of the other outcome measure are not reported in the registry record. A multiplicity plan, including any designation of confirmatory versus exploratory outcomes or adjustment for multiple comparisons, is not reported.

Multiplicity matters when several outcomes, time points, or statistical tests are examined. As a general statistical point, examining multiple results can increase the chance of at least one apparently notable finding, depending on the analysis strategy. This does not establish that multiplicity occurred in this study; the registry does not report enough analysis detail to determine which tests were conducted or how they were interpreted.

The record does not report the number of participants with complete baseline and follow-up MRI PDFF measurements. It does not state whether any primary endpoint measurements were missing, why measurements might be missing, or how missing values were handled. Thus, the amount and potential impact of missing data cannot be assessed. Enrollment of 14 is not a substitute for the endpoint analysis population.

The analysis population is described only as the NASH group for longitudinal evaluation. The registry does not report an intention-to-treat definition, a per-protocol definition, exclusions from analysis, or a participant flow for the endpoint. It also does not say how participants who lacked biopsy confirmation were treated in analyses. These analysis-population details are not reported in the registry record.

Because the numerical endpoint result and analysis methods are absent, readers cannot determine whether the estimate reflects all eligible participants, only those with paired measurements, or another subset. No imputation or sensitivity-analysis approach is reported. These are reporting gaps; they do not establish that data were missing or that any particular method was 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.

Most frequent non-serious adverse event terms

The registry reports no serious adverse events in either group. In the NASH group, 0 serious adverse events were reported among 4 at risk; 2 other adverse events were reported among 4 at risk, and there were 0 deaths. In the Non-NASH (NAFLD or Normal) group, 0 serious adverse events were reported among 10 at risk; 9 other adverse events were reported among 10 at risk, and there were 0 deaths.

These are counts recorded for the groups, not estimates from a comparative safety analysis. The category “other adverse events” is distinct from serious adverse events in the registry figures. The record does not provide the event terms, severity details for the other events, timing, relatedness assessments, or an explanation of how events were collected. The list of top serious adverse terms is empty.

The group counts should be read in light of the non-randomized design and the fact that the Non-NASH group was followed only up to the day of surgery, whereas the NASH group had longitudinal evaluation. The registry does not report a common follow-up period for adverse-event collection or a statistical comparison between groups. Consequently, these figures do not establish that one group had greater or lesser risk, and zero reported serious events should not be interpreted as proof that no serious event could occur.

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

The registry record answers some design questions but does not provide the central numerical outcome result. It identifies a planned assessment of mean percent change in MRI PDFF liver fat from baseline to 12 weeks after surgery in the NASH group. It also specifies the mean and standard deviation as the endpoint summary. The actual mean, standard deviation, and endpoint analysis sample size are not reported in the registry record.

Accordingly, readers cannot tell from the posted results whether liver fat increased or decreased on average, how large the change was, or how much individual changes varied. There is also no reported confidence interval or hypothesis-test result with which to judge precision or statistical compatibility. An outcome definition is not an outcome finding.

Even if a within-group change estimate were available, the design would not make that change equivalent to a randomized estimate of the effect of surgery. The study is non-randomized, and the Non-NASH group was included as a comparator population for baseline measurements only. It did not provide longitudinal control measurements for the primary endpoint. Changes after surgery can be described over time, but a before-and-after comparison alone does not isolate the cause of change.

The study’s stated purpose was to evaluate imaging and other biomarkers of non-alcoholic fatty liver disease before and after bariatric surgery. That purpose should not be mistaken for evidence that any biomarker performed well or that a clinical outcome changed. Numerical results for biomarker performance and details for the additional outcome measure are not reported in the registry record.

The adverse-event counts are limited descriptive information. They include zero reported serious adverse events in both groups, other adverse-event counts, and zero deaths. Without definitions, event details, comparable follow-up, or a statistical comparison, those counts do not establish comparative safety.

