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 Validation of a Novel Foot Offloading Device (NCT04378270), a na na study. The primary outcome is Change in Foot Pain From Screening/Baseline Visit to 4 Week Visit as Reported on the Pittsburgh Foot Survey..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04378270 |
| Phase | NA |
| Condition | Plantar Fasciitis, Chronic, Heel Pain Syndrome, Fat Pad Syndrome |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Jeffrey A. Gusenoff, MD |
| Results posted | Yes |
2. Clinical Question
Population
People with chronic plantar fasciitis, heel pain syndrome, or fat pad syndrome were the conditions of interest. The registry record states that 19 participants received the study device and 15 completed a four-week visit.
Intervention
Participants used the PopSole™ offloading device, an external insole intended to fit into a shoe. The record describes it as reusable for a participant and customizable in the area of offloading, arch support, and metatarsal elevation.
Comparator
There was no concurrent control group. This is a single-group study, so outcomes describe participants’ measurements over time while using the device, not a contrast against another treatment or an untreated group.
Primary question
The primary question was how the mean Pittsburgh Foot Survey pain score changed from screening/baseline to the four-week visit. The registry describes the score as ranging from 0 to 25, with higher scores indicating less pain reported.
The study also aimed to assess ease of use, fit and feel, compliance, durability, and participants’ reported satisfaction or difficulties with the device over four weeks. Validated patient-reported outcome measures were planned at baseline, two weeks, and four weeks. The primary endpoint focuses on the pain component of the Pittsburgh Foot Survey rather than treating all listed aims as a single outcome.
These questions are descriptive in a single-group setting. A change between baseline and follow-up can show how scores evolved among participants measured at both times, but it cannot by itself distinguish a device-related change from other influences over the same period. The registry record does not report a numerical mean change or its confidence interval, so the observed direction, size, and precision of the primary outcome cannot be assessed from the reported information.
3. Trial Design
This is a completed, single-group device study with no random allocation and no masking. The registry lists an enrollment of 20 and identifies the PopSole™ offloading device as the intervention. Its description says the device is an external insole that fits into a shoe and is reusable for a given participant. The registry lists chronic plantar fasciitis, heel pain syndrome, and fat pad syndrome as conditions of interest.
The study’s stated purpose was to validate the device by assessing pain improvement, ease of use, fit and feel, compliance, and durability over a four-week period. The registry says validated patient-reported outcome measures were to be collected at baseline, two weeks, and four weeks. The primary endpoint compares foot pain from screening/baseline to the four-week visit. Satisfaction and difficulties with the device are listed among the secondary outcomes.
The registry reports that 19 participants received the device and 15 completed a four-week visit. Those figures describe the recorded participation and follow-up; they do not establish why some participants did not complete that visit or how missing observations were handled. The registry record does not report a detailed recruitment process, eligibility criteria, protocol deviations, adherence results, or reasons for non-completion.
Because the design has one group, there is no randomized or otherwise concurrent comparator in the record. The stated allocation and masking fields are NA and none, respectively. The registry record does not report a protocol-based sample-size justification, a planned interim analysis, or a detailed statistical analysis plan. Therefore, the design supports description of outcomes over time in the observed group, but not an estimate of a comparative effect against a control condition.
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.
Before assignment: 1 participant was a screen failure and was not found eligible to continue to intervention.
Overall Study
| Stage | PopSole™ Offloading Device |
|---|---|
| STARTED | 20 |
| COMPLETED | 15 |
| NOT COMPLETED | 5 |
Reasons for not completing this period:
| Reason | PopSole™ Offloading Device |
|---|---|
| Lack of Efficacy | 1 |
| Withdrawal by Subject | 1 |
| Screen Failure | 1 |
| University Required, Research Covid Shut Down | 2 |
Analysis population for the primary outcome, as defined in the registry: 19 participants received the study device, 15 completed a 4 week visit.
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 | PopSole™ Offloading Device |
|---|---|---|
| Participants analysed | 20 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 12 |
| Age, Categorical: >=65 years | Participants | 8 |
| Sex: Female, Male: Female | Participants | 13 |
| Sex: Female, Male: Male | Participants | 7 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 20 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 |
| Race (NIH/OMB): Asian | Participants | 1 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 |
| Race (NIH/OMB): Black or African American | Participants | 0 |
| Race (NIH/OMB): White | Participants | 19 |
| Race (NIH/OMB): More than one race | Participants | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 |
| Region of Enrollment: United States | participants | 20 |
| Number of participants who received PopSole device at baseline | Participants | 19 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Foot Pain From Screening/Baseline Visit to 4 Week Visit as Reported on the Pittsburgh Foot Survey., measured over Four Weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | Score on a scale |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change in foot pain from screening/baseline to the four-week visit, measured with the Pittsburgh Foot Survey. The registry describes the survey as a questionnaire addressing pain and function. The pain score uses items 1–5, has a possible total score of 25, and is interpreted so that higher scores indicate less pain reported. The measure is reported as a mean score with a 95% confidence interval.
