A Renal Impairment Study for PF-04965842: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Renal Impairment Study for PF-04965842 (NCT03660241), a na phase 1 study. The primary outcome is Maximum Observed Plasma Concentration (Cmax) for PF-04965842.

2. Clinical Question

3. Trial Design

NCT03660241 is listed as a phase 1, non-randomized, open-label, single-dose, parallel-group study. The intervention was PF-04965842, described in the registry as an oral selective JAK 1 inhibitor. The study summary identifies participants with severe renal impairment and participants without renal impairment in Part 1, and participants with moderate renal impairment in Part 2. The registry lists an enrollment of 23 and a completed status.

Because allocation is listed as not applicable and masking as none, participants were not assigned through a randomized, blinded comparison as described in the registry. The groups were organized by renal-function status. This design can describe pharmacokinetic measurements in those groups, but it does not provide the protection against group differences that randomization is intended to provide. The record explicitly cautions that the arms are not a like-for-like control comparison.

The study start date is 2018-10-05, and the primary completion date is 2019-11-05. The registry record does not report the dose amount, detailed eligibility criteria, renal-function classification thresholds, or the rationale for the enrollment target. It also does not report whether interim analyses were planned or conducted, or provide a detailed statistical analysis plan. Those details should not be inferred from the phase, design, or enrollment information.

The record lists 12 outcome measures and 16 analyses. These counts describe the breadth of registered outcomes and analyses, but do not explain how analyses were selected, whether any were designated as exploratory, or how multiplicity was addressed. The primary endpoint was Cmax; several registered secondary outcomes concerned adverse events, laboratory abnormalities, vital signs, and electrocardiogram values.

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: The analysis population refers to all participants dosed who had at least 1 of the PK parameters of primary interest.

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 Maximum Observed Plasma Concentration (Cmax) for PF-04965842, measured over 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48 and 72 hours post-dose.

The primary endpoint was the maximum observed plasma concentration of PF-04965842, abbreviated Cmax. It describes the highest measured concentration in plasma during the specified post-dose observation schedule, with results expressed in nanograms per milliliter. The listed time points are 0 (pre-dose), 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 24, 36, 48 and 72 hours post-dose.

In general, Cmax is a pharmacokinetic measure used to characterize peak exposure after a dose. It can help describe how concentrations vary across groups or dosing conditions, but by itself it is not a measure of clinical benefit or long-term safety. Interpreting a difference between renal-function groups would require the actual group estimates and their uncertainty, together with the analysis approach and relevant study context.

The registry specifies that Cmax was summarized using a geometric mean, with a geometric coefficient of variation as the dispersion measure. These summaries are useful for concentration data that are analyzed on a multiplicative scale. The registry record does not report the observed Cmax estimates, the geometric coefficients of variation, or confidence intervals. The primary analysis population is defined as all participants dosed who had at least 1 of the pharmacokinetic parameters of primary interest.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does Cmax measure?

Cmax is the maximum observed plasma concentration after dosing. In general, pharmacokinetic studies collect concentration measurements over time and identify the highest observed value within the scheduled sampling period. For this study, the registry lists measurements from 0 (pre-dose) through 72 hours post-dose at the specified time points. The record does not report the individual concentration data or the observed maximum values.

The endpoint is a concentration measure, not a direct measure of a health outcome. It describes an aspect of drug exposure after the single dose. A Cmax comparison across groups can be informative about whether peak concentration patterns differ, but interpretation requires the actual estimates, their uncertainty, and clarity about the analysis population and methods. Those results are not reported in the registry record.

Why use a geometric mean?

The registry says that Cmax was summarized by a geometric mean and that dispersion was described with a geometric coefficient of variation. In general, a geometric mean summarizes values on a multiplicative scale: values are transformed, averaged on that scale, and expressed back in the original units. This can be suitable for positive concentration measurements when relative rather than absolute variation is central to the analysis.

In general, a geometric coefficient of variation describes the spread of values in relation to a geometric mean. It is not interchangeable with a standard deviation, and the two measures communicate variability in different ways. The registry record gives the selected summary measures but does not report their values or explain the distributional checks or transformations used in the analysis.

What does the group structure allow?

The study is described as non-randomized and parallel-group, with groups defined by renal-function status. In general, parallel groups allow measurements from separate participant groups to be described side by side. Because participants were not randomly assigned to renal-function categories, differences between groups may reflect characteristics beyond renal status. The record does not describe adjustment for such characteristics or provide a model that would account for them. It specifically cautions that the arms are not a like-for-like control comparison.

