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 RICE Trial: Rifaximin In Chronic Hepatic Encephalopathy - A Randomized, Controlled Trial (NCT00364689), a randomized phase 3 study. The primary outcome is Number of Hospitalizations for Hepatic Encephalopathy (HE).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00364689 |
| Phase | Phase 3 |
| Condition | Hepatic Encephalopathy |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 13 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Miami |
| Results posted | Yes |
2. Clinical Question
The RICE trial was intended to compare treatment regimens for hepatic encephalopathy. The registry describes three regimens: rifaximin alone, lactulose given with rifaximin, and lactulose given with a placebo. Its primary question concerned the number of hospitalizations for hepatic encephalopathy at Month 7. The record does not report results for that endpoint, so it cannot establish how the hospitalization counts differed across the regimens.
Population
People enrolled in a study concerning hepatic encephalopathy. The record reports enrollment of 13 participants but does not provide further participant characteristics or a detailed primary-outcome analysis population.
Intervention
The listed regimens included rifaximin alone and lactulose given with rifaximin. The record also lists rifaximin, lactulose, and placebo as interventions.
Comparator
The listed comparator regimen was lactulose given with a placebo (sugar pill). The registry does not report results comparing this regimen with either rifaximin-containing regimen.
Primary question
How many hospitalizations for hepatic encephalopathy occurred by the Month 7 timeframe? The registry states that outcome data were not reported and that data analysis was not performed.
These descriptions identify the question the trial was designed to address, not an answer to it. Although the trial was randomized, the record does not report a treatment-effect estimate, uncertainty interval, or test of differences for the primary endpoint. It also does not describe the specific characteristics of participants included in the planned endpoint assessment. Consequently, the clinical question can be stated from the trial record, but its comparative answer is unavailable.
3. Trial Design
The RICE trial is identified as a Phase 3, randomized, double-masked, parallel-group study. Its stated purpose was to compare three different treatments for hepatic encephalopathy. The listed treatment regimens were rifaximin alone, lactulose given with rifaximin, and lactulose given with a placebo. The University of Miami is identified as the sponsor.
The record reports enrollment of 13 participants and a status of terminated. The start is listed as 2006-08 and primary completion as 2008-07. The record explains that the study was terminated because of difficulty enrolling participants. Data collection ceased, analysis was not performed, and the collected data are no longer available because the retention period has passed.
Randomization ordinarily means that assignment to study groups is determined by a chance-based process. Double masking generally means that treatment assignment is concealed from participants and relevant study personnel, although the registry record does not explain the specific masking procedures. A parallel design ordinarily assigns participants to a regimen and follows their outcomes in that group. These are general descriptions of design terms; they do not add details about how this particular trial implemented them.
The registry record does not report the randomization method, allocation ratio, treatment duration, eligibility criteria, or the planned sample size. It also does not report how many participants were assigned to each regimen, received treatment, or completed follow-up. The enrollment figure alone does not answer those questions. The termination and absence of outcome analyses are central to interpreting this design: the record identifies an intended comparative trial, but it does not provide an analyzed comparison of its treatment groups.
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.
Before assignment: The number of participants that were assigned to each Arm/Group is not known due to the data for this study no longer being available as the retention period has passed.
Overall Study
| Stage | All Participants |
|---|---|
| STARTED | 13 |
| COMPLETED | 12 |
| NOT COMPLETED | 1 |
Reasons for not completing this period:
| Reason | All Participants |
|---|---|
| Lost to Follow-up | 1 |
Analysis population for the primary outcome, as defined in the registry: Outcome measure data is not reported as the study was terminated due to difficulty with enrolling participants. Collection of data ceased and data analysis was not performed. Data collected is no longer available as the retention period has passed.
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.
