Low-Level Laser Therapy for Prevention of Oral Mucositis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Low-Level Laser Therapy for Prevention of Oral Mucositis (NCT02682992), a na na study. The primary outcome is Percentage of Participants With Severe (WHO Grade 3-4) Oral Mucositis.

2. Clinical Question

3. Trial Design

The registry describes a prospective, single-group study of low-level laser therapy for prevention of oral mucositis in patients receiving chemotherapy and radiation for head and neck cancer. The official title calls it a Phase II trial, while the registry phase field is listed as NA. Enrollment was 47, and the study status is completed. The recorded start was 2016-06 and primary completion was 2020-11.

All participants were assigned to the single intervention group, Low Level Laser Therapy. The arm description says LLLT was to be given prophylactically in addition to standard-of-care measures for oral mucositis or other toxicity. The registry says that radiation and chemotherapy dosing, schedule, modality, technique, and required adjustments would not be influenced by the intervention, although the available description ends before completing that statement. Further details about the intervention protocol are not reported in the registry record.

This design can describe outcomes observed in the enrolled group, but it cannot by itself estimate how those outcomes would differ under a separate control condition. Allocation is recorded as NA, masking as NONE, and the model as SINGLE GROUP. Thus, there is no randomized or masked comparison described in the registry.

The primary outcome was severe oral mucositis, with secondary outcomes covering onset and duration of mucositis, cumulative radiation dose, feeding tube replacement, trismus, quality of life measured with the FACT-HN questionnaire, oral mucositis, and dysphagia. The registry lists 17 outcome measures, but reports zero analyses. Results for the primary and secondary outcomes are not reported in the registry record.

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: Treated patients experiencing severe oral mucositis.

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 Percentage of Participants With Severe (WHO Grade 3-4) Oral Mucositis, measured over Up to 1 year.

The primary endpoint is the percentage of participants who experienced severe oral mucositis, defined as WHO grade 3-4. The registry description characterizes these grades as ulcerative lesions of the oral mucosa. The outcome applies to patients treated to a cumulative radiation dose of at least 5000 cGy and has a timeframe of up to 1 year.

A percentage expresses how common an event was among the participants in the endpoint’s defined population. In general, this kind of binary endpoint is useful when the clinical question concerns whether a participant experienced an event, rather than the event’s duration or severity over time. The registry also lists time to onset and duration of oral mucositis as secondary outcomes, which address different aspects of the same complication.

The primary outcome is recorded as a number with a 90% confidence interval. A confidence interval conveys uncertainty around an estimated percentage; it is not a guarantee that the true value lies within the interval. The actual primary endpoint estimate and interval are not reported in the registry record. Accordingly, the registry does not establish the observed frequency or precision of severe oral mucositis in this study.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a percentage endpoint represent?

The primary outcome is a binary event measure: each participant either met the definition of severe oral mucositis or did not. The group percentage summarizes the frequency of that event in the endpoint population. In general, a percentage is interpretable only alongside its denominator and a clear description of who was eligible for analysis. Here, the registry specifies patients treated to a cumulative radiation dose of at least 5000 cGy, but the number meeting that condition and the resulting percentage are not reported in the registry record.

The listed endpoint unit is percentage of participants, and the event is WHO grade 3-4 oral mucositis. The registry’s outcome description also identifies ulcerative lesions of the oral mucosa. Because no numerical estimate is posted, there is no event percentage to explain as an observed finding.

How should a confidence interval be understood?

The endpoint specifies a 90% confidence interval. In general, a confidence interval communicates the statistical uncertainty associated with an estimate. A narrower interval indicates greater precision under the assumptions of the method; a wider interval indicates less precision. It does not show the range of outcomes experienced by individual participants, and it does not resolve limitations in the study design.

The confidence interval endpoints are not reported in the registry record. Without the estimate and interval, the frequency and precision of the primary endpoint cannot be assessed. The stated confidence level alone is not a result.

What can a single-group study estimate?

In general, a single-group study can describe the outcomes observed among participants receiving the study intervention and accompanying care. It does not provide a concurrent control group for estimating how outcomes would have differed without the intervention. A comparison with an external rate would require a suitable external source and careful assumptions; no such comparison is reported in the registry record.

For this study, the design is recorded as SINGLE GROUP, allocation as NA, and masking as NONE. The registry describes LLLT in addition to standard care. Therefore, the design can characterize the treated group if results are reported, but cannot isolate an intervention effect from other influences through a randomized between-group contrast.

What do the analysis and planning details mean?

