Comparison of Dorsal Column Stimulation to Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Comparison of Dorsal Column Stimulation to Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome (NCT03794024), a registered phase not stated study. The primary outcome is Change in Numerical Rating Scale for Pain Intensity.

2. Clinical Question

The clinical question is comparative: it concerns whether outcomes differ between two forms of neuromodulation in people with persistent complex regional pain syndrome. The registry also describes broader aims involving function, quality of life, satisfaction, and medication requirements. Those aims do not substitute for the primary endpoint, which is change in pain intensity.

The study was registered as a single-center, prospective comparative effectiveness study. Its title and description use randomized-study language, while the registry classification notes that allocation is not stated and that the arms are not a like-for-like control comparison. That distinction matters: a causal interpretation of a between-group contrast depends on how participants entered each treatment group and on whether the groups are comparable. The allocation details are not reported in the registry record, and the available primary-outcome information does not support a treatment comparison.

3. Trial Design

The registry describes a single-center, prospective comparison of dorsal column stimulation with dorsal root ganglion stimulation for complex regional pain syndrome. The two named devices are the Nuvectra Algovita Dorsal Column Spinal Cord Stimulator and the Axium Neurostimulator System. The record states that the intended population had symptoms persisting despite conservative management, including physical therapy and analgesic pharmacotherapy.

The study status is terminated. The record lists enrollment of 1 and gives no primary-outcome results: its primary endpoint description says no patients achieved the six-month endpoint. It therefore does not contain a completed comparison of six-month pain change between the two stimulation approaches. The reason for termination is not reported in the registry record.

The study title and official title describe a randomized prospective comparative effectiveness study. However, the registry classification states that this is not a randomized comparison and that allocation is not stated. The record does not describe how treatment assignment occurred, whether allocation was concealed, or what procedures were used to support comparable groups. Those design details are not reported in the registry record, so the randomized wording in the title cannot by itself establish that the observed groups arose from random assignment.

The primary outcome was change in Numerical Rating Scale pain intensity at 6 Months. A secondary outcome listed in the record is change in the Oswestry Disability Index for Pain Intensity. The record lists 8 outcome measures and 0 analyses. It does not give results for the additional outcome measures, analysis populations, or a statistical analysis plan. The planned methods for handling repeated measurements, missing data, or between-group differences are also not reported in the registry record.

The registry lists a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. These are described as planning assumptions, not as the trial's own design specifications. The record does not support interpreting such planning values as observed power or as evidence that a primary endpoint comparison was completed.

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: No patients achieved the 6 month endpoint

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 patients enrolled were randomized into the Dorsal Root Ganglion Stimulation arm.

6. Primary Endpoint

The registry lists the primary outcome as Change in Numerical Rating Scale for Pain Intensity, measured over 6 Months.

The primary endpoint is change in pain intensity measured with the Numerical Rating Scale at 6 Months. The scale is described as an 11-point scale from 0 to 10: zero indicates no pain and 10 indicates the worst possible pain imaginable. A change score represents movement in the recorded pain rating over the specified period, rather than pain intensity at a single isolated assessment.

In general, a patient-reported pain scale provides a standardized way to record a subjective symptom. Using the same scale across treatment groups and at planned assessment times can make outcomes easier to describe and compare. The scale does not eliminate measurement uncertainty, and a numerical score alone does not describe every aspect of pain, function, or quality of life. The registry's broader aims include those other domains, but the primary endpoint is specifically pain intensity.

The registry does not report a unit, summary parameter, or dispersion measure for the primary outcome. Most importantly, it states that no patients achieved the six-month endpoint. Consequently, no primary change estimate or between-group contrast is reported. Without endpoint observations, the scale's definition explains what the study intended to measure but cannot establish what the participants' pain ratings were or how the two approaches compared.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry gives a study description and some planning assumptions, but it does not report a completed primary-outcome analysis. That distinction is essential. A planned comparison describes the question investigators intended to answer; an analysis requires outcome observations, a defined contrast, and a method for quantifying uncertainty. The record states that no patients achieved the six-month endpoint, so it contains no primary endpoint comparison to interpret.

What does a non-inferiority question require?

In general, a non-inferiority study asks whether a treatment's outcome is not unacceptably worse than the comparator's outcome. This is different from testing whether two treatments are exactly equal. The study needs a prespecified non-inferiority margin, defining the largest clinically acceptable disadvantage, and an analysis that compares the estimated treatment difference with that margin. Interpretation also depends on the direction used for the contrast and on the endpoint's scoring. The registry states the non-inferiority hypothesis but does not report the margin, contrast definition, or analysis method. With no primary endpoint observations or contrast, the hypothesis cannot be assessed.

What do the planning assumptions describe?

The record describes a planning illustration using a two-sided significance level of 0.05, equal allocation, and a normal approximation, with planning based on fractions of the observed effect. These are assumptions for estimating sample size, not proof that the study attained a target precision or power. A planning calculation depends on the effect size and variability used as inputs; the registry does not report the underlying primary-outcome estimate or variability. The record says that time-to-event illustrations express total events and other illustrations express participants per arm. Those conventions describe how planning quantities are expressed, not what was observed in this terminated study.