Population: Data collected is no longer available as the retention period has passed.
| Characteristic | Unit | Lactulose Given With a Placebo (Sugar Pill) | Lactulose Given With Rifaximin | Rifaximin Given Alone | Total |
|---|---|---|---|---|---|
| Participants analysed | 0 | 0 | 0 | 0 | |
| Age, Categorical: <=18 years | — | — | — | — | |
| Age, Categorical: Between 18 and 65 years | — | — | — | — | |
| Age, Categorical: >=65 years | — | — | — | — | |
| Sex: Female, Male: Female | — | — | — | — | |
| Sex: Female, Male: Male | — | — | — | — |
6. Primary Endpoint
The registry lists the primary outcome as Number of Hospitalizations for Hepatic Encephalopathy (HE), measured over Month 7.
| Element | Registry entry |
|---|---|
| Result type | N/A |
| Measure of spread | not applicable |
| Unit | not stated |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was the number of hospitalizations for hepatic encephalopathy, with the timeframe listed as Month 7. This is a count outcome: it concerns how many hospitalization events occurred, rather than a score or a single yes-or-no status. The registry record does not specify whether the count was defined per participant, how recurrent hospitalizations were handled, or the exact assessment window around Month 7.
As a general statistical concept, hospitalization counts can describe the burden of events during a defined observation period. A comparison of counts may therefore address a different question from a comparison of whether each participant had at least one hospitalization. The appropriate analysis depends on details such as the observation period, follow-up, and the distribution of counts. Those details and the planned statistical approach are not reported in the registry record.
The endpoint was selected as the trial’s primary measure of hospitalization for hepatic encephalopathy. However, no outcome values are reported. The record says the study ended because of difficulty enrolling participants, data collection ceased, and analysis was not performed; it also says the collected data are no longer available because the retention period has passed. Thus, the endpoint’s definition and timing can be identified, but its observed distribution and any comparison between regimens cannot be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the intended primary outcome and the study’s treatment regimens, but it reports no primary outcome data. Specifically, it states that the number of hospitalizations for hepatic encephalopathy at Month 7 was not reported because the study was terminated due to difficulty enrolling participants. Data collection ceased and data analysis was not performed. The record further states that collected data are no longer available because the retention period has passed.
As a result, there is no reported estimate of the difference between any regimens, no confidence interval describing the precision of a treatment comparison, and no reported significance test for the primary endpoint. The registry lists zero analyses. These absences do not indicate that the regimens had the same outcomes; they mean that the record supplies no analyzed outcomes with which to assess whether they differed. The enrollment of 13 participants is not a substitute for an outcome estimate and does not establish the number assigned to or evaluated in any particular group.
The record lists other planned outcomes: hospitalization days for all causes, death or survival to liver transplantation, and the rate of adverse events with rifaximin treatment. It does not report results for these outcomes either. In the adverse-event information, the group is labeled “All Study Participants,” with zero participants at risk and zero affected for the displayed serious and other event counts, and zero deaths. Because the record reports zero at risk, these entries do not provide evidence that participants were assessed and had no events. They cannot be interpreted as a demonstrated absence of adverse events or deaths.
A confidence interval is, in general, a way to express the uncertainty around an estimated effect under a specified statistical method. Without an estimate and its underlying outcome information, there is no interval to interpret. Likewise, a p-value cannot be inferred from the trial’s design, enrollment, or termination status. Neither a favorable nor an unfavorable treatment effect can be concluded from the absence of reported analysis.
The principal statistical interpretation is therefore limited: the registry describes an intended randomized, double-masked, parallel comparison, but provides no analyzed result for the primary endpoint or listed secondary outcomes. The record does not support a quantitative comparison among the regimens, and it does not show that the study met its intended evidentiary objective.
9. Statistical Methods Explained
The design labels describe how a trial is organized, while statistical methods describe how observations are converted into estimates and uncertainty. The record identifies this study as randomized, double-masked, and parallel, but does not report the detailed statistical analysis plan. The explanations below are general statistical context, not a description of analyses performed for this trial.
What does randomization contribute?
In general, random assignment aims to make treatment groups comparable at the start of a trial with respect to both measured and unmeasured characteristics. It does not guarantee that groups will be identical, particularly when the number of enrolled participants is limited. The record confirms a randomized design but does not state the random sequence method, allocation concealment procedures, or numbers assigned to each regimen. It is therefore not possible to evaluate those implementation details from the registry.
What does masking contribute?
In general, masking can reduce the influence of knowledge about assigned treatment on participant experience, clinical care, outcome reporting, and assessment. The record labels the study double-masked, but does not specify who was masked, how masking was maintained, or whether it remained intact. The design label alone cannot establish how effectively masking was implemented.
How are count outcomes analyzed?
