Pentoxifylline Treatment in Acute Pancreatitis (AP): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pentoxifylline Treatment in Acute Pancreatitis (AP) (NCT02487225), a randomized phase 3 study. The primary outcome is Change in C-reactive Protein (C-RP) From Admission Baseline at One Week..

2. Clinical Question

3. Trial Design

This was a Phase 3, randomized, quadruple-masked, parallel-group trial comparing pentoxifylline with placebo in acute pancreatitis. Mayo Clinic is listed as the sponsor. The study status is completed. Its listed start was 2015-05, and its primary completion date was 2017-04-30. The registry lists enrollment of 83.

The treatment description specifies pentoxifylline 400 mg by mouth 3 times daily from enrollment until 72 hours from enrollment, with a maximum of 9 doses. The placebo description gives the same dosing frequency and period, also with a maximum of 9 doses. The registry describes the masking as quadruple, but does not specify in the record which roles were masked or how masking was maintained. Further details about random-sequence generation, allocation concealment, or protocol procedures are not reported in the registry record.

The endpoint population description lists 45 subjects in the treatment arm and 38 in the placebo arm. It reports that 18 treatment-arm subjects and 8 placebo-arm subjects completed the study. It also says blood collections were taken for 5 days or until dismissal, and that many subjects were dismissed at 2-3 days. This makes follow-up duration relevant to interpretation of the planned C-RP measurement: not every participant is described as having blood collections through the full stated collection period.

The registry lists 4 outcome measures and 8 analyses. It does not provide enough detail to reconstruct the complete outcome schedule, the intended analysis populations, or the statistical plan. In particular, the protocol, sample-size justification, interim-analysis plan, and prespecified handling of missing measurements are not reported in the registry record. The record's completion status indicates the study is listed as completed, but does not by itself establish how completely the outcomes were observed or reported.

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: Eighteen (18) of forty-five subjects (45) in the treatment arm and eight (8) of thirty-eight (38) subjects in the placebo arm completed the study. Additionally, subjects had blood collections for 5 days or until dismissal. Many subjects were dismissed at 2-3 days.

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 Change in C-reactive Protein (C-RP) From Admission Baseline at One Week., measured over Admission (baseline), day 5.

The primary endpoint is titled change in C-reactive protein (C-RP) from admission baseline at one week. C-RP is a substance produced by the liver in response to inflammation, and the registry describes it as a marker relevant to inflammation. The unit is mg/L, and the endpoint is summarized as a mean with standard deviation. The registry states that normal C-RP levels are below 3.0 mg/L.

In general, a change-from-baseline endpoint compares a participant's measurement after enrollment with that participant's baseline measurement. Comparing the average change between randomized groups can describe whether their observed trajectories differed over the measured period. It is important to distinguish such a comparison from a comparison of values at a single follow-up time: change incorporates both the follow-up value and the baseline value.

The endpoint wording specifies one week, while the listed timeframe says admission (baseline), day 5. The record also says blood collections continued for 5 days or until dismissal, and many subjects were dismissed at 2-3 days. These statements do not establish that all participants contributed a day-5 value or a one-week value. The registry record does not report the group means, the mean change in either arm, or a between-arm estimate. Thus, the direction and magnitude of the primary endpoint result are not available in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean change represent?

In general, a continuous endpoint such as C-RP can be summarized by a mean, which describes the average measured value in the analyzed group. A change-from-baseline measure is formed by comparing each participant's follow-up measurement with that participant's baseline measurement, then summarizing those changes. A difference between group mean changes is a between-arm contrast. Its interpretation depends on the time point, the participants included, and the method used to handle incomplete measurements.

The registry identifies the primary measure as a mean and its dispersion as a standard deviation. In general, a standard deviation describes how spread out individual measurements are around the group mean. It is not the same as a confidence interval: a standard deviation describes variation among measurements, while a confidence interval expresses uncertainty about an estimated quantity. The registry record does not report the primary means, standard deviations, contrast, or confidence interval, so none of these quantities can be interpreted for this trial.

Why does the measurement schedule matter?

For a change endpoint, the timing of the follow-up measurement is part of the definition of the result. The primary outcome title refers to one week, while the listed timeframe names admission (baseline) and day 5. The collection description says blood was collected for 5 days or until dismissal, and many participants were dismissed at 2-3 days. In general, differing measurement times can represent differing stages in a participant's course; measurements at different times should not automatically be treated as interchangeable. The record does not clarify which time point or summary was used in the primary analysis.

How should uncertainty be assessed?

In general, an estimate is more informative when presented with a confidence interval, because the interval shows a range of values compatible with the observed data under the analysis assumptions. A p-value, if reported, addresses compatibility with a specified null hypothesis under a statistical model; it does not express the size of an effect or the probability that a hypothesis is true. A confidence interval and a p-value answer related but distinct questions. Neither the primary confidence interval nor a primary test result is reported in the registry record. The registry results therefore do not permit an assessment of statistical uncertainty around the treatment contrast.

