Catheter Placement for Hepatic Hydrothorax: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Catheter Placement for Hepatic Hydrothorax (NCT02595567), a na na study. The primary outcome is Feasibility of Using Indwelling Tunneled Pleural Catheters for the Management of Hepatic Hydrothorax.

2. Clinical Question

The clinical context in the registry summary is persistent or recurring fluid-related shortness of breath despite conventional treatment. It describes diuretics and salt restriction, repeated thoracentesis, TIPS, and liver transplantation as aspects of the broader management context; it does not compare those approaches with ITPC in this study. In particular, the summary explains that repeated drainage may be temporary and that other options may not be effective, feasible, or promptly available for every patient. Those statements motivate the study question but are not results from a comparison within this record.

The question is therefore primarily one of feasibility in a single group, rather than whether ITPC produces better outcomes than another treatment. The record states an enrollment of 25. It does not report a primary outcome count, the number meeting the feasibility definition, or a numerical change in shortness of breath. Without those results, the registry entry defines what the investigators intended to assess but does not establish how often the defined outcome occurred.

3. Trial Design

This is a completed, single-group study of an indwelling tunneled pleural catheter for hepatic hydrothorax. The registry lists enrollment as 25, phase as NA, allocation as NA, and masking as none. The intervention is the ITPC; no separate control arm is described. As a result, the design addresses use of the catheter within the studied group and does not provide a randomized, like-for-like comparison against another treatment or against no catheter.

The registry lists Washington University School of Medicine as sponsor. The recorded study start is 2010-10-01, and the primary completion date is 2015-07-20. The current status is completed. These dates and status describe the registry record; they do not by themselves indicate what the endpoint results were or whether all planned observations were available.

The primary outcome is titled “Feasibility of Using Indwelling Tunneled Pleural Catheters for the Management of Hepatic Hydrothorax.” Its description combines successful placement, improvement in shortness of breath, and the ability to drain pleural effusions routinely at home. Shortness of breath was described as self-reported during routine clinical follow-up, and home drainage was documented using patient logs. The stated assessment period runs from ITPC administration until the first documented complication such as infection requiring catheter removal or until pleurodesis, whichever came first, assessed up to 12 months.

The registry record does not report detailed eligibility criteria, the number who received the intervention, losses to follow-up, or a participant flow. It also does not report a comparator, a masking procedure, or a statistical analysis plan. The single-group structure means that observed experiences can describe this enrolled group, but they cannot isolate an intervention effect from changes over time, clinical care, or other explanations.

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 Feasibility of Using Indwelling Tunneled Pleural Catheters for the Management of Hepatic Hydrothorax, measured over From date of ITPC administration until the date of first documented complication such as infection that would require catheter removal or date of pleurodesis, whichever came first, assessed up to 12 months.

The primary endpoint is feasibility of using an indwelling tunneled pleural catheter to manage hepatic hydrothorax. The record defines feasibility through successful catheter placement and improvement in shortness of breath after the procedure. It also describes feasibility in terms of participants’ ability to drain pleural effusions routinely at home, with drainage documented in patient logs. These components reflect both placement and subsequent practical use, rather than a single laboratory measurement.

The endpoint is used because the study’s stated aim is to assess whether this catheter approach can be used for managing fluid-related symptoms in the target clinical context. A feasibility outcome can capture whether an intervention can be implemented and used as intended. It is distinct from a comparative endpoint: without a control group, the record cannot estimate how the outcome would differ under another management strategy.

The endpoint description says that shortness of breath was assessed descriptively and self-reported during routine clinical follow-up. This means the registry describes a patient-reported symptom rather than a stated standardized numerical scale. It does not report the precise criteria used to classify an improvement, how the different feasibility components were combined, or how missing logs or symptom assessments were handled. Those details are not reported in the registry record.