In general, power is the probability that a specified analysis will reject a null hypothesis under a particular assumed effect and model. It is not a retrospective measure of whether a result is trustworthy, and it cannot replace an effect estimate with an uncertainty interval. A sample-size illustration is not observed power. Because no patients achieved the primary endpoint, a planning calculation cannot supply the missing clinical outcome information or establish whether a non-inferiority criterion was met.

Why do allocation and comparability matter?

Random allocation, when implemented and maintained appropriately, can help balance measured and unmeasured prognostic factors between treatment groups. In a nonrandomized comparison, differences in patient characteristics, treatment selection, or care can contribute to an apparent outcome contrast. The study titles use randomized language, but the registry classification says allocation is not stated and that the arms are not a like-for-like control comparison. The method of assignment, concealment procedures, and adjustment strategy are not reported in the registry record. Without those details and without endpoint results, neither a causal contrast nor a valid adjusted estimate can be reconstructed.

In general, an adjusted analysis may account for prespecified prognostic variables, but adjustment does not automatically remove bias. Its validity depends on variables measured, model form, data completeness, and the study design. The registry does not identify covariates or an adjustment plan. It would be inappropriate to presume that adjustment was performed or to construct an unreported analysis.

How should uncertainty be described?

A point estimate summarizes the observed contrast under a defined analysis. A confidence interval communicates the uncertainty around that estimate, conditional on the analysis assumptions. A p-value summarizes how unusual data would be under a specified null model; it does not measure the probability that a hypothesis is true and does not express clinical importance. When no primary estimate is available, none of these quantities can characterize the treatment comparison. The record reports 0 analyses, and no primary-outcome effect estimate, confidence interval, or p-value appears in the registry information.

Over-dispersion is a general concern when outcome variation exceeds what a statistical model assumes. If ignored, standard errors and intervals can be misleading. The registry does not report a fitted model or variance assessment, so there is no basis to say whether over-dispersion was relevant or addressed in this study. More broadly, model diagnostics and sensitivity analyses are not reported in the registry record. Explaining these methods does not imply that they were used.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 8 outcome measures and 0 analyses. It names change in Oswestry Disability Index for Pain Intensity as a secondary outcome, while the primary outcome is change in Numerical Rating Scale pain intensity at 6 Months. The registry does not provide outcome results for the secondary measure or the other listed measures. It also does not report which outcomes were analyzed, whether any were prespecified as confirmatory, or whether an adjustment for multiple comparisons was planned.

In general, multiplicity arises when many outcomes, time points, subgroup comparisons, or statistical tests are examined. Testing many hypotheses can increase the chance of finding a nominally unusual result even when there is no underlying effect. Methods such as hierarchical testing or adjusted significance thresholds can address some multiplicity concerns, but the appropriate approach depends on the prespecified analysis plan and the claims intended. No such plan is reported in the registry record, and no inferential outcome results are available to evaluate.

The record states that no patients achieved the primary six-month endpoint. It does not explain whether this reflects lack of follow-up, endpoint non-attainment, withdrawal, or another circumstance. Those possibilities should not be inferred from the wording. The timing and reasons for missing observations, rules for defining the analysis population, and any imputation or sensitivity analyses are not reported in the registry record.

Analysis populations are also not described. In general, an intention-to-treat population is defined by assigned treatment, while per-protocol analyses focus on participants meeting specified adherence criteria; the precise definitions depend on the study plan. These populations can be especially important in non-inferiority studies, but the registry does not state which population was intended or analyzed. No participant flow details or analysis-set counts beyond the listed enrollment and endpoint statement are available for evaluating these issues.

11. 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 registry's adverse-event information lists one participant at risk in the Dorsal Column Stimulation group and zero in the Dorsal Root Ganglion Stimulation group. It records zero serious adverse events, zero other adverse events, and zero deaths for the displayed group entries. No serious adverse event terms are listed. These are the posted counts; they should not be interpreted as a comparative safety estimate.

In general, an event count describes events recorded under the study's reporting definitions, while the number at risk describes the participants represented in that safety accounting. A zero recorded event count does not establish that a treatment has no risk. It can reflect limited observation, incomplete follow-up, or the fact that no event was recorded within the available study record. Here, the registry reports enrollment of 1 and says that no patients achieved the primary endpoint, but it does not explain the safety follow-up period or provide detailed exposure information.

The group entries do not support meaningful comparison: the listed at-risk counts differ, and the registry does not report the allocation process or a completed primary endpoint. The absence of reported events should therefore be read narrowly as absence of recorded events in the registry's adverse-event entries, not as evidence of equivalent safety or a guarantee of safety. The reasons for termination and the extent of safety surveillance are not reported in the registry record.

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

The record documents an intended comparison of dorsal column stimulation and dorsal root ganglion stimulation for complex regional pain syndrome. It identifies pain intensity at 6 Months as the primary outcome and describes a non-inferiority hypothesis. It also records that the study was terminated, enrollment was 1, and no patients achieved the primary endpoint. These registry entries describe an incomplete primary-outcome record rather than a comparative treatment result.

