Ablative Fractional Laser for Sclerotic GVHD-Associated Joint Contractures: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Ablative Fractional Laser for Sclerotic GVHD-Associated Joint Contractures (NCT02881047), a na na study. The primary outcome is Number of Subjects Who Show Improvement in Range of Motion, Flexion, and Extension.

2. Clinical Question

In statistical terms, this is a within-group question: did participants show a recorded change after treatment? Without a comparator, a change cannot by itself distinguish an intervention effect from other explanations, such as the natural course of disease, concurrent care, measurement variation, or changes in effort during assessment. The record does not report information that would allow those possibilities to be evaluated.

3. Trial Design

The registry describes a single-group study of ablative fractional laser for sclerotic GVHD-associated joint contractures. Its allocation field is NA, and the record lists no comparator. The planned enrollment is recorded as 8. The listed phase is NA, and the study status is TERMINATED. The reason for termination is not reported in the registry record.

The record gives a start date of 2013-11-11 and a primary completion date of 2016-08. These dates describe the registry entry, but do not establish how many participants completed treatment or follow-up. Completion counts and participant flow are not reported in the registry record.

The intervention list includes a CO2 laser device, ultrasound, and skin biopsy. The arm description identifies ablative fractional laser treatment for a target joint or limb affected by range-of-motion limitations and contractures due to sclerotic GVHD. The registry does not report the treatment schedule, number of treatment sessions, technical settings, or the specific roles of ultrasound and biopsy.

The primary outcome is a participant count: the number who show improvement in range of motion, flexion, and extension. Assessment is specified at 5 months from baseline, with the outcome description naming target-joint flexion, extension, supination, and pronation measured in degrees with a goniometer. The registry record does not state the threshold for improvement, whether assessors were blinded, or how missing measurements were handled.

Because there is no control group, the design can describe outcomes among participants who received the intervention, if those outcomes are reported. It cannot make a randomized, between-group comparison. The registry lists no statistical analyses, and it does not report a statistical analysis plan or a sample-size justification for the study itself.

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:

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 Subjects Who Show Improvement in Range of Motion, Flexion, and Extension, measured over 5 months from time point zero / baseline.

The primary endpoint is the number of participants who show improvement in range of motion, flexion, and extension at 5 months from baseline. It is a count of participants, rather than a mean change in degrees or a time-to-event measure. The outcome description says that movement of the target joint is measured in degrees using a goniometer, and it names flexion, extension, supination, and pronation.

Range of motion is a functional measure directly related to the joint limitation that the study aims to address. Recording joint movement in degrees gives a measurement scale for describing mobility, while the participant count expresses how many people meet the study’s improvement criterion. However, the registry record does not specify that criterion. It does not say whether improvement required a particular change in degrees, a change in any one movement direction, or improvement across a defined combination of movements.

The distinction between measuring movement and defining an improved participant matters. A goniometer may record degrees, but a rule is still needed to convert measurements into a participant-level yes-or-no outcome. Without that rule and the actual endpoint result, readers cannot determine how much change counted as improvement or how many participants met the endpoint.

The endpoint is set at 5 months from baseline. The registry record does not report additional assessment times for this primary measure, the handling of repeated measurements, or the primary endpoint result. Consequently, the endpoint’s stated purpose and measurement approach can be described, but its observed outcome cannot be evaluated from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends on how an outcome is defined, what comparison the design permits, and how uncertainty is quantified. In this study, the registry identifies a participant-count endpoint and a single-group design, but does not report the primary endpoint result or any statistical analyses. The concepts below explain how such information is generally interpreted; they do not describe unreported procedures used in this study.

What does a participant-count endpoint represent?

A participant-count endpoint classifies people according to whether they meet a specified outcome. Here, the stated outcome is improvement in range of motion, flexion, and extension, assessed at 5 months from baseline. Although the record describes measurement of joint movement in degrees, the primary endpoint is the number of participants meeting an improvement definition.

For this type of endpoint, the rule for classifying improvement is important. A threshold can distinguish meaningful change from small shifts that may reflect measurement variability. It can also make clear whether a participant must improve in a particular movement, in several movements, or according to another prespecified rule. The registry record does not report the threshold or classification rule, so the endpoint cannot be independently interpreted from measurements alone.

What can a single-group design estimate?

A single-group study can describe outcomes observed among the people studied. If baseline and follow-up measurements are both available, a within-person comparison can describe how measurements changed over time. Such a comparison does not include the counterfactual outcome: what would have happened to those same people over the same period without the intervention.

A control group can help estimate a between-group contrast, provided the design and analysis support a fair comparison. This study has no listed comparator, and allocation is recorded as NA. Accordingly, the design does not support a randomized comparison between treatment groups. General explanations of causal inference should not be mistaken for a treatment-effect estimate from this record.

How should uncertainty be understood?