The registry lists zero analyses. It does not report a statistical analysis plan, a sample-size justification, or interim analyses. These omissions mean that the intended modeling choices, analysis populations, and any prespecified handling of multiple outcomes cannot be established from the registry record.

The record includes planning illustrations based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Those assumptions describe planning illustrations, not the design of this single-group trial. The illustrations are not observed power, and they do not replace the trial’s missing primary outcome analysis. The observed primary effect used for those illustrations is not reported in the registry record, and no resulting sample-size values are stated in the registry record presented for interpretation.

In general, sample-size planning asks how many participants would be needed to detect a specified effect under stated assumptions. Such a calculation is distinct from the precision actually achieved in a completed study. It also cannot establish whether a finding is clinically important. Since the trial has no separate comparator and the primary result is absent, the planning assumptions do not provide a basis for an estimate of comparative effect or a conclusion about the primary outcome.

Why can event rates vary more than a simple model expects?

In general, over-dispersion occurs when outcomes vary more across participants or groups than a statistical model assumes. If it is ignored, uncertainty can be understated. It can matter in analyses of counts, clustered observations, or repeated measures. The registry does not report an over-dispersion assessment or a model requiring such an assessment, so its relevance to the trial’s actual analyses cannot be determined.

For a binary percentage, uncertainty depends in part on the number of participants with outcome information and the event frequency. The relevant primary endpoint denominator and event count are not reported. Accordingly, the precision of the primary estimate cannot be independently assessed from the registry record.

What does the safety summary contribute?

The adverse-event record provides counts of participants at risk and affected for serious and other adverse events, plus a count of deaths and a list of leading serious-event terms. In general, these descriptive safety summaries identify events recorded during a study, but they do not establish causation. A comparison of event rates would require a suitable comparison group and consistent ascertainment; this trial is single-group, and no causal attribution is established in the registry record.

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(47)
events <- c(11)
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  47  11  23.4  12.3  38.0  13.6  37.2  13.6  37.3

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 17 outcome measures, including the primary severe oral mucositis endpoint and secondary measures concerning mucositis, radiation dose, feeding tube replacement, trismus, quality of life, and dysphagia. When a study evaluates multiple outcomes, the chance of at least one apparently notable result can increase if each is tested separately. In general, a statistical plan may address multiplicity by identifying a primary outcome, specifying a testing hierarchy, or adjusting inference. The registry record does not report such a plan or any adjustment strategy.

The record lists zero analyses. It therefore does not report which outcomes were analyzed, whether any outcomes were omitted, how results were modeled, or what criteria governed the interpretation of multiple endpoints. These details are not reported in the registry record and should not be inferred from the outcome list alone.

Missing-data handling is also not reported in the registry record. The primary endpoint is limited to patients treated to a cumulative radiation dose of at least 5000 cGy, but the number who met that condition, the number with outcome information, and the treatment of participants without evaluable endpoint data are not reported. It is not possible to determine whether the reported enrollment of 47 matches the primary endpoint analysis population.

The population used for the primary analysis is not fully defined in the available information. The endpoint description refers to patients receiving the specified cumulative radiation dose, while the primary population field describes treated patients experiencing severe oral mucositis. The record does not clarify how those descriptions were operationalized in an analysis. The handling of withdrawals, incomplete assessments, or other missing observations is not reported in the registry record.

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: dysphagia (38.3%), oral mucositis (23.4%), dermatitis (4.3%), dry mouth (2.1%).

The safety summary lists 47 participants at risk for serious adverse events, with 18 participants affected. For other adverse events, it lists 47 participants at risk and 47 affected. The record also lists 7 deaths. These counts should be read as registry safety summaries for the LLLT group, not as estimates of a difference from another treatment group.

The leading serious-event terms are dysphagia at 38.3%, oral mucositis at 23.4%, dermatitis at 4.3%, and dry mouth at 2.1%. They are event terms in the serious-event summary; the percentages should not be interpreted as evidence that LLLT caused those events. The registry does not report a control group, a causal assessment for these events, or an analysis comparing safety between treatment strategies.

In general, adverse-event counts describe what was recorded among participants under observation. They do not by themselves distinguish events caused by an intervention from events related to the underlying condition, other treatments, or other causes. Further details about event timing, severity criteria, attribution, and the circumstances of the deaths are not reported in the registry record.

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

The record establishes that the study was designed to examine prophylactic LLLT for prevention of oral mucositis in patients receiving chemotherapy and radiation for head and neck cancer. It identifies severe WHO grade 3-4 oral mucositis as the primary endpoint, defines a radiation-dose condition for that endpoint, and states a timeframe of up to 1 year. It also records enrollment of 47 and describes a range of secondary outcomes.