A patient-reported pain measure is relevant to a study whose stated purpose includes assessing pain during use of a foot offloading device. A numerical score can express the measured outcome on a consistent scale, while assessing change from baseline focuses on how scores differ over the study period. The registry also describes survey content on pain interference and functionality, with response scales ranging from very much to not at all and from unable to do to without any difficulty.
The primary endpoint is specifically the mean change in the pain score, not a comparison of treatment groups. The record does not state whether change is calculated as follow-up minus baseline or baseline minus follow-up, so the sign convention cannot be inferred. More importantly, the registry record does not report the numerical mean change or its 95% confidence interval. Without those values, the amount and precision of the observed change cannot be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a primary endpoint: mean change in Pittsburgh Foot Survey pain score from screening/baseline to the four-week visit. However, it does not report the numerical result for that endpoint. The mean change and its 95% confidence interval are therefore not reported in the registry record. There is no basis in the registry information for describing the observed change as large or small, favorable or unfavorable, or precise or imprecise.
The score’s stated direction matters when interpreting a result: higher scores indicate less pain reported. But the registry does not define whether the change is calculated by subtracting baseline from follow-up or follow-up from baseline. Even if a numerical change were available, the sign alone would need to be read using the analysis’s stated convention. That convention is not reported in the registry record.
The participation information gives context for follow-up. The record states that 19 participants received the device and 15 completed a four-week visit. It does not report how many participants had usable baseline and follow-up scores for the primary analysis, whether all available observations were included, or how any missing scores were handled. Completion status alone is not enough to determine the analysis population or the influence of missing data.
This is a single-group study. A before-and-after change, if reported, would describe the group’s scores across the study period. It would not isolate the effect of the device from other explanations, such as changes over time, expectations, concurrent care, or measurement variability. The registry record does not report a control group, random allocation, or masking. The study can therefore be read as a validation and experience assessment, not as a randomized comparison.
The registry lists seven outcome measures and five analyses, but it does not report how the analyses were selected, whether the primary outcome was prespecified in a detailed analysis plan, or how multiple outcomes were accounted for. Nor does it report a threshold for a clinically important difference. A confidence interval, when available, would describe statistical uncertainty around an estimate; it would not by itself establish clinical importance.
The record reports no serious adverse events in the listed device group, one other adverse event, and no deaths. These are descriptive counts in the recorded group. They should not be treated as proof that the device has no risks, particularly because the study is limited in duration and the registry does not provide event details or a comparative group. Overall, the record identifies the questions studied and some follow-up and safety counts, but it does not provide the primary numerical result needed to evaluate the observed change in pain.
9. Statistical Methods Explained
What does a mean change represent? The primary endpoint is a mean change in a continuous score. In general, a mean summarizes the average value across observed measurements. For a change outcome, each participant’s follow-up score is related to that participant’s baseline score, and the mean summarizes those changes for the analysis population. This is different from comparing the average follow-up score alone, because a change measure incorporates the starting measurement. The registry identifies the mean as the parameter of interest, but does not report the calculated mean change or the exact analysis population.
The Pittsburgh Foot Survey pain score is described as having a possible total of 25, with higher scores indicating less pain reported. That direction is important: the meaning of a numerical change depends both on score direction and on how the difference was formed. The registry does not state whether the reported change is follow-up minus baseline or baseline minus follow-up. The direction of a hypothetical positive or negative change should therefore not be inferred from the endpoint description alone.
What does a confidence interval convey? In general, a confidence interval expresses the statistical uncertainty around an estimated quantity. A narrower interval indicates greater precision under the assumptions of the analysis; a wider interval indicates less precision. It is not a range containing a fixed proportion of individual participants’ scores, and it does not describe the range of responses. The registry specifies a 95% confidence interval for the primary mean, but the interval’s limits are not reported in the registry record. Its width and the precision of the estimate cannot be evaluated.
A confidence interval also does not answer every interpretive question. It concerns uncertainty in the estimate under the analysis model and does not, by itself, establish that a change is important to participants or that a device caused it. The registry record does not report a threshold for a clinically important change. The absence of the numerical estimate and interval leaves both the magnitude and statistical precision of the primary outcome unknown from the registry information.
What does a single-group analysis show? In general, repeated measurements in one group can describe how scores change over time among participants with observed data. The registry says that validated patient-reported outcome measures were to be collected at baseline, two weeks, and four weeks; the primary endpoint is baseline to four weeks. Such measurements can characterize the course of scores during the observation period. They do not supply the counterfactual outcome—what the same participants’ scores would have been over that period without the device.
