Low Level Laser Therapy for Radiation Induced Dermatitis in H & N Squamous Cell Carcinoma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Low Level Laser Therapy for Radiation Induced Dermatitis in H & N Squamous Cell Carcinoma (NCT02384434), a na na study. The primary outcome is Grade 3 or Higher Adverse Events.

2. Clinical Question

3. Trial Design

NCT02384434 is recorded as a completed, single-group study of low-level laser therapy for radiation-induced dermatitis in patients with head and neck squamous cell carcinoma. Enrollment is listed as 16. The study dates recorded are 2015-04-27 for the start and 2020-10-13 for primary completion. The phase is listed as NA.

The intervention is the THOR Laser System for low-level laser therapy, described in the arm information as a non-invasive, cold laser output treatment. The registry records no masking and lists allocation as NA. Because the design is single-group, the record does not describe random assignment between treatment groups or a concurrent comparison group. The safety outcomes are consequently descriptive for the listed group; they cannot by themselves separate outcomes associated with the intervention from outcomes that might have occurred without it.

The primary outcome is titled “Grade 3 or Higher Adverse Events.” It is defined as a count of participants with documented Grade 3 or higher adverse events according to CTCAE v4.0, with a timeframe of up to 12 months. The specified population is patients who received at least 1 dose of study treatment. The registry also lists University of Washington Quality of Life Questionnaire outcomes and the Brief Pain Inventory among secondary outcomes. It records 22 outcome measures and 0 analyses. The record does not describe the timing or procedures for laser sessions, any protocol deviations, or how the secondary outcomes were 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

Analysis population for the primary outcome, as defined in the registry: Patients who received at least 1 dose of study treatment.

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 Grade 3 or Higher Adverse Events, measured over Up to 12 months.

The primary endpoint concerns the number of participants with documented Grade 3 or higher adverse events, as classified using CTCAE v4.0. Its timeframe is up to 12 months, and its stated population includes patients who received at least 1 dose of study treatment. This makes the endpoint a safety measure: it counts participants meeting the specified adverse-event severity criterion rather than measuring a change in dermatitis, pain, or quality of life.

A count of affected participants can describe how many people in the study group met the endpoint definition. To interpret that count fully, readers also need the population denominator, a clearly linked endpoint result, and information about assessment and follow-up. The record defines the endpoint but does not report an analysis explicitly linked to it. The adverse-event figures listed elsewhere in the record should not automatically be treated as the primary endpoint result, because their relationship to the endpoint definition is not stated.

In general, a safety endpoint can help characterize events observed during a study, but a single-group count cannot establish whether the intervention caused an event or changed its likelihood. The endpoint also does not directly answer the study summary’s questions about dermatitis, acneiform rash, pain, or patient-reported quality of life. Those questions require their own outcome definitions and results; the record lists related secondary outcomes but does not report their analyses.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical interpretation begins with the study structure. This is a single-group record, not a randomized comparison. In a controlled trial, comparing outcomes between groups can support an estimate of the difference associated with the assigned intervention, subject to the design and analysis assumptions. Here, no such between-group contrast is available. The posted event counts describe the listed low-level laser therapy group only.

What does a participant count represent?

The primary endpoint is defined as a count of participants with documented Grade 3 or higher adverse events, rather than a continuous measurement such as a score. A participant count answers how many people met a stated event definition in the defined population. It is important to keep the endpoint’s population and timeframe in view: the record specifies patients who received at least 1 dose and a timeframe of up to 12 months. A count is not, by itself, a rate over time, a measure of severity beyond the stated grade threshold, or a causal estimate.

The registry’s adverse-event information separately reports participants at risk and participants affected for serious and other adverse events. Those are descriptive safety figures. The record does not explicitly connect them to the primary endpoint’s Grade 3-or-higher definition, so they should not be substituted for a formal primary outcome analysis. Event terms may also overlap within participants; the record does not state otherwise. For that reason, event-term percentages should be read individually rather than summed.

Why does the design affect interpretation?

A single-group study has no internal control group to represent outcomes under an alternative treatment or no study intervention. Consequently, an event observed during the study does not establish that the intervention caused it. Likewise, an outcome count cannot show whether the intervention reduced or increased events relative to a comparator. This is a design limitation, not something that can be repaired by a more elaborate calculation using the same group’s summary data.

In general, randomization can help balance known and unknown participant characteristics across comparison groups, while masking can reduce some forms of influence on treatment delivery or outcome assessment. The registry records allocation as NA and masking as none; it does not describe a randomized or masked comparison. The record does not report the procedures used to assess adverse events or whether assessments were independently reviewed.

How should uncertainty be considered?

