This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Low Intensity Ultrasound Therapy for Upper Back Pain Relief (NCT02135094), a randomized na study. The primary outcome is Pain on the Numeric Rating Scale (NRS).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02135094 |
| Phase | NA |
| Condition | Muscle Spasm |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 33 |
| Arms in the primary outcome | n/a |
| Lead sponsor | ZetrOZ, Inc. |
| Results posted | Yes |
2. Clinical Question
Population
The trial enrolled patients with trapezius muscle pain associated with the upper back. The registry record lists 33 participants and identifies muscle spasm as a condition. It does not report further eligibility details or a fuller description of the population in the primary outcome record.
Intervention
The active arm used the Sam Ultrasonic Diathermy Device on days when pain was at least 3 on the 0-10 Numeric Rating Scale. The active device emitted continuous ultrasound at 3 megahertz (MHz) and 0.132 watts/cm2 intensity. The device was applied for 4 hours on treatment days.
Comparator
The placebo device appeared and operated identically to the active device but did not emit ultrasound. Participants applied it for 4 hours on days when their trapezius pain was at least 3 on the 0-10 scale. This comparison was intended to distinguish the active ultrasound component from the experience of using the device.
Primary question
The registry names pain on the Numeric Rating Scale as the primary outcome, assessed during Week 1, Week 2, Week 3, and Week 4. The central question is how recorded pain scores in the active-device arm compare with those in the placebo-device arm over those weeks. The registry record does not report the outcome values or an analysis comparing the arms, so the observed size and precision of any difference cannot be described.
3. Trial Design
The registry describes a randomized, parallel-group trial with quadruple masking. Participants were assigned to an active ultrasound therapy device or a placebo ultrasound therapy device. In a parallel design, participants remain in their assigned group for the comparison rather than receiving both interventions in sequence. The registry record does not report details of the randomization procedure, allocation concealment, or which roles were included in the masking.
The planned treatment period was 4 weeks. Participants were instructed to use their assigned device on days when trapezius muscle pain met the stated threshold of at least 3 on the 0-10 Numeric Rating Scale. Use was described as 4 hours per treatment day. The registry summary describes clinical visits at enrollment and weeks 2 and 4, and daily pain diary entries. On treatment days, pain was also recorded 30 minutes into treatment, 2 hours into treatment, and after 4 hours.
The active device emitted continuous ultrasound at 3 megahertz (MHz) and 0.132 watts/cm2 intensity. The placebo device looked and operated identically but did not emit ultrasound. This design aims to preserve masking while comparing the active device with a device-use control.
The trial is listed as completed, with an enrollment of 33. Its start is recorded as 2014-06 and primary completion as 2015-09. The registry identifies ZetrOZ, Inc. as sponsor. It lists the phase as NA. The record does not report a detailed protocol, a sample-size justification, or further design information beyond the listed features.
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
| Stage | Active Ultrasound Therapy Device | Placebo Ultrasound Therapy Device |
|---|---|---|
| STARTED | 25 | 8 |
| Week 2 | 25 | 8 |
| Week 3 | 25 | 8 |
| Week 4 | 25 | 8 |
| COMPLETED | 25 | 8 |
| NOT COMPLETED | 0 | 0 |
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.
| Characteristic | Unit | Active Ultrasound Therapy Device | Placebo Ultrasound Therapy Device | Total |
|---|---|---|---|---|
| Participants analysed | 25 | 8 | 33 | |
| Age, Continuous | years | 34.2 (SD 13.9) | 30.3 (SD 10.9) | 33.3 (SD 13.3) |
| Sex: Female, Male: Female | Participants | 16 | 5 | 21 |
| Sex: Female, Male: Male | Participants | 9 | 3 | 12 |
| Region of Enrollment: United States | participants | 25 | 8 | 33 |
| Height | cm | 169.8 (SD 12.1) | 169.1 (SD 9.7) | 169.6 (SD 11.4) |
| Weight | kg | 75.1 (SD 13.1) | 72.2 (SD 22.4) | 74.4 (SD 15.0) |
6. Primary Endpoint
The registry lists the primary outcome as Pain on the Numeric Rating Scale (NRS), measured over Week 1, Week 2, Week 3, Week 4.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | units on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is pain measured with the Numeric Rating Scale (NRS), reported in units on a scale. The scale runs from 0, meaning no pain, to 10, meaning the worst pain possible. A numerical scale gives participants a way to record pain intensity repeatedly and allows group summaries to be expressed as means and standard deviations.
