Response to Intermittent Pneumatic Compression Therapy in Head and Neck Cancer-Related Lymphedema: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Response to Intermittent Pneumatic Compression Therapy in Head and Neck Cancer-Related Lymphedema (NCT02946021), a non-randomized phase 1, phase 2 study. The primary outcome is Lymph Movement Measured by ICG Lymphography..

2. Clinical Question

The clinical question is about imaging evidence of lymphatic movement during pneumatic compression, rather than a comparison with no treatment. The registry also lists dermal backflow, symptom alleviation, and ease of use as secondary outcomes. The record identifies four outcome measures overall, but it does not provide numerical primary-outcome findings or analyses. Consequently, the endpoint’s purpose can be described, but the posted information does not establish the magnitude, precision, or direction of a primary outcome result.

3. Trial Design

This was a Phase 1/Phase 2 study with non-randomized allocation, no masking, and a parallel-group model. It enrolled 11 participants and is listed as completed. The study began in 2016-10, with primary completion in 2018-02. Tactile Medical is identified as the sponsor.

The two groups used head and neck garments for a pneumatic compression device at different daily frequencies: one session per day or two sessions per day. NIR fluorescence lymphatic imaging with ICG was used in conjunction with treatment. The registry describes ICG as indocyanine green and identifies imaging as part of the assessment of lymphatic structure and function before and after treatment and during recovery.

Because allocation was non-randomized, the groups should not be treated as exchangeable by design. Any difference between them could reflect factors other than session frequency, including differences in the participants assigned to each group. The registry record does not describe a randomized comparison or a separate untreated control group, so it does not support a causal, like-for-like comparison between the two frequencies.

The primary outcome was lymph movement measured by ICG lymphography. Its stated timeframe covered a single treatment and two weeks of treatment. Three secondary outcomes were listed: dermal backflow measured by ICG lymphography, symptom alleviation measured by survey response, and ease of use measured by survey response. Although the registry reports 11 enrolled participants, the primary analysis description identifies 10 analyzable participants after excluding a participant who reported wearing the garment upside down during the two-week period. The registry record does not report further protocol details, the reasons participants entered one frequency group rather than the other, or a statistical analysis plan.

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: The analysis population included all enrolled subjects who completed the study and properly used the device. One subject reported wearing the head garment upside down during the two week treatment period, therefore the subject was excluded from the analysis population for a cohort of 10 analyzable data sets.

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 Lymph Movement Measured by ICG Lymphography., measured over Single Treatment, 2 Weeks of Treatment.

The primary endpoint is lymph movement measured by ICG lymphography, with the unit described as participants. The endpoint description says the assessment was intended to demonstrate the ability of the Flexitouch system to move lymph or enhance lymphatic uptake. The stated imaging indicators were increased functionality of vessels and/or changes in the area of dermal backflow. The timeframe covers a single treatment and two weeks of treatment.

Imaging is used in this endpoint to assess lymphatic structure and function rather than relying only on a participant’s reported symptoms. In general, an imaging measure can provide an observable indicator of a physiological process; it does not by itself establish how a participant feels or functions. Those aspects were addressed separately through the listed survey outcomes for symptom alleviation and ease of use.

The endpoint is described as a participant count, and the record characterizes the outcome type as participants with an event. However, the registry record does not state the event threshold or give the number of participants meeting the endpoint, an effect estimate, or a measure of uncertainty. It therefore remains possible to explain what the endpoint was intended to capture, but not to quantify the observed lymph movement from the posted information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Interpreting this study begins with separating the design, the outcome definition, and the reported numerical evidence. The design was non-randomized and parallel, with two treatment-frequency groups. The primary endpoint was an imaging-based assessment of lymph movement. The registry record gives these features, but it does not provide numerical primary-outcome results or an analysis for that endpoint. Statistical interpretation must therefore remain descriptive rather than infer an effect estimate that is not reported.

