TENS and Opioid Use After Cesarean Delivery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for TENS and Opioid Use After Cesarean Delivery (NCT03843788), a randomized na study. The primary outcome is Post-operative Pain Ratings.

2. Clinical Question

3. Trial Design

The registry describes a randomized, parallel-group study with no masking. It lists the study as terminated and records enrollment of 16. The study start date is 2018-11-09, and the primary completion date is 2020-01-31. The reason for termination is not reported in the registry record. The phase is recorded as NA.

The listed arms distinguish TENS from routine pharmacologic care and separately identify arms for participants described as opioid addicted. The available description for that subgroup says participants were targeted on the basis of opioid addiction and methadone maintenance. The TENS arms involved education in using the device; the routine-care descriptions state that routine pharmacologic care was provided. Some arm-description text is incomplete in the registry record, so the full device-use protocol cannot be established from it.

The primary endpoint was postoperative pain ratings, summarized as a mean and standard deviation, at 3-4 post-operative days. The outcome description identifies a 0-10 VAS and says that higher scores correspond to higher self-reported pain intensity. The registry also lists secondary outcomes involving medication dosages, time to out of bed, time to first bowel movement, sedation, device acceptability, and the McGill Pain Questionnaire.

The sponsor is Rutgers, The State University of New Jersey. Although randomization is recorded, the method used to generate or conceal allocation is not reported in the registry record. The record does not state how treatment adherence was assessed or whether the primary analysis followed assignment to randomized groups. Those details should not be inferred from the study's randomized designation alone.

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

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 Post-operative Pain Ratings, measured over 3-4 post-operative days.

The primary endpoint is postoperative pain intensity measured by self-report on the Visual Analog Scale. The registry describes the scale as ranging from 0-10, with higher scores meaning higher pain intensity. The reported summary is the mean rating with its standard deviation for each arm at 3-4 post-operative days.

A pain rating is a patient-reported outcome: it records the participant's own assessment rather than an observer's judgment or a laboratory measurement. A mean gives a summary of the average rating in an arm, while the standard deviation describes how spread out individual ratings are around that mean. These summaries can help readers understand both the typical recorded rating and its variability, but they do not by themselves establish whether groups differ beyond what might occur by chance.

The endpoint is relevant to the study's stated aim of exploring TENS for postpartum pain management. It is distinct from opioid consumption, which is identified as an objective and appears among the secondary outcomes as milligrams morphine equivalent. The primary pain ratings alone do not show how much opioid medication participants used. The registry does not report a clinically important difference threshold for the VAS or explain how the selected assessment time was chosen.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary outcome is continuous: each participant's VAS pain rating is a numerical score, and the registry summarizes each arm with a mean and standard deviation. The following explanations are general statistical context, not claims about unreported methods used by this trial.

What does a mean describe?

In general, a mean is the arithmetic average of the observed values in a group. It gives a compact description of the group's central tendency, but it does not show the complete distribution. Two groups can have different means while still having considerable overlap in individual observations. Conversely, similar means do not prove that the underlying groups are identical.

For this endpoint, a mean pain rating summarizes the VAS reports within an arm. The registry lists means of 2.9, 3.7, 2.58, and 4.24 for the four named arms. These summaries should be kept distinct from a treatment contrast: a contrast would directly quantify the difference between specified groups and would ordinarily include uncertainty, such as a confidence interval. No such estimable comparison is posted for this continuous endpoint.

What does the standard deviation describe?

In general, the standard deviation describes the dispersion of observations around a mean, in the same measurement units as the outcome. A larger standard deviation indicates that observed ratings are more spread out around the arm mean. It is not the standard error of the mean, and it is not a confidence interval. The registry lists standard deviations of 1.9, 2.97, 2.29, and 2.9 for the corresponding arms.

Standard deviations are useful for understanding variability, but they do not on their own show how precise a mean is. Precision also depends on the amount of information available. When group sizes are small, estimated means and standard deviations can be strongly affected by individual observations. Here, the endpoint arm sizes are 5, 3, 5, and 2. These small group sizes make cautious interpretation especially important; they do not justify treating the displayed averages as stable estimates of a broader population value.

Why is a direct comparison important?

In general, a randomized comparison is designed to estimate how outcomes differ between assigned groups, subject to the trial's conduct, missing data, and analysis choices. A direct estimate can be paired with an interval that communicates the range of effects compatible with the data under the chosen model. Without that estimate and uncertainty interval, readers cannot judge the magnitude and precision of a group contrast from the arm summaries alone.