The stated timeframe extends from ITPC administration to the first documented complication such as infection requiring catheter removal or to pleurodesis, whichever came first, with assessment up to 12 months. The registry record does not provide the observed endpoint result or clarify the number who completed that assessment period.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The study uses a single-group design. In general, a single-group study observes participants who receive an intervention without a concurrent comparison group. Such a design can describe whether an intervention was used and what outcomes were recorded in the enrolled group. It cannot, by itself, show what would have happened to those participants under a different treatment strategy. Changes in symptoms may have explanations other than the intervention, and a comparison is needed to estimate differences between strategies.

What does the feasibility outcome capture?

The registry’s primary outcome definition combines several practical and clinical elements: successful catheter placement, improvement in shortness of breath, and routine home drainage of pleural effusions. The description says that shortness of breath was self-reported and assessed descriptively at routine clinical follow-up. Home drainage was documented by patient logs. This is a multidimensional outcome: placement, symptom experience, and use at home are related but distinct aspects of feasibility. The registry does not specify whether every component had to be met, how a participant was classified if components disagreed, or whether the components were analyzed separately.

In general, a composite outcome combines multiple events or criteria into one endpoint. Its interpretation depends on the exact rule for combining those components. If the components differ in importance or frequency, a single combined result can obscure that variation. Because the record does not give a complete classification rule or component-specific results, the operational meaning of a potential overall feasibility count is not fully assessable.

How should the timeframe be understood?

The stated timeframe begins at ITPC administration and ends at the first documented complication such as infection requiring catheter removal, or at pleurodesis, whichever came first, with assessment up to 12 months. In general, a time window defines when an outcome is observed and can affect how results are interpreted. Ending observation at an event such as catheter removal or pleurodesis may mean participants have different observation periods. The record does not report the observed duration for each participant or how the endpoint was summarized over that interval.

Time-to-event methods are generally used when the timing of an event matters and observation periods vary. Such methods require details about the event definition, censoring, and follow-up. The registry record does not report a time-to-event analysis or the number of participants with relevant events for the primary endpoint. The timeframe alone does not establish that a time-to-event method was used.

What can a statistical comparison establish?

In general, random assignment can make groups more comparable, on average, with respect to factors that might affect outcomes. This study is recorded as single-group, with allocation listed as NA, so no randomized comparison is described. The absence of a comparator means there is no between-group treatment contrast in the record. An outcome observed after catheter placement cannot be interpreted as the difference caused by placement, because the corresponding outcome under an alternative strategy is not observed in a concurrent group.

Effect estimates are usually accompanied by uncertainty measures. A confidence interval, in general, expresses uncertainty around an estimate under the assumptions of the statistical method. It is not a guarantee that the true value lies within the interval, and its width is informative about precision. No primary endpoint estimate, confidence interval, or p-value is reported in the registry record. As a result, readers cannot assess an effect’s magnitude or statistical precision from the primary outcome information.

What does the sample size say?

The registry records enrollment of 25. Enrollment is the number recorded for the study, but it does not by itself identify the number included in a particular endpoint analysis. The record does not report an endpoint-specific analysis population or the number with complete data. A sample-size justification for the study is not reported in the registry record.

In general, planning calculations depend on assumptions about the outcome, the effect a study is intended to detect, the significance level, allocation, and the statistical model. Planning illustrations based on an observed effect are not observed power and do not show that a study was adequately planned before enrollment. The registry’s design assumptions do not provide a study-specific justification or a reported primary outcome calculation that could establish precision.

Why can event counts be limited?

For count outcomes, statistical methods may need to account for variation in the data. In general, over-dispersion occurs when observed variability is greater than a model expects. Ignoring it can make uncertainty appear smaller than it is. This concept is not a claim about this study: the primary endpoint is described as feasibility, and the record does not report a count model or a dispersion assessment. More generally, choosing a method requires knowing the outcome structure and the analysis plan; those details are not reported.

