This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for An Implantable Spinal Cord Stimulation Pain Management System (NCT00205855), a na phase 3 study. The primary outcome is Change in Visual Analog Scale (VAS) Score From Baseline to 2 Week Post Initial Fitting..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00205855 |
| Phase | Phase 3 |
| Condition | Chronic Pain, Pain, Intractable, Pain |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 65 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Boston Scientific Corporation |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists chronic pain, intractable pain, back pain, and failed back surgery syndrome among the conditions studied. The specific eligibility criteria and a fuller description of the enrolled population are not reported in the registry record.
Intervention
Participants received the Precision spinal cord stimulation system, described in the record as the Precision SCS Stimulus system.
Comparator
No separate comparator group is listed. The study is recorded as a single-group study, with allocation listed as not applicable.
Primary question
At two weeks after initial fitting, how many participants had more than 50% improvement in their Visual Analog Scale pain score compared with baseline?
This question is narrower than whether pain changed on average. The registry identifies the primary outcome as the number of participants whose VAS score improved by more than 50%. The underlying VAS asks participants to rate their average pain over the past 7 days, on a scale from 0 for no pain to 10 for worst pain imaginable. The record says the score was captured at baseline and again two weeks after initial fitting.
The study is not a randomized comparison of stimulation against another treatment or against no treatment. It therefore describes an outcome in the group receiving the device, rather than an estimated difference between treatment groups. The registry does not report the number meeting the primary outcome threshold, the group’s baseline or follow-up VAS values, or an estimate of change. The primary result is not reported in the registry record.
The question also does not, on its own, describe how long any observed improvement lasted. The listed endpoint is assessed at the stated two-week time point. Later outcomes, eligibility details, and other features needed to define the intended clinical population are not reported in the registry record.
3. Trial Design
The registry classifies this as a phase 3, completed, single-group study of the Precision SCS device. Enrollment is listed as 65. The study start is recorded as 2003-02 and primary completion as 2003-10. Boston Scientific Corporation is listed as the sponsor.
Allocation is listed as not applicable, and the study model is single group. Masking is listed as none. These design features mean the record does not describe random assignment to different treatment groups, a blinded comparison, or a separate control arm. The record describes participants receiving the Precision spinal cord stimulation system.
A single-group design can record outcomes among people who receive an intervention, but it does not provide a concurrent group for estimating what would have happened over the same period without that intervention or under an alternative intervention. Changes observed from baseline can reflect multiple influences, including the passage of time and other care or circumstances. Without a comparison group, the registry outcome cannot distinguish those influences from any contribution of the device.
The primary completion date marks the registry’s stated primary-completion timing; it does not establish that the primary result was posted. In this record the primary outcome is described, but its result is not reported. The record also lists no analysis entries. Details of the protocol, eligibility criteria, follow-up beyond the primary time point, and the statistical analysis plan are not reported in the registry record.
The registry names several pain-related conditions, including chronic pain, intractable pain, back pain, and failed back surgery syndrome. Those condition labels do not establish that every enrolled participant had each condition, nor do they provide a detailed account of the enrolled group. Such population details are not reported in the registry record. Accordingly, interpretation should remain tied to the single-group design and the limited outcome information 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.
Overall Study
| Stage | Spinal Cord Stimulation (SCS) Group |
|---|---|
| STARTED | 65 |
| COMPLETED | 44 |
| NOT COMPLETED | 21 |
Reasons for not completing this period:
| Reason | Spinal Cord Stimulation (SCS) Group |
|---|---|
| Only received temporary implants | 16 |
| Withdrawal by Subject | 5 |
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.
| Characteristic | Unit | Spinal Cord Stimulation (SCS) Group |
|---|---|---|
| Participants analysed | 65 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 54 |
| Age, Categorical: >=65 years | Participants | 11 |
| Age Continuous | years | 52 (SD 14) |
| Sex: Female, Male: Female | Participants | 26 |
| Sex: Female, Male: Male | Participants | 39 |
| Region of Enrollment: United States | participants | 65 |
6. Primary Endpoint
The registry lists the primary outcome as Change in Visual Analog Scale (VAS) Score From Baseline to 2 Week Post Initial Fitting., measured over 2 weeks post initial fitting.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants with > 50% VAS improvement |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint concerns change in a patient-rated Visual Analog Scale score from baseline to two weeks after initial fitting. Participants rated average pain over the past 7 days on a scale from 0, meaning no pain, to 10, meaning worst pain imaginable. The registry describes the measurement as the percent difference between the follow-up VAS score and the baseline score. It identifies the endpoint unit as participants with more than 50% VAS improvement.
