Prineo Sensitivity Dressing Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prineo Sensitivity Dressing Study (NCT06011603), a non-randomized phase 4 study. The primary outcome is Number of Participants With Contact Allergic Dermatitis or Adverse Skin Reaction at 1 Week Post Surgery.

2. Clinical Question

The clinical context described in the registry is concern about wound complications after joint arthroplasty and possible allergic skin reactions associated with Prineo dressing. The study is intended to assess reactions in people with and without previous exposure. That question is clinically relevant because prior exposure is the defining distinction between the groups, while the dressing used in each group is the same.

The comparison should be interpreted as an observational contrast between exposure histories, not as an estimate of the effect of Prineo versus another dressing. Because the groups were not randomly assigned and there is no alternative-dressing group described, the record cannot isolate the effect of using Prineo from other differences between people classified by prior exposure. The endpoint result needed to describe the allergic-reaction frequency is not reported in the registry record.

3. Trial Design

The registry identifies this as a Phase 4, prospective study with nonrandomized allocation, no masking, and a single-group model. Its enrollment is 303. The record lists Rush University Medical Center as sponsor and marks the study completed. The recorded study start is 2023-08-17, and the primary completion date is 2024-11-01.

The study description presents a prospective controlled design to assess adverse allergic reactions in patients who are Prineo-naive and patients with previous exposure. In the arm descriptions, both groups receive Prineo dressing. The Prineo-naive group is defined as patients without previous joint replacement surgery. The Prineo-exposed group includes patients who have undergone previous hip or knee joint replacement and received Prineo dressing, and it also includes people with prior glue or mesh dressing exposure as a patient or healthcare worker.

Although the study description calls the design controlled, the registry records allocation as nonrandomized and notes that the arms are not a like-for-like control comparison. Group membership is determined by prior exposure rather than random allocation. This matters because baseline characteristics and exposure histories may differ between groups, and the posted record does not describe an adjustment strategy to address such differences.

The intervention is Prineo dressing. The primary outcome is the number of participants with contact allergic dermatitis or an adverse skin reaction at 1 week after surgery. A secondary outcome is the number of participants with postoperative complications. The registry lists three outcome measures, but it records no analyses and does not report the primary endpoint result. Details of the other outcome measures and their results are not reported in the registry record.

The registry does not report a detailed statistical analysis plan, a sample-size justification, planned interim analyses, or methods for handling group differences. The completed status therefore indicates the study's registry status, but it does not supply the missing endpoint estimates or establish that the planned comparison was analyzed.

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 Number of Participants With Contact Allergic Dermatitis or Adverse Skin Reaction at 1 Week Post Surgery, measured over 7 days post surgery.

The primary endpoint is the number of participants with contact allergic dermatitis or an adverse skin reaction at 1 week after surgery. The unit is participants, and the registry describes the assessment as using a classification of skin reactions from mild to severe. This is a binary participant-level outcome for whether a qualifying reaction was recorded at the specified follow-up, although the registry description also indicates that reaction severity is classified.

Such an endpoint is used to describe how often the reaction occurs in the population being followed. Reporting participants with an event, rather than only describing symptoms in general terms, can make the event frequency interpretable across groups. A severity classification can also preserve information about the range of recorded reactions, rather than treating every reaction as clinically identical. These are general properties of event endpoints; the registry record does not report how severity categories were operationalized or whether they were analyzed separately.

The 1-week assessment defines the endpoint's time point. It does not, by itself, describe reactions arising outside that follow-up or establish the longer-term course of a skin reaction. The registry provides no additional follow-up details for this endpoint in the available record.

Most importantly, the endpoint definition is not an endpoint result. The registry does not report the number of participants with contact allergic dermatitis or another adverse skin reaction in either group. The adverse-event record lists separate serious-event and other-event fields, but those entries should not be substituted for the specifically defined primary endpoint. Without the primary endpoint counts and corresponding group denominators, the reported frequency and the contrast between exposure groups cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a prospective study, but records no analyses. That distinction is important: the design tells readers how the groups were formed and what was intended to be measured, while the analysis record would show how the outcome data were compared. In this record, the primary endpoint is defined, but no statistical estimate or test of that endpoint is reported.

