The Effect of Low Level Laser Therapy on Neck and Shoulder Pain: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Effect of Low Level Laser Therapy on Neck and Shoulder Pain (NCT03941912), a na na study. The primary outcome is Percentage of Subjects With 30% or Greater Change in Pain Rating on the Visual Analog Scale (VAS).

2. Clinical Question

This is a response-rate question, not a comparison of average pain ratings between treatment and control groups. The registry record supplies the endpoint definition and design, but lists zero analyses and no primary outcome result. Thus, it describes what the study set out to assess without allowing the reader to estimate the observed response rate or judge its precision.

3. Trial Design

The registry identifies NCT03941912 as a completed study titled The Effect of Low Level Laser Therapy on Neck and Shoulder Pain. Its official title is An Evaluation of the Erchonia EVRL on Neck and Shoulder Pain of Musculoskeletal Origin. Erchonia Corporation is listed as the sponsor. The recorded study start date is 2018-04-16, and the primary completion date is 2019-03-10.

The study model is single group. Allocation is listed as NA, and masking is listed as none. The record therefore describes an intervention group without a randomized or masked comparison. The intervention is the Erchonia EVRL device, with an arm description of 635 nanometers (nm) and 405 nm dual-diode laser application. The registry summary describes applying red and violet low level laser light to the neck and shoulders to assess pain.

Enrollment is listed as 44. Enrollment does not establish how many participants contributed data to the primary endpoint; the analyzed population and the number with endpoint observations are not reported in the registry record. The record lists one outcome measure and zero analyses. It describes the primary endpoint as a percentage of subjects meeting an individual response definition, measured from baseline to an endpoint one day later. Treatment administration is described as lasting 13 minutes.

The record lists phase as NA, which does not identify a phase category. A protocol-level statistical analysis plan, sample-size justification, detailed eligibility criteria, and any interim analysis plan are not reported in the registry record. Since there is no control group, the design can describe change over the evaluation period among participants with observations, but it cannot directly estimate how that change compares with what would have happened without the device.

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 Percentage of Subjects With 30% or Greater Change in Pain Rating on the Visual Analog Scale (VAS), measured over one day.

The primary endpoint is the percentage of subjects with a 30% or greater change in VAS pain rating from baseline to the endpoint measurement one day later. The endpoint description says the individual change is calculated across that evaluation period following 13-minute treatment administration. A negative percent change indicates a decrease in pain level and counts as individual success when the decrease reaches the stated threshold. A positive percent change indicates an increase in pain level and does not count as success.

This endpoint converts each subject’s change into a binary classification: meeting or not meeting the individual success definition. The resulting percentage is intended to express how common that defined response was among the assessed subjects. It is different from reporting the average amount of change in VAS scores. A response threshold can make a result easier to interpret as the proportion reaching a prespecified degree of change, while also omitting information about how far individual changes were from that threshold.

The registry record states a study-level success criterion of at least 65%±5% of subjects meeting the individual criterion. That criterion is a target for judging the group response; it is not an observed result. The record does not report the observed percentage, its uncertainty, or whether the stated criterion was satisfied. The endpoint is a short-term measure, with the recorded timeframe of one day, and does not itself describe pain response beyond that assessment point.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a binary response percentage represent?

The primary outcome is a binary response measure. Each subject is classified according to whether their VAS change meets the specified individual definition. The group percentage is the share of subjects in the relevant analysis population who meet that definition. It is not an average pain score and does not preserve the size of each person’s change once the success classification has been assigned.

That distinction matters for interpretation. A threshold makes the outcome correspond to a defined response category, but two participants with different-sized decreases can contribute identically if both meet the threshold. Participants with very similar changes may be assigned to different categories if one is on either side of the cutoff. General statistical practice is to read a binary response percentage alongside its definition, denominator, and uncertainty. The registry record defines the threshold but does not report an observed percentage, analysis denominator, or interval estimate.

How should the stated success criterion be understood?

The record specifies overall study success as at least 65%±5% of subjects meeting the individual success definition. This is a stated group-level criterion, separate from the individual 30% or greater change rule. It does not show that the criterion was reached. To assess that question, readers would need the observed number or percentage of successes and the analysis population to which it applies. Neither is reported in the registry record.

In general, a prespecified threshold can provide a decision rule for interpreting a response rate. It does not replace a full estimate of the outcome or its precision. If a result is near a criterion, uncertainty can be especially relevant to how confidently the result can be distinguished from that criterion. No observed result or inferential analysis is listed for this study, so that assessment cannot be made from the registry record.

Why does uncertainty matter for a percentage?

A point estimate is a single summary of the observed response proportion. A confidence interval is a statistical range that conveys uncertainty about the underlying response rate, conditional on the data and the method’s assumptions. General statistical interpretation considers both the estimate and its interval: a narrow interval indicates greater precision, while a wider interval indicates more uncertainty. The registry record provides neither the estimate nor an interval for the primary endpoint.