What can randomization and masking contribute?

In general, random assignment aims to make treatment groups comparable at the start of a trial, including with respect to factors that may not have been measured. Masking can reduce the influence of knowledge about assignment on participant experience, care, measurement, or assessment. The record describes randomized allocation and quadruple masking, but does not specify the masked roles or the implementation details. These design labels do not replace reporting of the outcome estimates, missing-data methods, and analysis procedures needed to interpret the result.

What does the planning illustration mean?

The registry record describes a planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It says that the effect to detect is expressed as a stated fraction of the observed effect, and that non-time-to-event outputs are participants per arm. Such calculations are hypothetical planning illustrations: they ask how many participants per arm would be needed under the stated assumptions to detect a specified effect. They are not the trial's observed power, and they do not establish that the study was designed with those assumptions. The registry record does not give a sample-size justification for the trial. The numerical planning outputs are not reported in the record summarized in these results.

Why do distributional assumptions matter?

General explanation: a normal approximation is a modeling choice that can be useful for estimating uncertainty or planning sample sizes. It may be less suitable when measurements are highly skewed or when a small number of observations have a large influence on the mean. C-RP measurements can be examined using distributional summaries and plots, but the registry record does not report the distribution of the trial's measurements or any diagnostic checks. A standard deviation alone would not establish that a normal model is appropriate.

General explanation: over-dispersion means that observed variability is greater than a model assumes. When that occurs, standard errors based on the narrower assumed variability can understate uncertainty. The term is most often used for count outcomes, but the broader principle applies to model assumptions for continuous data as well: uncertainty estimates need to reflect the actual variability and analysis structure. The registry record does not report evidence of over-dispersion, nor does it report the model used for the primary endpoint.

Which analysis details remain unknown?

The registry lists multiple outcomes and analyses, and notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not identify a single reported primary contrast or provide the complete statistical methods. The choice of analysis population, any adjustment for baseline C-RP, the treatment of repeated observations, and the handling of missing data are not reported in the registry record. Without these details and the corresponding estimates, the result cannot be reconstructed from the registry information.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 4 outcome measures and 8 analyses. It also notes that the primary outcome has several categories or time points and was not reduced to one comparison. When a study considers multiple outcomes, time points, or comparisons, the chance of at least one apparently unusual result can increase. General statistical practice may address this through a prespecified primary contrast, an adjustment for multiple comparisons, or a clear distinction between confirmatory and exploratory analyses. The registry record does not report a multiplicity strategy, so it is not possible to determine whether or how the analyses accounted for multiple testing.

Missing measurements are a particular concern for the C-RP outcome. The population description says 18 of 45 treatment-arm subjects and 8 of 38 placebo-arm subjects completed the study. It also states that blood collections continued for 5 days or until dismissal and that many subjects were dismissed at 2-3 days. These registry entries indicate that completion and measurement availability need to be considered separately. The record does not say how many participants contributed to the primary analysis, whether measurements after dismissal were unavailable, or how missing observations were handled.

In general, complete-case analysis uses participants with the required measurements, while other methods may use available repeated observations or make assumptions about missing values. Different approaches can yield different estimates, particularly when the reason for missingness is related to health status or outcome values. The registry record does not identify the method used or the assumptions made. The intended analysis population, whether all randomized participants were included, and any sensitivity analyses for missing data are not reported in the registry record. This prevents assessment of how attrition may have affected the primary comparison.

11. 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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: hospitalized for psychological evaluation, considered a danger to self (2.2%).

The registry reports serious adverse events in 1 of 45 participants in the pentoxifylline group and 0 of 38 participants in the placebo group. It lists 12 participants in the treatment group and 5 in the placebo group with other adverse events. The death counts are 2 in the pentoxifylline group and 0 in the placebo group. A serious adverse event term listed in the registry is “Hospitalized for psychological evaluation, considered a danger to self,” with a reported value of 2.2%.

These are descriptive counts. By themselves, they do not establish whether an event was caused by the assigned treatment, nor do they show how the event counts were defined, adjudicated, or distributed over time. The registry record does not provide additional event narratives or enough detail to reconcile the listed serious-event term with the group-level figures. The counts also do not quantify uncertainty around differences between groups. Rare events can be difficult to compare precisely in a trial of this size, and no comparative safety estimate or confidence interval is reported in the registry record.

The death counts should be read as reported counts, not as an estimate of treatment effect. No conclusion about comparative safety can be drawn from these figures alone.

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

The registry record establishes that a randomized, quadruple-masked, placebo-controlled trial of pentoxifylline in acute pancreatitis was conducted and is listed as completed. It identifies mean change in C-RP as the primary endpoint and gives the intended treatment schedule and measurement description. It also reports arm sizes in the endpoint population description, completion counts, and selected adverse-event counts.