This threshold-based endpoint expresses the outcome as a count of participants meeting a stated level of improvement, rather than as a group average VAS change. Such responder outcomes can be easier to interpret as the frequency of people reaching a defined change threshold. However, the registry record does not explain how the threshold was selected or provide details about handling baseline scores, missing measurements, or the exact calculation used to determine improvement. Those details are not reported in the registry record.
The endpoint is limited to the specified assessment at two weeks post initial fitting. It does not, by itself, establish the pattern of pain scores across the intervening period or the duration of any improvement. The record gives no primary endpoint count or estimate. Thus, the stated measure and its intended assessment time can be described, but the observed primary outcome cannot be characterized from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive point is that the registry states a primary outcome but does not report its result. It specifies a count of participants with more than 50% VAS improvement at two weeks after initial fitting, yet gives no count, percentage, estimate of change, confidence interval, or test result for that endpoint. The number of participants meeting the primary threshold is therefore not reported in the registry record. No conclusion about the observed primary outcome can be drawn from this entry.
The study is described as single group, with allocation not applicable and no masking. There is no separate comparator in the registry record. Even if a before-and-after score had been reported, a change within one group would not, on its own, establish that the device caused the change. Without a concurrent comparison, other influences on scores cannot be separated from changes associated with the study period or intervention. This is a design limitation, not a reason to assume that the group did or did not improve.
The endpoint itself is a threshold outcome: participants count as meeting it if their VAS improvement exceeds the stated threshold. A threshold can communicate how many crossed a chosen level, but it does not show the full distribution of score changes. Participants just above and well above the threshold would both be counted as meeting it, while those just below it would not. The registry does not report the individual or group score data needed to examine that distribution.
Precision is also impossible to evaluate for the primary endpoint from this record. A confidence interval would ordinarily communicate the range of estimates compatible with the observed data under a specified statistical method. No primary endpoint estimate or interval is reported. A p-value would address a statistical comparison under a specified analysis, but no primary test result or analysis is listed. Neither statistical significance nor the magnitude and uncertainty of the primary result can be assessed.
Enrollment is listed as 65, but the record does not say how many participants contributed data to the primary endpoint. Enrollment alone does not establish how complete follow-up was or what analysis population was used. The registry does not report missing primary measurements, exclusions from the analysis, or reasons for any loss of outcome data. These gaps limit interpretation of both the outcome and its precision.
The safety information is separate from the primary pain outcome. The registry lists 12 participants affected by serious adverse events among 65 at risk and 20 affected by other adverse events among 65 at risk. It also lists serious adverse-event terms and percentages. These figures describe recorded adverse events in the study group; they are not a comparison against another group, and they do not substitute for the unreported primary outcome. The record does not report deaths.
Overall, this registry entry allows a description of the study design, planned primary measure, its time point, and some safety counts. It does not provide the primary result or inferential statistics. The appropriate interpretation is therefore limited: the outcome was defined, but its observed value and uncertainty are not reported in the registry record. The single-group design would also restrict causal interpretation even if a within-group result were available.
9. Statistical Methods Explained
The registry record gives limited information about statistical methods. It describes a single-group study and one primary outcome measure, but lists no analysis entries. The statistical analysis plan, the method used to summarize the primary endpoint, and any inferential procedure are not reported in the registry record. The concepts below are general statistical context, not a description of methods confirmed for this study.
What does a single-group design estimate?
In a single-group study, an outcome can be described among participants who receive the intervention. If measurements are taken at baseline and follow-up, the change between those measurements can also be described. But a before-and-after change is not the same as a treatment effect estimated against a concurrent comparator. Changes over time may have more than one explanation. A comparison group can help estimate how outcomes differ under alternative conditions, provided the design and analysis support that comparison. This registry record does not list such a group.
Because allocation is listed as not applicable and the model as single group, a between-group treatment contrast is not available in the recorded design. No masking is listed. Masking is a design feature that can reduce some influences on measurement or behavior, depending on the study and outcome. The record does not describe masking procedures beyond listing masking as none. No further details about outcome assessment procedures are reported.