Without a concurrent comparison group, changes can reflect influences other than the device. General examples include natural variation over time, expectations, other care, or changes in how a participant responds to a questionnaire. These are possible limitations of a single-group before-and-after design, not claims about what occurred in this study. The registry does not report information that would separate these explanations.
How should missing follow-up be considered? In general, missing outcome data can affect an estimate if participants with unobserved outcomes differ from those with observed outcomes. The registry reports that 19 participants received the study device and 15 completed a four-week visit. It does not report reasons for incomplete follow-up, the number with paired primary-outcome measurements, or the method used for missing values. Methods such as complete-case analysis or imputation should not be attributed to this study because the registry record does not report which approach was used.
What does the planning illustration mean? General sample-size calculations estimate how many participants might be needed under specified assumptions to detect an effect with a chosen statistical power and significance level. The assumptions listed for the planning illustration are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a fraction of the observed effect. The record describes these as planning assumptions, not as the trial’s own design justification. They do not describe observed power or the single-group design. No planning-illustration results or protocol-based sample-size rationale are reported in the registry record.
Why can over-dispersion matter in general? For some outcome types, observed variation can exceed what a basic statistical model assumes. When that happens, standard errors and confidence intervals from an unsuitable model may be too small, making results appear more precise than warranted. This is a general statistical concern, not an assertion about the analysis of this continuous pain score. The registry record does not report a model specification or a discussion of over-dispersion for the primary endpoint.
What is not established by a significance test? In general, a p-value summarizes how compatible observed data are with a specified null model, given the test’s assumptions. It does not measure the probability that a treatment works, the probability that the null hypothesis is true, or the clinical importance of an estimated change. The registry record does not report a primary-outcome p-value or detailed testing procedure. No conclusion about statistical significance can be drawn from the endpoint description alone.
Finally, the registry lists seven outcome measures and five analyses. Multiple outcomes can create several opportunities to identify a result that appears notable by chance if testing is not planned or adjusted appropriately. The registry record does not report a multiplicity strategy, hierarchy for all outcomes, or full analysis plan. This limits assessment of how confirmatory or exploratory the reported analyses were intended to be.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists seven outcome measures and five analyses. The primary endpoint is the mean change in Pittsburgh Foot Survey pain score from screening/baseline to four weeks. Participants’ reported satisfaction and/or difficulties with the device are listed as a secondary outcome. The registry record does not report a complete outcome hierarchy, a multiplicity adjustment, or a detailed statistical analysis plan explaining how the multiple outcomes and analyses were handled.
In general, when several outcomes or statistical tests are examined, the chance of obtaining at least one apparently notable finding can increase if the analyses are treated as independent opportunities without an appropriate plan. Adjustments or prespecified priorities can help address this issue, but the registry record does not state that any particular approach was used. The existence of multiple listed outcomes does not, on its own, indicate that the results are invalid; it means that the interpretation of findings depends on analysis details that are not reported.
Missing data are also relevant because the registry reports that 19 participants received the device and 15 completed a four-week visit. It does not report the number with paired primary-outcome measurements, the reasons for non-completion, or whether missing measurements were imputed, excluded, or handled by another method. The analysis population for the primary endpoint is therefore not fully described. The registry record also does not report whether analyses followed an intention-to-treat principle or another defined population.
These gaps prevent evaluation of how sensitive the primary estimate might be to missing observations or analytic choices. No assumptions about the missing outcomes or multiplicity procedure should be made from the record alone.
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 |
|---|---|---|---|
| PopSole™ Offloading Device | 0 | 20 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| PopSole™ Offloading Device | 0 of 20 |
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 |
|---|---|
| PopSole™ Offloading Device | 1 of 20 |
Most frequent non-serious adverse event terms
| Event term | Organ system | PopSole™ Offloading Device |
|---|---|---|
| pain at left metatarsal on left foot | General disorders | 1 of 20 |
The registry lists one device group. For that group, 20 participants were recorded as at risk for serious adverse events, with 0 participants affected; 20 were recorded as at risk for other adverse events, with 1 participant affected. The record lists 0 deaths. It does not list any serious adverse-event terms.
These figures are descriptive counts from the registry record, not a comparison of risks between groups. The study has no control group, and the record does not give details about the one other adverse event, its timing, severity, or relationship to the device. The absence of recorded serious events does not establish that serious events are impossible or that no event went unreported.
The observation period described for the device assessment was four weeks. Safety counts from this study should be read in that context and should not be generalized to longer use or other populations. The registry record does not report a comparative safety estimate or additional event-level information.
