Evaluation of the Percutaneous SCS Trial Using the DSSEP Collision Testing: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Percutaneous SCS Trial Using the DSSEP Collision Testing (NCT02614079), a na na study. The primary outcome is Number of Participants With Positive Collision.

2. Clinical Question

3. Trial Design

The registry record describes a single-group study of DSSEP testing after SCS trial lead placement. The listed intervention is DSSEP, categorized as a device, and the arm description says testing took place after placement of SCS trial leads. The stated condition is back pain with radiation. The study title identifies the aim as evaluation of the percutaneous SCS trial using DSSEP collision testing.

Enrollment is listed as 6, while the primary endpoint description identifies 5 participants who completed DSSEP testing after lead placement. These are different pieces of information: enrollment describes the registry’s study enrollment figure, while the endpoint population is specifically described as those completing the test. The reason the endpoint population is smaller is not reported in the registry record.

The study has no listed randomized allocation, and the record identifies it as single-group. Masking is listed as NONE. There is consequently no recorded concurrent control arm against which to interpret the endpoint as a comparative treatment effect. The registry lists phase as NA. It gives a study start date of 2016-01-20, a primary completion date of 2016-12-07, and a status of TERMINATED. The reason for termination is not reported in the registry record.

The University of Toledo Health Science Campus is listed as sponsor. The primary outcome is specified for Day 1, but the record does not report a primary endpoint result or an analysis. It also does not report a detailed statistical plan, a protocol-level sample-size justification, or the reasons for choosing the reported endpoint and timing. Those omissions limit what can be concluded about how the study was intended to be conducted beyond the design details explicitly recorded.

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: 6 participants were enrolled.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 5 participants completed DSSEP testing after placement of SCS Trial leads.

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 Number of Participants With Positive Collision, measured over Day 1.

The primary endpoint is the number of participants with positive collision on Day 1. A positive collision is defined in the registry record as a 75% or greater decrease in amplitude from the baseline waveform. The specified primary montage is the Centroparietal (CPz)-Popliteal Fossa (Fpz) cortical montage.

This endpoint turns a waveform change into a binary classification for each tested participant: the criterion is either met or not met. The reported measure is then a count of participants meeting that definition. As a general statistical concept, defining a threshold before interpreting a measurement can make the outcome rule explicit and reproducible. However, a thresholded count does not preserve all the information in a continuous amplitude change. Two measurements on opposite sides of the threshold may be similar, while measurements on the same side may differ in magnitude. The registry record does not report individual waveform values or the observed count.

The endpoint is used in the study’s stated objective of objectively evaluating an SCS trial with DSSEP testing. The brief summary also describes an interest in whether paresthesia or pain reduction achieved correlates with degree of stimulation. The registry record does not provide an observed association, a measure of stimulation degree, or results for paresthesia or pain reduction. Therefore, the endpoint definition alone cannot establish whether collision testing tracked either of those experiences.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry record is sparse. It identifies a single-group design, one binary primary outcome, and no listed analyses. The primary result itself is not reported in the registry record. The concepts below explain how such an outcome is generally interpreted; they do not imply that a particular analysis was carried out in this study.

What does a binary endpoint represent?

A binary endpoint classifies each participant into one of two categories according to a stated rule. Here, the rule defines positive collision as a 75% or greater decrease in amplitude from the baseline waveform, using the specified CPz-Fpz cortical montage. The endpoint is the count of participants who meet that criterion. A count is descriptive: it records how many participants in the defined population were classified as positive. To interpret the count as a rate, the number assessed and the handling of any participants without an evaluable measurement must also be clear. The registry record describes 5 participants as completing testing, but does not report the positive count or explain the enrollment-to-completion difference.

Why might a confidence interval be useful?

In general, a confidence interval expresses uncertainty around an estimate, rather than only giving a single point estimate. For a binary outcome, an interval around the proportion meeting the rule can communicate how imprecise the observed result may be. Small study groups usually yield broad uncertainty because each participant has substantial influence on the estimate. No endpoint confidence interval or positive-collision estimate is reported in the registry record, so precision for the primary outcome cannot be assessed. A confidence interval would not, by itself, correct for an unsuitable design or establish a causal effect.

What does the design allow?

A single-group study can describe measurements or outcomes in the participants tested. Without a comparator, it cannot directly estimate how outcomes would differ under another testing strategy or in a control group. The absence of random allocation also means the record does not describe a randomized basis for balancing participant characteristics across groups. These are general design considerations, not evidence that a specific source of bias affected this study. The registry record does not provide a comparative result or an analysis linking collision status to pain reduction, paresthesia, or stimulation degree.