In general, a confidence interval gives an uncertainty range around an estimate under specified statistical assumptions. A narrow interval suggests greater statistical precision than a wide interval, but neither interval width nor a small p-value establishes that an intervention caused an outcome. No confidence interval, p-value, or inferential analysis for the adverse-event figures is reported in the registry record. The record lists 0 analyses, so there is no reported model or hypothesis test to interpret.

In general, binary-event analyses must account for the fact that participants either meet an event definition or do not, while the uncertainty depends on the number of observations and the event frequency. More complex models may be needed for repeated observations, clustered data, or variation beyond a model’s assumptions. Such methods cannot be selected or evaluated for this record because the registry does not report an analysis plan, repeated-measure structure, or model results. Over-dispersion is a concern for count models when the observed variability exceeds the model’s assumptions; it is not a reason to infer a different result from the participant counts.

What do the planning illustrations mean?

The stated sample-size assumptions describe planning illustrations computed from an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. These are planning assumptions, not the study’s own design justification, which is not reported in the registry record. In particular, an equal-allocation, two-arm planning setup does not match the recorded single-group design. No planning output values are available in the record, and such illustrations must not be interpreted as observed power or as evidence about this study’s effect.

More generally, sample-size planning estimates how much information a proposed design may need to detect a specified effect under stated assumptions. It does not show that an effect exists, and it does not tell readers whether the completed study had adequate power unless the design, target effect, and analysis assumptions are appropriate and clearly reported. The registry does not report a sample-size justification or protocol-based target, so the enrollment figure alone cannot establish whether the study met a planned statistical objective.

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("Low Level Laser Therapy")
n      <- c(9)
events <- c(9)
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  Low Level Laser Therapy  9  9  100.0  66.4  100.0  70.1  100.0  69.2  99.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 22 outcome measures, including repeated entries for the University of Washington Quality of Life Questionnaire and an entry for the Brief Pain Inventory. It records 0 analyses. The record does not explain how the outcomes were grouped, whether the repeated questionnaire entries correspond to different assessment times or measures, or which outcomes were designated for formal testing. Their repetition in the record should not be taken as evidence of separate analyses.

When many outcomes are assessed, the chance of finding an apparently notable result can increase if each is tested without accounting for multiplicity. In general, multiplicity procedures can control the overall false-positive risk or prioritize a limited set of outcomes. The registry record does not report a multiplicity strategy, statistical testing plan, or adjusted results. Since no analyses are listed, there is no reported testing framework from which to assess this issue.

Missing-data methods and analysis populations are also not described. The primary endpoint population is specified as patients who received at least 1 dose, but the registry does not report how many participants contributed data to each outcome, whether follow-up was complete, or how missing measurements were handled. It does not describe an intention-to-treat population or another analysis set. These omissions limit assessment of whether the posted counts represent complete follow-up and how participants without recorded outcomes were treated.

In general, missingness can affect interpretation when participants with unavailable measurements differ from those with observed data. Statistical methods can address some missing-data patterns only under assumptions that should be described. The registry record does not report those assumptions or methods, so the impact of missing data cannot be evaluated from the posted information.

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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: mucositis oral (25.0%), dysphagia (18.8%), fatigue (6.2%), pain (6.2%), dermatitis radiation (6.2%).

The registry reports 9 participants with serious adverse events among 16 at risk and 16 participants with other adverse events among 16 at risk in the low-level laser therapy group. It also reports 12 deaths. These are distinct safety entries as recorded; the record does not explain how the serious-event and other-event categories relate to one another, or provide context linking the deaths to timing, cause, or treatment exposure. They should not be combined or interpreted as mutually exclusive categories.

The serious adverse-event terms listed include Mucositis oral at 25.0%, Dysphagia at 18.8%, and Fatigue, Pain, Dermatitis radiation, and Anorexia at 6.2% each. The registry does not state whether participants could experience multiple terms, and these percentages should not be added together. Nor do the terms establish causation: an event reported during a study is not necessarily caused by the study intervention.

The primary endpoint specifies Grade 3 or higher adverse events per CTCAE v4.0, but the record does not explicitly link the serious-event figures to that endpoint definition or provide a corresponding analysis. The posted safety figures therefore warrant descriptive reading, not a causal or comparative conclusion. Information on event timing, relatedness assessments, and the circumstances of the deaths is not reported in the registry record.

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

The record documents a completed, single-group study of low-level laser therapy and lists adverse-event counts for the study group. It also describes study aims involving radiation dermatitis, acneiform rash, pain, and patient-reported quality of life. These details establish what the registry says the study set out to examine and what safety information it reports; they do not establish a treatment effect.

