Spinal Cord Stimulation to Restore Cough: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Spinal Cord Stimulation to Restore Cough (NCT00116337), a na na study. The primary outcome is Effectiveness of Expiratory Muscle Activation to Generate Large Airway Pressures Characteristic of Normal Cough..

2. Clinical Question

3. Trial Design

The registry record describes a completed, single-group study titled “Spinal Cord Stimulation to Restore Cough.” Its stated purpose is to determine the efficacy of spinal cord stimulation to produce an effective cough in patients with spinal cord injuries. The recorded enrollment is 17. The study start is listed as 2004-09-30 and primary completion as 2017-10-10. The sponsor is MetroHealth Medical Center. The phase and allocation are each listed as NA, and masking is listed as none.

The intervention listings include “Spinal Cord Stimulation to restore cough” as a procedure and “Expiratory Muscle Stimulator” as a device. The arm description for the Expiratory Muscle Stimulator identifies the procedure as spinal cord stimulation to restore cough. The record does not give enough detail to determine how these labels map onto particular device components, treatment steps, or exposure schedules. Such details are not reported in the registry record.

The primary outcome is a repeated measurement in the same single-group study population: airway pressure generation before implantation and at one year after implantation. This design can describe change over time within the participants assessed, but it does not include a separate group to represent what would have happened without the intervention. The record does not describe random assignment, and it does not provide an allocation scheme for a treatment comparison. The absence of masking is recorded; further details about who knew treatment status or how outcome measurements were obtained are not reported in the registry record.

The registry lists Incident of Acute Respiratory Tract Infections and Trained Caregiver Support for Secretion Clearance as secondary outcomes. It reports four outcome measures and two analyses, but the detailed analysis methods and results are not reported in the registry record. The study status is completed. That status indicates the registry listing is completed; it does not itself convey whether the primary outcome met a particular threshold or how precisely it was estimated.

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: Male - 14; Female - 3

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 Effectiveness of Expiratory Muscle Activation to Generate Large Airway Pressures Characteristic of Normal Cough., measured over baseline (pre-implant) and 1 year follow up (post-implant).

The primary endpoint is the effectiveness of expiratory muscle activation to generate large airway pressures characteristic of normal cough. The registry describes airway pressure generation achieved with the spinal cord stimulation cough system at baseline before implantation and at one year after implantation. The measurement unit is cmH2O. The endpoint is specified as a mean of a continuous measure, and its dispersion is described using the standard error.

Airway pressure is a physiological measure related to the force generated during expiration. In this study, it is used to assess whether stimulation produces pressure generation resembling the characteristic pressures of a normal cough. That makes it relevant to the stated aim of producing an effective cough, but the endpoint is not itself a direct measure of airway infection, secretion-clearance assistance, or another patient-centered outcome. The registry lists acute respiratory tract infections and trained caregiver support for secretion clearance separately as secondary outcomes.

The registry record does not report the baseline mean, the one-year mean, their standard errors, a change estimate, or a confidence interval. It also does not state a threshold for what would count as a clinically meaningful pressure change. Without those details, the endpoint definition can be described, but the magnitude and precision of the observed result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is continuous: it records airway pressure in cmH2O, and the registry specifies the mean as its summary parameter. Continuous outcomes can take a range of numerical values rather than being limited to categories. A mean provides a summary of the measurement level in a group, while the standard error describes uncertainty in the estimated mean. General explanation: the standard error is not a description of how far apart individual participants’ measurements are; that kind of variability is commonly described by a standard deviation. The registry record does not report a standard deviation or the individual measurements.

The time points are baseline before implantation and one year after implantation. Because the study is listed as single group, the natural conceptual contrast is a within-group change across time. For paired observations, each participant’s measurements at the two times are linked; an analysis can use that pairing to estimate the average change. The registry record does not state whether the analysis used paired observations, how participants with only one measurement were treated, or what model or test was used. It is therefore not possible to describe the actual calculation from the outcome definition alone.

A confidence interval is a statistical range intended to convey uncertainty around an estimated quantity. General explanation: a narrower interval indicates greater precision under the method used, while a wider interval indicates greater uncertainty. A confidence interval for a change would help readers assess which magnitudes of change are compatible with the data and analysis. No confidence interval for the primary outcome is reported in the registry record, so its precision cannot be assessed this way. A p value, if reported, would address compatibility with a specified null hypothesis under an analysis model; it would not by itself show the size or practical importance of a change. The registry record does not report a p value for the primary outcome.

The record identifies the standard error as the dispersion measure for the primary mean. That choice is useful for communicating uncertainty in an estimated mean, but does not show the range of participant-level values. General explanation: a result can have a relatively precise mean while individual observations remain variable. To understand both the estimated average and participant-to-participant spread, readers would need the relevant summaries or the underlying data. Those additional summaries are not reported in the registry record.

