Open-label Study of Tofacitinib for Moderate to Severe Skin Involvement in Young Adults With Lupus: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Open-label Study of Tofacitinib for Moderate to Severe Skin Involvement in Young Adults With Lupus (NCT03288324), a na phase 1, phase 2 study. The primary outcome is Oral Clearance (CL/F) (Cohort 1 Only).

2. Clinical Question

3. Trial Design

This was an open-label, single-group Phase 1/2 study of tofacitinib, with the study summary describing it as a 3-part Phase 1b/2 trial. It enrolled 13 participants and is recorded as completed. The registry dates are 2017-08-23 for study start and 2022-11-01 for primary completion. The study summary describes a 76-week study of young adults aged 18 to 45 with moderately to severely active lupus-related skin involvement.

The study was intended to examine pharmacokinetics, pharmacodynamics, safety, tolerability, and preliminary effectiveness. Its primary endpoint focused on oral clearance in Cohort 1 on Day 5. Secondary outcomes listed include the CLASI Activity Score, several pharmacokinetic measures for Cohort 1, and total adverse events for Cohorts 1 and 2. The registry lists 12 outcome measures overall, but the numerical results for the primary endpoint and the listed secondary measures are not reported in the registry record.

The study summary identifies Cincinnati Children's Hospital Medical Center and MetroHealth Medical Center in Cleveland as study locations. The sponsor is Children's Hospital Medical Center, Cincinnati. Because the design has one treatment group and no randomized comparator, changes observed during participation cannot by themselves distinguish treatment effects from time trends, other care, or variation in measurement. The record does not report a detailed protocol, allocation procedure beyond allocation being not applicable, or the sequence and content of the three parts.

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: Tofacitinib PK was collected from in total of 8 patients, PK parameters were generated for N=7 patients. The PK data for one patient was not used when generating the PK parameters and descriptive summaries due to a dosing event error.

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 Oral Clearance (CL/F) (Cohort 1 Only), measured over Day 5.

The primary endpoint was oral clearance, CL/F, for tofacitinib in Cohort 1 on Day 5. It is described as the apparent total clearance of the drug from plasma after oral administration, measured in L/hr. The registry specifies a geometric mean and geometric coefficient of variation. The endpoint is a pharmacokinetic measure: it characterizes drug disposition rather than directly measuring lupus skin activity or a clinical benefit.

In general, oral clearance summarizes the relationship between drug exposure and the amount administered by mouth. The “apparent” designation matters because oral administration does not independently establish how much drug reaches systemic circulation. A geometric mean is often used for pharmacokinetic measurements when values are positively skewed; the geometric coefficient of variation describes relative spread on a multiplicative scale. These are general statistical interpretations of the measures, not findings about this study’s distribution.

The registry states that pharmacokinetic data were collected from 8 patients and parameters were generated for N=7 patients. Data for one patient were not used to generate the pharmacokinetic parameters and descriptive summaries because of a dosing event error. The actual CL/F estimate and its dispersion are not reported in the registry record, so the magnitude and precision of the primary endpoint cannot be assessed from the posted record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary measure as a geometric mean with geometric coefficient of variation. These statistics are commonly used for positive-valued pharmacokinetic quantities, which can vary multiplicatively and may be asymmetric on their original scale. A geometric mean summarizes the center after a logarithmic transformation and then expresses that center on the original scale. A geometric coefficient of variation describes relative dispersion rather than an absolute spread in L/hr. These are general explanations of the statistical measures; the registry does not report the calculation details or the observed values for this study.

What does the primary measure represent?

CL/F is apparent oral clearance: a summary of drug removal from plasma relative to oral dosing, expressed in L/hr. In general, a pharmacokinetic endpoint can help characterize exposure and drug disposition. It is different from a disease activity endpoint such as the listed CLASI Activity Score. The record specifies Day 5 and Cohort 1 for the primary measure, but does not report the actual estimate, its geometric coefficient of variation, or an inferential interval. No claim about the precision of the estimate can therefore be made from the registry record.

Why does the analysis population matter?

The registry says pharmacokinetic data were collected from 8 patients and that parameters were generated for N=7 patients. It also states that one patient’s data were not used to generate pharmacokinetic parameters and descriptive summaries because of a dosing event error. A result based on the parameter-generating set would not have the same denominator as the enrollment total of 13. The registry does not give further detail about the event, the exact analysis procedure, or whether any alternative analysis was conducted. Those details are not reported in the registry record.

In general, excluding data can affect both the estimate and its uncertainty, especially in a small study. Whether exclusion is appropriate depends on the reason, prespecified rules, and the way the data were affected. Here, the stated dosing event provides the registry’s reason for not using that patient’s data in the pharmacokinetic summaries, but the record does not report a complete missing-data plan or sensitivity analysis. No conclusion about the impact of the exclusion is possible without the patient-level data and analysis details.

How should a confidence interval be understood?

