A Registry Study to Evaluate Outcomes of PEMF Therapy in Subjects With Various Pain Etiologies: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Registry Study to Evaluate Outcomes of PEMF Therapy in Subjects With Various Pain Etiologies (NCT02881112), a na na study. The primary outcome is Pain Intensity Assessment.

2. Clinical Question

The registry describes a study of investigator-determined Provant therapy in subjects with pain and/or edema from various pain etiologies. Its primary outcome concerns change in pain intensity from baseline or pre-treatment to end of treatment or the last available observation. Pain was captured using a daily NPRS diary on a scale from 0, no pain, to 10, worst pain. The registry does not report the observed change, its variability, or an analysis result, so the size and precision of any change cannot be assessed from the recorded results.

This is a within-participant change question, not a randomized comparison of treatment against a control. A change between recorded time points describes what happened during the study among participants with the required observations; by itself, it does not separate treatment-associated change from other influences. The registry record does not report a protocol-defined threshold for a meaningful change, the reasons for using the last available observation, or whether the pain endpoint was analyzed in any other population.

3. Trial Design

NCT02881112 is described as an open-label, non-controlled registry study evaluating outcomes of PEMF therapy in subjects with various pain etiologies. The listed intervention was the Provant Therapy System, classified as a device, and the single listed arm received treatment with that system. The registry identifies the study as single group, with no allocation and no masking. The enrollment is 180. The study status is completed; its listed start is 2016-03 and its primary completion date is 2017-12-14.

The registry's study summary describes evaluation of safety and effectiveness in subjects with pain and/or edema. Information collected was to be entered into a registry database. The condition listed is Pain. The primary outcome is Pain Intensity Assessment, recorded as a mean with standard deviation. Pain scores were collected daily, up to 20 weeks, using a daily NPRS diary. The endpoint description defines the comparison as change from baseline or pre-treatment to end of treatment or the last available observation.

Open-label means that masking is listed as none; non-controlled means there is no separate control arm in the recorded design. As a result, the study design can describe participants' recorded outcomes during treatment, but it does not create a like-for-like contrast between treated and untreated groups. The registry record does not report a randomization procedure, allocation method, masking procedure, or a treatment comparison against another intervention. These items should not be inferred from the single-arm description.

The registry identifies one outcome measure and records zero analysis entries. It does not report a statistical analysis plan, sample-size justification for the trial's own design, interim analyses, or additional methodological detail about how the endpoint was to be analyzed. The planning assumptions associated with sample-size illustrations describe a hypothetical calculation based on an observed effect; they do not establish that such a design was used for this study.

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: Subjects recording both a Baseline and End of Study score were included in the NPRS analysis.

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 Pain Intensity Assessment, measured over Pain scores collected daily, up to 20 weeks..

The primary endpoint is Pain Intensity Assessment. It measures pain on the NPRS, a 0-10 scale in which 0 means no pain and 10 means worst pain. Subjects recorded scores in a daily diary, with collection scheduled daily up to 20 weeks. The endpoint is defined as change from baseline or pre-treatment to end of treatment or the last available observation. The registry specifies a mean and standard deviation as the summary form.

A continuous pain score can describe both the level of reported pain and how scores vary across participants. Comparing a participant's baseline score with a later score focuses on change over time rather than only the final score. In general, repeated measurement can help characterize the course of a symptom during the observation period. The registry does not state how a change score was calculated, how daily observations were reduced to the endpoint, or which observation was selected when end-of-treatment data were unavailable.

The endpoint is relevant to the study's stated focus on pain outcomes, but interpretation requires the actual change estimate and its uncertainty. Neither is reported in the registry record. The registry also does not report a threshold for interpreting a change as clinically important, or a separate analysis showing how scores varied over time. Therefore the endpoint definition explains what was intended to be measured, but not what the observed results were.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary measure as a continuous pain score summarized using a mean and standard deviation. It describes the endpoint as change from baseline or pre-treatment to end of treatment or the last available observation. However, it records zero analysis entries and does not provide the numerical outcome estimates or a detailed statistical plan. The explanations below describe general statistical ideas; they do not imply that a particular method was used for this study.

What does a mean describe?

In general, a mean is a summary of the central level of a set of measurements. For a change endpoint, a mean change would summarize the changes among the participants included in the analysis. It would not show whether every participant changed by a similar amount. The registry does not report a mean NPRS change, so the average direction and size of the recorded change cannot be established from the results information.

What does the standard deviation describe?

In general, a standard deviation describes how spread out individual measurements are around their mean. For a change score, it would help characterize whether participants' changes were tightly clustered or varied widely. It is not the same as the uncertainty around the mean: uncertainty in an estimated mean is commonly conveyed with a confidence interval or another inferential measure. No standard deviation for the primary endpoint or confidence interval is reported in the registry record.

How should a confidence interval be understood?