There is no like-for-like control comparison. The study’s single-group, unmasked design means a pre-to-post contrast is not the same as a randomized treatment effect. General explanation: a control group can help distinguish an intervention-related change from other changes that occur over time, while randomization can reduce systematic differences between groups. Neither a separate comparator nor random allocation is described in this record. The results, if available, would therefore need to be interpreted as within-group observations rather than as a randomized comparison.

The sample-size assumptions describe planning illustrations based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They state that the effect to detect is a specified fraction of the observed effect. These are assumptions for hypothetical planning, not a description of the trial’s actual single-group design. Sample-size illustrations are not observed power and do not establish that the completed study had adequate power. The registry record does not report the trial’s own sample-size justification or design calculations. It also does not give the numerical observed effect or numerical planning outputs needed to assess those illustrations.

General explanation: over-dispersion occurs when observed variability is greater than a model assumes. If it is present, a model that understates variability may produce uncertainty estimates that are too small. The registry record does not report a count model or an over-dispersion assessment for the continuous primary outcome, so this concept should not be mistaken for a reported feature of this analysis. The endpoint is described as a mean of airway pressure, not as a count outcome.

The record reports four outcome measures and two analyses. It does not provide enough detail to identify which model, test, covariance assumptions, or estimation method was used for each analysis. It also does not report whether the primary outcome analysis was prespecified in a statistical analysis plan, whether assumptions were checked, or whether any sensitivity analyses were performed. Those methods are not reported in the registry record. Without them, a reader cannot reproduce the analysis or determine whether the reported standard error accounts for the repeated measurements and any incomplete follow-up.

For a study with a baseline and follow-up measurement, missingness can affect the estimated change if participants without follow-up differ from those with follow-up. General explanation: complete-case analyses use participants with the required measurements, while other methods may make different assumptions about unobserved values. The registry record does not state the analysis population, the number of participants assessed at each time, or the method used for missing data. It is not appropriate to assume that all 17 enrolled participants contributed paired data.

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("Pre-Implant - Spontaneous Effort", "Post-Implantation - Spinal Cord Stimulation (SCS)")
n   <- c(17, 17)
m   <- c(25, 121)
sp  <- c(3, 14)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
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  Pre-Implant - Spontaneous Effort  17  25.000  12.369  18.640  31.360
CARM  Post-Implantation - Spinal Cord Stimulation (SCS)  17  121.000  57.723  91.321  150.679

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists four outcome measures and two analyses. It names Incident of Acute Respiratory Tract Infections and Trained Caregiver Support for Secretion Clearance as secondary outcomes, in addition to the primary airway-pressure outcome. The detailed definitions and results for the other listed measures are not reported in the registry record.

When a study examines multiple outcomes or performs multiple analyses, the chance of at least one apparently notable result can be affected by how many comparisons are made. General explanation: multiplicity procedures can control or otherwise address that issue, but their appropriateness depends on the analysis plan and the questions being tested. The registry record does not report a multiplicity adjustment, a hierarchy among outcomes, or a prespecified strategy for interpreting multiple tests. It also does not say which two analyses were conducted or whether they involved the same outcome.

Missing-data methods and analysis populations are also not reported in the registry record. The enrollment is 17, but the numbers assessed at baseline and at one year, and the numbers included in each analysis, are not given. There is no stated approach to missing measurements, withdrawals, or incomplete follow-up. As a result, the extent to which missingness might influence the primary outcome cannot be assessed from the record.

The record does not describe an intention-to-treat or per-protocol population, nor does it state whether any participants were excluded from an analysis. These omissions do not establish that a particular method was or was not used; they mean that the relevant information is not reported in the registry record. The available outcome definitions alone are insufficient to evaluate multiplicity control, missing-data handling, or the composition of the analysis population.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: infection (5.9%).

The registry lists a post-implantation group for spinal cord stimulation. For serious adverse events, it reports 17 at risk and 1 affected. For other adverse events, it reports 17 at risk and 3 affected. The reported number of deaths is 0. The top listed serious adverse event term is Infection, with 5.9% shown.

These are safety counts in the registry record; they do not describe the timing, duration, severity beyond the serious-event classification, relatedness to the procedure, or individual clinical details. The record does not provide event narratives or explain how events were adjudicated. The Infection percentage is presented as a serious-event term, but the record does not provide additional context for interpreting it.

The at-risk counts indicate the group size used for these safety listings, while the affected counts indicate the reported number affected. These figures should not be treated as evidence that all possible events were captured or that the study can precisely characterize uncommon harms. The registry record does not state the monitoring procedures or give a comparison group. Safety interpretation is therefore limited to the adverse-event figures as listed, without a comparative estimate or further clinical detail.