In general, a confidence interval expresses the uncertainty around an estimate under a specified statistical procedure. A narrow interval indicates greater statistical precision than a wide interval, while neither width nor location alone establishes clinical importance. The registry record does not report a confidence interval for CL/F or for the listed secondary outcomes. It also does not report a standard error, a model-based estimate, or a hypothesis-test result for these outcomes. Precision therefore cannot be quantified from the posted results.

What can a single-group design establish?

The study has one treatment group and is open-label. In general, a single-group design can describe outcomes observed among participants receiving the study intervention, but it cannot use randomized between-group comparisons to control for factors that change over time or differ between participants. Open-label assessment can also be susceptible to expectations or knowledge of treatment, particularly for outcomes involving judgment or participant reporting. These are general design considerations, not evidence that a particular bias occurred in this study. The record does not report procedures intended to assess or reduce such effects.

The registry lists no statistical analyses. It does not specify a statistical model for the primary endpoint, covariate adjustment, a plan for handling repeated assessments, or a method for estimating uncertainty. These details are not reported in the registry record. The lack of a posted analysis means the reader cannot determine whether the reported endpoint was intended to be descriptive only or whether an inferential procedure was planned outside the registry entry.

What do the planning illustrations mean?

The planning assumptions describe an illustration based on a stated fraction of an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. In general, such calculations estimate the sample size that would be needed under their assumptions to detect a specified effect with a chosen power. They are planning illustrations, not observed power and not evidence that the trial had those design features. This study itself is recorded as a single-group design with allocation not applicable, so an equal-allocation two-arm scenario is not a description of its actual treatment assignment.

For time-to-event calculations, the stated convention is to give a total number of events; for other calculations, the convention is participants per arm. These are general planning conventions. The record does not report a trial-specific sample-size justification, power target, or planned minimum detectable effect. It also does not provide numerical planning results in the information available for this analysis. Such illustrations cannot substitute for the missing primary endpoint estimate or an analysis comparing randomized groups.

Over-dispersion is a general concern when observed variation exceeds what a statistical model assumes. If a model underestimates variability, uncertainty estimates may be too small and inferential conclusions may be overly confident. The registry does not report a model or an over-dispersion assessment for this trial, so there is no basis to say that over-dispersion occurred or was addressed. More broadly, the available record supports a description of design and selected counts, but not a reconstruction of the statistical methods or a reanalysis of unreported results.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists multiple outcome measures spanning pharmacokinetics, skin disease activity, and safety. When several outcomes or repeated analyses are examined, the chance of at least one apparently notable result can increase unless the analysis plan addresses multiplicity. In general, a multiplicity strategy may prioritize an endpoint, define a testing sequence, or adjust inference. The registry record does not report a multiplicity plan, a hierarchy among the secondary outcomes, or which outcomes would receive confirmatory interpretation.

The record identifies oral clearance as the primary endpoint and names the CLASI Activity Score and several pharmacokinetic and safety measures as secondary outcomes. It lists 12 outcome measures overall. However, it does not report numerical results for the primary endpoint or the listed secondary outcomes in the information available. It also lists no statistical analyses. Without a posted analysis plan and results, it is not possible to assess whether multiplicity was handled or how conclusions were intended to account for the number of outcomes.

Missing-data reporting is limited. The record states that pharmacokinetic data were collected from 8 patients, with parameters generated for N=7, because one patient’s data were not used after a dosing event error. This identifies one exclusion from pharmacokinetic parameter generation, but does not describe missingness or exclusions for the other outcomes. A general distinction is important: an unusable measurement due to a dosing event is not automatically equivalent to an ordinary missing observation, and the implications depend on the protocol and analysis.

The registry does not report the analysis populations for all outcomes, rules for incomplete follow-up, imputation methods, sensitivity analyses, or the handling of withdrawals. Those details are not reported in the registry record. The enrollment count of 13 therefore cannot be assumed to be the denominator for every outcome. The available pharmacokinetic population counts are specific to that endpoint and should not be generalized to the other measures.

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: pelvic inflammatory disease (9.1%), appendicitis (9.1%), migraine with aura (9.1%).

For Cohorts 1 and 2 combined, the registry reports 11 at risk for serious adverse events and 1 affected. It reports 11 at risk for other adverse events and 9 affected. Deaths are reported as 0. The top serious-event terms are pelvic inflammatory disease, appendicitis, and migraine with aura; each is paired with a registry-reported value of 9.1%.

These are safety counts for the recorded study group, not a comparison against an untreated or randomized control group. The serious-event terms and percentages do not by themselves show whether events were related to tofacitinib, when they occurred, how long they lasted, or how they were managed. Those details are not reported in the registry record. The record also does not give enough information to determine whether one participant experienced more than one event or how event terms were classified. The figures describe the posted safety summary and should not be interpreted as a causal estimate.