The registry marks the continuous two-arm comparison as missing or not estimable. It also records zero analyses. Accordingly, there is no posted treatment-effect estimate, confidence interval, or p-value to interpret for the primary outcome. It would be inappropriate to substitute a newly calculated comparison for the sponsor's analysis; in any case, the registry does not report an estimable two-arm result to compare against. No adjustment method or model specification is reported in the registry record.

How should the planning illustrations be understood?

General sample-size planning asks how much information a future study might need to detect a specified effect under stated assumptions. The registry's planning description says the illustrations use the observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. For non-time-to-event outcomes, the stated planning quantities are participants per arm. The effect considered is described as a stated fraction of the observed effect.

These are planning illustrations, not observed power for this trial and not evidence that the study had adequate power. The registry does not report its own sample-size justification or design assumptions, so the illustrations should not be represented as the original trial plan. Sample-size calculations depend on the assumed effect and statistical model; if those assumptions do not match a future study, the planning results may not apply. The presence of a planning calculation also does not supply the missing primary comparison or resolve uncertainty in the observed arm means.

General statistical interpretation should separate descriptive results from inferential evidence. The arm means and standard deviations describe posted data. A treatment-effect estimate with an uncertainty interval would address the comparative question more directly, but that result is not reported in the registry record. No claim about statistical significance, equivalence, or a causal effect can be drawn from the descriptive summaries alone.

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("Post-CS TENS", "Opioid Addicted Post-CS TENS", "Post-CS Routine Care", "Opioid Addicted Post-CS Routine Care")
n   <- c(5, 3, 5, 2)
m   <- c(2.9, 3.7, 2.58, 4.24)
sp  <- c(1.9, 2.97, 2.29, 2.9)
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  Post-CS TENS  5  2.900  1.900  0.541  5.259
CARM  Opioid Addicted Post-CS TENS  3  3.700  2.970  -3.678  11.078
CARM  Post-CS Routine Care  5  2.580  2.290  -0.263  5.423
CARM  Opioid Addicted Post-CS Routine Care  2  4.240  2.900  -21.815  30.295

11. Multiplicity, Missing Data and Analysis Populations

The registry lists secondary outcomes including milligrams morphine equivalent, acetaminophen dosage, ibuprofen dosage, time to out of bed, time to first bowel movement, level of sedation, device acceptability, and the McGill Pain Questionnaire. The record states that 12 secondary outcomes were posted and that there were 13 outcome measures. It does not report which secondary outcomes were analyzed or provide a hierarchy for interpreting them.

When a study examines multiple outcomes or multiple comparisons, general statistical practice considers multiplicity: the more questions tested, the greater the chance that at least one result may appear notable by chance. Possible approaches include specifying a primary comparison in advance or adjusting inference across a family of tests. The statistical plan, any multiplicity adjustment, and any interim analyses are not reported in the registry record. It is therefore not possible to determine how multiplicity was handled or whether it affected interpretation.

Missing-data methods and analysis populations are also not reported in the registry record. The endpoint summaries list group sizes, but they do not establish whether those counts reflect all randomized participants, all participants with available measurements, or another analysis population. The record does not explain whether any measurements were missing, how missing values were handled, or whether participants were analyzed according to randomized assignment. The reason for termination is also not reported in the registry record.

These gaps matter because analysis choices can affect estimates and their uncertainty. The posted record supports a description of the reported arm summaries, but it does not allow a detailed assessment of the prespecified analysis strategy, missingness, or the completeness of outcome reporting.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry reports zero serious adverse events and zero other adverse events in each listed group, with deaths recorded as 0 in each group. The numbers listed as at risk for serious and other adverse events are 5, 3, 5, and 2 across the respective groups. These are the registry's reported safety counts for the listed groups.

A count of zero reported events does not establish that an intervention has no risks. It means that no events of those categories were recorded in the registry results for the groups and period represented. The record does not provide detailed event descriptions, exposure duration, methods for soliciting or classifying events, or a narrative explaining whether any events were considered related to treatment. The serious adverse event terms list is empty.

Because the groups are small, the safety counts have limited ability to characterize uncommon events. A zero count in a small group is compatible with uncertainty about the underlying event risk. These results should be read as a report of recorded events, not as proof of safety or as a comparison establishing that one care approach is safer than another.

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

The registry record provides descriptive postoperative pain ratings for four randomized arms: TENS and routine care, each with an arm designated for participants with opioid use. It also reports arm-specific standard deviations and group sizes. Those data describe the reported outcome at 3-4 post-operative days, but the registry does not provide an estimable two-arm comparison for the continuous primary endpoint.