The registry lists no analyses. It therefore does not identify which statistical tests, models, covariate adjustments, or missing-data procedures were used. General statistical concepts can explain what such methods would address, but they cannot fill in unreported features of this study.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("ITPC")
n      <- c(25)
events <- c(25)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  ITPC  25  25  100.0  86.3  100.0  86.7  100.0  86.8  99.9

11. Multiplicity, Missing Data and Analysis Populations

The primary outcome description includes multiple elements: successful placement, improvement in shortness of breath, and routine home drainage. The registry does not explain whether these elements were treated as one combined endpoint, whether each was also reported separately, or how conflicting component results would be classified. It does not report a multiplicity strategy. In general, multiplicity arises when several outcomes or comparisons are tested; conducting many tests can increase the chance of at least one apparently unusual result. A prespecified analysis plan can clarify which results are primary and how multiple tests are handled. Such a plan is not reported in the registry record.

The record lists one outcome measure and 0 analyses. It does not include a primary endpoint result, an analysis population, or a description of missing-data handling. Enrollment is recorded as 25, but the record does not state how many participants contributed complete symptom reports, drainage logs, or other endpoint information. Nor does it state whether participants with incomplete follow-up were excluded, retained in an analysis, or handled using an imputation method. These details are not reported in the registry record.

Missing data can affect interpretation when participants with and without recorded outcomes differ in relevant ways. In general, analysis of only complete observations can be biased if completeness is related to the outcome or participant characteristics. Imputation and other approaches rely on assumptions that need to be stated and assessed. No such assumptions or procedures are reported. The stated endpoint window, which ends at a documented complication requiring removal or at pleurodesis, also makes the handling of variable observation time relevant; the registry does not describe that handling.

The record does not describe interim analyses or stopping rules. These should not be inferred from the completed status or from the stated assessment window. With no reported endpoint analysis, multiplicity plan, or account of missing observations, the robustness of any primary outcome estimate cannot be evaluated from this record.

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’s adverse-event information lists the ITPC group with 25 participants at risk for serious adverse events and 0 affected. Deaths are listed as 0. For the other adverse-event count, the record lists 25 at risk and 0 affected. These are the counts recorded for the study group; they do not provide a comparative safety estimate because there is no control group.

A zero count in a registry entry means that no affected participants are recorded in that category. It should not be read as proof that the intervention has no risk, or that no complication of any kind occurred. The primary outcome description refers to a documented complication such as infection requiring catheter removal, but the registry does not provide a separate count of all such complications or detailed event narratives. It also does not report the methods used to collect or classify adverse events.

In general, safety interpretation depends on how events were defined, how long participants were observed, and whether events were actively collected. The primary endpoint timeframe is described as ending at the first specified event or pleurodesis, assessed up to 12 months; the safety record does not provide participant-level follow-up duration. The posted counts are therefore a limited description of recorded adverse events, not a complete account of all possible harms or a comparison with another approach.

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

The record establishes that a completed, single-group study enrolled 25 participants to assess feasibility of indwelling tunneled pleural catheter use for hepatic hydrothorax. It describes the intended feasibility criteria, including successful placement, self-reported improvement in shortness of breath, and routine drainage at home documented by patient logs. It also records the assessment timeframe and a set of adverse-event counts. These details clarify the study’s question and the outcomes it intended to observe.

The record does not report how many participants met the primary feasibility definition or the results for its individual components. It therefore does not show the observed frequency of feasibility, the extent of symptom improvement, or the proportion able to drain fluid at home. No estimate of uncertainty is reported. The missing result is important: knowing the outcome definition and enrollment does not reveal the outcome itself.

The study also cannot answer a comparative question. With no comparator group and no randomized allocation described, the record does not estimate how outcomes differ between catheter use and another treatment. Even a reported outcome count from one group would not on its own identify a treatment effect. Other influences and the course of the condition could contribute to outcomes in an uncontrolled study.

The recorded safety counts show 0 participants affected among 25 at risk for serious adverse events, and 0 deaths. Those figures describe what is recorded in the registry; they do not establish that no event occurred outside the reported categories or that the catheter has no risks. Event definitions, collection procedures, and participant-level follow-up are not reported in sufficient detail to support broader safety conclusions.

