BlueWind Medical Reprieve System for the Treatment of PNP: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for BlueWind Medical Reprieve System for the Treatment of PNP (NCT02062398), a na na study. The primary outcome is The Incidence of System and/or Procedure Related Serious Adverse Events (SAEs)..

2. Clinical Question

In statistical terms, this is a descriptive safety question in a small, single-group device study. The reported event count can describe what was observed among enrolled participants, but without a comparator it cannot estimate how the event frequency would differ under another treatment or under no implantation. The registry does not report an outcome analysis, a confidence interval, or a formal comparison for the primary endpoint. Therefore, the figures support a count-based account of reported events, not a comparative estimate of safety or an estimate of an underlying event rate with stated precision.

3. Trial Design

The registry identifies this study as a completed, single-group device study of the BlueWind Medical Reprieve System for patients with peripheral neuropathic pain. It lists an enrollment of 13 participants and describes implantation of the Reprieve system in eligible patients. Implant parameter settings were to be set according to the patient’s sensations. The study has no randomized allocation and no masking; a control arm is not reported in the registry record.

The registry lists the study start as 2014-05 and primary completion as 2015-12. The phase is recorded as NA, which is consistent with the record’s device focus but does not supply a further design description. The record gives a primary endpoint concerning system- and/or procedure-related serious adverse events. Although its timeframe is listed as 6 months, the endpoint description says the incidence is assessed throughout the entire study period. The registry does not explain how those two descriptions relate.

The record lists five outcome measures and repeats “Clinical Success 6 Months Post Activation” as a secondary outcome title. Outcome definitions, analysis populations, assessment schedules beyond the stated timeframe, and methods for handling incomplete follow-up are not reported in the registry record. No outcome analyses are listed. Thus, the design information supports a description of the study structure and intended safety focus, but not a reconstruction of a complete statistical protocol or a full account of how each outcome was assessed.

Because all participants are in one group, the observed safety counts are not a like-for-like comparison between randomized groups. The design can document events in the treated cohort, but it cannot by itself separate events related to the device or procedure from background events through a concurrent control comparison.

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

Reasons for not completing this period:

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 The Incidence of System and/or Procedure Related Serious Adverse Events (SAEs)., measured over 6 months.

The primary endpoint counts participants with system- and/or procedure-related serious adverse events. A participant count is a binary outcome summarized as the number who experienced at least one qualifying event, rather than as the total number of events. The registry names serious adverse events as the focus and specifies a timeframe of 6 months. Its description also says that the incidence is assessed throughout the entire study period; the record does not clarify this difference in wording.

Safety endpoints of this kind are used to describe whether serious harms were observed during a study and how many participants were affected. Counting participants can make the measure straightforward to interpret, especially when the key question is whether a person experienced any qualifying event. It does not, by itself, describe the number of events per participant, the timing or duration of events, their severity beyond the serious-event classification, or their causal certainty.

The posted figures report 1 participant with a serious adverse event among 13 at risk in the Reprieve System Implantation group. The registry does not report a primary endpoint analysis, a confidence interval, or a formal estimate of incidence. The count therefore describes the recorded experience in this cohort, but its precision and comparative meaning cannot be assessed from an analysis result in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the primary outcome as binary and defines its unit as participants. In general, a binary outcome records whether each participant did or did not meet a specified condition. For this endpoint, the condition is experiencing a system- and/or procedure-related serious adverse event. A participant count is distinct from an event count: one participant may experience more than one event, while the participant-level measure counts that person once if the endpoint is defined as having any qualifying event.

The posted serious-event figures list 1 participant affected and 13 participants at risk in the Reprieve System Implantation group. No primary outcome analysis is listed. A count can be reported without an inferential model, but it does not by itself quantify sampling uncertainty. General statistical principle: a confidence interval describes a range of values compatible with the data under a specified statistical method and assumptions. No confidence interval for this primary endpoint is reported in the registry record.

What does a single-group design allow?

A single-group study can describe observed events in the participants who received the device. It does not contain a concurrent comparison group from which to estimate a difference in event frequency. Even if an event is classified as system- or procedure-related, the registry’s group structure does not independently establish what would have occurred to those same participants without the device. A randomized comparison can help distinguish treatment-group differences from background variation; that kind of comparison is not reported in this record.

The absence of masking is also recorded. Masking is a design feature intended to limit awareness of treatment assignment for participants, clinicians, or assessors, depending on the protocol. In a single-group implantation study, no masking is listed, and the registry does not describe any blinded outcome assessment. The consequences for assessment cannot be determined from the record alone. In particular, the registry does not specify how serious-event relatedness was adjudicated.