What does the threshold endpoint capture?
The primary endpoint is framed as a count of participants with more than 50% VAS improvement. A threshold-based endpoint classifies each participant according to whether their measured change crosses the defined cutoff. The count can then be interpreted as the number meeting that criterion, if the count and the analyzed population are reported. Here, neither the primary count nor the analysis population is stated.
As a general statistical matter, converting a continuous score into a threshold outcome discards information about how far each participant’s change lies from the threshold. A responder count does not describe the full range or distribution of changes. It also depends on the threshold definition and the calculation used to classify participants. The registry gives the threshold and describes a percent difference from baseline, but does not report the detailed calculation procedure or individual score data. It is therefore not possible to reconstruct or verify the primary endpoint from this record.
Why do estimates need uncertainty measures?
General statistical interpretation considers both an estimate and its uncertainty. A confidence interval is one way to express uncertainty around an estimate, conditional on the method and assumptions used. An interval can help readers distinguish a relatively precise estimate from one compatible with a wider range of values. It does not remedy design limitations, and it does not by itself establish a causal effect. The registry record contains no primary endpoint estimate or confidence interval, so the precision of the primary result cannot be assessed.
A hypothesis test and p-value, when used, answer a question defined by a null hypothesis and analysis model. They do not measure the size or clinical importance of an effect. Their interpretation depends on the chosen endpoint, analysis population, and statistical assumptions. The registry record does not report a primary p-value, null hypothesis, or testing procedure. No statistical significance claim can be evaluated from the posted information.
What is over-dispersion, and does it apply?
General statistical context: count outcomes can vary more than a simple model assumes. Over-dispersion refers to variability in count data that exceeds the model’s assumed level. If present and ignored, uncertainty estimates from a model may be too small. Whether over-dispersion is relevant depends on the outcome and analysis model. The registry does not report a model for the primary endpoint, and there are no analysis entries from which to determine whether this issue was assessed. It would not be appropriate to claim that over-dispersion occurred or that a particular correction was used.
The primary measure is described as a number of participants crossing a threshold, rather than a count of recurrent events per participant. The record does not state that a count regression model was used. General discussion of count models therefore cannot be taken as the method used in this study. The model, if any, is not reported in the registry record.
How should the planning assumptions be read?
The record includes general assumptions for sample-size planning illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and effects defined as stated fractions of an observed effect. These are planning assumptions, not evidence that the study itself used a two-arm design. The actual study is listed as single group. The planning description also says that time-to-event illustrations use a total number of events, while other illustrations use participants per arm.
Planning calculations explore how a hypothetical future study might be sized under stated assumptions. They are not observed results and are not observed power for the completed study. The registry does not report a primary endpoint effect estimate from which to judge the basis for these assumptions. A sample-size justification for the trial, the assumptions used in its original design, and any interim analyses are not reported in the registry record. The illustration assumptions should therefore be kept separate from the study’s actual design and from its unreported primary result.
In general, a planning calculation depends on the target effect, the selected significance level, allocation, statistical model, and desired power. Changing those assumptions changes the calculated sample size. A planning illustration cannot establish that a completed study was adequately powered, particularly when its primary outcome result and analysis details are unavailable. No numerical sample-size conclusion for this trial can be drawn from the information recorded.
What analysis details are absent?
The registry does not specify the analysis population, handling of missing data, adjustment for baseline values, covariates, confidence-interval method, or multiplicity procedure. It also does not report whether any analysis was adjusted or unadjusted. These omissions prevent a detailed appraisal of how the primary endpoint would have been calculated and tested. They should be treated as unreported information, rather than filled in by assuming common methods.
In short, the record supports a description of the outcome definition and study design, but not a reconstruction of the statistical analysis. Statistical concepts can clarify what kinds of information would normally aid interpretation; they cannot supply the missing result or establish which method the investigators used.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists one primary outcome measure, but lists no analysis entries. That does not establish how many statistical tests were conducted, whether secondary outcomes were analyzed, or whether any multiplicity adjustment was planned. A multiplicity strategy is not reported in the registry record. It would be inappropriate to infer that no multiplicity issue arose solely from the listing of one primary measure.