The primary timeframe includes Week 1, Week 2, Week 3, and Week 4. Participants recorded daily pre-treatment pain. On days when the device was used, they also recorded pain 30 minutes into treatment, 2 hours into treatment, and after 4 hours. The registry states that the post-treatment score was used to find the weekly average and standard deviation. Thus, the weekly primary summaries concern post-treatment scores, while the other recorded times provide additional pain assessments.
Repeated measurement can describe pain across the treatment period rather than at a single assessment. It also creates several time-specific summaries that need to be interpreted in relation to the planned endpoint. The registry record does not report the actual weekly means or standard deviations, the number of observations contributing to each summary, or an estimated comparison between groups. The endpoint is therefore defined, but its observed values and statistical precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes the outcome and the intended comparison but does not report numerical primary outcome results or statistical analyses. It lists pain on the Numeric Rating Scale as the primary outcome, with weekly summaries for Week 1 through Week 4. It also states that the post-treatment score was used to calculate a weekly average and standard deviation. Without those values, the amount and direction of any difference between the active and placebo groups cannot be assessed from the record.
The record lists 33 participants enrolled. That total describes enrollment, not necessarily the number contributing data at every assessment. The number assessed at each week, the number with usable diary entries, and the analysis population are not reported in the registry record. No participant flow or outcome-specific denominators are described in the posted results.
The primary outcome contains several time points. The registry explicitly notes that it was not reduced to one comparison. This matters because an outcome measured repeatedly can be summarized in different ways: a group contrast at each week, an average across weeks, a change from baseline, or a model using repeated measurements. Those approaches answer related but distinct questions. The registry record does not report which inferential approach, if any, was used for the primary outcome.
A mean describes the central level of a continuous measure, while a standard deviation describes the spread of individual observations around that mean. Neither measure alone describes the uncertainty in a comparison between groups. A confidence interval would show a range of values compatible with the data under the specified analysis, and a p-value would summarize evidence against a null hypothesis under model assumptions. Neither confidence intervals nor p-values for the primary comparison are reported in the registry record.
The absence of reported results should not be read as evidence that the groups had identical outcomes, or that one group had a particular advantage. It means that the record does not present the information needed to quantify the observed contrast or its precision. The trial's stated design and endpoint can be described, but conclusions about the magnitude, consistency, or statistical uncertainty of its primary outcome cannot be drawn from the registry record.
9. Statistical Methods Explained
The registry identifies a continuous primary outcome: pain measured on the Numeric Rating Scale. A continuous outcome can take a range of values and is often summarized with a mean and standard deviation. The mean gives a measure of the group average; the standard deviation describes how dispersed individual scores are around that average. The registry specifies those summary measures and states that weekly summaries use the post-treatment pain score. It does not report the resulting means or standard deviations.
What does a group comparison estimate?
A comparison between randomized groups is intended to estimate how the outcome differs under assignment to the active device versus assignment to the placebo device. Randomization can support a fair comparison by distributing measured and unmeasured participant characteristics across groups on average, but it does not guarantee that every factor is balanced in a particular trial. The method used to estimate the group contrast, and any adjustment for baseline measures or other variables, are not reported in the registry record.
For a continuous outcome, an analysis might compare group means at a defined time point or model measurements collected repeatedly over time. These methods do not necessarily target the same quantity. A weekly mean comparison focuses on a specific week; a repeated-measures model can use the pattern across assessments and account for how measurements from the same participant are related. The record identifies four weekly time points but does not report a model or a prespecified summary across them.
Why does repeated measurement matter?
Pain was recorded daily, with additional within-treatment assessments on days the device was used. Repeated scores from one person are generally related rather than independent. A method that treats every recorded score as unrelated could misstate uncertainty. Methods for repeated data account for the structure of observations within participants, but the registry record does not say whether such a method was used. Nor does it describe how diary entries that were absent or incomplete were handled.
The registry's primary outcome description uses post-treatment scores to calculate weekly averages and standard deviations. This distinguishes the specified weekly summary from the additional recordings at 30 minutes into treatment and 2 hours into treatment. Those measurements are also listed among the secondary outcomes. The record does not state whether the primary comparison was based on each week's summary separately, whether the weeks were combined, or how any multiple comparisons were handled.
What would uncertainty measures add?