The primary endpoint is a count of hospitalizations for hepatic encephalopathy at the Month 7 timeframe. In general, count-data analyses use methods suited to nonnegative event counts. The choice depends on the outcome definition and features of the data, such as whether participants had different amounts of observation time and whether the counts vary more than a simple model would expect. The registry does not report the event counts, observation-time details, or a planned model. It is therefore not possible to identify or assess a trial-specific count analysis.
Over-dispersion is a general statistical issue that occurs when count outcomes vary more than an assumed model allows. If present, it can affect estimated uncertainty and make a model’s standard errors unreliable when the extra variation is ignored. That is a reason analysts may examine the count distribution and model assumptions. It is not possible to determine whether over-dispersion occurred in this trial, because its outcome data and analysis are not reported.
What would an estimate and interval mean?
In general, a treatment-effect estimate describes the contrast defined by an analysis, while a confidence interval communicates the estimate’s uncertainty under the method’s assumptions. For a count endpoint, an analysis might define a contrast in counts or in a modeled event rate, but the registry record does not state which contrast or method was planned. There is no reported estimate or confidence interval to interpret for this trial. No effect size can be reconstructed from the enrollment figure or from the design description.
A significance test, when used, evaluates data against a specified null hypothesis under a statistical model. Its result depends on observed outcomes and the analysis choices. The registry reports that data analysis was not performed and lists zero analyses. Therefore, no p-value or test result is available. It would be inappropriate to infer one from the trial’s termination or from the absence of outcome reporting.
What can planning calculations establish?
In general, sample-size planning considers a target effect, variability or event rates, a significance level, power, allocation, and an analysis model. A planning illustration based on an observed effect is distinct from a trial’s original design justification, and it is not observed power. The registry does not report a sample-size justification or the trial’s planned enrollment target. It also provides no observed effect for the primary endpoint from which to interpret a planning illustration. No planning calculation can supply the missing trial outcomes.
These methods concepts clarify what would normally be needed for a statistical comparison. For this study, the record reports design labels and a primary endpoint, but not the participant-level or summary outcome data, the analysis plan, or any performed analysis. The general concepts therefore help define the missing information; they do not yield a result for the trial.
10. Multiplicity, Missing Data and Analysis Populations
The trial lists three treatment regimens and several outcomes: the primary measure of hospitalizations for hepatic encephalopathy, hospitalization days for all causes, death or survival to liver transplantation, and the rate of adverse events with rifaximin treatment. Considering multiple outcomes or multiple pairwise comparisons can raise multiplicity concerns. In general, repeated testing may increase the chance of finding an apparently notable result by chance unless the analysis plan addresses how comparisons will be interpreted or adjusted. The registry record does not report a multiplicity strategy, the planned comparison hierarchy, or an analysis plan. Since no analysis was performed, the record offers no results from which to assess multiplicity in practice.
The record says data collection ceased after termination and that outcome data are not reported. It also states that data collected are no longer available because the retention period has passed. It does not describe how many participants had missing endpoint observations, the reasons for any missing observations, or any method for handling missing data. The termination explanation concerns difficulty enrolling participants; it should not be treated as a description of individual participants’ follow-up or missingness patterns.
The registry reports enrollment of 13 participants, but does not state the numbers randomized to each regimen, treated, followed, or included in an analysis population. It does not say whether an intention-to-treat, per-protocol, safety, or other population was defined or used. These populations can answer different questions in general, so the analysis population matters when interpreting a trial estimate. Here, there is no reported analysis population or estimate to interpret. The adverse-event entry lists zero participants at risk, which does not establish that a safety population was assessed without events.
11. What the Result Does, and Does Not, Mean
The record establishes that a randomized, double-masked, parallel trial was intended to compare treatment regimens for hepatic encephalopathy. It identifies hospitalization count for hepatic encephalopathy at Month 7 as the primary endpoint and reports enrollment of 13 participants. It also documents that the trial was terminated because of difficulty enrolling participants.
What the record does not establish is whether any regimen changed hospitalization counts, whether outcomes differed between regimens, or how precisely any difference could be estimated. No primary outcome data or analysis is reported. The same limitation applies to the listed secondary outcomes. A missing result is not evidence of no effect, equivalence, or equal safety. It is also not evidence of benefit or harm.