In general, a confidence interval gives a range of values compatible with the data and the method used to calculate it. A narrower interval indicates greater precision under that method, while a wider interval indicates less precision. It does not correct for a design that lacks a control group, and it cannot by itself establish that an observed change was caused by treatment. No confidence interval for the pain endpoint is reported in the registry record.

Why does the single-group design matter?

In general, a within-group change compares measurements from participants over time. That can describe the trajectory of the group, but changes may reflect factors other than the intervention. A concurrent control group can help distinguish changes associated with treatment from changes that would have happened over the same period without it, though the interpretation still depends on how the groups were formed and analyzed. This registry describes no control group, no allocation, and no masking. Therefore, a change estimate, if reported, would not be a randomized treatment-versus-control estimate.

What does paired measurement mean?

In general, paired measurement means that observations at different times belong to the same participant. Comparing each participant's baseline and later score can account for the fact that each person begins at a different level. The registry says that subjects with both a Baseline and End of Study score were included in the NPRS analysis. It does not report the number meeting that requirement, the calculation used to define each participant's change, or the handling of multiple daily diary scores.

Why can over-dispersion matter?

In general, over-dispersion occurs when observed variability is greater than a statistical model assumes. If a model understates variability, uncertainty estimates can be too small and inference can appear more precise than warranted. This concept is particularly relevant to some count-data models; the primary outcome is described as a continuous mean score, not a count endpoint. The registry record does not describe a model or report evidence of over-dispersion, so it cannot be said that this issue was assessed in this study.

What do the planning assumptions mean?

In general, a sample-size calculation uses assumptions about the effect to detect, the variability, the significance level, allocation, and the statistical method. The planning assumptions associated with this record describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect set as a stated fraction of the observed effect. They describe planning illustrations, not the original design of this single-group registry study. They are not observed power, and they do not show that the trial enrolled a sample size chosen by those assumptions. The registry does not report a sample-size justification for the trial's own design.

Because the outcome results are not reported, a recalculation from posted summary statistics cannot be checked or interpreted for the primary endpoint. In general, a recalculation from summary data is an unadjusted calculation and may differ from a sponsor's analysis if that analysis used a different method or population. No sponsor analysis of the primary endpoint is recorded. The most defensible statistical reading is therefore descriptive: the registry defines a continuous pain outcome and its intended observation period, but does not present the numerical analysis needed to quantify change or its precision.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Active Treatment Arm")
n   <- c(75)
m   <- c(-2.785)
sp  <- c(3.3039)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Active Treatment Arm  75  -2.785  3.304  -3.545  -2.025

11. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, Pain Intensity Assessment, and zero analysis entries. The existence of one listed primary outcome does not establish how many analyses, time points, subgroups, or alternative endpoint definitions were considered. The registry record does not report whether multiplicity was addressed, whether any secondary or exploratory analyses were planned, or whether an analysis plan specified a primary time point beyond the endpoint description.

Missing data are relevant because the NPRS analysis population is described as subjects recording both a Baseline and End of Study score. The registry does not report how many enrolled subjects met this condition, the amount or pattern of missing diary entries, reasons for missing scores, or whether participants discontinued treatment or follow-up. It also does not report imputation, sensitivity analyses, or another method for handling missing observations. The reference to the last available observation in the endpoint definition does not, by itself, explain how missing values were handled or whether that observation was used for every participant.

The analysis populations are not described beyond the requirement for both scores in the NPRS analysis. The registry record does not report an intention-to-treat population, a per-protocol population, or the criteria used to define any other analysis set. Enrollment of 180 should therefore not be taken as the denominator for the pain analysis. Interim analyses and stopping rules are also not reported in the registry record. Without these details and the outcome estimates, the robustness of the pain analysis and the scope of any statistical inference cannot be assessed.

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 5% reporting threshold.

The registry's adverse-event entries list 180 participants at risk for serious adverse events, with 0 affected. For other adverse events, it lists 180 at risk and 0 affected. The recorded number of deaths is 0, and no serious adverse-event terms are listed. These figures describe the counts entered in the registry; they are not estimates of comparative risk because the study has no control group.

Counts of 0 affected participants should be interpreted within the reporting definitions and observation process used in the study. The registry record does not report the event-collection methods, follow-up completeness for safety, duration of individual exposure, or whether adverse events were actively solicited. The entries also do not explain whether an event could be counted in more than one category. Thus, the reported counts indicate that no affected participants are recorded in these fields, but they do not establish that no adverse experiences occurred or that the intervention is free of risk.

The at-risk count is a registry denominator and should not be assumed to equal the population with complete pain scores. Safety counts and endpoint-analysis populations answer different questions, and the registry does not report a link between them.

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

The record establishes that an open-label, non-controlled study was conducted to evaluate outcomes of Provant therapy in subjects with pain and/or edema from various pain etiologies. It identifies the Provant Therapy System as the intervention and describes a daily NPRS pain measure, with scores collected up to 20 weeks. It also defines the primary pain outcome as change from baseline or pre-treatment to end of treatment or the last available observation. Those details explain the study's focus, but they are not numerical findings.