The study is open-label, and masking is listed as none. That describes the masking status; it does not establish whether any particular measurement was more or less susceptible to expectation or assessment effects. The registry does not provide further information about measurement procedures, laboratory methods, or quality-control procedures, so those features should not be assumed.

How should uncertainty be considered?

In general, a confidence interval expresses the uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision, while a wider interval indicates less precision. The registry record does not report confidence intervals for the primary endpoint, so the precision of any group estimates cannot be assessed from the listed outcome definition alone. No significance tests or primary endpoint estimates are reported in the registry record.

In general, small studies can yield imprecise estimates, particularly when results are divided across groups. The registry lists an enrollment of 23, but this fact alone does not establish the precision of the Cmax estimates. Group-specific analysis counts, observed variability, and the actual estimates would be needed to evaluate precision. The registry does not report a sample-size justification, and the enrollment should not be interpreted as evidence that the study had a particular level of power.

How do the planning illustrations differ from the trial design?

The sample-size assumptions describe planning illustrations based on the observed effect, not the study's own design. They specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. In general, such illustrations ask how many participants per arm might be needed under chosen assumptions; they are not observed power and do not establish what the investigators planned for this trial.

The illustrations are not a substitute for the registry's missing sample-size rationale or statistical plan. The record does not report that the trial used equal allocation, a normal approximation, or a particular target effect in its design. The sample-size assumptions also state that time-to-event calculations give a total number of events, while other calculations give participants per arm. That distinction describes the planning method; it does not turn those calculations into observed study results.

What do adverse-event counts describe?

The registry reports counts of participants at risk and affected for serious adverse events and for the other adverse-event category, along with deaths. These are counts, not adjusted comparisons, and the listed figures do not include an estimate of uncertainty. In general, safety counts from a study of this size are descriptive and may not characterize uncommon events precisely. The record does not report the event-term detail for serious events, and no serious-event terms are listed.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 12 outcome measures and 16 analyses, including the primary Cmax endpoint and secondary outcomes related to adverse events, laboratory abnormalities, vital signs, and electrocardiogram values. With multiple outcomes or analyses, the chance of obtaining a nominally unusual result can depend on how many comparisons are made and how they are interpreted. In general, multiplicity procedures can control or otherwise address this issue, but the registry record does not report whether any such procedure was planned or used.

The record does not provide a detailed statistical analysis plan, identify all analysis populations beyond the primary pharmacokinetic population definition, or explain how the 16 analyses relate to the 12 outcome measures. It does not state which analyses were primary, secondary, or exploratory beyond the named primary endpoint and listed secondary outcomes. Therefore, the analysis hierarchy and any adjustment for multiple testing are not reported in the registry record.

For the primary pharmacokinetic analysis, the registry defines the population as all participants dosed who had at least 1 of the pharmacokinetic parameters of primary interest. This definition does not explain how missing concentration measurements were handled, how many participants met the definition, or whether all scheduled samples were available. Imputation, exclusions, and other missing-data procedures are not reported in the registry record.

Missingness can affect interpretation if the availability of measurements is related to participant characteristics or outcomes. In general, the analysis should make clear how incomplete measurements were handled and whether the assumptions are plausible. Those details, along with any sensitivity analyses, are not reported in the registry record. Without the results and analysis details, it is not possible to assess the robustness of the primary endpoint findings or the effect of multiplicity.

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 5% reporting threshold.

Most frequent non-serious adverse event terms

The registry's serious adverse-event figures list 8 participants at risk and 0 affected in the normal renal function group, 7 at risk and 0 affected in the moderate renal impairment group, and 8 at risk and 0 affected in the severe renal impairment group. Deaths are listed as 0 in each group. No serious adverse-event terms are listed in the registry record.

For the other adverse-event category, the registry lists 8 participants at risk and 1 affected in the normal renal function group, 7 at risk and 1 affected in the moderate renal impairment group, and 8 at risk and 0 affected in the severe renal impairment group. These figures should be read as reported counts, not as evidence of a comparative treatment effect. They do not establish whether events were related to PF-04965842, and the record does not give event descriptions for these counts.

The registry also names treatment-emergent adverse events and several other safety outcomes among its secondary measures. The counts above do not replace those outcome details. The record does not report further information about event timing, severity, duration, or attribution. Zero affected participants in a listed group is a reported observation, not proof that the underlying risk is absent.

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

This study addresses the pharmacokinetic characterization of a single dose of PF-04965842 in participants with different renal-function statuses. The primary endpoint, Cmax, is a measure of peak observed plasma concentration. The registry's endpoint description and sampling schedule clarify what the study set out to measure, but the group estimates and their uncertainty are not reported in the registry record.