As a result, the posted summaries do not establish whether the pain ratings differed because of TENS, whether any difference was clinically important, or whether a difference was estimated precisely. The record does not provide a confidence interval or inferential test for the primary outcome. It also does not report an outcome threshold that would define a clinically important VAS change.

The study's objectives include opioid use, alternative pain relief, and postpartum outcomes. A mean pain rating does not answer how much opioid medication was used, and the record's list of secondary outcomes is not itself evidence of results for those outcomes. No conclusion about opioid consumption, sedation, mobility, bowel function, or device acceptability can be drawn from the primary endpoint summaries alone.

The results do not establish equivalence between TENS and routine care, nor do they establish benefit or lack of benefit. Lack of an estimable comparison is not the same as a finding of no difference. The small reported arm sizes and the absence of inferential results leave substantial uncertainty around any comparative interpretation.

The registry lists the study as terminated, but the reason is not reported in the registry record. Without information on the circumstances of termination, missing measurements, analysis populations, and the statistical plan, the completeness and intended interpretation of the posted results cannot be fully assessed. The most defensible reading is limited: the record reports these arm-level pain summaries and no estimable comparative analysis for the primary endpoint.

14. Why This Trial Matters Statistically

This trial illustrates why a randomized label and arm-level outcome summaries are not sufficient for a comparative conclusion. Random allocation can support a fair comparison when the study is implemented and analyzed appropriately, but readers still need a clearly reported treatment-effect estimate and its uncertainty to assess the primary question. In this record, the primary endpoint summaries are available, while an estimable two-arm comparison is not.

The four arms also highlight an interpretive challenge: the record distinguishes participants by both care approach and opioid-use designation. These subgroup arms are very small, so their means are particularly vulnerable to the influence of individual pain ratings. Comparing each mean informally would not substitute for a defined analysis of the treatment contrast or its uncertainty.

The trial's termination status and the absence of reported details about missing data, analysis populations, and the statistical plan further limit what can be learned from the registry results. These omissions do not explain why the results look as they do, and the reason for termination is not reported in the registry record. They do show why transparent reporting of design and analysis decisions is important for clinical researchers and statisticians.

The registry's planning illustrations can be useful as prospective design exercises, but they should not be confused with evidence that the completed study had a particular probability of detecting an effect. The stated assumptions describe a planning calculation, not observed power. Overall, the record is a useful example of the distinction between descriptive summaries, a planned comparative question, and an analysis result that can support inference.

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 primary endpoint results are available only as arm-level means and standard deviations. The registry does not report an estimable two-arm comparison, confidence interval, or inferential test. This prevents assessment of the size and precision of a comparative effect from the posted primary results.

The reported arm sizes are small, especially in the arms designated for opioid use. This limits the stability of descriptive summaries and the ability to characterize variability or uncommon outcomes. The record does not report a sample-size justification for the trial, so the intended precision or detectable effect cannot be assessed from its original design plan.

The registry does not report the reason for termination, the randomization method, allocation concealment, adherence, missing-data handling, or the analysis population. The arm descriptions are partly incomplete, limiting understanding of the full TENS procedure. The stated primary assessment period is 3-4 post-operative days, and the record does not report other assessment timing for the primary measure.

The registry lists multiple secondary outcomes but does not report a statistical plan for multiplicity, interim analyses, or the analysis of those outcomes. It does not report a clinically important difference threshold for the pain scale. These limitations prevent a comprehensive assessment of the planned analysis, outcome completeness, and clinical interpretation of the recorded ratings.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: TENS and Opioid Use After Cesarean Delivery — NCT03843788.
• Registry record last updated 2024-10-29; status last verified 2024-10.
• Results first posted 2024-10-29.
• 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 identifies NCT03843788 as a randomized, unmasked, parallel study of TENS and opioid use after cesarean delivery. It lists enrollment of 16, status as terminated, a start date of 2018-11-09, and a primary completion date of 2020-01-31. The sponsor is Rutgers, The State University of New Jersey.

The primary outcome is postoperative pain rating on a 0-10 VAS at 3-4 post-operative days, summarized by arm as a mean and standard deviation. Results are reported for Post-CS TENS, Opioid Addicted Post-CS TENS, Post-CS Routine Care, and Opioid Addicted Post-CS Routine Care. The registry does not report an estimable two-arm comparison for this continuous endpoint, and it records zero analyses.

Secondary outcomes include medication dosages, postpartum timing and sedation measures, device acceptability, and the McGill Pain Questionnaire. The registry reports zero serious adverse events, zero other adverse events, and zero deaths in each listed group. The reason for termination and several details of the statistical plan are not reported in the registry record.