What a participant-count endpoint represents

The primary outcome is described in terms of participants and is characterized as participants with an event. A binary outcome, in general, classifies each participant according to whether a defined event or criterion was met. Counts can then describe how many participants met that criterion in a group. For this endpoint, the registry says the imaging indicators were increased functionality of vessels and/or changes in the area of dermal backflow. The record does not further specify the operational threshold used to classify a participant as having the endpoint, nor does it report the resulting counts.

Counts are often easier to understand than model-based summaries, but counts alone do not convey precision or establish that a difference reflects treatment. In general, uncertainty around a count-based comparison depends on the number of participants and the observed outcome pattern. A confidence interval, when reported, describes a range of values compatible with the data and the stated method; it is not a guarantee that the true effect lies within that range. No primary confidence interval is reported in the registry record, so there is no basis to characterize the precision of the primary result.

Why the group allocation matters

Random allocation is used in general to reduce systematic differences between groups at the start of a study. This trial was non-randomized, so the one-session and two-session groups may differ in ways that are associated with their outcomes. An observed group difference, if reported, could reflect treatment frequency, participant characteristics, or other factors. The record does not describe adjustment methods that would account for such differences. It also explicitly indicates that the arms are not a like-for-like control comparison. The safest interpretation is therefore not to treat a between-group contrast as a randomized treatment effect.

The parallel design means the registry describes separate groups receiving the two stated frequencies. The record does not report a crossover design or a randomized treatment sequence. It also does not describe why a participant was assigned to one frequency rather than the other. These omissions limit how far a statistical comparison could be interpreted, even if group-specific outcomes were available.

What is and is not reported about inference

The registry record lists zero analyses. It does not report a statistical model, hypothesis test, adjustment for baseline characteristics, confidence interval, or p-value for the primary outcome. Those methods are not reported in the registry record, so they should not be inferred from the endpoint title or the study design. In general, a p-value addresses how compatible data are with a specified null model under stated assumptions; it does not measure the size or clinical importance of an effect. A confidence interval communicates uncertainty about an estimate. Neither can be interpreted when the estimate and inferential results are absent.

Over-dispersion is a general concern when count data vary more than a chosen statistical model expects. It can make standard errors too small if the model’s assumptions are not appropriate. That concept is relevant only when an analysis uses a count model and its assumptions need evaluation. The registry record does not describe such a model, and the primary endpoint is stated as a participant count rather than a repeated event rate. No claim about over-dispersion or its handling can be made for this study.

How planning illustrations differ from observed evidence

The registry’s sample-size assumptions describe a planning illustration computed from the observed effect, using a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For time-to-event outcomes, the assumption is expressed as a total number of events; for other outcomes, it is expressed as participants per arm. These are planning conventions, not observed trial outcomes and not evidence of observed power. The record does not give the numerical planning results in the registry record for this explanation, so no sample-size value should be inferred.

In general, a sample-size calculation asks how many observations a design would require under specified assumptions. It does not show that a study with a particular enrollment achieved a given power after completion. A planning illustration based on an observed effect is also sensitive to the effect chosen as its reference. It cannot replace a reported estimate and uncertainty interval for the endpoint. The assumptions listed in the registry should be understood as assumptions for planning, not as proof that those assumptions describe the enrolled groups or the actual analysis.

Reading the evidence at its stated scope

The registry’s primary analysis population comprises participants who completed the study and properly used the device, with the upside-down garment use cited as the reason for one exclusion. This is a particular analysis population, not necessarily every enrolled participant. In general, restricting analysis according to completion or device use can affect interpretation if the excluded participants differ from those analyzed. The record does not report a sensitivity analysis or an alternative analysis population to show whether the result changes under other inclusion rules.