The denominator is essential because the same percentage can have different precision in populations of different sizes. Here, the record lists enrollment of 44, but does not state how many had evaluable endpoint data or were included in the primary analysis. The enrollment figure should not be treated as the analysis denominator. Missing or unevaluable endpoint observations could affect the denominator and the interpretation of the response percentage; the record does not report how these situations were handled.

What do the design and statistical assumptions imply?

The single-group model means the primary endpoint is not a randomized contrast between intervention and control. General statistical methods for estimating a within-group response can summarize the observed proportion, but they do not remove confounding or create a counterfactual comparison. With masking listed as none, the design also does not provide blinded outcome assessment as a safeguard against expectation-related influences. The registry record does not describe additional methods that might address these issues.

The record does not report the statistical test, confidence-interval method, adjustment strategy, or analysis population for the primary outcome. Those methods should not be inferred from the endpoint definition. Nor does the registry record provide a protocol-based sample-size justification. Any planning illustrations associated with the posted material are not the trial’s own design justification and are not observed power. The stated assumptions for those illustrations are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. Those assumptions describe hypothetical planning calculations; they do not change the actual single-group design.

For general interpretation, a sample-size calculation estimates the number of participants needed under specified assumptions to detect a chosen effect with a chosen level of statistical power. It does not tell whether a study actually observed an effect, and post hoc power calculated from an observed estimate is not a substitute for the estimate and its uncertainty. In this case, the registry record does not report a primary endpoint estimate on which to base an independent assessment of the response or its precision.

What can be said about multiplicity and analysis choices?

The registry record lists one outcome measure and zero analyses. The single listed outcome does not establish that there were no additional outcomes or planned comparisons in the protocol; such details are not reported in the registry record. Multiplicity refers generally to the increased chance of false-positive findings when multiple hypotheses or outcomes are tested. Whether any multiplicity adjustment was relevant or planned cannot be determined from the record.

The statistical analysis plan, handling of missing data, treatment of protocol deviations, and definition of analysis populations are not reported in the registry record. These omissions prevent assessment of whether the posted endpoint definition was applied as planned and whether all enrolled participants were represented. No conclusion about an analysis method or result should be inferred merely from the study’s completed status or its enrollment figure.

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("Erchonia EVRL")
n      <- c(44)
events <- c(33)
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  Erchonia EVRL  44  33  75.0  59.7  86.8  60.6  85.4  60.5  85.4

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and zero analyses. The listed primary endpoint is the percentage of subjects meeting the 30% or greater VAS change definition. That record-level count does not establish that the complete protocol contained only one outcome, nor does it establish that only one analysis was planned or conducted. Details of any additional outcomes, subgroup analyses, repeated assessments, interim analyses, or statistical adjustment for multiple testing are not reported in the registry record.

Multiplicity is a general concern when researchers test several hypotheses or examine multiple outcomes: even if each test is evaluated using a conventional threshold, the chance of at least one apparently notable finding can rise as the number of tests increases. Whether that concern applies to analyses beyond the listed primary measure cannot be determined from the posted record. No adjustment method is described.

Missing-data procedures and analysis populations are not reported in the registry record. Enrollment is listed as 44, but the number included in the primary endpoint analysis is not given. The record does not state how missing VAS measurements, incomplete assessments, withdrawals, or participants without an evaluable endpoint were treated. It also does not describe whether the analysis population was defined by enrollment, treatment received, or availability of endpoint data.

These omissions matter because a response percentage depends on both the success classification and the denominator. If the assessed participants differ from those without endpoint data, the resulting percentage may not represent all enrolled participants. Without the analysis denominator and missing-data approach, the reader cannot assess that possibility or reproduce the endpoint calculation. A protocol, analysis plan, and detailed results are 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.

The safety record lists the Erchonia EVRL group with 44 participants at risk for serious adverse events and zero serious adverse events. It also lists 44 participants at risk for other adverse events and zero other adverse events. The recorded number of deaths is zero, and no top serious adverse-event terms are listed.

These figures describe what is recorded for this study group; they do not establish that no adverse events occurred outside the categories or reporting captured by the registry entry. The record does not provide event narratives, severity details beyond the serious-event category, timing, duration, attribution, or information about how events were collected. It also does not provide a comparison group. Therefore, the figures cannot support a comparative safety estimate.

The number at risk is a safety denominator, not a measure of treatment effect. Because the registry record does not report the primary endpoint result, these safety entries should be interpreted separately from the pain-response question. Zero recorded events in this entry should not be treated as proof that the device has no safety risks; they are a description of the posted registry figures for the reported group.

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

The registry record describes a study designed to assess the percentage of subjects with a 30% or greater decrease in VAS pain rating from baseline to an endpoint one day later. It also states that at least 65%±5% meeting that individual definition would satisfy the overall study-success criterion. These registry entries explain the intended outcome and decision threshold, but they are not evidence that the target was reached.