Why do the observation window and endpoint wording matter?

The timeframe is listed as 6 months, but the endpoint description refers to the entire study period. General statistical principle: an event frequency depends on the period in which participants are followed and events are captured. If follow-up differs between participants, a simple participant count may not represent comparable observation time. The registry does not report individual follow-up durations, rules for censoring, or clarification of the endpoint window, so those details cannot be incorporated into interpretation.

For event-count data, exposure time can sometimes be incorporated with methods designed for rates or time-to-event outcomes. Those approaches require information about event timing and/or time at risk, and their suitability depends on the study design and data. Such analyses are not reported. The outcome is described as a participant count, and no time-to-event analysis is listed.

What can a significance level or power calculation say?

The registry includes assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. It specifies that non-time-to-event planning values are participants per arm. These are planning assumptions, not evidence that the trial was designed with those assumptions. The actual study is single-group, and the registry does not report its sample-size justification or statistical plan.

General statistical principle: a significance level is a threshold used in a specified testing procedure; it is not the probability that a finding is true. Power is the probability, under stated assumptions, of detecting a specified effect with a particular test. Planning illustrations based on an observed effect do not represent observed power and do not establish that the study could reliably detect an effect. The registry provides no primary endpoint analysis from which to interpret a test result. No planning output values are reported in the registry record.

General statistical principle: over-dispersion occurs when observed variability in count data is greater than a model assumes. It can make standard errors too small if the model does not account for that extra variability. That issue is relevant to some count models, but the primary endpoint is a participant count and no model or dispersion estimate is reported. It would be inappropriate to assert that over-dispersion was assessed or present in this study.

Overall, the statistical information available supports a descriptive reading of the participant counts. The record does not specify inferential methods, covariate adjustment, handling of repeated events, or an analysis population. Those methods cannot be inferred from the posted outcome description or from the planning assumptions alone.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("The Reprieve System Implantation")
n      <- c(13)
events <- c(1)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  The Reprieve System Implantation  13  1  7.7  0.2  36.0  1.4  33.3  1.8  33.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists five outcome measures, including the primary serious-adverse-event endpoint and secondary outcome titles. “Clinical Success 6 Months Post Activation” appears three times in the secondary-outcome list. The record does not explain whether these repeated entries represent distinct measures, separate assessments, or duplicate titles. Definitions for the secondary outcomes are not reported in the registry record.

No outcome analyses are listed. The registry does not report a statistical plan for prioritizing outcomes, controlling multiplicity, or interpreting multiple tests. General statistical principle: when many outcomes or hypotheses are tested, the chance of at least one apparently notable result can increase unless the analysis accounts for multiplicity. Since no test results or multiplicity approach are reported, this concern cannot be quantified for this study.

Missing-data methods and analysis populations are also not reported in the registry record. It is not stated whether all enrolled participants contributed to each outcome, how incomplete follow-up was handled, or whether any participants were excluded from analyses. The safety group lists 13 participants at risk, but this does not supply a general rule for denominators across all outcomes. No imputation method, sensitivity analysis, or missingness summary is reported.

These gaps limit interpretation of completeness and robustness. The available count can be described as recorded for the named safety group, but the registry does not establish how missing observations were handled or whether all planned outcomes were analyzed. No assumptions about the direction or effect of missingness can be justified from the registry record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: low grade infection and delayed closure of surgical wound (7.7%).

The serious-adverse-event figures list 13 participants at risk and 1 participant affected in the Reprieve System Implantation group. The registry also lists 0 deaths. These figures describe participant counts, not a comparison between treatment groups. The study has no randomized allocation and no control group reported in the registry record.

The serious-event term listed is “low grade infection and delayed closure of surgical wound,” recorded as 7.7%. The registry does not provide a fuller description of this event, its timing, duration, management, or how its relationship to the system or procedure was assessed. The term appears in the serious-event listing even though it includes the words “low grade”; the record does not offer further context to explain its classification.

The registry separately lists 4 participants with other adverse events among 13 at risk. Serious and other adverse-event counts should be kept distinct because they represent different categories in the record. A participant may potentially be represented in more than one category, and the registry does not state whether participant overlap occurred. It also does not report the total number of individual events or event-level follow-up time.

The endpoint description refers to the entire study period, while its timeframe is listed as 6 months. Without clarification, the observation window should not be treated as more precisely defined than the registry states. The counts are descriptive and do not by themselves establish comparative risk or causal attribution.