12. What the Result Does, and Does Not, Mean
The record describes a completed, single-group validation study of the PopSole™ offloading device. Its primary question concerned mean change in foot pain from screening/baseline to the four-week visit, using the Pittsburgh Foot Survey. It also records aims related to ease of use, fit and feel, compliance, durability, and participants’ satisfaction or difficulties.
The registry record does not report the numerical mean change in the primary score or its 95% confidence interval. Consequently, the amount and precision of the measured change cannot be stated. The record also does not specify the change-score sign convention, which would be needed to interpret the direction of a numerical change unambiguously.
Even if a before-and-after score change were reported, this single-group design would not establish that the device caused it. There is no concurrent comparator to help distinguish changes associated with device use from other changes over time. The study also does not provide a randomized comparison with another insole or with no device.
The participation figures indicate that 19 participants received the device and 15 completed a four-week visit. They do not explain why some participants did not complete follow-up, identify the primary-outcome analysis population, or show how missing outcomes were handled. The registry record therefore does not allow a full assessment of possible missing-data effects.
The safety figures record 0 serious adverse events, 1 other adverse event, and 0 deaths in the device group. These counts are limited to the recorded study experience and do not establish comparative safety or rule out uncommon or longer-term events. Overall, the registry describes the study’s intended measures, design, participation, and recorded safety counts, but leaves the primary outcome result and several analysis details unreported.
13. Why This Trial Matters Statistically
Device validation studies often involve more than a question about symptom scores. The stated aims for this study include pain, ease of use, fit and feel, compliance, durability, and satisfaction or difficulties. These domains address different aspects of use and should not be collapsed into a single claim about performance. The registry identifies the outcomes of interest, while the available record does not provide a numerical primary pain result or detailed results for those other aims.
Statistically, the study is useful to read as a single-group assessment over a defined four-week period, with repeated patient-reported measurements planned at baseline, two weeks, and four weeks. That design can describe measured experience over time, but it does not estimate a contrast against a concurrent control. Keeping that distinction clear prevents a within-group change from being mistaken for a controlled treatment effect.
The record also illustrates why reporting the estimate and its uncertainty matters. Naming a mean change and a 95% confidence interval identifies the intended summary, but without the numerical result readers cannot judge its magnitude or precision. Reporting who contributed outcome data and how missing observations were handled is also important for understanding what population the estimate describes.
Finally, the record lists multiple outcomes and analyses while not reporting a detailed multiplicity plan. Clear prespecification and transparent analysis reporting help readers distinguish a primary confirmatory question from additional descriptive or exploratory findings. These considerations matter for interpreting this study’s evidence without overstating what a single-group validation design can establish.
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 primary limitation for interpreting the posted results is that the registry record does not report the numerical mean change in the primary pain score or its 95% confidence interval. Without those values, the magnitude and precision of the endpoint cannot be assessed. The registry also does not state the change-score sign convention, which limits interpretation of direction even if a change value were available.
The single-group design has no concurrent control condition. Any change over the study period would therefore be descriptive of the observed group and could not, by itself, separate the device’s contribution from other influences. The registry lists no random allocation and no masking.
Follow-up information is incomplete for assessing the primary analysis. The record states that 19 participants received the device and 15 completed a four-week visit, but does not report reasons for non-completion, the number with paired primary measurements, or the method used to handle missing values. It also does not report a detailed analysis population or whether adherence was quantified.
The registry lists seven outcome measures and five analyses but does not report a detailed statistical analysis plan, a multiplicity approach, or a protocol-based sample-size justification. The primary endpoint’s clinically important threshold is also not reported in the registry record. Finally, the safety information is limited to group-level counts, with no details for the one other adverse event. These omissions constrain interpretation of efficacy-related outcomes, analysis robustness, and safety beyond the recorded counts.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Validation of a Novel Foot Offloading Device — NCT04378270.
- Registry record last updated 2024-01-31; status last verified 2024-01.
- Results first posted 2022-10-12.
- 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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18. Record Summary
NCT04378270 is a completed, single-group study titled Validation of a Novel Foot Offloading Device. The registry lists the PopSole™ offloading device as the intervention and chronic plantar fasciitis, heel pain syndrome, and fat pad syndrome as conditions of interest. Enrollment is listed as 20.
The primary endpoint is mean change in Pittsburgh Foot Survey pain score from screening/baseline to the four-week visit, with a 95% confidence interval specified. The registry describes higher pain scores as indicating less pain reported. It states that 19 participants received the device and 15 completed a four-week visit, but does not report the numerical primary result or the method used to handle missing outcome data.
The listed safety counts are 0 serious adverse events, 1 other adverse event, and 0 deaths in the device group. The record lists seven outcome measures and five analyses; a detailed statistical analysis plan and multiplicity approach are not reported in the registry record.