Gabapentin for Post-Operative Pain Control and Narcotic Reduction in Scrotal Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Gabapentin for Post-Operative Pain Control and Narcotic Reduction in Scrotal Surgery (NCT04230980), a randomized phase 3 study. The primary outcome is Pain Score as Measured by the NRS-11 Scale.

2. Clinical Question

3. Trial Design

This was a Phase 3, randomized, double-masked, parallel-group trial sponsored by Weill Medical College of Cornell University. The registry record marks the study as completed and lists enrollment of 74. It gives a start date of 2020-07-28 and a primary completion date of 2022-11-28.

Participants were assigned to gabapentin or placebo. The gabapentin schedule was a 600mg pre-operative tablet followed by 300mg three times a day for 3 days. The placebo schedule was a tablet pre-operatively and three times a day for 3 days. The record identifies the study as double-masked but does not specify which people were masked, how masking was maintained, or how allocation was generated or concealed.

The primary outcome was pain measured using the NRS-11 from post-operative day 0 through post-operative day 7. The registry describes the endpoint as a mean, with standard deviation as the dispersion measure. The record lists secondary outcomes concerning opioid tablet consumption, frequency of narcotic tablets taken, and duration of narcotic tablet consumption. It does not report the results for these outcomes.

The primary outcome description notes exclusions after loss to follow-up in both groups and an adverse event leading to removal from study medication in the placebo group. The text describing that latter participant is incomplete. The registry record does not report the full analysis population, the handling of missing pain scores, the statistical analysis plan, or a protocol-based sample-size justification. The stated sample-size assumptions are explicitly described as a planning illustration based on the observed effect, not as the trial’s own design.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: 1 subject has been lost to followup in the gabapentin arm and was therefore excluded from analysis. 2 subjects have been lost to followup in the placebo arm and were therefore excluded from analysis. 1 subject experienced an adverse event in the placebo arm and was taken off the study medication and was therefore excluded from analysis.

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: 1 subject on the gabapentin arm and 3 subjects on the placebo arm were excluded as data collected from these participants was insufficient for analysis.

6. Primary Endpoint

The registry lists the primary outcome as Pain Score as Measured by the NRS-11 Scale, measured over Post-operative day 0 (the day of surgery, after surgery was completed) through post-operative day 7.

The primary endpoint is pain measured with the Numerical pain Rating Scale, called the NRS-11 in the registry. It is an 11-point numerical scale: 0 means no pain and 10 means severe pain. The outcome is described as a mean score, with standard deviation used to describe variability among participants. Measurements cover post-operative day 0, the day of surgery after surgery was completed, through post-operative day 7.

In general, a pain rating scale converts a participant’s subjective assessment into a standardized numerical measure. This allows a trial to describe the distribution of reported pain and compare group summaries. A mean conveys the average score, while the standard deviation indicates how spread out individual scores are around that average. Neither statistic alone describes the full distribution or establishes whether a difference between groups is important to participants.

The stated timeframe spans multiple post-operative days. Pain can vary over time, so a comparison needs to make clear whether it concerns scores at particular time points, an average across time, or another summary. The registry record notes that the primary outcome has several categories or time points and was not reduced to one comparison. It does not report a single primary pain estimate, group means, standard deviations, or an estimated contrast. Accordingly, the endpoint’s measurement and timeframe can be described, but its observed result cannot be interpreted from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean pain score describe?

The primary measure is continuous: each NRS-11 score is numerical, and the registry specifies a mean as the summary measure. In general, a mean is the arithmetic average of the observations included in an analysis. It gives a compact description of the group’s average reported pain, but it can conceal variation between participants and changes over time. The registry also specifies standard deviation, which describes how dispersed the scores are around the mean. It is not the uncertainty of the estimated mean; uncertainty about a group comparison would ordinarily be conveyed by an estimate and an uncertainty measure such as a confidence interval.

The record does not report group means, standard deviations, or an estimated comparison. It also does not say whether the primary comparison used scores at each post-operative time point, a summary across the timeframe, or a particular repeated-measures model. The registry notes that the outcome has several categories or time points and was not reduced to one comparison. Thus, the endpoint definition does not by itself specify the analysis model.

How should the comparison be understood?

In general, a randomized comparison aims to estimate how outcomes differ between assigned groups, while accounting for the design and the analysis population. The estimated contrast needs a clearly stated direction and scale. For a mean pain outcome, an analysis might express a difference in average scores, but the registry record does not report such an estimate or state the exact contrast used. No result should be reconstructed from the arm descriptions or enrollment information.

The trial is recorded as randomized, double-masked, and parallel-group. These design labels describe the broad structure, not all operational details. The method used to generate the allocation sequence, conceal allocation, maintain masking, or handle departures from assigned treatment is not reported in the registry record. The statistical analysis plan is also not reported in the registry record.