A confidence interval for a group contrast would express the statistical uncertainty around the estimated difference, conditional on the analysis method and its assumptions. A narrower interval indicates greater precision than a wider interval, but precision is not the same as clinical importance. A p-value addresses compatibility with a specified null hypothesis under the chosen model; it does not give the probability that the null hypothesis is true. The registry record reports no confidence interval, p-value, or estimated group contrast for the primary outcome.
Standard deviations should not be confused with standard errors or confidence intervals. The standard deviation describes variation among participant scores. A standard error describes the uncertainty in an estimate such as a mean, and depends on the data and analysis. The record lists standard deviation as the primary outcome's dispersion measure but gives no numerical values from which precision can be interpreted.
How should planning illustrations be read?
The registry includes a statement that sample-size planning illustrations are based on the observed effect, with a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed trial outcomes and not evidence that the trial had a particular probability of finding a result. The registry record does not report the trial's own sample-size justification. Because no observed effect estimates are reported, the planning assumptions cannot establish the magnitude or precision of the trial's primary result.
Over-dispersion is a general concern when observed variability is greater than a statistical model assumes. In that situation, model-based standard errors can be too small, making estimates appear more precise than warranted. Whether over-dispersion was relevant to this trial is not reported in the registry record. More generally, every inferential method relies on assumptions; the method, diagnostics, and sensitivity analyses for this outcome are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome is assessed across Week 1, Week 2, Week 3, and Week 4, and the record also lists secondary pain assessments before, during, and after treatment, along with a Global Rating of Change outcome. Considering multiple time points and outcomes can raise multiplicity concerns: when many hypotheses are tested, the chance of at least one apparently notable finding can increase. A prespecified analysis plan may define a primary comparison or adjust for multiple testing. The registry record does not report a multiplicity strategy, a hierarchy of tests, or an analysis plan that resolves how the multiple assessments should be interpreted.
The registry notes that the primary outcome has several categories or time points and was not reduced to one comparison. This leaves the intended inferential contrast unclear. It is not reported whether each week was meant to be tested separately, whether one week was primary, or whether an overall repeated-measures contrast was planned. No primary comparison result is reported in the registry record.
Missing data can affect estimates if participants do not complete diaries or miss later assessments. The record describes daily diaries and clinic visits, but does not report missingness by time point, reasons for missing data, imputation methods, or sensitivity analyses. The number of participants included in each weekly outcome summary is not reported in the registry record.
The record does not describe the analysis population, such as whether participants were analyzed according to randomized assignment or only when they completed treatment. It also does not report deviations from assigned device use or how those might have been handled. These omissions limit assessment of both the analysis strategy and the potential influence of incomplete observations.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Active Ultrasound Therapy Device | 0 | 25 | 0.0% |
| Placebo Ultrasound Therapy Device | 0 | 8 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Active Ultrasound Therapy Device | 0 of 25 |
| Placebo Ultrasound Therapy Device | 0 of 8 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Active Ultrasound Therapy Device | 0 of 25 |
| Placebo Ultrasound Therapy Device | 0 of 8 |
The registry lists serious adverse event figures separately for the active and placebo device groups. For the active ultrasound therapy device, 25 participants were listed as at risk, with 0 serious adverse events and 0 deaths. For the placebo ultrasound therapy device, 8 participants were listed as at risk, with 0 serious adverse events and 0 deaths. The record also lists 0 other adverse events for each group, with 25 at risk in the active group and 8 at risk in the placebo group.
These figures are counts recorded in the registry, not estimates of comparative risk. They should be read alongside the group sizes and the scope of adverse-event reporting. The registry record does not report further detail on how events were collected, the observation period for safety, event definitions, or whether all participants had the same duration of safety follow-up.
A recorded count of zero does not establish that an event is impossible, nor does it by itself demonstrate equivalence between groups. In particular, the listed groups differ in the numbers at risk, and no statistical comparison or uncertainty estimate is reported. The figures describe what the registry reports; they do not support a broader conclusion about safety beyond those recorded counts.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a randomized, quadruple-masked, parallel-group comparison was conducted between an active ultrasound device and a placebo device for trapezius muscle pain. It defines a continuous pain outcome on a 0-10 Numeric Rating Scale and identifies post-treatment weekly summaries across Week 1, Week 2, Week 3, and Week 4. It also describes daily diary recording and additional pain ratings during treatment.
