Direct Comparison of Spinal Cord Stimulator Parameter Settings: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Direct Comparison of Spinal Cord Stimulator Parameter Settings (NCT05283863), a randomized na study. The primary outcome is Visual Analog Pain Scale.

2. Clinical Question

The clinical question is framed around whether subthreshold stimulation can be compared with sham stimulation without relying on a sensory percept. The registry also describes a secondary question comparing subthreshold patterns with conventional stimulation that produces paresthesias, and asks whether subthreshold high-frequency stimulation can affect axial pain or the affective component of pain. Those stated aims do not establish that each comparison is represented in the posted primary results. The mismatch in terms and frequency descriptions makes it important to distinguish the planned question from the specific outcome labels attached to the reported values.

3. Trial Design

The registry describes a randomized, triple-masked crossover study, marked completed, with enrollment of 4. Its recorded start is 2015-06 and primary completion is 2015-08. A crossover design means that participants receive more than one study condition in sequence, so each participant may contribute observations under multiple conditions. Randomization can determine the order in which the conditions are received. The registry does not report the details of how the random sequence was generated or how masking was maintained.

The arm descriptions specify two sequences. In one, participants first receive subthreshold high-frequency stimulation for 2 weeks, then undergo a 2-week washout period, and then receive sham stimulation. In the other, sham stimulation comes first for 2 weeks, followed by a 2-week washout and then subthreshold high-frequency stimulation. The sham is described as 1200 Hz at 0 V amplitude; the active setting is described as 1200 Hz, a 200 μsec pulse width, and an amplitude 90% of the sensory-percept detection threshold. The primary outcome timeframe is 8 weeks.

The outcome description names conventional baseline stimulation, high-density stimulation, conventional “washout” stimulation, and sham stimulation as phases. The reported primary outcome groups, however, are High-density Stimulation and Placebo Stimulation. These labels differ from the intervention names and the sequence descriptions, so the registry record does not make the relationship among all named phases and reported groups fully clear. The objective also refers to 1000 Hz, while the arm descriptions specify 1200 Hz. These differences cannot be resolved from the registry record.

A crossover study can be efficient when participants serve as their own comparison, but interpretation depends on the sequence, timing, and possible carryover between periods. The registry identifies a washout period but does not report an analysis accounting for period or sequence effects, nor does it state how carryover was assessed. Details on eligibility criteria, participant characteristics, and the number completing each phase are not reported in the registry record.

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.

First Intervention (14 Days)

Washout (14 Days)

Second Intervention (14 Days)

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.

Population: No subjects were randomized to the conventional spinal cord stimulation group

6. Primary Endpoint

The registry lists the primary outcome as Visual Analog Pain Scale, measured over 8 weeks.

The primary endpoint is the Visual Analog Pain Scale, reported in units on a scale. The registry describes assessment of the overall degree of back and leg pain during stimulation phases. Scores range from 0 - 100, with a higher score indicating more pain. The posted summary gives a mean and standard deviation for each reported group, rather than individual participant scores.

A pain scale is used to quantify a participant-reported experience in a form that can be summarized and compared across study conditions. As a general statistical point, a continuous scale can retain gradations in responses that would be lost if pain were reduced to a simple yes-or-no outcome. The mean describes the average score in a group; the standard deviation describes how spread out the scores are around that mean. Neither statistic alone shows the full range of participants’ experiences.

The study summary says the primary objective also considers the Brief Pain Inventory, the SF-36, and the Pain Vigilance and Awareness Questionnaire. The registry lists changes in the Brief Pain Inventory and SF-36, the Pain Vigilance and Awareness Questionnaire, and the number of patients with stimulation side effects as secondary outcomes. The posted record reports four secondary outcomes, but secondary results are not included in the registry entries. The primary outcome’s measure is therefore distinguishable from the broader set of planned clinical questions.