Missing-data handling is also not reported. The registry does not state how many participants had a VAS measurement at baseline or at two weeks, whether anyone lacked a follow-up measurement, or how missing values were treated. It does not report imputation, complete-case analysis, or another approach. The listed enrollment of 65 cannot be assumed to equal the primary endpoint analysis population.
The analysis population is not described. The record does not say whether all enrolled participants, only participants who received a particular procedure, or another group contributed to the primary outcome. The population definition and any exclusions are not reported in the registry record.
These omissions matter because the reported endpoint is a threshold count. The number classified as meeting the threshold depends on the outcome measurements available and the rules used to classify them. Without the denominator, missing-data approach, and analysis population, the primary outcome count and its interpretation cannot be checked. The primary result itself is not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Spinal Cord Stimulation (SCS) Group | 12 | 65 | 18.5% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Spinal Cord Stimulation (SCS) Group | 20 of 65 |
Most frequent serious adverse event terms
| Event term | Organ system | Spinal Cord Stimulation (SCS) Group |
|---|---|---|
| Lead Migration | Surgical and medical procedures | 5 of 65 |
| New Lead Placement | Surgical and medical procedures | 2 of 65 |
| Infection | Infections and infestations | 2 of 65 |
| Loss of Therapy | Surgical and medical procedures | 1 of 65 |
| Implantable Pulse Generator Movement | Surgical and medical procedures | 1 of 65 |
| Pain | Surgical and medical procedures | 1 of 65 |
| Device Malfunction | Surgical and medical procedures | 1 of 65 |
| Death | Musculoskeletal and connective tissue disorders | 1 of 65 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Spinal Cord Stimulation (SCS) Group |
|---|---|---|
| Device Malfunction | Injury, poisoning and procedural complications | 8 of 65 |
| Lead Migration | Surgical and medical procedures | 4 of 65 |
| Over and Under stimulation during SCS Trial | Injury, poisoning and procedural complications | 4 of 65 |
| CSF leak | Injury, poisoning and procedural complications | 3 of 65 |
| Unpleasant Stimulation | Injury, poisoning and procedural complications | 2 of 65 |
| Abstinence syndrome | Nervous system disorders | 1 of 65 |
| Infection | Infections and infestations | 1 of 65 |
| Grand-Mal Seizure | Nervous system disorders | 1 of 65 |
| Nausea & Vomiting | Gastrointestinal disorders | 1 of 65 |
| Reduced Telemetry Range | Injury, poisoning and procedural complications | 1 of 65 |
Serious events with the highest arm-level rate: lead migration (7.7%), new lead placement (3.1%), infection (3.1%), loss of therapy (1.5%), implantable pulse generator movement (1.5%).
The registry lists 12 participants affected by serious adverse events among 65 at risk, and 20 participants affected by other adverse events among 65 at risk. These are separate categories in the safety record. No calculation or comparison between them is needed to read the posted counts. The record does not report deaths.
The serious adverse-event terms listed are Lead Migration at 7.7%, New Lead Placement at 3.1%, Infection at 3.1%, Loss of Therapy at 1.5%, Implantable Pulse Generator Movement at 1.5%, and Pain at 1.5%. These percentages describe the listed terms in the registry entry; the record does not provide further event-level detail, timing, severity grading, or a comparison group for these terms. The percentages should not be treated as a comparative estimate of risk.
Safety counts from a single-group study describe events recorded among participants in that group. They do not establish how the event frequency would compare under another treatment or in the absence of the device. The registry record also does not explain how adverse events were collected or adjudicated, or whether all events were included in the displayed terms. Further safety-analysis methods are not reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed phase 3, single-group study evaluated the Precision SCS system and defined a primary outcome based on VAS improvement at two weeks after initial fitting. It also reports enrollment and selected safety information. Those details allow readers to understand the general design and the intended primary measurement.
The record does not report the observed primary outcome. It gives no number of participants with more than 50% VAS improvement and no VAS change estimate, confidence interval, or test result. As a result, the posted information cannot show the size or precision of the primary outcome. The absence of a reported result is not evidence that the endpoint was or was not met; it means the result is not reported in the registry record.
The design also limits what a within-group result could establish. With no separate comparator group, the study does not provide a randomized contrast against another treatment or a control condition. Any baseline-to-follow-up change, if it were reported, would describe change in the study group but would not isolate the effect attributable to the device from other possible influences. The record does not support a causal estimate against an alternative.