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

The study asks a pharmacokinetic question about oral clearance in Cohort 1 on Day 5, while also listing disease activity, other pharmacokinetic outcomes, and safety measures. The record establishes that 13 participants enrolled and that the study was open-label and single-group. It also reports that pharmacokinetic parameters were generated for N=7 patients from data collected from 8 patients, with one patient’s data excluded from parameter generation and descriptive summaries because of a dosing event error.

Those details do not reveal the size of the CL/F estimate, its variability, or its precision. The numerical primary endpoint result is not reported in the registry record. Numerical results for the listed CLASI Activity Score and other secondary outcomes are also not reported. Thus, the registry entry cannot support a conclusion about the amount of change in skin activity or the magnitude of the pharmacokinetic findings.

Even if within-group changes were reported, a single-group design would not provide a randomized comparator for separating changes associated with the intervention from other explanations. The study’s open-label nature is also relevant when interpreting outcomes that may involve assessment or participant reporting. These are general limitations of the design; they do not demonstrate that bias occurred.

The safety summary reports serious and other adverse-event counts and zero deaths, alongside three listed serious-event terms. These observations are descriptive. Without a comparator and without event-level details, they cannot establish whether treatment caused an event or provide a comparative risk estimate. The registry record does not report event relatedness, timing, or the complete clinical context.

Accordingly, the record documents the study’s purpose, structure, selected analysis counts, and limited safety observations. It does not report the primary numerical result or enough statistical detail to judge its precision. These limitations mean the posted record is insufficient for a treatment-effect conclusion, but they do not establish that an effect is absent.

13. Why This Trial Matters Statistically

This trial is statistically notable for the mismatch between its broad clinical aims and its primary endpoint. The study summary describes pharmacokinetic and pharmacodynamic properties, safety, tolerability, and preliminary effectiveness, but the primary outcome is oral clearance in Cohort 1. That endpoint characterizes drug disposition; it is not itself a direct measure of lupus skin activity. The CLASI Activity Score appears among the secondary outcomes, but its numerical result is not reported in the registry record.

The study also illustrates why analysis denominators matter. Although enrollment was 13, pharmacokinetic parameters were generated for N=7, from data collected from 8 patients. The record attributes the exclusion of one patient’s data from parameter generation and descriptive summaries to a dosing event error. Reading the endpoint without its population count could give an incorrect impression of how many observations contributed.

A single-group, open-label design can be appropriate for describing early pharmacokinetic and safety observations, but it cannot provide a randomized comparison. This distinction is important when interpreting any apparent change over time: without a control group, the observed course cannot be separated statistically from other influences using a between-group contrast.

The registry’s limited numerical reporting further constrains interpretation. It provides selected safety counts, but not the primary endpoint estimate, its dispersion, a confidence interval, or listed secondary outcome results. The case therefore demonstrates that a clearly named endpoint and an explicit design do not alone allow assessment of magnitude or precision; the numerical results and analysis details are also essential.

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 primary limitation is that the numerical oral clearance result is not reported in the registry record. Although the endpoint definition includes the unit, summary measure, dispersion measure, cohort, and time point, no estimate or uncertainty measure is available. The listed secondary outcomes likewise lack numerical results in the record, including the CLASI Activity Score.

The study enrolled 13 participants and had no randomized comparator. Its open-label, single-group structure limits causal interpretation and does not permit a controlled treatment-effect estimate. The record describes a 76-week study and identifies Cincinnati and Cleveland locations, but does not report the timing or completeness of outcome assessments across that period.

For pharmacokinetics, data were collected from 8 patients and parameters were generated for N=7, with one patient’s data excluded due to a dosing event error. The record does not report further information about that event or its possible effects on other measures. Nor does it provide analysis populations for all outcomes, missing-data rules, sensitivity analyses, or a complete statistical analysis plan.

The registry lists 12 outcome measures but does not report statistical analyses or a multiplicity strategy. It also does not report a trial-specific sample-size justification, power target, or the rationale for the enrollment target. These details are not reported in the registry record. The available safety figures are limited to counts and listed serious-event terms, without event timing, relatedness, or fuller clinical context.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Open-label Study of Tofacitinib for Moderate to Severe Skin Involvement in Young Adults With Lupus — NCT03288324.
• Registry record last updated 2026-03-03; status last verified 2026-02.
• Results first posted 2024-07-30.
• 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

NCT03288324 is a completed, open-label, single-group Phase 1/2 study of tofacitinib in young adults aged 18 to 45 with moderate to severe lupus-related skin involvement. Enrollment was 13. The registry dates study start as 2017-08-23 and primary completion as 2022-11-01; the study summary describes a 76-week, 3-part Phase 1b/2 study.

The primary endpoint was Cohort 1 oral clearance on Day 5, expressed as a geometric mean in L/hr with geometric coefficient of variation. Pharmacokinetic parameters were generated for N=7 patients from data collected from 8; one patient’s data were excluded because of a dosing event error. The primary numerical result is not reported in the registry record. Safety reporting for Cohorts 1 and 2 includes 1 serious adverse event affected among 11 at risk, 9 affected by other adverse events among 11 at risk, and 0 deaths.