Twice Daily Altabax Application for the Treatment of Uncomplicated Soft Tissue Infection: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Twice Daily Altabax Application for the Treatment of Uncomplicated Soft Tissue Infection (NCT01126268), a na phase 4 study. The primary outcome is Number of Participants Whose Wound Cultures Were Positive for MRSA and Who Were Determined to be a Clinical Success at the Follow-up Visit.

2. Clinical Question

In statistical terms, the study asks whether a specified clinical status was present at follow-up in the target culture-positive population after treatment in a single-group setting. It does not, as described in the registry, estimate how that status compares with what would have occurred under a different treatment or no treatment. The record’s stated purpose also refers to bacteriological efficacy, but the primary measure specifically names clinical success among participants with MRSA-positive wound cultures. The interpretation therefore needs to follow the registered endpoint wording rather than assume that the primary measure itself is a comparative or bacteriological clearance result.

3. Trial Design

The registry identifies this as a completed Phase 4 study with a single-group model and no masking. Allocation is listed as not applicable. The sponsor is The University of Texas Health Science Center, Houston. The record gives a start date of 2010-04 and a primary completion date of 2012-11. Enrollment is recorded as 38 participants.

The intervention was retapamulin ointment 1%. The study summary describes topical use twice daily for five days, after wound cultures were collected at enrollment. It says recruitment was from a university-based dermatology clinic and describes patients with impetigo, folliculitis, minor soft tissue infections, and secondarily infected eczema presumed to be caused by methicillin-resistant Staphylococcus aureus. These statements describe the intended study context; the registry record does not report how many enrolled participants had each condition or how many had MRSA-positive cultures.

The summary anticipated enrollment of approximately 75 patients, with approximately 50 expected to have MRSA infections. Those are expectations in the study description, not the recorded enrollment or a report of the number with MRSA. The recorded enrollment is 38. The record does not explain the difference between the anticipated and recorded enrollment, nor does it report whether recruitment ended as planned.

Because this was a single-group, unmasked study, the outcome is observed after treatment without a concurrent randomized comparator. This structure can describe outcomes among enrolled participants, but it does not by itself separate changes associated with treatment from changes that could occur over time or from other influences. The registry record does not report a statistical analysis plan, an allocation procedure beyond stating that allocation was not applicable, or further design details such as an interim-analysis plan.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Participants whose wound cultures were positive for MRSA

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 Whose Wound Cultures Were Positive for MRSA and Who Were Determined to be a Clinical Success at the Follow-up Visit, measured over 6 to 8 days after treatment.

The primary endpoint is the number of participants whose wound cultures were positive for MRSA and who were classified as clinical successes at the follow-up visit. Follow-up is specified as 6 to 8 days after treatment. The success definition requires no further signs or symptoms of infection, with erythema, purulence, crusting, edema, warmth, and pain listed as examples. The endpoint is therefore a participant count tied to both a culture-defined population and a clinical assessment.

Clinical assessments are used in trials because they translate observed signs and symptoms into a defined outcome that can be recorded consistently. In general, a prespecified definition helps make outcome classification more reproducible than an informal judgment. Here, the listed criteria clarify what the registry means by clinical success. They do not, on their own, show how consistently assessments were made or whether outcome assessors were blinded; masking is listed as none.

The endpoint is not a comparative measure: it does not state a difference between treatment groups. Nor does its title specify a repeat-culture requirement for clinical success. The study summary discusses clinical and bacteriological efficacy, but the registered primary measure identifies participants by their wound-culture result and then counts clinical success. The observed count, its denominator within the MRSA-positive population, and any uncertainty estimate are not reported in the registry record. Without those results, the endpoint definition can be described, but the frequency or precision of clinical success cannot be evaluated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help distinguish what this study was designed to observe from what the registry record reports. The explanations below are general unless they refer directly to a stated feature of the study.

What does a single-group design estimate?

A single-group study follows participants receiving the intervention and records outcomes in that group. In general, it can describe the outcomes observed among participants who were assessed. A treatment effect, by contrast, is a comparison between outcomes under different treatment conditions. A concurrent comparator helps estimate that contrast by providing a reference group observed over the same period. This record identifies a single-group design and does not describe a comparator. Accordingly, a within-group outcome count should not be treated as a comparative treatment effect.

The study is also listed as unmasked. In general, masking can reduce the influence of knowledge about treatment assignment on assessments or reporting. Without masking, judgments based on clinical signs may be more vulnerable to expectation or measurement influences. This does not show that any assessment was biased; it identifies a design consideration. The registry record does not report who assessed the endpoint or whether any safeguards were used.

What kind of outcome is the primary endpoint?

The primary measure is a count of participants meeting a defined clinical-success criterion within the population whose wound cultures were positive for MRSA. It is a categorical outcome at a specified follow-up, rather than a continuous measurement such as a laboratory value or a time-to-event outcome. In general, a count is interpretable only alongside the population to which it applies and the number of participants assessed. Here, the registry identifies the target population but does not report its size, the success count, or the number assessed at follow-up.