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

The registry record identifies a clinically motivated physiological question: whether spinal cord stimulation can generate airway pressures characteristic of normal cough. It specifies a continuous primary outcome, a measurement unit, a dispersion measure, and assessments before implantation and at one year after implantation. These details clarify what the study aimed to measure and when, but do not reveal the observed values.

The primary outcome results are not reported in the registry record. Without the baseline and follow-up means, an estimate of change, and an uncertainty measure, the direction, magnitude, and precision of any change cannot be determined from this record. The outcome definition is not a result, and the completed status does not show whether a particular outcome was achieved.

Even if a within-group pressure change were available, the single-group design would not provide a randomized comparison against a separate control group. A change over time could be described, but the design would not by itself establish that the intervention caused that change. The registry record does not report an analysis addressing alternative explanations for a pre-to-post difference.

Airway pressure generation is the primary physiological measure; it does not directly report the incidence of acute respiratory tract infections or the extent of trained caregiver support for secretion clearance. Those are listed as secondary outcomes, but their results are not reported in the registry record. The available information therefore cannot establish how the primary pressure measure relates to those outcomes.

The appropriate interpretation is narrow: the registry describes a single-group study with a baseline-to-one-year airway-pressure endpoint and lists safety counts, but does not report the primary outcome values or the detailed analysis. Conclusions about the size or precision of the primary result, the secondary outcomes, or comparative effects are not supported by the information reported in the registry record.

14. Why This Trial Matters Statistically

This study raises a statistical question that is common in clinical research: how to interpret a physiological measurement collected before and after an intervention when there is no separate control group. The primary outcome is continuous and repeated over time, so the analysis needs to account for the relationship between measurements from the same participants. The registry record identifies the time points and summary measure, but does not report enough analysis detail to determine how that relationship was handled.

The design also illustrates the distinction between describing a change and attributing a change. A single-group comparison can describe what was observed across assessments, while a concurrent control group can help distinguish intervention-associated change from other influences. This study is listed as single group, with allocation NA and masking none. Those features place limits on causal interpretation that should be kept separate from the definition of the physiological endpoint.

The record also makes clear why results need more than an endpoint name. To judge a continuous outcome, readers need the observed estimates and a measure of uncertainty, along with information on who contributed data and how incomplete observations were treated. The registry record identifies the mean and standard error but does not report their values for the primary outcome. Thus the estimand is identifiable in broad terms, but its observed size and precision cannot be assessed.

Finally, the listed secondary outcomes show that the study included questions beyond pressure generation, but their results and analysis details are not reported in the registry record. That limits assessment of how the physiological measure relates to the broader outcomes named in the study. Statistically, the record is useful for identifying the study structure and endpoint, while also demonstrating the importance of complete outcome reporting and transparent analysis methods.

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 specific to this study follow from the registry information. The design is single group, with no separate comparator described. The baseline and one-year measurements can support a within-group description, but the record does not describe a concurrent control comparison that could help distinguish intervention-related change from other changes over time. Allocation is listed as NA and masking as none.

The central limitation for interpreting the primary endpoint is that its numerical results are not reported in the registry record. Although the measure, unit, time points, and dispersion type are specified, the means, standard errors, and any change estimate are absent. The record also does not report a confidence interval or p value for that outcome. The observed magnitude and precision therefore cannot be evaluated.

The recorded enrollment is 17, and the primary outcome population is described as Male - 14; Female - 3. The number with measurements at each time point and the analysis population are not reported in the registry record. Follow-up completeness and missing-data handling are also not reported. This prevents assessment of whether the analyzed participants represent everyone enrolled or whether incomplete follow-up could affect the result.

The registry lists four outcome measures and two analyses, but does not describe the analysis methods, multiplicity approach, or statistical analysis plan. It names two secondary outcomes without reporting their results. Further details about the stimulation procedure, the relationship between the listed device and procedure, and outcome measurement methods are not reported in the registry record. These omissions limit reproducibility and the ability to interpret the endpoint in clinical context.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Spinal Cord Stimulation to Restore Cough — NCT00116337.
• Registry record last updated 2020-05-04; status last verified 2020-04.
• Results first posted 2020-04-13.
• 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 completed, single-group study sponsored by MetroHealth Medical Center, with recorded enrollment of 17. It lists spinal cord stimulation intended to restore cough and a primary outcome measuring mean airway pressure generation in cmH2O at baseline before implantation and at one year after implantation. Standard error is the stated dispersion measure.

The listed secondary outcomes are Incident of Acute Respiratory Tract Infections and Trained Caregiver Support for Secretion Clearance. The record reports safety figures of 1 serious adverse event affected among 17 at risk, 3 other adverse events affected among 17 at risk, and 0 deaths; Infection is the top listed serious term at 5.9%.

The primary outcome values, detailed analysis methods, analysis population, and missing-data handling are not reported in the registry record. The single-group design does not provide a separate control comparison.