Overall, the statistical methods that can be described are limited to the non-randomized parallel design, the participant-count endpoint, the stated analysis-population rule, and the planning assumptions. A statistical test, model, adjustment strategy, or precision estimate is not reported in the registry record. General principles can explain what such methods would mean, but they cannot fill gaps in the posted analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures overall: the primary lymph-movement endpoint and three secondary outcomes. The secondary outcomes concern dermal backflow measured by ICG lymphography, symptom alleviation measured by survey response, and ease of use measured by survey response. The registry record does not report how these outcomes were prioritized for statistical testing or whether any adjustment was planned for testing multiple outcomes.

Multiplicity is a general issue that arises when several outcomes or hypotheses are examined. If many tests are conducted, the chance of finding at least one apparently unusual result can increase. Statistical approaches can address this concern, but the appropriate approach depends on the planned questions and analysis strategy. No multiplicity procedure is reported in the registry record, so it is not possible to say whether reported tests were adjusted or how secondary findings should be interpreted as a family.

The primary analysis population is described as participants who completed the study and properly used the device. The registry states that one participant who reported wearing the head garment upside down during the two-week treatment period was excluded, resulting in a cohort of 10 analyzable participants. This is the stated handling of that participant for the primary analysis. The record does not report a broader missing-data policy, an imputation method, or sensitivity analyses for missing or excluded observations. It also does not provide a complete account of missing outcome measurements by group.

Because the record lists zero analyses and gives no numerical primary or secondary outcome results, the effect of missing observations and the handling of multiplicity cannot be assessed from the posted information. The available description should not be expanded into assumptions about an analysis plan that is not reported in the registry record.

11. 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 non-serious adverse event terms

The registry reports safety counts for the two pneumatic compression groups. In the one-session-per-day group, 6 participants were at risk for serious adverse events and 0 had a serious adverse event; 6 were at risk for other adverse events and 0 had an event in that category. In the two-sessions-per-day group, 5 participants were at risk for serious adverse events and 0 had a serious adverse event; 5 were at risk for other adverse events and 3 had an event in that category. Deaths were 0 in each group.

These are counts, not comparative risk estimates. The groups were not randomized, and the record indicates that they are not a like-for-like control comparison. The counts therefore do not establish that treatment frequency caused any difference in other adverse events. The denominators describe participants at risk in the registry’s safety information; they should not be assumed to represent a separate efficacy analysis population.

The serious adverse event section lists no serious event terms. The record does not give further detail about the types, timing, duration, or severity of the other adverse events. With the counts as posted, the appropriate reading is descriptive: the registry records zero serious adverse events in both groups, three other adverse events in the two-sessions-per-day group, and zero in the one-session-per-day group. These figures alone do not establish comparative safety.

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

The registry record establishes what the investigators intended to assess: lymph movement and lymphatic uptake during intermittent pneumatic compression, measured by ICG lymphography. It also describes the treatment frequencies, the stated timeframe, and a primary analysis population of 10 analyzable participants from 11 enrolled. These details clarify the scope of the question and how the reported population was defined.

However, the record does not report the numerical primary-outcome result, an effect estimate, or an uncertainty interval. It is therefore not possible to quantify how many participants met the imaging endpoint, how large any change in lymphatic function was, or how precise an estimate might be. The registry also lists three secondary outcomes but does not report their numerical findings or analyses in the information available for this explanation.

The non-randomized design further limits interpretation of any potential contrast between the one-session and two-sessions groups. Participants were not assigned by random allocation, and the registry explicitly cautions that the groups are not a like-for-like control comparison. Consequently, even if a group difference were available, it could not be attributed to frequency alone from this design description.

The safety counts document zero serious adverse events in each group and other adverse event counts of 0 in the one-session-per-day group and 3 in the two-sessions-per-day group. These are descriptive observations from the recorded groups; they do not provide a randomized comparison or establish a causal safety difference. Overall, the posted information describes the intended endpoint, study structure, analysis-population exclusion, and selected safety counts. It does not provide the numerical efficacy findings needed to estimate the primary result or its precision.