The available record therefore does not establish the size, direction, or precision of any difference in Cmax between groups. It also does not support a conclusion about whether renal-function status changes drug exposure. Such a conclusion would require the actual pharmacokinetic results and an assessment of uncertainty, not simply the endpoint name or the fact that the study was completed.

The design further limits causal interpretation. Participants were not randomized to renal-function groups, and the record cautions that the arms are not a like-for-like control comparison. If group measurements differ, the registry information does not show whether the difference can be attributed to renal function rather than other differences between participants. The study is single-dose, so its design description does not address repeated dosing or longer-term outcomes.

The safety figures are also limited. The record lists no serious adverse events and no deaths in the reported groups, as well as the specified counts in the other adverse-event category. These observations describe the registry entries; they do not demonstrate that all relevant risks have been characterized. The record does not include detailed event terms or broader safety results.

In general, a phase 1 pharmacokinetic study can characterize exposure under its study conditions. It should not be read as a direct assessment of clinical benefit, nor as a complete account of long-term safety. The registry does not report the dose amount, full results, or enough analysis detail to answer questions beyond the study's stated purpose and the limited counts recorded.

13. Why This Trial Matters Statistically

Renal function is a relevant context for describing drug pharmacokinetics because a study can examine whether measured exposure differs across groups with different renal status. This trial's statistical focus is the maximum observed plasma concentration of PF-04965842 after a single dose. Its parallel-group structure organizes that question by renal-function category, rather than by randomized treatment assignment.

The endpoint also illustrates why a result needs both a summary and an account of variability. A geometric mean describes the central level on a multiplicative scale, while the geometric coefficient of variation describes dispersion in relation to that scale. Without the actual estimates and variability measures, readers cannot judge the size or precision of any group pattern. The registry record does not report these primary results.

The design makes clear why descriptive comparisons and causal comparisons are not the same. Renal-function groups are not randomized arms, and the registry warns against treating them as like-for-like controls. Statistical interpretation must therefore attend to the way groups were formed and to the information that is absent, including adjustment methods and detailed analysis results.

The study also shows the distinction between outcome registration and outcome reporting. The record names 12 outcome measures and 16 analyses, but the presence of those entries alone does not reveal findings, uncertainty, or how multiple analyses were handled. Reporting counts for selected safety categories adds useful descriptive information, while leaving important details about events and the primary pharmacokinetic result unavailable.

For biostatisticians and clinical researchers, the central lesson is to separate the question a study was designed to examine from the conclusions its posted results can support. Here, the design and endpoint are clear, but the primary estimates and much of the analysis context are not reported in the registry record.

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.

The main limitation for interpreting this trial from the registry record is the absence of the primary Cmax results. The record identifies the endpoint, unit, sampling schedule, and summary statistics, but does not report the geometric means, geometric coefficients of variation, confidence intervals, or detailed comparisons. Without those results, the magnitude and precision of the pharmacokinetic findings cannot be assessed.

The non-randomized design is another important limitation for comparisons across renal-function groups. The groups were not described as randomized, and the record cautions that they are not like-for-like control arms. The registry does not report adjustment for participant characteristics or a model for comparing groups. The definitions and thresholds used to classify renal impairment are not reported in the registry record.

The study is described as single-dose, which limits what can be inferred about pharmacokinetics under repeated dosing. The dose amount and fuller dosing details are not reported in the registry record. Enrollment is listed as 23, but the record does not provide a sample-size justification or enough primary endpoint results to assess precision by group.

Several analysis details are also absent. The registry does not report how missing concentration measurements were handled, whether sensitivity analyses were performed, how multiplicity was addressed, or whether covariate adjustment was used. It lists safety counts but does not report event-term detail for serious adverse events or fuller descriptions of the other events. These omissions constrain interpretation; they should not be filled in by assumptions about common phase 1 practice.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Renal Impairment Study for PF-04965842 — NCT03660241.
• Registry record last updated 2022-03-22; status last verified 2022-03.
• Results first posted 2020-12-17.
• 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.

18. Record Summary

NCT03660241, titled A Renal Impairment Study for PF-04965842, is listed as a completed phase 1 study sponsored by Pfizer. The registry describes a non-randomized, open-label, single-dose, parallel-group study of PF-04965842 in participants with renal impairment and participants with normal renal function. Enrollment is listed as 23. The study started on 2018-10-05, and its primary completion date is 2019-11-05.

The primary outcome was maximum observed plasma concentration (Cmax), summarized using a geometric mean and geometric coefficient of variation. The record lists 12 outcome measures and 16 analyses, as well as selected adverse-event counts by renal-function group. The primary Cmax results and detailed statistical analysis plan are not reported in the registry record.