What does nonrandomized allocation mean?

In a randomized study, assignment to groups is determined by a chance process. Here, allocation is recorded as nonrandomized, and group membership is based on prior Prineo exposure. One group is described as Prineo-naive; the other includes people with previous joint replacement and Prineo dressing, along with people who have had prior exposure to glue or mesh dressing as a patient or healthcare worker. The comparison therefore reflects differences between exposure-history groups, not assignment to different dressings.

Randomization is used in general to reduce systematic differences between groups, on average. Without it, group differences in the outcome may be related to other differences between patients as well as exposure history. Statistical adjustment can sometimes account for measured characteristics, but it cannot guarantee removal of confounding, especially from characteristics not measured or not included in an analysis. The registry does not report adjustment methods or which characteristics would be considered.

How should a binary endpoint be analyzed?

The primary endpoint records whether each participant had contact allergic dermatitis or another adverse skin reaction at 1 week after surgery. For a binary outcome, a basic summary would report the number with the event and the number assessed in each group. A comparison might then describe group-specific event frequencies and an effect measure with uncertainty. These are general analytical options, not methods reported for this study. The registry provides no primary endpoint counts, group-specific estimates, confidence intervals, or test results.

A confidence interval is a statistical range expressing uncertainty around an estimated quantity under an analysis model. It helps distinguish a precisely estimated result from one with substantial uncertainty. An interval's interpretation depends on the analysis and assumptions; it does not establish causation or correct for bias in group formation. No confidence interval for the primary endpoint is reported in the registry record.

Why does the denominator matter?

For an event frequency, the denominator is the number of participants whose outcome status is known or included in the analysis. The registry's adverse-event entries give at-risk counts, but those are not identified as the primary endpoint denominators. The record does not state how many participants had an assessment at 1 week, how many lacked outcome information, or whether all enrolled participants were analyzed. Without those details, an endpoint frequency cannot be reconstructed or interpreted.

In general, excluding participants with missing outcome data can bias a result if the probability of missingness is related to the outcome or to group membership. Statistical methods for missing data depend on why data are missing and on assumptions about that process. The registry does not describe a missing-data method, so no assumption about the completeness of follow-up is justified.

What can a zero event entry establish?

The adverse-event record lists 0 affected for both serious and other events in each group. A zero in such a field means that the record contains no affected participants for that particular entry; it does not automatically mean that the primary outcome had no events. These adverse-event fields and the primary contact-dermatitis endpoint are not identified as interchangeable. The record does not explain the relationship between these entries and the outcome measure, so they should be reported separately.

In general, an observed zero does not prove that the underlying event risk is zero. The precision of an event estimate depends on the number assessed and the data collection process, and uncertainty should be presented using an appropriate method. Since the primary endpoint counts and uncertainty estimates are not reported, the event risk for that endpoint cannot be evaluated from the registry.

What do the listed design details not tell us?

The study is marked Phase 4 and completed, and its model is recorded as single group even though the record also describes two exposure-history groups. These registry classifications do not substitute for an analysis plan. They do not reveal whether the groups were compared using an unadjusted test, a regression model, or another method. The number of outcome measures is listed as three, but the record does not provide an analysis of those measures.

The sample-size justification, assumptions used to plan enrollment, any interim analyses, and a prespecified statistical plan are not reported in the registry record. In general, planning assumptions describe the effect and uncertainty a study aims to detect; they are not evidence that the study observed that effect. No inference about power or adequacy of sample size can be made from the record alone. Any sample-size illustration based on an observed effect would also require a reported effect, which is absent for the primary endpoint.

Accordingly, the statistical content available is principally descriptive of the registered design and adverse-event entries. The registry supports a careful account of the intended primary endpoint and the limits of what has been posted, but it does not support a quantitative comparison of primary endpoint outcomes.