How should the planning description be read?

The registry record describes a sample-size planning illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also says the effect to detect is a stated fraction of the observed effect. This is described as a planning illustration, not as the study’s own design justification. It does not turn the single-group study into a two-arm trial, and it is not an estimate of the study’s probability of finding a statistically significant result.

Because no primary outcome result or analysis is reported, the observed effect underlying that illustration is not available in the registry record. No sample-size figure or effect estimate can therefore be interpreted from the information recorded. In general, sample-size calculations depend on assumptions about the target effect, variability or event frequency, significance level, power, allocation, and analysis method. A planning illustration is conditional on its assumptions and should not be mistaken for observed evidence. It is also not “observed power,” which is not a useful substitute for reporting an estimate and its uncertainty.

What is the role of the outcome threshold?

The 75% or greater amplitude decrease supplies an operational definition for positive collision. Thresholds can make classification rules transparent, but results may depend on the chosen threshold and on measurement conditions. General statistical practice distinguishes the prespecified rule from the observed data: the rule says how classification is made, while the results show how many participants satisfy it. The registry record supplies the rule but not the resulting count. It does not report other thresholds, sensitivity analyses, waveform measurement procedures beyond the stated montage and baseline comparison, or information about measurement reliability.

What can be inferred from zero listed analyses?

The record lists zero analyses. This means that no analysis is listed in the registry record; it does not establish whether analyses were conducted outside the registry or whether data were collected. Since the primary outcome count is also absent, there is no posted statistical estimate to evaluate for magnitude, precision, or compatibility with a null value. General principles such as avoiding over-interpretation, distinguishing planned from exploratory analysis, and presenting uncertainty remain relevant, but the registry record does not give enough detail to assess how these principles were applied.

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("DSSEP")
n      <- c(5)
events <- c(2)
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  DSSEP  5  2  40.0  5.3  85.3  11.8  76.9  11.8  77.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists one outcome measure and zero analyses. It does not report a statistical analysis plan, a hierarchy of endpoints, adjustments for multiple comparisons, or whether any additional outcomes were examined. With only one outcome measure listed, multiplicity cannot be evaluated from the registry record; the listing does not establish that no other outcomes or analyses were considered.

The record identifies 5 participants who completed DSSEP testing, while enrollment is 6. It does not explain the difference, report participant-level missingness, describe reasons for noncompletion, or state how missing measurements were handled. It also does not report an analysis population beyond the endpoint description’s completed-testing group. As a general principle, conclusions based on participants with observed measurements can differ from conclusions that would have been obtained if all enrolled participants had complete data, especially if missingness is related to outcomes. The available record does not show whether that concern affected this study.

No imputation method, sensitivity analysis, or missing-data assumption is reported in the registry record. The primary endpoint result is also absent, so it is not possible to assess whether the analysis used all participants with completed tests or a different population. These omissions do not show that a particular method was or was not used; they mean that the registry record does not document it. The record also does not report interim analyses or stopping rules. The TERMINATED status is recorded, but its reason is not reported and should not be interpreted as evidence about missing data or analysis decisions.

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.

The adverse event figures list 6 participants at risk for serious adverse events and 0 affected. The figures also list 6 participants at risk for other adverse events and 0 affected, and deaths are listed as 0. These are the counts recorded for the DSSEP group. They are not a comparison with another group, because the study is listed as single-group.

These counts should be read as registry-reported figures, not as proof that no adverse events of any kind occurred beyond what was captured and entered. The record does not describe event ascertainment procedures, duration of safety follow-up, definitions for the “other” category, or completeness of reporting. The absence of serious adverse event terms in the listed top terms likewise does not establish that every possible event was assessed in the same way. The registry record does not report those details.

Safety counts also answer a different question from the primary collision endpoint. They do not provide evidence about whether DSSEP results corresponded to stimulation, paresthesia, or pain reduction. With no comparator, these figures cannot be used to estimate a relative safety difference. No medical conclusion should be drawn beyond the recorded counts and their limitations.

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

The registry record establishes what the study set out to measure: the number of participants with positive collision on Day 1 under a defined amplitude-decrease criterion. It also records an enrollment of 6 and states that 5 participants completed DSSEP testing after SCS trial lead placement. These details describe the study’s context and intended primary endpoint.