What can be learned from the planning assumptions?

The registry includes assumptions for a sample-size planning illustration: a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect and clarifies that this is a planning illustration computed from the observed effect, not the trial’s own design. It also explains that non-time-to-event planning values are participants per arm.

These assumptions do not supply the trial’s original sample-size justification. That justification is not reported in the registry record. The planning description is not observed power and should not be interpreted as evidence that the completed trial had a particular probability of detecting an effect. No sample-size illustration values are described in the record summary used for this explanation, and no new values can be inferred from the assumptions alone.

In general, a normal approximation is a mathematical way to approximate the sampling behavior of an estimator. Its suitability depends on the data and analysis. The record does not report diagnostic checks or details that would allow an assessment of the approximation for this particular outcome.

Why do time points and missing observations matter?

The primary outcome covers post-operative day 0 through post-operative day 7. When measurements are taken over time, results can be reported separately for time points or through a prespecified summary of the trajectory. These approaches answer different questions. The registry’s note that the outcome has several categories or time points and was not reduced to one comparison means that a single primary contrast is not available in the posted record. The precise time-specific results and the method used to account for within-participant measurements are not reported.

The endpoint description states that 1 subject was lost to followup in the gabapentin arm and excluded from analysis, and 2 subjects were lost to followup in the placebo arm and excluded from analysis. It also says that 1 subject experienced an adverse event in the placebo arm and was taken off study medication, but the sentence ends without explaining how that participant’s outcome data were handled. In general, missing observations can affect both the number of analyzed participants and the interpretation of an estimate. The registry does not describe imputation, sensitivity analyses, or a complete analysis population definition.

For these reasons, the available record supports a description of the planned endpoint and some exclusions, but not an independent reconstruction of the primary analysis. The estimate, its uncertainty, the model, and the handling of incomplete repeated measurements are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary pain outcome with several categories or time points and identifies secondary outcomes relating to opioid tablet counts, frequency of narcotic tablet use, and duration of use. It also records 4 outcome measures and 2 analyses. The record does not explain how those analyses correspond to the outcome measures, which comparisons were prespecified, or whether any adjustment for multiple comparisons was used.

In general, multiplicity arises when several outcomes, time points, or comparisons are examined. If many tests are conducted, the chance of observing an apparently notable result by chance can increase. An analysis plan can address this by defining a primary comparison in advance, adjusting inference, or clearly labeling additional analyses as exploratory. Which approach was used in this trial is not reported in the registry record. The primary outcome is specifically noted as not reduced to one comparison, so a single primary contrast and its multiplicity treatment cannot be identified from the record.

The record states that 1 subject was lost to followup in the gabapentin arm and excluded from analysis, and 2 subjects were lost to followup in the placebo arm and excluded from analysis. It also notes that 1 placebo participant experienced an adverse event and was taken off study medication. The description does not finish explaining that participant’s analysis status. The reasons for loss to followup, timing of missing measurements, and handling of incomplete outcome data are not reported.

In general, an analysis population can be defined by randomized assignment, treatment received, or availability of outcome data. These choices can affect the interpretation of a group comparison. The record’s stated exclusions do not fully identify the population used for every outcome, and it does not report an intention-to-treat analysis, imputation procedure, or sensitivity analysis. Consequently, the impact of missing data and the robustness of the findings cannot be assessed from the registry record.

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 1% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: syncopal episode (5.3%).

The registry lists serious adverse events among 36 participants at risk in the gabapentin group: 0 were affected. In the placebo group, 2 of the 38 participants at risk were affected. Deaths are listed as 0 in each group. These are descriptive figures as recorded, not estimates of a causal safety difference.

For other adverse events, the registry lists 16 affected among 36 participants at risk in the gabapentin group and 15 among 38 in the placebo group. The record also identifies “syncopal episode” as a top serious event term, with 5.3% shown alongside it. The record does not give further detail about the event description, timing, severity classification process, or how that percentage was calculated.

In general, event counts depend on the definitions used, the period of observation, and how events were collected. A count alone does not indicate how long participants were observed or whether all events were captured consistently. The registry record does not provide a fuller account of these procedures or statistical comparisons for adverse events. The counts should therefore be read as the posted descriptive safety information, not as proof of a difference or equivalence between groups.

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

The record documents a randomized, double-masked comparison of gabapentin and placebo in a scrotal surgery trial, with pain measured using the NRS-11 from post-operative day 0 through post-operative day 7. It also describes the medication schedules, the stated enrollment, and some exclusions from analysis. Those details make the research question and broad design understandable.