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("Prineo Naive Group", "Prineo-exposed Group")
n      <- c(208, 95)
events <- c(2, 2)
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  Prineo Naive Group  208  2  1.0  0.1  3.4  0.3  3.4  0.3  3.4
ARM  Prineo-exposed Group  95  2  2.1  0.3  7.4  0.6  7.4  0.6  7.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, identifies the number of analyses as 0, and names contact allergic dermatitis or an adverse skin reaction at 1 week after surgery as the primary endpoint. It also lists the number of participants with postoperative complications as a secondary outcome. Details of the third measure are not reported in the registry record. No analysis results are reported for the primary or secondary outcomes.

Multiplicity refers, in general, to the increased chance of a chance finding when multiple outcomes, comparisons, or analyses are examined. Prespecified testing strategies can address that concern, for example by defining which endpoint is primary or adjusting how evidence is evaluated across tests. The registry names a primary endpoint but does not report a multiplicity strategy, a testing hierarchy, or which outcomes were analyzed. It is therefore not possible to determine whether any adjustment was planned or needed.

Missing-data handling is also not reported in the registry record. The record does not state how many participants had the 1-week assessment, whether all enrolled participants were included in endpoint analyses, or how unavailable assessments were treated. Those details matter because an endpoint denominator can differ from enrollment, and estimates may be biased if missing outcomes are related to exposure history or skin reactions. No imputation, complete-case approach, or sensitivity analysis is documented.

The analysis populations are not described. The registry does not specify an intention-to-treat, per-protocol, or other analysis set, nor does it explain whether participants were excluded from analyses. Because the study is nonrandomized, the distinction between enrolled participants, those assessed, and those included in each analysis would be particularly helpful for interpreting group comparisons. These reporting omissions prevent assessment of the primary endpoint's completeness, multiplicity handling, and analysis population.

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 adverse-event record reports, for the Prineo Naive Group, 208 at risk and 0 affected for serious events, and 208 at risk and 0 affected for other events. For the Prineo-exposed Group, it reports 95 at risk and 0 affected for serious events, and 95 at risk and 0 affected for other events. The record lists 38 deaths in the Prineo Naive Group and 12 in the Prineo-exposed Group. No top serious-event terms are listed.

These entries should be read as fields in the registry's adverse-event record, not as a complete account of all clinical outcomes. In particular, the 0 affected entries do not supply the primary endpoint result, which is specifically defined as contact allergic dermatitis or another adverse skin reaction at 1 week after surgery. The registry does not explain whether the event fields correspond to that endpoint or how the adverse-event data were collected.

The listed death counts are not accompanied by timing, causes, or an assessment of relationship to Prineo or the study. They therefore cannot be attributed to the dressing or interpreted as evidence of a causal safety effect. The record also does not provide contextual details needed to understand the counts, such as the observation period or completeness of reporting. The figures are registry entries, and their interpretation is limited to what those entries explicitly state.

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

The registry record establishes that a prospective study was designed to assess contact allergic dermatitis or another adverse skin reaction 1 week after joint arthroplasty in patients grouped by prior Prineo exposure. It also identifies Prineo dressing as the intervention received by both groups, describes the study as nonrandomized, and marks it completed. These details clarify the question the study was intended to address.

The primary outcome result is not reported in the registry record. Therefore, the posted information does not establish the number of participants who experienced the defined skin reaction, the frequency in either group, or the size and precision of any difference between groups. The adverse-event entries report 0 affected for serious and other events in both groups, but they are not a substitute for the missing primary endpoint result.

The record also does not support a causal conclusion about Prineo. Both groups receive the dressing, and the comparison is based on exposure history rather than random assignment. Any difference between groups, if reported elsewhere, could reflect exposure history or other differences between the groups. The registry does not provide an adjusted analysis or describe how such differences were addressed.