The record’s outcome description uses four phase labels, while the posted group results contain two group names. That distinction matters: the two reported means should not be interpreted as a complete account of every phase named in the endpoint description.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary outcome is continuous, and its parameter is the mean. A mean is the arithmetic average of the recorded scale values within a group. The standard deviation is a measure of dispersion: it describes how much individual scores vary around the group mean. In this record, both the mean and standard deviation are reported for High-density Stimulation and Placebo Stimulation. These summaries are useful for describing central tendency and spread, but they do not preserve the full participant-level data.

What does the standard deviation describe?

As a general statistical explanation, a standard deviation reflects within-group variability, not the precision of a comparison between groups. Precision of a group mean or a treatment contrast is usually expressed using a standard error or a confidence interval, which also depends on the amount of information available. The registry does not report confidence intervals or standard errors for the posted primary values. The standard deviations should therefore not be read as confidence limits, nor do they directly show how uncertain the contrast is.

How does crossover structure affect interpretation?

In a crossover trial, participants receive conditions in sequence. In principle, comparing conditions within the same participant can account for stable characteristics that differ between people. General statistical methods for crossover data may model the participant, treatment condition, period, and sequence, depending on the design and data. The registry describes randomized order and a washout period, but it does not report the analysis method, whether within-participant contrasts were used, or whether period, sequence, or carryover effects were evaluated. The posted group means alone do not reveal whether the comparison uses paired participant data or treats the groups as independent.

A washout period is intended to separate treatment periods when effects could persist after a condition ends. Whether a particular duration is adequate depends on the intervention and the outcome. The record describes a 2-week washout but does not report the reasoning for its duration or any assessment of residual effects. This is relevant because a condition received earlier could influence observations in a later period if its effects persist. No conclusion about such persistence can be drawn from the registry summaries.

What can be learned from the reported summaries?

The means describe average pain scale values in the named groups, and the standard deviations describe the spread of recorded values. Higher scale scores indicate more pain according to the registry. A group-level mean can conceal different individual patterns: some participants may have scores above the mean and others below it. Without participant-level results, the size and direction of within-person changes cannot be examined. The registry does not report an effect estimate with a confidence interval, a test statistic, or a p-value for the primary comparison.

General statistical interpretation distinguishes estimation from hypothesis testing. An estimate describes the magnitude of an observed contrast; a confidence interval expresses a range of values compatible with the data and a specified method. A p-value, when reported, evaluates data under a defined null model and does not quantify clinical importance or the probability that a hypothesis is true. None of those inferential quantities is posted for the primary outcome in this record. The descriptive means should not be treated as if they were a formal adjusted analysis.

Why does a small sample matter?

With 4 participants in each reported group, the summaries are based on very few observations. General statistical reasoning indicates that estimates from small samples can be sensitive to the values of individual participants, and uncertainty is often substantial. The posted standard deviations offer some information about observed spread, but cannot substitute for an uncertainty interval or a clearly specified analysis. No claim about observed power is warranted from these descriptive results.

The record includes assumptions for a planning illustration based on the observed effect: two-sided significance level 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. Such calculations are planning illustrations, not evidence about the study’s original design or the chance that the observed result is real. The registry does not report the trial’s sample-size justification. Values for a planning calculation are not reported in the registry record, so no participant target should be inferred from that description.

What does multiplicity change?

The registry describes several clinical measures and secondary outcomes in addition to the primary pain scale. General statistical reasoning recognizes that when many outcomes or comparisons are examined, the chance of finding an apparently unusual result can increase unless the analysis plan addresses multiplicity. The record does not report a multiplicity procedure, a hierarchy among outcomes, or the set of statistical tests performed. Since no inferential analyses are posted, the secondary outcome list alone cannot establish which comparisons were analyzed or how their uncertainty should be interpreted.