The clinical-success definition lists the signs and symptoms that must no longer be present. A precise operational definition helps readers understand what classification means. It does not show whether all components were evaluated in every participant, how missing assessments were handled, or whether adjudication procedures were used. Those details are not reported in the registry record.

How should uncertainty be understood?

In general, an estimate based on participants in a study is subject to sampling uncertainty: a different group of comparable participants could produce a different estimate. A confidence interval is one way to express the range of values compatible with the data under a specified statistical method. It is not a guarantee that the true value lies in the interval, and its interpretation depends on the method and assumptions. The registry record does not report a primary estimate or confidence interval for this study, so there is no posted precision measure to interpret.

A p-value, in general, evaluates how compatible data are with a specified null hypothesis under a model; it is not a measure of the size or clinical importance of an effect. No primary p-value or statistical test is reported in the registry record. Without an analysis result and its context, statistical significance cannot be assessed.

What does the planning information mean?

The record’s planning conventions describe sample-size illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They describe detecting a stated fraction of an observed effect. Such planning calculations are not observed outcomes, and sample-size illustrations are not observed power. In general, they depend on assumptions about the effect and design, and they do not replace a reported analysis.

The described calculation framework assumes two arms with equal allocation, whereas the actual study is recorded as single-group. Therefore, that generic framework does not correspond directly to the registered study design. The registry record does not report the trial’s own sample-size justification or a trial-specific statistical plan. No numerical planning results are stated in the record summarized for this study, so they cannot be used to infer the study’s achieved precision.

Why does the analysis population matter?

In general, the analysis population specifies which participants contribute to an outcome estimate—for example, all enrolled participants, those meeting eligibility criteria for an endpoint, or those with an observed follow-up assessment. Different populations can produce different results, especially when not every participant has complete follow-up. The primary endpoint is restricted to participants with positive MRSA wound cultures, but the number meeting that condition and the analysis population used are not reported in the registry record. It also does not state how missing cultures or clinical assessments were handled.

These methodological distinctions explain why a study description alone cannot answer how often the primary outcome occurred or how confidently it can be generalized. The registry provides a defined endpoint and design context, but outcome estimates and the analysis procedures needed to interpret them are not reported.

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("Retapamulin Ointment 1%")
n      <- c(7)
events <- c(5)
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  Retapamulin Ointment 1%  7  5  71.4  29.0  96.3  35.9  91.8  34.9  91.5

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 19 outcome measures, including clinical response at follow-up, microbiologic response at follow-up, therapeutic success, and signs or symptoms recorded at baseline or follow-up. It reports 0 analyses. The presence of several outcome measures creates a general multiplicity concern: when many outcomes are tested, the chance of at least one apparently notable result can increase if results are selected or interpreted without accounting for the number of comparisons. This is a general statistical issue, not evidence that a particular finding occurred in this study.

The registry record does not report a multiplicity adjustment, a hierarchy among outcomes, or a plan for distinguishing confirmatory from exploratory analyses. The primary outcome is identified, but the record does not state how it was prioritized analytically relative to the other measures or whether any outcome-specific hypotheses were prespecified beyond the endpoint descriptions.

Missing-data handling is also not reported in the registry record. The record does not state how participants with unavailable follow-up, missing culture results, or incomplete clinical assessments were treated in analyses. This matters because the primary endpoint applies to the MRSA-positive population and requires a follow-up clinical classification. Without the analysis denominator and missing-data rules, readers cannot determine whether the reported enrollment corresponds to the population assessed for the primary endpoint.

Analysis populations are not reported in the registry record. The count of enrolled participants therefore should not be assumed to be the count contributing to any particular outcome. The record does not describe an intention-to-treat analysis, a per-protocol analysis, or another prespecified population. These omissions limit assessment of how outcome data would have been included and how robust any result might be to missing observations or alternative analysis choices.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent non-serious adverse event terms

The safety record lists 0 serious adverse events among 38 participants at risk and 4 other adverse events among 38 participants at risk in the retapamulin ointment 1% group. The record does not list serious-event terms. It also does not identify the terms for the other events in the safety information. The death count is not reported in the registry record.

These are event counts reported for the study group, not comparative safety estimates. Because the study has no concurrent comparator group, the counts do not show how event occurrence compares with another treatment or with an untreated condition. In general, an adverse event is not automatically an event caused by the intervention; attribution requires information about assessment and causality. The registry record does not provide that assessment for the listed other events.

The at-risk counts indicate the number used as the safety denominator in the record. They should not be interpreted as the primary-endpoint population, which is defined by MRSA-positive wound cultures. Nor do the safety figures describe the duration or severity of the other events. The counts are useful as a limited description of what the record reports, but they do not support broader comparative or causal conclusions.

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

The record establishes that a completed Phase 4, single-group study examined topical retapamulin ointment 1% for uncomplicated soft tissue infections and specified a clinical-success outcome among participants with MRSA-positive wound cultures. It also documents the treatment schedule in the study summary and the follow-up timing for the primary endpoint. These design and endpoint details explain the question the study set out to address.