The endpoint is a threshold measure at a specified time point, not a complete account of pain trajectories, longer-term outcomes, or participant experience. The registry does not report the underlying score distribution or later pain outcomes. The safety counts likewise describe the recorded study group and are not comparative estimates.
Accordingly, the registry record is useful for identifying the study’s design, intended primary endpoint, and listed adverse-event information, while leaving the primary efficacy result and key analysis details unavailable. It should not be read as evidence for or against a treatment effect. The unreported outcome, lack of a comparator, and missing analysis details constrain the conclusions that can be drawn from this record.
13. Why This Trial Matters Statistically
This study illustrates why an outcome definition and an outcome result are not interchangeable. The registry describes a specific primary measure: the number of participants with more than 50% VAS improvement at two weeks after initial fitting. But without the observed count, denominator, or uncertainty estimate, readers cannot assess how often the stated endpoint was met or how precisely it was estimated.
It also demonstrates the interpretive limits of a single-group design. Baseline and follow-up measurements can describe change within a group, but a treatment comparison requires an appropriate contrast. Allocation is listed as not applicable, the model is single group, and no separate comparator is recorded. The study therefore cannot supply a randomized between-group estimate from the design described in the registry.
The threshold endpoint highlights a further statistical distinction. A responder count can be accessible to readers, but it compresses continuous score changes into whether each participant crossed a cutoff. Without score distributions or additional outcomes, it does not describe the range of changes or how participants near the threshold compare with those farther from it. The registry does not explain the cutoff’s rationale or provide the data needed to examine that information.
Finally, the record shows why statistical planning assumptions must be kept distinct from observed evidence. Planning illustrations use stated assumptions about significance level, allocation, approximation, and fractions of an observed effect; those assumptions do not report the study’s primary result or establish observed power. In this case, the primary result and detailed analysis plan are not reported in the registry record. Statistical interpretation depends not just on a study label or endpoint definition, but on the actual estimate, its uncertainty, and the design that produced it.
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.
Several limitations specific to this registry entry restrict interpretation. It records a single-group design, with allocation listed as not applicable and masking as none. No separate comparator is described, so the record does not support a randomized treatment contrast. The design can describe outcomes in the receiving group, but cannot by itself separate intervention-associated change from other influences over time.
The primary outcome result is not reported in the registry record. There is no responder count, denominator for the primary endpoint, VAS summary, confidence interval, or test result. The record describes the measure and its timing but does not provide the data needed to evaluate its observed magnitude or precision.
The population description is also limited. The registry lists several pain-related conditions, but specific inclusion and exclusion criteria, participant characteristics, and the distribution of diagnoses are not reported. The enrollment entry is 65, but the number contributing primary outcome data and the analysis population are not given.
Further limitations arise from absent analysis details. The registry does not report how missing outcome values were handled, how the percent improvement was calculated, whether analyses were adjusted, or what statistical procedures were used. It lists no analysis entries. The protocol, sample-size justification for the completed study, interim analyses, and multiplicity strategy are not reported in the registry record.
Follow-up information is limited to the primary endpoint’s stated assessment at two weeks post initial fitting. Later outcomes and the duration of any observed change are not reported. Safety information includes counts and selected serious adverse-event terms, but details about collection, adjudication, timing, and comparative risks are not reported. These limitations are specific to the information recorded and should not be replaced by assumptions about the trial’s conduct.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: An Implantable Spinal Cord Stimulation Pain Management System — NCT00205855.
- Registry record last updated 2012-10-26; status last verified 2012-09.
- Results first posted 2012-10-26.
- 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.
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18. Record Summary
The registry describes a completed phase 3, single-group study of the Precision SCS Stimulus system, with enrollment listed as 65. The study start is recorded as 2003-02 and primary completion as 2003-10. Allocation is not applicable, and masking is listed as none.
The primary outcome is the number of participants with more than 50% improvement in a patient-rated VAS score from baseline to two weeks after initial fitting. The registry does not report the primary outcome result or analysis entries. The record also lists 12 participants affected by serious adverse events and 20 affected by other adverse events, each among 65 at risk, as well as selected serious adverse-event terms and percentages.
No separate comparator, primary outcome estimate, confidence interval, or inferential result is reported in the registry record. Population details, analysis population, missing-data methods, and statistical analysis procedures are also not reported.