Because no comparator group is listed, the record cannot show whether the observed adverse events were more or less frequent than they would have been under another approach. It cannot establish that laser therapy caused the reported events or deaths, nor can the counts estimate a reduction in dermatitis or pain. The serious-event terms are descriptive entries, and the record does not explain whether they overlap within participants or how they were judged related to treatment.

The endpoint definition is useful for understanding the intended safety question: it concerns participants with documented Grade 3 or higher adverse events under CTCAE v4.0 during follow-up of up to 12 months. However, a primary endpoint result or analysis explicitly linked to that definition is not reported in the registry record. The posted safety counts should therefore not be presented as a definitive result for the primary endpoint without that linkage.

The record also does not report analyses of the quality-of-life or pain outcomes, uncertainty intervals, missing-data handling, or an analysis plan. As a result, the precision and completeness of the findings cannot be assessed. The enrollment figure and posted counts are not enough to establish a clinically meaningful effect or to determine how the findings apply to patients beyond the study group.

In general, a registry record is most informative when its outcome definitions, analysis populations, methods, and results can be matched directly. In this case, the available information supports a cautious description of the study design and listed safety events. It does not support a controlled efficacy conclusion or a causal safety conclusion.

14. Why This Trial Matters Statistically

This study raises a relevant statistical distinction between a clinical question and the design used to address it. The summary describes interest in mitigating radiation-related skin effects and pain and assessing quality of life, while the primary endpoint is a safety count. Those are related but different questions. A safety count can describe events in the treated group, but it does not directly quantify changes in dermatitis, pain, or quality of life.

The single-group design makes that distinction especially important. Without a concurrent comparator, the registry can record what happened among participants receiving low-level laser therapy, but cannot estimate how outcomes differ from an alternative. This is a useful example of why an observed event count should not be mistaken for evidence of treatment benefit or harm attributable to the intervention.

The record also illustrates the value of clear connections among endpoint definitions, analysis populations, and reported results. The primary outcome specifies a severity threshold, a measurement system, a timeframe, and a population, yet the record does not report an analysis explicitly tied to that definition. Clear linkage would help readers understand which participants and events contribute to a result and how that result should be interpreted.

Finally, the registry lists multiple outcome measures but no analyses. Without analysis methods, uncertainty estimates, or missing-data information, readers cannot assess precision or the possibility of selective reporting. These are not merely technical details: they determine what conclusions can reasonably be drawn from a completed study. The record is therefore useful for showing the limits of what descriptive registry safety information can establish.

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.

Important details needed to assess the study are not reported in the registry record. Participant characteristics beyond the condition and study context are absent, so the reader cannot assess how well the group represents a particular clinical population. The record also does not describe the degree of dermatitis at entry, the timing of radiation treatment relative to laser therapy, or the treatment schedule and duration.

The absence of a comparator prevents a direct estimate of outcomes under an alternative. The record does not report randomization, and masking is listed as none. It also does not describe who assessed adverse events, how events were attributed, or whether outcome assessors used standardized procedures beyond the stated CTCAE v4.0 definition for the primary endpoint.

Although a primary endpoint is defined, no analysis explicitly linked to it is reported. The record lists 0 analyses and does not provide confidence intervals, p-values, or a statistical analysis plan. It also does not explain how the 22 outcome measures relate to one another, how the repeated quality-of-life entries should be interpreted, or whether multiplicity was addressed.

Missing-data procedures, outcome-specific denominators, follow-up completeness, and the analysis population for outcomes other than the stated primary population are not reported. The safety information includes deaths, but the record does not give their timing, causes, or relationship to the intervention. These gaps limit interpretation of both event frequency and participant follow-up. The sample-size justification and any protocol-based planning assumptions are also not reported in the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Low Level Laser Therapy for Radiation Induced Dermatitis in H & N Squamous Cell Carcinoma — NCT02384434.
• Registry record last updated 2025-06-27; status last verified 2025-06.
• Results first posted 2025-06-27.
• 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

NCT02384434 is a completed, single-group study of the THOR Laser System for low-level laser therapy in the context of radiation-induced dermatitis among patients with head and neck squamous cell carcinoma. Enrollment is recorded as 16. Allocation is listed as NA and masking as none.

The primary endpoint is the count of participants with documented Grade 3 or higher adverse events per CTCAE v4.0, assessed up to 12 months, among patients who received at least 1 dose. The registry lists 22 outcome measures and 0 analyses. Safety information includes 9 participants with serious adverse events among 16 at risk, 16 with other adverse events among 16 at risk, and 12 deaths. The record does not report a primary endpoint analysis, a comparator, or enough detail to establish causation or evaluate the precision of the findings.