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

The registry records a safety experience for 13 participants who underwent Reprieve System implantation. It lists 1 participant with a system- and/or procedure-related serious adverse event, 4 participants with other adverse events, and 0 deaths. These counts describe the posted record for this group. They do not establish a comparative effect because no control group or randomized allocation is reported.

The serious-adverse-event endpoint is relevant because it focuses on serious harms attributed to the system and/or procedure. However, the registry does not report a primary endpoint analysis, confidence interval, or statistical test. The available information therefore does not quantify the precision of an underlying event frequency. A count from a small cohort is a description of observed participants, not a guarantee of the frequency in a wider population.

The record also leaves important interpretive details unresolved. The endpoint timeframe is listed as 6 months, while its description refers to the entire study period. The record does not state how relatedness was determined, how many events occurred per affected participant, whether all participants completed follow-up, or how missing outcome data were handled. These omissions constrain any attempt to assess the completeness or consistency of event ascertainment.

Nothing in these counts alone shows whether the device caused or prevented events, or how its safety compares with another approach. A single-group safety record can identify events observed during a study and provide a basis for describing the cohort’s experience. It cannot supply the counterfactual comparison needed to estimate what would have happened under an alternative. The statistical meaning is therefore descriptive and limited to the participants and outcomes recorded, with broader generalization and comparative claims not established by the registry record.

14. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the distinction between documenting events and estimating comparative effects. A single-group device study can record serious adverse events among participants who undergo implantation. Those observations are valuable as a description of the cohort, but without a control group they cannot show whether event frequency differs from that under another treatment or no implantation.

The registry lists 13 participants at risk and 1 participant with a serious adverse event. In a cohort of this size, each participant’s experience contributes visibly to the observed count. General statistical principle: small samples commonly leave substantial uncertainty about the frequency of uncommon outcomes. The record does not report a confidence interval, so readers cannot assess a formal range of uncertainty for the endpoint.

The difference between the listed 6-month timeframe and the endpoint description’s reference to the entire study period is also statistically important. Event counts depend on the period over which events are sought, and interpretation requires a clear definition of follow-up. The record does not clarify the discrepancy or describe participant-level observation time.

Finally, the registry reports no outcome analyses. The planning assumptions for illustrative sample-size calculations should not be confused with the study’s actual design or with evidence of observed power. The trial is recorded as single-group, whereas those assumptions refer to equal allocation between two arms. Recognizing that mismatch helps prevent planning calculations from being read as an analysis of comparative efficacy or as a description of the study’s original statistical justification.

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.

The principal limitation for interpretation is the absence of a comparison group. The registry records a single-group, unmasked study with no randomized allocation. The safety counts therefore cannot estimate a between-group difference or distinguish the observed experience from what might have occurred under an alternative.

Enrollment was 13 participants. This gives a limited basis for characterizing event frequency beyond the enrolled cohort, particularly for serious events. The registry does not report a confidence interval or another estimate of statistical precision for the primary endpoint. General statistical principle: limited sample information can leave substantial uncertainty even when a participant count is exact.

The primary endpoint’s observation period is not fully clear: the timeframe is listed as 6 months, while the description refers to the entire study period. Follow-up duration by participant, event timing, and rules for event ascertainment are not reported. The registry also does not describe how system- or procedure-relatedness was determined or how serious events were classified.

Analysis details are sparse. No outcome analyses are listed, and the registry does not report a sample-size justification, a statistical analysis plan, missing-data methods, analysis populations, or multiplicity handling. Secondary outcome titles are repeated, without an explanation of whether these are separate measures or duplicate entries. These gaps restrict evaluation of outcome completeness and of the methods that would be needed for inferential conclusions. They do not change the reported counts, but they limit what can be concluded from them.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: BlueWind Medical Reprieve System for the Treatment of PNP — NCT02062398.
• Registry record last updated 2019-12-30; status last verified 2018-11.
• Results first posted 2019-12-30.
• 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

NCT02062398 is a completed, single-group study of the BlueWind Medical Reprieve System for peripheral neuropathic pain. The registry lists enrollment of 13 participants, no masking, and no randomized allocation. The primary outcome concerns participants with system- and/or procedure-related serious adverse events. Its timeframe is listed as 6 months, while the description refers to the entire study period.

The safety record lists 1 participant with a serious adverse event among 13 at risk, 4 participants with other adverse events among 13 at risk, and 0 deaths. The listed serious-event term is “low grade infection and delayed closure of surgical wound,” recorded as 7.7%. No outcome analyses are listed, and a primary endpoint analysis result is not reported in the registry record. The posted counts are descriptive and do not provide a controlled comparison or a quantified estimate of statistical precision.