Overall, the available statistical information supports description of the posted group means, standard deviations, and adverse-event counts. It does not document the inferential method needed to assess a crossover contrast or to quantify 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("High-density Stimulation", "Placebo Stimulation")
n   <- c(4, 4)
m   <- c(2.29, 6.31)
sp  <- c(0.41, 1.22)
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  High-density Stimulation  4  2.290  0.410  1.638  2.942
CARM  Placebo Stimulation  4  6.310  1.220  4.369  8.251

11. Multiplicity, Missing Data and Analysis Populations

The registry names one primary outcome and several secondary measures: change in the Brief Pain Inventory, change in the SF-36, the Pain Vigilance and Awareness Questionnaire, and the number of patients with stimulation side effects. The study summary also describes broader objectives involving back and leg pain, paresthesia-producing stimulation, axial pain, and the affective component of pain. The record reports 5 outcome measures and 0 analyses. It does not provide statistical results for the listed secondary outcomes.

When a study evaluates multiple outcomes or contrasts, multiplicity can affect how results are interpreted. As a general statistical point, examining many possible findings can increase the chance that some appear notable by chance. A prespecified hierarchy or adjustment can address particular multiplicity concerns, but no such approach is reported in the registry record. The record also does not state whether all listed outcomes were analyzed or whether any outcomes were omitted from reporting.

Information about missing data is not reported in the registry record. The record does not describe withdrawals, incomplete outcome measurements, imputation, or how participants with missing observations were handled. It also does not specify the analysis population, such as whether all randomized participants were included in an analysis. The number completing each treatment period and the number contributing to each posted outcome are not reported separately. Although each outcome group is listed with 4 participants, that does not resolve how missing measurements or crossover completion were handled.

The analysis plan, including prespecified models, covariate adjustment, handling of repeated observations, and rules for exclusion, is not reported in the registry record. Without those details, readers cannot determine whether the descriptive result reflects a prespecified analysis or how robust it is to alternative reasonable methods.

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 non-serious adverse event terms

The registry reports serious adverse events for two groups. For High-Frequency Stimulation, 0 of 4 participants were at risk in the reported group denominator and 0 were affected by a serious adverse event. For Placebo Stimulation, 0 of 4 were at risk and 0 were affected by a serious adverse event. No deaths are reported in either group. The serious adverse-event terms list is empty.

The record also reports other adverse events in each group: 2 of 4 participants in the High-Frequency Stimulation group and 2 of 4 in the Placebo Stimulation group were affected. These are counts, not estimates of comparative risk, and no statistical comparison is posted. The registry does not give the nature, severity, timing, or outcome of the other events in the registry record for this record.

Zero reported serious events does not establish that serious events cannot occur. General statistical interpretation is especially cautious when the number of participants is small: an absence of observed events in a small group provides limited information about the range of possible event rates. The registry’s safety figures describe what was reported for this trial; they should not be treated as a comprehensive safety profile or as a comparison adjusted for the crossover design.

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

The posted primary outcome summaries show mean Visual Analog Pain Scale values of 2.29 units for High-density Stimulation and 6.31 units for Placebo Stimulation. The corresponding standard deviations are 0.41 and 1.22, and each group is listed with 4 participants. Because higher scores represent more pain, these figures describe lower average scores in the group labeled High-density Stimulation than in the group labeled Placebo Stimulation.

That descriptive pattern is not, by itself, a definitive estimate of a treatment effect. The registry does not post a confidence interval, p-value, or inferential analysis for the primary comparison. It also does not state how the crossover sequence was incorporated in the analysis. The reported summaries therefore do not quantify the precision of the comparison or establish whether the observed difference is distinguishable from chance variation.

The result should not be generalized beyond what the record supports. Enrollment was 4, and the reported outcome groups each contain 4 participants. Participant characteristics and analysis-population details are not reported in the registry record. The result cannot establish how similar findings would be in a larger or different group of people.

The terminology also limits conclusions about exactly which stimulation conditions the means represent. The study objective uses 1000 Hz, the arm descriptions use 1200 Hz, and the posted primary outcome groups are named High-density Stimulation and Placebo Stimulation. The intervention and sequence descriptions refer to high-frequency and sham stimulation. The record does not reconcile these labels, so the group names should be retained when describing the posted values rather than treating them as unambiguous confirmation of every stated objective.