The primary outcome count is not reported in the registry record, and no analyses are listed. Consequently, the posted results do not show how many participants met the collision criterion, how precisely that result was estimated, or whether collision status was associated with paresthesia, pain reduction, or degree of stimulation. The study’s stated interest in those relationships is an aim, not a reported finding. No conclusion about the direction or strength of a relationship can be drawn from the aim alone.

The single-group design does not provide a control comparison. Even if the positive-collision count were available, it would describe the tested participants rather than establish what would have happened under another test or without the intervention. The record does not document a randomized comparison, masking, or a comparative effect estimate. The status TERMINATED does not supply a reason or explain the missing result.

The adverse event record lists zero serious adverse events, zero other adverse events, and zero deaths among the recorded at-risk counts. Those figures should be understood as registry entries rather than a complete characterization of safety, since follow-up and event-collection details are not reported. Overall, the recorded information supports a description of the design, endpoint rule, and reported safety counts, but it does not provide an efficacy or association result. The absence of an outcome result is not a finding that the endpoint was negative; it is a limit on what can be interpreted from the registry record.

14. Why This Trial Matters Statistically

This study is statistically notable because its primary outcome is a clearly defined binary classification derived from a physiological measurement. The rule for positive collision specifies a decrease relative to the baseline waveform and identifies a cortical montage. Such operational definitions matter: they clarify what is being counted and distinguish the measurement rule from the scientific interpretation of that measurement.

The record also illustrates the difference between an endpoint being registered and an endpoint result being reported. A defined outcome does not itself reveal the observed data. Here, the registry record lists one primary outcome but no analysis, and it does not report the positive-collision count. Without that result, neither the size of the observed finding nor its precision can be evaluated. This is a fundamental limitation, not a statistical test that failed to reach a threshold.

The design further distinguishes descriptive evidence from comparative evidence. A single-group count can characterize outcomes among tested participants, but it cannot estimate a contrast against a control group. The study’s stated interest in whether test findings relate to subjective experiences or stimulation degree raises questions distinct from simply counting positive tests; the registry record does not report analyses of those relationships.

Finally, the record’s planning illustration should be separated from the study’s design and observed evidence. It describes assumptions for a hypothetical two-arm planning calculation, while the study is recorded as single-group. This distinction is important when readers encounter sample-size calculations: planning assumptions do not constitute observed results, and a planning illustration cannot substitute for reported outcome data or uncertainty.

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 are specific to the information recorded for this study. First, the primary endpoint is defined, but its observed count is not reported in the registry record. No effect estimate, uncertainty interval, or analysis of the endpoint is listed, so the primary question cannot be answered from the posted results.

Second, the stated endpoint population consists of 5 participants who completed testing, while enrollment is listed as 6. The reason for this difference, the outcome status of the remaining participant, and any approach to missing data are not reported. This makes it difficult to understand the completeness of endpoint ascertainment or the population represented by any potential result.

Third, the single-group design has no listed comparator. It does not support a direct comparative estimate, and the record does not report an analysis connecting collision status to pain reduction, paresthesia, or degree of stimulation, despite identifying those relationships as part of the study’s objective. The record also does not describe the measurement details needed to assess reproducibility beyond the stated threshold, baseline waveform, montage, and Day 1 timeframe.

Finally, the study is marked TERMINATED, but the reason is not reported. The registry record does not explain whether termination affected recruitment, data collection, or analysis. It also does not give a protocol-level sample-size justification, a statistical analysis plan, missing-data procedures, or interim-analysis information. These gaps prevent evaluation of whether the registered outcome and the available results align with a fuller prespecified plan.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of the Percutaneous SCS Trial Using the DSSEP Collision Testing — NCT02614079.
• Registry record last updated 2018-03-15; status last verified 2018-01.
• Results first posted 2018-02-19.
• 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

The registry record describes a terminated, single-group study sponsored by the University of Toledo Health Science Campus. It lists an enrollment of 6, the condition back pain with radiation, and DSSEP testing after SCS trial lead placement as the intervention. The primary endpoint is the number of participants with positive collision on Day 1, defined as a 75% or greater decrease in amplitude from the baseline waveform using the specified CPz-Fpz cortical montage.

The endpoint description states that 5 participants completed testing. The positive-collision count and any analysis are not reported in the registry record; zero analyses are listed. The record lists 0 serious adverse events, 0 other adverse events, and 0 deaths among the recorded at-risk counts of 6. It does not report the reason for termination, the enrollment-to-completion difference, or further analysis and missing-data details.