What the record does not establish is the observed primary outcome. The number of eligible MRSA-positive participants, the number classified as clinical successes, and the number assessed at follow-up are not reported. No primary estimate, confidence interval, or statistical test is reported. The outcome definition is not a result, and the enrollment figure is not a success count.

The design also does not establish a comparative treatment effect. In general, a post-treatment outcome in a single group cannot show what would have happened to the same participants under another treatment or without treatment. The absence of masking is another consideration when interpreting clinical assessments, though the record does not establish that assessments were affected by it.

The safety information reports 0 serious adverse events and 4 other adverse events in the recorded group, with 38 participants at risk for each category. These counts are descriptive. The record does not identify the other events or report whether they were attributed to treatment. They cannot be used to infer a comparative safety profile.

Accordingly, the registry record supports an account of the study’s intended population, intervention, design, endpoint, and limited safety counts. It does not provide enough outcome information to determine how frequently clinical success occurred, how precise an estimate would be, or whether the intervention caused an observed outcome. Those unanswered questions should remain distinct from the study’s stated aims.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of why a clear endpoint and a reported result are both necessary for interpretation. The registry defines clinical success using specific signs and symptoms and gives a follow-up window of 6 to 8 days after treatment. That definition tells readers what outcome the study intended to count. Yet the registry record does not report the resulting count, the subgroup denominator, or an uncertainty estimate. A well-described endpoint cannot substitute for outcome data.

The single-group design also illustrates the distinction between describing outcomes and estimating effects. A count of clinical successes, if reported, would describe what was observed among the assessed participants. Without a concurrent comparator, it would not alone quantify how outcomes differed from another treatment condition. This distinction is important whenever an outcome is presented without a randomized comparison.

The record’s anticipated enrollment and actual enrollment also serve different purposes. The study summary anticipated approximately 75 patients, including approximately 50 expected to have MRSA infections, while the record reports enrollment of 38. Expectations are planning statements, not observed subgroup sizes or results. The registry does not explain the enrollment difference or report the number who met the MRSA criterion.

Finally, the record lists multiple outcome measures but 0 analyses. This makes the distinction between an outcome being named and an outcome being reported especially important. Without reported analyses, readers cannot assess estimates, uncertainty, missing-data handling, or multiplicity procedures. The study’s statistical contribution in the registry is therefore mainly its documented design and endpoint definition, rather than a result that supports inference about efficacy or comparative safety.

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.

Several limitations follow specifically from the information available in the registry record. The study is recorded as single-group and unmasked, with allocation not applicable. It therefore lacks a concurrent randomized comparison for interpreting outcomes. General changes over time, other care, and assessment influences cannot be separated from intervention-associated outcomes using a single-group outcome count alone.

The primary endpoint applies only to participants whose wound cultures were positive for MRSA. The record reports enrollment of 38, but does not report how many had positive cultures, how many contributed to the primary endpoint, or how many completed follow-up. The anticipated MRSA count in the study summary is an expectation, not an observed subgroup size. This prevents assessment of the endpoint denominator and the precision of any estimate.

The primary outcome result is not reported in the registry record. Nor are statistical analyses, confidence intervals, p-values, or details of the analysis population. The record does not report how missing culture results or follow-up assessments were handled, whether endpoint assessments were adjudicated, or whether multiplicity was addressed across the listed outcomes. These gaps prevent evaluation of the analysis choices and the robustness of a result.

The study summary describes the target age range and clinical conditions, but the record does not provide enrolled-participant characteristics or condition-specific outcome results. Generalizability across those conditions or ages therefore cannot be assessed from the registry information. The record also does not report adherence to the planned treatment schedule.

Finally, safety information includes counts but not event terms for the other adverse events or a reported death count. It does not give comparative safety estimates or event-attribution details. These limitations constrain interpretation to the documented design and the limited safety counts, rather than supporting broad conclusions about outcomes or causes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Twice Daily Altabax Application for the Treatment of Uncomplicated Soft Tissue Infection — NCT01126268.
• Registry record last updated 2016-02-17; status last verified 2016-01.
• Results first posted 2016-02-17.
• 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.

19. Record Summary

The registry identifies NCT01126268 as a completed Phase 4, unmasked, single-group study sponsored by The University of Texas Health Science Center, Houston. It records enrollment of 38 and describes topical retapamulin ointment 1%, applied twice daily for five days in the study summary. The listed primary measure is the number of participants with MRSA-positive wound cultures who were clinical successes at follow-up 6 to 8 days after treatment.

The record defines clinical success as no further listed signs or symptoms of infection. It does not report the primary outcome count, the size of the MRSA-positive analysis population, or statistical analyses. It lists 19 outcome measures and 0 analyses. Safety information reports 0 serious adverse events and 4 other adverse events, each with 38 participants at risk; the death count is not reported in the registry record.

The record therefore describes the study’s design, planned treatment, and outcome definitions, but does not provide the results needed to estimate primary-outcome frequency or precision, or to assess a comparative treatment effect.