Accordingly, the evidence available in the registry is descriptive of design and recorded event counts, but incomplete for evaluating the primary endpoint. It does not establish effectiveness, lack of effectiveness, or comparative safety. The primary endpoint result, its precision, and the analysis details are not reported in the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable for the distinction between a clearly stated feasibility question and the absence of a posted primary outcome result. The record specifies what feasibility was intended to mean: successful catheter placement, reported improvement in shortness of breath, and routine home drainage. A well-defined outcome is essential for interpreting a study, but a definition alone does not provide evidence about how often the outcome occurred. The missing result prevents assessment of the endpoint’s observed frequency and uncertainty.

The single-group design also makes the estimand—the quantity a study seeks to estimate—descriptive rather than comparative. In general, a single-group study can characterize what occurred among participants in that group. It does not supply the counterfactual outcome that would have occurred under another strategy, which is needed to estimate a treatment contrast. Readers should keep that design limit in mind even when considering the clinical rationale described in the registry.

The endpoint combines practical implementation, a self-reported symptom, and home use documented by logs. These measures reflect different dimensions of feasibility and may be recorded in different ways. Statistical interpretation depends on how they were combined, how incomplete records were handled, and what counted as improvement. The registry record does not report those operational details or the analysis approach. That makes it difficult to determine precisely what a hypothetical overall result would represent.

Finally, enrollment and completion status are not substitutes for analysis results. The record states enrollment of 25 and marks the study completed, but it does not report how many participants contributed data to each endpoint component, any primary estimate, or an uncertainty interval. The statistical lesson is that design, outcome definitions, and complete reporting all matter: each contributes a different piece of evidence, and none can replace the others.

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 primary limitation for interpretation is that the registry record does not report a result for the stated primary endpoint. It gives no count meeting the feasibility definition and no component-specific result for placement, shortness of breath, or home drainage. Consequently, the main study question cannot be answered from the posted results, and the precision of any endpoint estimate cannot be judged.

The study is recorded as single-group, with allocation listed as NA and no masking. No comparator is described. This prevents a controlled estimate of how outcomes differ from another treatment or management approach and leaves observed outcomes open to explanations other than the intervention. The record does not report detailed eligibility criteria or participant characteristics, limiting assessment of who the findings would describe even if results were available.

The primary outcome has several elements, but the record does not specify how they were combined or classified. Shortness of breath is described as self-reported and descriptive; the record does not identify a measurement scale or a threshold for improvement. Home drainage is based on patient logs, but completeness and adjudication of those logs are not described. Participant-level follow-up, missingness, and the number contributing to each outcome are not reported.

The registry does not report a statistical analysis plan, the methods used for the primary outcome, an analysis population, or a sample-size justification. It also does not report interim analyses or stopping rules. Safety counts are limited and lack detailed event descriptions and collection methods. These gaps restrict interpretation of both efficacy-related outcomes and safety. The completed status does not resolve these reporting limitations.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Catheter Placement for Hepatic Hydrothorax — NCT02595567.
• Registry record last updated 2018-05-08; status last verified 2018-04.
• Results first posted 2018-05-08.
• 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

The registry record describes NCT02595567, “Catheter Placement for Hepatic Hydrothorax,” a completed, single-group study sponsored by Washington University School of Medicine. It lists enrollment of 25 and an indwelling tunneled pleural catheter as the intervention. Allocation is NA and masking is none. The recorded start date is 2010-10-01, with primary completion on 2015-07-20.

The primary outcome is feasibility, defined through successful placement, improvement in shortness of breath, and routine home drainage documented by patient logs. Assessment is described from catheter administration until a specified complication requiring removal or pleurodesis, whichever came first, assessed up to 12 months. The registry does not report a primary outcome result or an analysis.

For the ITPC group, the record lists 25 at risk and 0 affected for serious adverse events, 0 for other adverse events, and 0 deaths. The record does not report a comparator, statistical analysis plan, analysis population, or missing-data procedures.