The posted information does not show whether either approach reduced pain, whether one approach produced a larger change, or whether the approaches met a non-inferiority criterion. There is no reported primary-outcome estimate, uncertainty interval, or inferential result. It would be incorrect to treat absence of an endpoint result as evidence that pain did not change, that the treatments were equivalent, or that either treatment was inferior.

The record also does not establish that the groups were comparable. Although the study title uses randomized language, the registry classification says allocation is not stated and that the arms are not a like-for-like control comparison. The assignment process and any adjustment for differences are not reported. Even if outcome observations were available, these design details would matter when interpreting an observed between-group contrast.

The planning assumptions do not alter these limitations. Planning illustrations are intended to describe sample-size requirements under stated assumptions; they are not observations, and they are not observed power. The record does not provide a primary effect estimate from which to judge the precision of a treatment comparison. Similarly, the adverse-event entries report no recorded events, but the limited and unequal at-risk entries cannot establish comparative safety.

In general, an incomplete or terminated study can still clarify what question was intended and what evidence is absent. In this case, the registry record identifies the treatments, population, endpoint, and broad study aim, but it does not answer the comparative clinical question. Any conclusion about effectiveness, non-inferiority, or differences in safety would go beyond the results reported.

13. Why This Trial Matters Statistically

This record is statistically important because it illustrates the difference between a stated study question and an estimable treatment effect. The registry describes a prospective comparison and a non-inferiority hypothesis, but it reports no patients achieving the primary endpoint. Without endpoint observations, the intended comparison cannot produce a primary estimate or an uncertainty interval. A hypothesis is not itself evidence that the question was answered.

The record also demonstrates why design labels need to be read alongside allocation details. A title can describe a study as randomized, while the registry classification indicates that allocation is not stated and that the arms are not a like-for-like comparison. In general, the credibility of a treatment contrast depends on how treatment groups were formed, the outcome data collected, and the analysis methods applied. The registry does not report enough information to assess those elements.

For non-inferiority questions, the statistical standard is particularly important. The margin, contrast definition, analysis populations, and uncertainty around the effect all contribute to whether non-inferiority can be supported. Those details are not reported in the registry record, and there is no primary result to evaluate against a margin. The stated hypothesis therefore remains an aim, not a finding.

The record's planning assumptions offer another useful distinction: sample-size planning is conditional on assumptions, whereas study results depend on observed data. Planning illustrations cannot substitute for an estimate or be described as observed power. Likewise, zero adverse-event counts in limited group entries are not evidence that risk is absent or equal. Careful interpretation keeps these different kinds of information separate and makes the missing evidence explicit.

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 principal limitation is the absence of a primary endpoint result. The registry states that no patients achieved the six-month endpoint, so it reports no pain-change estimate or comparison between the stimulation approaches. The reason that no patients achieved the endpoint is not reported in the registry record, and the wording does not establish why outcome data are unavailable.

The study status is terminated, but the reason for termination is not reported. Enrollment is listed as 1, and the record does not provide a participant flow account that explains treatment receipt, follow-up, or the endpoint status in greater detail. The allocation process is not stated, despite randomized language in the title, and the registry classification cautions that the arms are not a like-for-like control comparison. These limitations prevent assessment of group comparability and causal interpretation.

The registry does not report the non-inferiority margin, statistical analysis plan, analysis populations, missing-data procedures, or a multiplicity strategy. It lists 8 outcome measures and 0 analyses, but does not provide results for the secondary outcome or the other outcomes. No confidence intervals or primary-outcome p-values are available to describe precision or statistical uncertainty.

Safety information is also limited. The adverse-event entries list unequal numbers at risk across the displayed groups, zero recorded serious and other adverse events, and zero deaths. The registry does not report the safety follow-up period or detailed exposure information. These entries cannot support a robust comparison of harms. The record's limitations should not be filled by assumptions about protocol conduct, reasons for missing data, or analyses that are not described.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Comparison of Dorsal Column Stimulation to Dorsal Root Ganglion Stimulation for Complex Regional Pain Syndrome — NCT03794024.
• Registry record last updated 2023-02-27; status last verified 2023-02.
• Results first posted 2020-06-24.
• 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.

18. Record Summary

The registry describes a single-center prospective comparison of dorsal column stimulation with dorsal root ganglion stimulation for complex regional pain syndrome. The primary outcome is change in Numerical Rating Scale pain intensity at 6 Months, and the study description states a non-inferiority hypothesis. The record lists enrollment of 1 and status as terminated, and says no patients achieved the six-month endpoint.

No primary outcome estimate, between-group contrast, or analysis result is reported. The registry lists 8 outcome measures and 0 analyses. It does not report the allocation method, non-inferiority margin, reason for termination, analysis populations, or missing-data plan. Adverse-event entries show zero recorded serious and other events and zero deaths, but the displayed at-risk counts are limited and unequal.

The record therefore documents the intended question but does not establish comparative effectiveness, non-inferiority, or comparative safety.