The registry does not report the observed pain-score change, the standard deviation of that change, a confidence interval, or an analysis result. It is therefore not possible to determine the direction, magnitude, or precision of the pain outcome from the recorded results. Nor can the record establish whether any change was clinically important, because it does not provide a threshold for that interpretation.

Even if a within-participant change estimate were available, the single-group design would not show how participants' outcomes would have differed without treatment. General statistical reasoning distinguishes an observed change over time from a causal treatment effect. With no concurrent control group and no masking, other influences and expectations cannot be ruled out by the design alone. This does not establish that any particular influence affected the results; it defines the limit on causal interpretation.

The adverse-event entries report 0 affected participants in both the serious and other event categories, with 0 deaths recorded. These entries should not be expanded into a claim that no adverse experiences occurred, because the record does not describe event ascertainment or reporting completeness. Similarly, the enrollment figure is not a substitute for the unreported number of participants with complete NPRS data.

In short, the registry provides an outcome definition and study description, but does not report the primary endpoint findings. It supports no conclusion about the size or certainty of pain change, and it cannot establish a comparative treatment effect. These gaps are not evidence of either benefit or lack of benefit; they mean the relevant numerical results are not reported in the registry record.

14. Why This Trial Matters Statistically

This study illustrates an important distinction between registering an outcome and reporting its result. A registry can specify what investigators intend to measure, the population to be included, and the observation period. Those elements are useful for understanding the question. They do not allow readers to assess the size or precision of an effect unless estimates and uncertainty are also recorded.

The study's single-group design makes the distinction between description and causal inference especially important. A before-and-after pain measure can describe how recorded scores changed among participants with the required observations. Without a concurrent control group, the change cannot be separated from other changes over time by the design alone. This is a general issue in interpreting uncontrolled longitudinal data, not a conclusion about what happened to any individual participant in this study.

The eligibility rule for the NPRS analysis also highlights why denominators matter. The study enrolled 180, while the pain analysis was defined for subjects with both baseline and end-of-study scores. The number who met that requirement is not reported in the registry record. Readers therefore cannot determine how much of the enrolled group contributed to the endpoint or assess the consequences of missing observations.

Finally, the record shows how safety counts require context. Zero recorded affected participants are informative as registry entries, but their meaning depends on event definitions, ascertainment, and follow-up completeness, which are not described. Together, these features make the record statistically instructive: study design, outcome definition, analysis population, and numerical results each contribute distinct information, and one cannot substitute for another.

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 record restrict interpretation. The study is open-label and non-controlled, with one treatment arm and no allocation. There is no concurrent comparison group to provide a reference for changes over time. The registry also identifies no masking. These design features limit the ability to attribute a within-group change to the intervention.

The primary endpoint is described, but its numerical analysis is not reported. The registry records one outcome measure and zero analysis entries. There is no reported mean change, standard deviation, confidence interval, or test result. As a result, neither the observed outcome nor its precision can be evaluated. A stated endpoint is not a substitute for an estimate.

The analysis population is restricted to subjects recording both a Baseline and End of Study score, but the number meeting that condition is not reported. The amount and pattern of missing diary data, reasons for missingness, and methods for handling unavailable observations are also not reported in the registry record. The endpoint's reference to the last available observation does not resolve these questions.

The record does not report the trial's sample-size justification, a statistical analysis plan, interim analyses, multiplicity procedures, or details of the analysis method. It also does not report a threshold for a clinically important NPRS change. These omissions limit assessment of design adequacy, analysis choices, and clinical interpretation.

For safety, the recorded counts are not accompanied by details about event ascertainment, follow-up completeness, or exposure duration. The listed zero counts therefore need to be read as registry entries rather than a comprehensive demonstration that no adverse experiences occurred. Taken together, these limitations mean the record is informative about study structure and measurement intent, but not about the magnitude or certainty of the primary pain result.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: A Registry Study to Evaluate Outcomes of PEMF Therapy in Subjects With Various Pain Etiologies — NCT02881112.
• Registry record last updated 2020-04-06; status last verified 2020-04.
• Results first posted 2019-11-25.
• 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

NCT02881112 is a completed, open-label, non-controlled, single-group registry study of the Provant Therapy System in subjects with pain and/or edema from various pain etiologies. Enrollment is 180. The listed start is 2016-03, and the primary completion date is 2017-12-14.

The primary outcome is Pain Intensity Assessment, summarized as a mean and standard deviation. NPRS pain scores were collected daily up to 20 weeks on a scale from 0, no pain, to 10, worst pain. The endpoint is change from baseline or pre-treatment to end of treatment or the last available observation; the NPRS analysis population includes subjects recording both required scores.

The registry lists zero analysis entries and does not report the primary pain result. Adverse-event entries record 0 affected participants for serious events, 0 for other events, and 0 deaths. Details about missing-data handling, analysis methods, and safety ascertainment are not reported in the registry record.