In general, a confidence interval describes a range of values compatible with the observed data under the assumptions of the statistical method. A narrow interval indicates greater precision than a wide interval, while an interval that includes values representing little or no difference may leave substantial uncertainty about the size of an effect. A confidence interval does not repair limitations in the design, such as the absence of a comparator, and it does not show that a causal interpretation is warranted.

No confidence interval or other uncertainty measure for the primary endpoint is reported in the registry record. With the endpoint result itself absent, there is no registry-based estimate whose precision can be assessed. The enrollment entry of 8 does not by itself determine precision: the number with available endpoint data and the observed outcome distribution would also matter, and those details are not reported.

What do the planning assumptions mean?

The registry describes sample-size illustrations based on a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. These are planning assumptions for illustrations, not evidence of the study’s own design. They do not change the fact that this registry record describes a single-group study with no comparator.

In general, planning calculations ask how much information a hypothetical study would need to detect a chosen effect under specified assumptions. A smaller target effect generally calls for more information than a larger target effect, all else being equal. Such calculations depend on the assumed effect, outcome variability or event frequency, analysis method, and design. The actual numerical planning outputs and the fractions used are not reported in the registry record. The registry also does not report its own sample-size justification, so the planning illustrations should not be treated as the study’s prespecified target or as observed power.

Observed power is not a substitute for an estimate and its uncertainty. Once a study is complete, interpretation should focus on the observed outcome and its precision rather than treating a retrospective power calculation as evidence that a result is reliable or unreliable. No observed primary endpoint estimate is reported, so no study-specific observed power can be interpreted.

Why do adverse-event counts need context?

For binary safety outcomes, a count of affected participants conveys how many people had at least one recorded event in a category. A participant-level count is not necessarily the same as an event count: one participant could have more than one event, unless the registry specifies otherwise. The record gives participants at risk and participants affected for serious and other adverse events, but does not report event-level totals or detailed definitions for these categories.

Over-dispersion is a general issue when data vary more than a statistical model assumes. For example, event counts may cluster within participants or vary substantially across people. A model that assumes less variability than is present can produce uncertainty estimates that are too optimistic. The registry record does not report a count model or an analysis of adverse-event rates, so over-dispersion is a methodological consideration in general, not a feature that can be confirmed for this study.

For this record, the most defensible statistical reading is descriptive: the registry reports the stated participant counts and serious-event terms, while leaving the primary outcome result, analysis details, and uncertainty measures unreported.

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("rAblative Fractional Laser for Sclerotic GVHD-Asso")
n      <- c(6)
events <- c(6)
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  rAblative Fractional Laser for Sclerotic GVHD-Asso  6  6  100.0  54.1  100.0  61.0  100.0  59.0  99.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. It does not report which outcomes were designated secondary, how they were ordered, or whether any formal hypothesis tests were planned. A statistical analysis plan is not reported in the registry record.

Multiplicity arises when several outcomes or comparisons are tested. In general, making many statistical tests can increase the chance that at least one appears notable by chance. Researchers may address this through a prespecified primary outcome, adjustment procedures, or a clearly descriptive approach. The record identifies a primary endpoint, but does not report any multiplicity strategy. It is therefore not possible to determine whether multiple outcomes were analyzed inferentially or how any resulting uncertainty was handled.

The primary outcome result is not reported in the registry record, and no analysis is listed. Missing-data methods, reasons for missing measurements, and the number of participants contributing to each outcome are also not reported. Without this information, readers cannot assess whether the reported enrollment represents the analysis population or whether available-case, imputed, or other methods were used.

The record does not report an intention-to-treat population, a per-protocol population, or another analysis-population definition. In general, analysis populations clarify which participants are included and how deviations from treatment or missing follow-up are handled. Their absence from the record limits assessment of the results, but does not establish that any particular method was or was not used outside the registry entry.

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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: left brachial artery clot (12.5%), biopsy site infection (12.5%).

The registry reports serious adverse events for 8 participants at risk, with 1 participant affected. It also reports other adverse events for 8 participants at risk, with 1 participant affected, and lists 0 deaths. The serious-event terms shown are Left Brachial artery clot and Biopsy site infection, each reported as 12.5%.

These are descriptive registry figures. The number of participants affected is not necessarily the number of individual events, since a participant may experience more than one event; event-level totals are not reported in the registry record. The record does not explain whether the same participant contributed to both the serious and other adverse-event categories. It also does not report timing, duration, severity details beyond the serious-event listing, or a causal assessment linking events to the intervention.

The listed percentages should be read as the registry’s reported values, not as a comparison against another treatment group. There is no comparator group in this single-group study, so the safety figures do not estimate a relative risk. The record also does not provide enough detail to evaluate event ascertainment or follow-up completeness. The figures describe what is recorded and should not be interpreted as proof that an event was or was not caused by treatment.