The record lists zero analyses and does not report the primary outcome percentage, the number of subjects meeting the endpoint definition, an analysis denominator, or an uncertainty interval. As a result, the posted information does not establish the observed response rate or how precisely it was estimated. Enrollment of 44 is a design and recruitment figure in the record, not a reported count of endpoint successes or necessarily the number included in an analysis.

The study’s single-group design also limits what a response, if reported, could establish. A change from baseline would describe what happened during the measured period among the assessed participants. Without a concurrent comparator, it would not by itself show how much of that change was attributable to the device rather than other influences. The absence of masking is another design feature to consider when interpreting a subjective pain-rating outcome.

The endpoint is restricted to the one-day timeframe specified in the record. It does not answer whether any change persisted, nor does the binary threshold show the full distribution or magnitude of score changes. Those are distinct questions that would require additional reported outcomes and follow-up information.

Accordingly, the registry record supports a description of the study question, intervention, design, endpoint definition, and recorded safety figures. It does not support a conclusion about the observed primary response or comparative effectiveness. The absence of a posted primary analysis is not itself evidence for or against a treatment effect; it is a limit on what can be concluded from this record.

14. Why This Trial Matters Statistically

This study illustrates why an endpoint definition and an outcome result must be kept distinct. The registry record precisely describes what counted as individual success: a decrease in VAS pain rating meeting the 30% or greater change threshold. It also specifies a group-level success criterion. But without the observed response percentage, the reader cannot determine whether the criterion was met. A clear target is not a result.

It also highlights the difference between an individual response classification and a group summary. A percentage meeting a threshold answers how many assessed participants crossed that boundary, not how much pain ratings changed on average or how variable individual changes were. Readers need the denominator and an uncertainty estimate to judge the precision of a response percentage. Those are not reported for the primary endpoint in the registry record.

The single-group, unmasked design is statistically important because a change over time is not the same as a treatment-versus-control effect. A comparator helps characterize what might have occurred in the absence of the intervention; this study’s registry description does not include one. That limitation is especially relevant when the outcome is a self-reported pain rating and the assessment follows a brief treatment period.

Finally, the record demonstrates the value of complete reporting. A completed status, enrollment figure, outcome definition, and safety counts do not replace results, analysis methods, missing-data details, or uncertainty estimates. Without these elements, interpretation must remain focused on what was planned and recorded rather than on claims about efficacy or precision. The distinctions are broadly useful when reading clinical trial registries, especially for uncontrolled studies with binary response endpoints.

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 study follow from the registry description. The single-group model has no concurrent comparator, so any change in pain rating over the one-day evaluation period cannot be contrasted with the course of symptoms under another condition. The registry lists masking as none, and the endpoint is based on VAS pain ratings. This combination leaves the result vulnerable to influences associated with participant expectations or assessment context; the record does not describe methods used to reduce those influences.

The primary endpoint is a thresholded response measure. It classifies participants according to whether they meet the stated change rule, but does not by itself show the magnitude of change for each participant or the distribution of changes. Its one-day timeframe also provides no information about longer-term response. The registry record does not list additional follow-up results that would address persistence.

Enrollment is listed as 44, but the primary analysis denominator and number with evaluable VAS data are not reported. The record also does not describe missing-data handling, baseline participant characteristics, detailed eligibility criteria, adherence, or protocol deviations. These gaps make it difficult to judge who contributed to the endpoint and how representative that group was of all enrolled participants.

Most importantly, the registry record lists zero analyses and no primary outcome result. It therefore does not provide an estimate, confidence interval, or test result for the main question. The protocol-level statistical plan, sample-size justification, and analysis-population definitions are not reported in the registry record. These are limitations of the available study record; they do not establish what may or may not have been analyzed outside the registry.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: The Effect of Low Level Laser Therapy on Neck and Shoulder Pain — NCT03941912.
• Registry record last updated 2021-10-14; status last verified 2021-10.
• Results first posted 2021-10-14.
• 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

NCT03941912 is a completed, single-group study sponsored by Erchonia Corporation, evaluating the Erchonia EVRL device for musculoskeletal neck and shoulder pain. The registry describes 635 nanometers (nm) and 405 nm dual-diode laser application, with a 13-minute treatment administration and a one-day primary assessment timeframe. Enrollment is listed as 44, with no masking and no comparison group.

The primary endpoint is the percentage of subjects meeting a 30% or greater decrease in VAS pain rating, with a stated overall success criterion of at least 65%±5%. The registry record lists one outcome measure and zero analyses, and does not report the observed primary outcome, analysis denominator, uncertainty, missing-data approach, or statistical analysis plan. Safety entries list zero serious adverse events, zero other adverse events, and zero deaths among the reported group. These details describe the registry record but do not establish whether the primary criterion was met or provide a comparative estimate of the intervention’s effect.