In general, a randomized design can support a causal comparison when assignment, follow-up, outcome measurement, and analysis are sufficiently documented and the results are available. The design label alone does not supply those results. Similarly, enrollment tells the reader that participants entered the study, but not how they were assigned, what outcomes they experienced, or how many contributed data to a comparison.
The adverse-event record requires particular caution. Its displayed counts are zero, but the number at risk is also zero. Those entries cannot be read as a finding that there were no adverse events among assessed participants. The record does not provide a usable estimate of adverse-event frequency.
The appropriate conclusion is about the state of the evidence in this record: it documents an attempted trial and its termination, but not a comparative statistical result. Any claim about the relative outcomes of the listed regimens would go beyond what the registry reports.
12. Why This Trial Matters Statistically
This trial matters statistically because its record illustrates the distinction between a well-defined research question and an answer supported by analyzed data. The study specified a primary endpoint—hospitalizations for hepatic encephalopathy at Month 7—and listed three treatment regimens. It also had a randomized, double-masked, parallel design. Yet the registry reports no outcome data or analysis after the trial was terminated for difficulty enrolling participants.
That distinction is important when reading trial records. A design can describe how a comparison was intended to work, but design features cannot replace the observed outcomes. Without an estimate and its uncertainty, readers cannot judge the magnitude or precision of a treatment contrast. The absence of analysis also means there is no basis in this record for comparing the primary outcome or the listed secondary outcomes.
The record also shows why transparent reporting of enrollment, follow-up, and analysis populations matters. It reports enrollment of 13, but does not report group-specific numbers, endpoint completion, or an analysis population. Those details are necessary to understand which participants contributed to an estimate and how much information supports it. The record’s statement that collected data are no longer available further limits the possibility of clarifying the reported outcome gap from the registry information.
Statistically, the most informative conclusion is not a treatment comparison but a boundary: the registry record supports describing the intended design and reason for termination, but not estimating the effects of the regimens. Recognizing that boundary prevents an unavailable result from being mistaken for a neutral or definitive finding.
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 main limitation is that the registry reports no primary outcome data and says analysis was not performed. It attributes termination to difficulty enrolling participants and states that data collection ceased. The collected data are no longer available because the retention period has passed. Consequently, no comparative estimate, confidence interval, or statistical test can be examined for the primary endpoint.
The enrollment figure is 13, but the record does not report group-specific enrollment, treatment receipt, follow-up completion, or the number contributing to any endpoint. It does not describe participant characteristics, eligibility criteria, or the analysis population. These omissions prevent assessment of how representative the enrolled participants were or how complete outcome ascertainment was.
The endpoint is described as the number of hospitalizations for hepatic encephalopathy at Month 7, but the record does not specify the detailed counting rule, exact observation window, handling of recurrent events, or treatment of differing follow-up. Nor does it report the planned statistical model. These gaps matter for interpreting a count outcome, even if results were available.
The record lists secondary outcomes but provides no results for them. It does not report a statistical plan for handling multiple outcomes or comparisons, or a method for missing data. The adverse-event summary has zero participants at risk, so its zero event counts do not support a conclusion about safety among assessed participants.
Finally, the registry does not report the original sample-size justification, detailed allocation procedures, or implementation of masking. The record supports describing the trial’s stated design, but not evaluating these operational or statistical details.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: RICE Trial: Rifaximin In Chronic Hepatic Encephalopathy - A Randomized, Controlled Trial — NCT00364689.
- Registry record last updated 2019-09-17; status last verified 2019-08.
- Results first posted 2019-09-17.
- 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 RICE trial was a Phase 3, randomized, double-masked, parallel study sponsored by the University of Miami. It concerned hepatic encephalopathy and listed rifaximin alone, lactulose with rifaximin, and lactulose with placebo as treatment regimens. The primary endpoint was the number of hospitalizations for hepatic encephalopathy at Month 7.
The record reports enrollment of 13 participants and a terminated status. It gives 2006-08 as the start and 2008-07 as the primary completion. The stated reason for termination was difficulty enrolling participants. The record says data collection ceased, analysis was not performed, and collected data are no longer available because the retention period has passed.
No primary or secondary outcome results are reported, and the registry lists zero analyses. The record therefore describes the intended trial question and its termination, but does not provide a statistical comparison of the treatment regimens.