The numbers do not establish the effects of the secondary outcomes, including the Brief Pain Inventory, SF-36, and Pain Vigilance and Awareness Questionnaire, because secondary results are not reported. Nor do the adverse-event counts establish a broader safety comparison. The registry supports a limited description of reported outcomes, not a conclusion about clinical benefit, lack of benefit, or the overall safety of either stimulation strategy.

14. Why This Trial Matters Statistically

This record illustrates why study design and reporting details matter alongside a numerical result. A randomized crossover design can compare conditions within participants, but the meaning of the comparison depends on treatment order, period effects, carryover, and the analysis of repeated observations. The registry describes randomization and a washout period, yet does not report how those features entered the analysis. The posted means therefore cannot be assumed to represent a paired or adjusted estimate.

It also shows the difference between a descriptive result and an inferential one. Means and standard deviations convey the observed average and spread, but the record does not provide an uncertainty interval or a formal test for the primary contrast. With enrollment of 4 and 4 participants listed in each outcome group, the limits of precision are central to interpretation. A visible difference between group means is not a substitute for assessing uncertainty.

Terminology consistency is another statistical issue. The objective refers to 1000 Hz, the arm descriptions specify 1200 Hz, and the posted groups use High-density and Placebo labels. The outcome description names additional stimulation phases. Without reconciliation, readers must take care not to infer that a particular reported comparison corresponds exactly to every intervention described in the objectives.

Finally, the registry lists multiple outcomes but posts no analyses. This makes it difficult to evaluate multiplicity, missing-data handling, or whether the results follow a prespecified analysis plan. These are not merely reporting details: they determine what the numerical summaries can support. The record is useful as a compact example of why small-sample estimates, crossover structure, outcome definitions, and transparent analysis reporting must be considered together.

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 sample is very small: enrollment is 4, and each posted primary outcome group is listed with 4 participants. This leaves little information for assessing variability across participants or the precision and generalizability of the observed summaries. The registry reports standard deviations but not confidence intervals or an inferential analysis.

The intervention descriptions are not fully consistent. The primary objective refers to 1000 Hz, while the arm descriptions specify 1200 Hz. The arms describe high-frequency and sham stimulation, but the reported outcome groups are labeled High-density Stimulation and Placebo Stimulation. The primary outcome description also names conventional baseline and washout phases. The registry does not explain how these terms and phases map to the posted groups.

Although the study is identified as a randomized, triple-masked crossover trial, the record does not report how masking was implemented, how allocation was generated, or how crossover observations were analyzed. The washout duration is described, but its justification and any evaluation of carryover are not reported in the registry record. Details on participant characteristics, withdrawals, missing measurements, and analysis populations are also not reported.

The registry lists secondary outcomes but provides no secondary analyses in the available record, and it does not report a multiplicity strategy or statistical analysis plan. Safety reporting gives counts but little detail about the other adverse events. Together, these limitations make the record suitable for cautious description of the posted summaries, but insufficient for a complete assessment of uncertainty, robustness, and the full set of stated objectives.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Direct Comparison of Spinal Cord Stimulator Parameter Settings — NCT05283863.
• Registry record last updated 2024-05-21; status last verified 2024-05.
• Results first posted 2024-05-21.
• 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

This completed randomized, triple-masked crossover trial is titled “Direct Comparison of Spinal Cord Stimulator Parameter Settings.” The registry lists enrollment of 4 and records a start of 2015-06 and primary completion of 2015-08. Its objectives concern subthreshold stimulation, sham stimulation, conventional stimulation, pain, and side effects.

The primary outcome is the Visual Analog Pain Scale at 8 weeks. The posted means are 2.29 units for High-density Stimulation and 6.31 units for Placebo Stimulation, with standard deviations of 0.41 and 1.22, respectively. Each group is listed with 4 participants. The registry posts 0 analyses and does not provide an inferential comparison or results for the listed secondary outcomes.

For serious adverse events, 0 of 4 participants are reported in each group, with 0 deaths. Other adverse events are reported for 2 of 4 participants in each group. Key details about missing data, analysis populations, and crossover analysis are not reported in the registry record. Intervention terminology and frequency descriptions also differ across the study objectives, arm descriptions, and outcome labels.