What the record does not establish is the primary treatment contrast. Numerical arm-level C-RP changes, a between-arm estimate, its uncertainty, and a test result are not reported in the registry record. The record also does not resolve the difference between the endpoint title's one-week wording and the timeframe's day-5 wording. As a result, the statistical direction, magnitude, and precision of the primary result cannot be determined from the available registry information.

This absence should not be interpreted as evidence of no difference, nor as evidence of a difference. Statistical interpretation requires the estimate and its uncertainty, together with information about the analyzed participants and the measurement time. Completion counts and collection details raise relevant questions about missing data, but they do not reveal how the primary analysis handled incomplete measurements.

The adverse-event figures likewise describe reported counts rather than comparative causal effects. They should be considered in the context of the group sizes and the limited detail available, without treating a numerical difference in counts as proof of a treatment-related effect.

Overall, the registry record is useful for identifying the design, planned primary measure, and some safety counts. It does not contain enough primary outcome information to judge the observed C-RP contrast or its precision. A fuller interpretation would require the trial's reported outcome estimates, analysis methods, and accounting of participants and measurements.

13. Why This Trial Matters Statistically

This trial illustrates why a registry record needs to be read at more than the level of its design labels. Randomization, masking, a placebo comparator, and a defined primary endpoint describe important features of a study, but they do not themselves show the estimated treatment contrast. In this record, the primary endpoint is named and its general measurement is described, yet the arm-level results and uncertainty are not reported.

The record also highlights the importance of aligning endpoint wording, measurement timing, and data availability. The endpoint title refers to one week, its timeframe identifies day 5, and the collection description allows sampling until dismissal, with many participants dismissed at 2-3 days. These details make it necessary to know which measurements entered the analysis and how the chosen time point was defined. Without that information, even a nominally clear endpoint label may not fully describe the analyzed quantity.

Completion is another statistical issue, not merely an administrative detail. The reported completion counts differ from the arm counts listed in the endpoint population description. For a repeated measurement outcome, the relevant number of observations can depend on whether participants posted the measurements at the specified time. The registry record does not report the analysis population or missing-data method, so the consequences of incomplete follow-up cannot be assessed.

Finally, the record's note that the primary outcome has several categories or time points and was not reduced to one comparison demonstrates why prespecification and multiplicity reporting matter. A clearly identified contrast, accompanied by an estimate and confidence interval, helps readers distinguish the principal question from other analyses. Those details are not reported in the registry record. The statistical lesson is that design information and outcome reporting are complementary: both are needed for a transparent interpretation.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

Several trial-specific limitations of interpretation arise from the registry information. First, the primary endpoint result is not numerically reported. No arm means, mean changes, between-arm estimate, confidence interval, or test result is available, so the magnitude and precision of the primary comparison cannot be assessed.

Second, the endpoint time description is not fully aligned. The title refers to change at one week, while the timeframe lists admission (baseline), day 5. The collection description says blood samples were taken for 5 days or until dismissal, and that many subjects were dismissed at 2-3 days. The record does not clarify the analyzed time point or how measurements from participants dismissed earlier were treated.

Third, the endpoint population description reports 18 of 45 treatment-arm subjects and 8 of 38 placebo-arm subjects completed the study. The record does not state how many participants had the measurements required for the primary analysis, define the analysis population, or describe missing-data methods. This limits assessment of possible attrition effects.

Fourth, the registry does not report the statistical plan, multiplicity handling, baseline-adjustment strategy, or analysis model for the primary outcome. It notes that the primary outcome has several categories or time points and was not reduced to one comparison. This leaves the intended primary contrast unclear in the reported results. The record also does not provide details of randomization or masking implementation.

Finally, adverse-event counts are presented without detailed event narratives or comparative uncertainty estimates. These counts alone cannot establish causation or a precise difference in risk. The limitations are limitations of what can be interpreted from the registry record; they do not determine what the complete trial report may contain.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Pentoxifylline Treatment in Acute Pancreatitis (AP) — NCT02487225.
• Registry record last updated 2019-01-23; status last verified 2019-01.
• Results first posted 2019-01-23.
• 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.

18. Record Summary

The registry record describes a completed Phase 3, randomized, quadruple-masked, parallel-group trial sponsored by Mayo Clinic. It compares oral pentoxifylline with placebo in acute pancreatitis. The pentoxifylline regimen was 400 mg 3 times daily from enrollment until 72 hours from enrollment, for up to 9 doses; placebo followed the same schedule.

The primary endpoint is mean change in C-RP from admission baseline, with the title referring to one week and the listed timeframe identifying day 5. The endpoint population description lists 45 treatment-arm subjects and 38 placebo-arm subjects, with 18 and 8 completing the study, respectively. Blood collections were described as continuing for 5 days or until dismissal, and many subjects were dismissed at 2-3 days.

The record reports selected adverse-event and death counts but does not report the primary outcome estimates or their uncertainty. It also does not report the primary analysis population, missing-data method, or multiplicity approach. Accordingly, the primary C-RP comparison cannot be quantitatively interpreted from the registry record.