However, the registry record does not report the primary pain results or the secondary opioid-consumption results. It gives no group means, treatment-effect estimate, confidence interval, or p-value for the primary outcome. Therefore, it is not possible to determine from this record whether observed pain scores were higher, lower, or similar between groups, or how precisely any difference was estimated. The trial’s hypothesis about reducing pain and narcotic use is not evidence that either outcome changed.

The absence of reported estimates is not evidence that the groups had identical outcomes. It also does not establish that an effect was present. Without the results and analysis details, neither a positive nor a null conclusion can be supported from the record. The safety counts are distinct from efficacy and do not fill this gap.

In general, interpreting a clinical trial requires more than knowing its design and outcome definitions. Readers need the actual outcome summaries, the between-group estimate, uncertainty around that estimate, and sufficient information about the analysis population and missing data. The registry record does not report those elements for the primary comparison. Its listed planning assumptions are explicitly a sample-size illustration based on the observed effect, not a report of the trial’s original design or proof of an outcome.

The appropriate reading is therefore limited: the trial was completed and its registry describes the intended comparison, but the posted record does not provide the results needed to characterize the treatment effect.

13. Why This Trial Matters Statistically

This trial raises statistical questions that are common in clinical research: how to summarize a subjective outcome, how to compare groups across several time points, and how to account for participants whose measurements are unavailable. The registry identifies these issues indirectly by defining a mean NRS-11 endpoint over post-operative day 0 through post-operative day 7, noting multiple time points, and documenting exclusions after loss to followup.

The record also illustrates why a trial’s hypothesis and its results must be kept separate. A rationale for adding gabapentin to multimodal analgesia describes the question researchers sought to test. It does not report what happened to pain scores or narcotic consumption. Without effect estimates and uncertainty, readers cannot assess either the magnitude or precision of the observed comparison.

Randomization and masking are important design features, but they do not replace transparent reporting of outcomes and analyses. To interpret a repeated pain measure, readers need to know what comparison was defined, how the time course was summarized, and how incomplete measurements were handled. Those details are not reported in the registry record. The record’s note that the endpoint was not reduced to one comparison further underscores why a clear primary contrast matters.

The safety information has a separate role. It records serious and other adverse events, but descriptive counts alone cannot establish a comparative effect. Taken together, the record demonstrates a central statistical principle: a study’s design can be described even when its outcome evidence is unavailable, but conclusions about effects require reported estimates and their uncertainty.

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.

A central limitation for interpreting this trial from the registry record is that the primary pain results are not reported. The record provides neither group summaries nor a treatment-effect estimate and uncertainty measure. The listed secondary outcomes also lack results. This prevents assessment of the direction, magnitude, and precision of the outcomes the trial was intended to evaluate.

The primary outcome spans post-operative day 0 through post-operative day 7, and the registry notes that it has several categories or time points without reducing it to one comparison. The specific time-point results, overall summary, and statistical model are not reported. As a result, readers cannot tell how the recorded endpoint was converted into the primary analysis.

Missingness is another limitation. The endpoint description states that 1 subject in the gabapentin arm and 2 subjects in the placebo arm were lost to followup and excluded from analysis. It also mentions a placebo participant taken off study medication after an adverse event, but the description is incomplete. The reasons for missingness, outcome availability for that participant, and missing-data methods are not reported.

The registry record does not report the allocation-generation or concealment procedures, the details of masking, the statistical analysis plan, multiplicity handling, or the trial’s own sample-size justification. It does list a planning illustration based on the observed effect and makes clear that this is not the trial’s design. Finally, the safety figures are descriptive and lack detail about event collection and comparative analysis. These gaps limit interpretation of both efficacy and safety from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Gabapentin for Post-Operative Pain Control and Narcotic Reduction in Scrotal Surgery — NCT04230980.
• Registry record last updated 2023-10-18; status last verified 2023-10.
• Results first posted 2023-10-18.
• 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

NCT04230980 is a completed, randomized, double-masked, parallel-group Phase 3 trial sponsored by Weill Medical College of Cornell University. Enrollment was 74. The registry lists non-obstructive azoospermia as the condition and describes a comparison of gabapentin with placebo following scrotal surgery.

The primary outcome was mean NRS-11 pain score, with standard deviation, measured from post-operative day 0 through post-operative day 7. Secondary outcomes concerned opioid tablet consumption, frequency of narcotic tablets taken, and duration of narcotic tablet consumption. The registry describes exclusions after loss to followup and notes a placebo participant taken off study medication after an adverse event.

The record does not report the primary or secondary outcome estimates, the primary analysis method, or a complete account of missing-data handling. It lists descriptive serious and other adverse event counts. Consequently, the registry record describes the study design and outcome measures but does not provide the results needed to estimate the clinical outcome differences.