13. Why This Trial Matters Statistically

This study is statistically informative because it illustrates the distinction between a clearly described research question and a fully reported numerical result. The registry specifies an imaging-based primary endpoint for lymph movement, gives a treatment timeframe, and identifies two treatment frequencies. Those details help define what the study set out to measure. At the same time, no numerical primary-outcome result or analysis is reported in the registry record, so the scientific question cannot be answered quantitatively from the posted information.

The non-randomized design is also important. A comparison between the two frequencies may look like a treatment contrast, but allocation was not random and the record does not describe a comparable control group. General statistical interpretation must account for this design limitation: differences between groups can reflect differences in who entered each group, not only differences in treatment frequency. The registry itself cautions against treating the arms as a like-for-like control comparison.

The analysis-population description makes another useful point. The record distinguishes 11 enrolled participants from 10 analyzable participants and explains an exclusion based on device use. Transparent reporting of who was analyzed and why is relevant to understanding which population a result would describe. Here, however, the outcome results and fuller missing-data handling are not reported, limiting assessment of the consequences of that exclusion.

Finally, the safety counts show why raw counts need context. Serious adverse events were recorded as zero in each group, while other adverse events were recorded in one group. Without randomized allocation, fuller event descriptions, or a causal analysis, these observations should be treated as descriptive. The study’s statistical value lies in clarifying the measurement question and highlighting the limits imposed by design and incomplete numerical reporting, rather than in supporting a quantified treatment comparison.

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.

The main trial-specific limitation is that the registry record describes the primary endpoint but does not report its numerical result or an analysis. There is no stated number of participants meeting the imaging criterion, effect estimate, confidence interval, or test result. As a result, neither the direction nor the precision of the primary finding can be assessed from the posted information.

The study used non-randomized allocation and did not include a like-for-like control comparison, according to the registry’s own caution. The two treatment-frequency groups may therefore differ in participant characteristics or other factors. The record does not describe how treatment frequency was assigned or report an adjustment strategy that would address potential group differences.

The stated analysis population excluded a participant who reported wearing the head garment upside down during the two-week treatment period. Although this exclusion is described, the registry does not provide a broader accounting of incomplete observations or explain how missing outcomes were handled. It also does not report sensitivity analyses to assess the effect of the exclusion.

The registry lists four outcome measures but provides no reported analyses. It does not state a multiplicity strategy, statistical model, or inferential approach for the primary or secondary outcomes. Safety information is limited to counts: the record gives no further description of the other adverse events and lists no serious adverse event terms. These limitations mean the posted information supports a description of design, endpoint intent, analysis population, and selected safety counts, but not a detailed efficacy or comparative safety assessment.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Response to Intermittent Pneumatic Compression Therapy in Head and Neck Cancer-Related Lymphedema — NCT02946021.
• Registry record last updated 2019-04-09; status last verified 2019-03.
• Results first posted 2019-03-20.
• 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.

18. Record Summary

The registry record describes NCT02946021, a completed Phase 1/Phase 2, non-randomized, unmasked, parallel study sponsored by Tactile Medical. The study enrolled 11 participants with head and neck cancer-related lymphedema and assessed pneumatic compression using head and neck garments at one session per day or two sessions per day. NIR fluorescence lymphatic imaging with ICG was used to assess lymphatic structure and function.

The primary endpoint was lymph movement measured by ICG lymphography, with a stated timeframe of a single treatment and two weeks of treatment. The primary analysis description identifies 10 analyzable participants and notes that a participant who reported wearing the garment upside down was excluded. The registry lists three secondary outcomes: dermal backflow, symptom alleviation, and ease of use.

Numerical primary and secondary outcome analyses are not reported in the registry record. Safety counts show zero serious adverse events in both groups, and the record lists other adverse events in the two-sessions-per-day group. Because allocation was non-randomized, the groups are not a like-for-like control comparison.