The appropriate reading is therefore narrow: the record describes a completed study, its group structure, and a longitudinal imaging endpoint, but it does not post the primary result needed to quantify change. It cannot support a conclusion about the magnitude, precision, or cause of change in liver fat.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of why a clearly defined endpoint and a reported estimate are both needed. BARI specifies a measurable primary outcome: mean percent change in MRI PDFF liver fat from baseline to 12 weeks after surgery in the NASH group. It also names the summary statistic and dispersion measure. Those definitions help clarify what the investigators intended to quantify.

At the same time, the registry record does not report the numerical endpoint estimate or its variability. Without those values, readers cannot evaluate either the observed size of change or how heterogeneous participant results may have been. Without an uncertainty measure, the precision of the mean is also unknown. This demonstrates the distinction between a documented outcome definition and a reportable statistical result.

The study design also highlights the importance of matching the comparison to the question. The Non-NASH group was included for baseline comparison, but it was not assessed longitudinally as a control for the primary endpoint. A baseline comparator and a longitudinal control answer different questions. The non-randomized, single-group structure means that a within-group change, if reported, would not by itself identify the effect attributable to surgery.

The record’s description of 14 enrolled participants and its adverse-event counts add context, but neither replaces the endpoint analysis. Enrollment does not show how many participants posted paired measurements, and safety counts without event detail and comparable follow-up do not provide a controlled comparison.

Statistically, the record underscores how reporting analysis populations, missing data, uncertainty, and analysis methods is essential for interpretation. These details are not reported in the registry record. The study’s value for readers is therefore in clarifying the design and illustrating the limits of inference when a planned biomarker outcome is not accompanied by its numerical result.

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 most direct limitation is that the registry record does not report the primary endpoint estimate. Although the endpoint is defined as mean percent change in MRI PDFF liver fat from baseline to 12 weeks after surgery, neither the mean nor its standard deviation is posted. The number of participants contributing paired measurements and an uncertainty interval are also not reported. The size, direction, variability, and precision of the outcome therefore cannot be assessed.

The registry lists enrollment of 14, but does not provide a participant flow or an endpoint-specific analysis population size. The number of participants in the NASH group with biopsy confirmation and complete longitudinal data is not reported in the registry record. Missing-data status, reasons for missingness, and any handling strategy are also not reported.

The design is non-randomized, unmasked, and described as single-group. Although there is a Non-NASH group, it serves as a baseline comparator and is studied only up to the day of surgery. It does not provide longitudinal comparison data for the primary endpoint. The registry therefore does not describe a like-for-like control comparison for change over time.

Further statistical details are absent: the record lists 0 analyses, and does not report a statistical model, hypothesis test, confidence interval, covariate adjustment, sensitivity analysis, or multiplicity approach. The sample-size justification and any interim analyses are not reported in the registry record. Details of the second outcome measure are also not reported.

Safety interpretation is limited by the lack of event terms, collection details, comparable follow-up information, and a statistical comparison. The record gives counts but does not provide enough context to evaluate event patterns. These limitations arise from what is reported in the registry record; they should not be taken as evidence that a particular method or analysis was or was not used outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Biomarkers of Liver Pathology in Patients With Presumed Non-Alcoholic Steatohepatitis Following Bariatric Surgery — NCT03294850.
• Registry record last updated 2021-07-16; status last verified 2021-07.
• Results first posted 2021-06-14.
• 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

BARI was a completed, non-randomized, unmasked, single-group study sponsored by AdventHealth Translational Research Institute, with enrollment of 14. Its recorded start date was 2018-07-18, and its primary completion date was 2019-11-14. The study evaluated biomarkers before and after bariatric surgery.

The primary endpoint was mean percent change in MRI PDFF liver fat between baseline and 12 weeks after surgery among participants in the NASH group. The Non-NASH group served as a baseline comparator and was not followed longitudinally for that endpoint. The numerical primary result, endpoint analysis sample size, and statistical analysis are not reported in the registry record.

The safety record reports 0 serious adverse events and 0 deaths in each group, alongside other adverse-event counts. Those figures are descriptive and do not provide a comparative analysis. Overall, the record defines the study question and design but does not report the primary outcome estimate needed to assess the observed change or its precision.