The record does not report the primary endpoint result or any outcome analyses. Consequently, it does not show the observed percentage of participants who developed severe oral mucositis, the precision of that estimate, or how secondary outcomes were distributed. The registry’s stated endpoint and purpose should not be mistaken for evidence of an outcome.

The single-group design also limits what any observed rate could mean. Without a separate control group, a rate among participants receiving LLLT with standard care would not, by itself, tell how that rate compares with what would have occurred under standard care alone. It would describe outcomes in this enrolled group, not a randomized treatment contrast.

The safety summary documents serious and other adverse-event counts and deaths, but it does not establish that LLLT caused them. The listed serious-event terms are descriptive. A comparison of safety between treatment strategies is not available in the registry record.

In general, a clinical trial result is interpreted by considering the estimate, its uncertainty, the analysis population, the study design, and how outcomes were handled. Several of those elements—including the primary estimate, its confidence interval, and missing-data methods—are not reported in the registry record. The available information therefore supports a description of the study and its recorded safety counts, but not a conclusion about the primary endpoint or a causal effect of the intervention.

14. Why This Trial Matters Statistically

This trial illustrates the distinction between a well-defined clinical question and a reported statistical result. The registry names a primary endpoint, specifies its severity definition and timeframe, and describes the population as patients treated to a cumulative radiation dose of at least 5000 cGy. Those details are necessary for interpreting an outcome, but they do not substitute for the event count, percentage, and confidence interval.

The single-group design also makes the distinction between description and comparison especially important. A percentage from the LLLT group could describe the occurrence of severe mucositis in that group. It could not directly estimate a difference from standard care alone because no separate control group is listed. The registry’s allocation and masking information reinforce that no randomized, masked comparison is described.

There are multiple outcome measures, spanning mucositis and other aspects of treatment experience. In general, prespecifying an analysis strategy for multiple outcomes helps readers understand which questions were primary and how other findings should be interpreted. The registry lists zero analyses and does not report how multiplicity was addressed, which limits statistical interpretation.

The record also shows why safety counts need context. Event counts and percentages describe what was recorded, while causal attribution requires additional evidence. The serious-event summary cannot independently determine whether an event was due to LLLT or other circumstances, and a comparison group is not available for comparative safety interpretation.

For researchers, the record underscores the value of reporting endpoint denominators, estimates, uncertainty intervals, analysis populations, missing-data handling, and prespecified methods. Without those details, a completed trial’s clinical question may be identifiable while its statistical findings remain unavailable for assessment.

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 most direct limitation for interpretation is that the primary outcome result is not reported in the registry record, despite the study being marked completed. The primary estimate and its stated 90% confidence interval are absent, and the record lists zero analyses. Thus, the frequency and precision of severe oral mucositis cannot be evaluated from the posted information.

The single-group design has no concurrent control group. It can describe outcomes among participants receiving LLLT with standard care, but it does not support a direct randomized comparison with standard care alone. Allocation is listed as NA and masking as NONE. The registry does not report an alternative comparative analysis.

The primary outcome applies to patients treated to a cumulative radiation dose of at least 5000 cGy, but the number meeting that condition and the endpoint analysis denominator are not reported. The registry does not explain how participants without endpoint information were handled or whether missing observations occurred. The analysis population is therefore unclear from the available record.

The registry lists 17 outcome measures but does not report an analysis plan, multiplicity strategy, or interim analyses. The details of the LLLT protocol are also limited in the available arm description. Further information on eligibility criteria, event ascertainment, adverse-event attribution, and the circumstances of the deaths is not reported in the registry record. These limitations restrict assessment of outcome validity, precision, and causal interpretation.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Low-Level Laser Therapy for Prevention of Oral Mucositis — NCT02682992.
• Registry record last updated 2022-04-13; status last verified 2022-04.
• Results first posted 2022-04-13.
• 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 completed prospective, single-group study of prophylactic low-level laser therapy added to standard care for patients receiving chemotherapy and radiation for head and neck cancer. The official title identifies the study as Phase II, while the registry phase field is NA. Enrollment was 47; the recorded start was 2016-06 and primary completion was 2020-11.

The primary endpoint was the percentage with severe WHO grade 3-4 oral mucositis, among patients treated to a cumulative radiation dose of at least 5000 cGy, over a timeframe of up to 1 year. The primary result and its 90% confidence interval are not reported in the registry record. The registry lists 17 outcome measures and zero analyses.

The safety summary records serious adverse events affecting 18 of 47 participants, other adverse events affecting 47 of 47, and 7 deaths. These counts do not establish causation. No separate comparator group is described.