More generally, the absence of a reported primary estimate is not evidence that no skin reactions occurred. It means that the registry does not provide the result needed to assess that endpoint. Likewise, the adverse-event fields cannot establish that the underlying risk is zero; they only record the entries. No conclusion about treatment benefit, lack of benefit, or comparative safety should be drawn from the available endpoint reporting.

The clearest conclusion is about reporting rather than clinical effect: the registry describes the study's intended comparison and provides limited adverse-event entries, but it does not report the primary outcome results necessary to answer its central question.

14. Why This Trial Matters Statistically

This study raises a useful statistical distinction between a clinically relevant question and a result that can be evaluated from the registry. The question concerns whether prior Prineo exposure is associated with contact allergic dermatitis or another adverse skin reaction after a later arthroplasty. The registered endpoint is specific in outcome and timing, but the result itself is not reported. A well-defined endpoint is necessary for interpretation, yet it cannot replace the event counts and uncertainty estimates needed to assess the finding.

The design also illustrates why group formation matters. The groups are distinguished by prior exposure, not random assignment, and both receive Prineo dressing. This makes the comparison relevant to an exposure-history question but limits what it can say about the dressing relative to an alternative. In nonrandomized comparisons, statistical interpretation must account for the possibility that group differences are associated with other patient or clinical characteristics. The registry does not report an adjustment plan or adjusted estimate.

The adverse-event entries reinforce the importance of keeping outcome definitions separate. Zero affected is recorded for serious and other events, while the primary endpoint is a defined skin-reaction outcome at 1 week. Treating the entries as interchangeable would risk answering a different question from the one registered as primary. The listed death counts also lack contextual information about timing and attribution, so they should not be converted into causal claims.

Finally, a completed status does not itself convey the results. Statistical transparency depends on reporting estimates, denominators, uncertainty, analysis populations, and methods for missing outcomes and multiple endpoints. Their absence limits the conclusions that readers can draw, even when the research question and study design are described.

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 main limitation for interpreting this study from the registry is that the primary endpoint result is not reported. The record provides no number of participants with contact allergic dermatitis or another adverse skin reaction at 1 week, no group-specific estimate, and no uncertainty measure. The endpoint cannot therefore be quantitatively assessed from the posted record.

The comparison is nonrandomized and based on prior exposure. The registry itself cautions that the arms are not a like-for-like control comparison. All participants are described as receiving Prineo, so there is no alternative-dressing group in the arm descriptions. The record does not report adjustment for differences between groups, or enough detail to judge how comparable they were.

Follow-up and analysis details are limited. The registry does not report how many participants were assessed at the primary endpoint time, how missing data were handled, or which participants were included in analyses. It also does not report the primary endpoint's severity distribution, despite describing a mild-to-severe classification. The number of outcome measures is listed as three, but details and results for all measures are not available.

Safety interpretation is restricted by the lack of context for the adverse-event entries. The listed deaths have no reported timing, cause, or attribution, and the relationship between the zero serious and other event entries and the primary skin-reaction endpoint is not explained. These limitations prevent strong conclusions about either the primary outcome or the safety meaning of the posted figures.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Prineo Sensitivity Dressing Study — NCT06011603.
• Registry record last updated 2026-07-10; status last verified 2026-07.
• Results first posted 2026-07-10.
• 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 NCT06011603, a completed Phase 4, prospective study sponsored by Rush University Medical Center. It records nonrandomized allocation, no masking, a single-group model, and enrollment of 303. The study compares patients classified as Prineo-naive with patients classified as Prineo-exposed; both groups are described as receiving Prineo dressing.

The primary endpoint is the number of participants with contact allergic dermatitis or another adverse skin reaction 1 week after surgery. Its results are not reported in the registry record. A secondary outcome concerns postoperative complications. The record lists no analyses.

The adverse-event entry reports 0 affected for serious and other events in each group, with at-risk counts of 208 for the Prineo Naive Group and 95 for the Prineo-exposed Group. It also lists 38 deaths and 12 deaths, respectively, without contextual details about timing or attribution. These entries do not provide the missing primary endpoint result or establish causality.