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

The record establishes that a single-group study was registered to examine ablative fractional laser treatment for sclerotic GVHD-associated joint contractures. It specifies range of motion as the primary outcome and identifies a 5-month assessment from baseline. The outcome description names joint movements to be measured in degrees using a goniometer, and the registry lists enrollment as 8.

What the record does not establish is whether participants improved on that endpoint. The number meeting the improvement definition is not reported in the registry record, and the definition itself is not reported. No statistical analyses or uncertainty estimates are listed. As a result, the magnitude and precision of any change cannot be assessed from this information.

The single-group design also limits what an observed change, if available, could mean. A before-and-after description would not separate the intervention’s contribution from other influences on participants’ movement over time. There is no like-for-like control comparison in the registry record, and no randomized contrast can be inferred.

The safety entries describe 1 participant affected among 8 at risk in each of the serious and other adverse-event categories, and 0 deaths. The registry lists Left Brachial artery clot and Biopsy site infection as serious-event terms, each at 12.5%. These figures are not comparative estimates and do not establish causation. Details needed to understand timing, attribution, and overlap between categories are not reported.

The appropriate conclusion is therefore bounded: the record describes a study question, design, endpoint, and selected safety figures, but it does not provide the primary outcome result needed to judge observed range-of-motion change. It cannot establish whether the intervention caused improvement or quantify a treatment effect.

14. Why This Trial Matters Statistically

This study raises a statistically important distinction between measuring a clinical outcome and reporting an interpretable result. The registry describes joint movement measured in degrees, but the primary endpoint converts those measurements into a count of participants who improve. The improvement rule is not reported, and neither is the resulting participant count. Without both, readers cannot connect the measurement plan to a clear clinical summary.

The record also illustrates how study design shapes the claims that can be supported. A single-group study can offer descriptive information about people receiving an intervention, but it cannot provide a controlled estimate of what would have happened without it. This matters especially for an outcome measured over time, because changes may have multiple explanations. The absence of a comparator is a design feature, not a statistical detail that can be corrected by a more complex analysis.

Registry reporting is another part of statistical interpretability. Enrollment, endpoint timing, and safety counts are useful details, yet a primary endpoint result, analysis population, missing-data approach, and uncertainty measure are not reported in the registry record. These omissions make it difficult to assess the completeness and precision of the evidence from the registry entry.

Finally, planning illustrations must be kept separate from observed study results. The registry describes hypothetical two-arm assumptions for planning calculations, while the registered design is single-group. Such illustrations can explain what assumptions might be used in a future design, but cannot serve as evidence about this study’s effect, adequacy, or power. The trial’s statistical value to readers depends on transparent outcome reporting as well as a clearly described design.

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 specific to this registry record constrain interpretation. The study is listed as TERMINATED, but the reason for termination is not reported in the registry record. The entry records a primary completion date of 2016-08, but does not report participant flow, follow-up completion, or the number with an evaluable primary endpoint. The enrollment entry of 8 therefore cannot be assumed to equal the analysis population.

The primary endpoint is described as a participant count based on improvement in range of motion, flexion, and extension, with movement measured in degrees by goniometer. The registry does not report the threshold or operational rule defining improvement. It also does not report assessor procedures, measurement reliability, or how the named movement directions were combined to classify a participant.

The record lists ultrasound and skin biopsy alongside the CO2 laser, but their roles and timing are not reported. Treatment schedule and technical details are also not reported. These gaps limit the ability to understand precisely what intervention and assessment procedures participants experienced.

There is no comparator, and allocation is recorded as NA. Consequently, even a reported within-group change would not supply a controlled estimate of treatment effect. The primary endpoint result, statistical analysis, uncertainty interval, analysis population, missing-data method, and sample-size justification are not reported in the registry record. The reason for termination and any relationship to outcome availability are also not reported. These are limitations of what the registry entry communicates; they do not establish what may have been collected or analyzed outside that record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Ablative Fractional Laser for Sclerotic GVHD-Associated Joint Contractures — NCT02881047.
• Registry record last updated 2020-04-16; status last verified 2020-04.
• Results first posted 2020-04-16.
• 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 describes a terminated, single-group study of ablative fractional laser treatment for sclerotic GVHD-associated joint contractures. Enrollment is listed as 8, and the primary endpoint is the number of participants showing improved range of motion, flexion, and extension at 5 months from baseline. The outcome description specifies goniometer measurement of target-joint movement in degrees.

No comparator is listed, allocation is recorded as NA, and the registry lists 0 analyses. The primary endpoint result, improvement criterion, analysis population, and missing-data approach are not reported in the registry record. Safety entries report 1 participant affected among 8 at risk for serious adverse events and 1 among 8 for other adverse events, with 0 deaths. The listed serious-event terms are Left Brachial artery clot and Biopsy site infection, each reported as 12.5%. The record does not report the reason for termination or event attribution.