Those design details do not reveal the outcome of the comparison. The registry record does not report the weekly means, standard deviations, estimated difference between groups, confidence interval, or p-value. Consequently, the direction, size, and precision of any contrast cannot be determined from the registry record. No claim that the active device lowered pain, or that it did not, is supported by the outcome information reported there.
The enrollment count of 33 does not indicate how many participants contributed data at each assessment. Likewise, the safety counts describe events listed in the record and do not substitute for the missing primary outcome analysis. The absence of a reported analysis is not equivalent to a finding of no effect, and it is not evidence that the groups were the same.
In general, interpreting a treatment comparison requires both an estimate and an account of its uncertainty, together with enough detail to understand the analysis population and missing observations. Those elements are not reported in the registry record. The available record therefore supports a description of the trial's design, treatment conditions, intended outcome, and listed adverse-event counts, but not an estimate of the comparative pain outcome.
13. Why This Trial Matters Statistically
This trial illustrates why a registry entry can describe a clear clinical question without reporting enough statistical information to answer it. The record identifies the active and placebo device conditions, a randomized parallel design, masking, a repeated pain measure, and a treatment period. Yet it reports no primary outcome values or inferential comparison. Without those results, readers cannot assess the observed contrast or how precisely it was estimated.
The repeated measurement schedule also highlights an important statistical issue. Pain was recorded daily, and further assessments were planned during device use. Several weekly summaries and secondary assessments can describe different aspects of a participant's experience. Statistical interpretation depends on knowing which comparison was primary, how repeated observations were modeled, and how multiple analyses were treated. Those details are not reported in the registry record.
The trial also demonstrates why enrollment and outcome-analysis counts should not be treated as interchangeable. The registry reports 33 enrolled participants, while outcome-specific denominators and missing-data handling are not reported. A reader therefore cannot determine how complete the weekly measurements were or whether the analysis included all randomized participants.
Finally, the listed serious adverse event counts are descriptive. They do not provide a statistical comparison, and the unequal numbers at risk make it especially important not to infer comparative safety from raw counts alone. Taken together, these features show the value of complete reporting: outcome estimates, uncertainty measures, analysis populations, missing-data methods, and multiplicity decisions are needed for a transparent statistical interpretation.
14. 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.
A key trial-specific limitation of the registry record is that it defines the primary outcome but supplies no outcome estimates or analysis. There are no reported weekly means or standard deviations, and no comparison estimate with a measure of uncertainty. This prevents assessment of the direction, size, consistency, or precision of the pain findings.
The endpoint involves several time points, while the registry notes that it was not reduced to one comparison. Without a specified primary contrast, the intended interpretation of the weekly assessments is unclear. The record does not explain whether the weeks were to be analyzed separately or jointly, or whether the repeated measurements were handled with a model accounting for their within-participant relationship.
The registry reports an enrollment of 33, but does not report outcome-specific participant counts, missing diary entries, or reasons for missing assessments. It also does not report an analysis population or the handling of treatment nonadherence. These gaps prevent assessment of how the available observations relate to the enrolled group.
The record describes quadruple masking but does not specify the roles masked or the procedures used to maintain masking. It does not report a detailed randomization method, sample-size justification, or analysis plan. These details are relevant to evaluating the design and its statistical implementation, but should not be inferred from the listed design labels.
Safety reporting is limited to group counts and numbers at risk. The registry does not describe event ascertainment or provide further context for follow-up. These limitations apply to interpretation of the registry record and do not establish that unreported procedures or analyses were not conducted.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Low Intensity Ultrasound Therapy for Upper Back Pain Relief — NCT02135094.
- Registry record last updated 2020-04-02; status last verified 2020-03.
- Results first posted 2018-06-11.
- 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.
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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed randomized, parallel-group trial of active and placebo ultrasound devices for trapezius muscle pain. It lists quadruple masking and an enrollment of 33. The active device emitted continuous ultrasound at 3 megahertz (MHz) and 0.132 watts/cm2 intensity; the placebo device did not emit ultrasound. Use was described for 4 hours on days when pain was at least 3 on the 0-10 Numeric Rating Scale.
The primary outcome was pain on the Numeric Rating Scale, summarized after treatment across Week 1, Week 2, Week 3, and Week 4. The registry record does not report outcome values, an analysis comparing the groups, uncertainty estimates, or details of missing-data handling. It lists 0 serious adverse events and 0 deaths in both groups, with 25 at risk in the active group and 8 in the placebo group. These are descriptive registry counts and do not establish a comparative safety result.