LESS TEP vs. Three Port TEP for Inguinal Hernia Repair: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for LESS TEP vs. Three Port TEP for Inguinal Hernia Repair (NCT04303182), a randomized na study. The primary outcome is Postoperative Pain.

2. Clinical Question

This is a question about the average recorded pain scores between the randomized groups at the specified assessment time. It is not a question about every aspect of recovery, nor does the primary endpoint by itself describe operating time, complications, hospital stay, recurrence, or patient satisfaction. Those topics appear among the secondary outcomes, but the registry record contains results for only some of them.

The comparison is clinically framed around two approaches to the same type of repair, while the statistical question is whether the observed group means are sufficiently distinct and precisely estimated to distinguish them. The posted estimate is a mean difference, with LESS TEP compared with standard three-port TEP. Its confidence interval is important because it expresses the range of differences compatible with the estimate and its uncertainty. The record does not state a threshold for a clinically important pain difference, so the numerical contrast cannot be judged against a trial-defined threshold.

3. Trial Design

The registry record describes a prospective, randomized, double-blind clinical trial with a parallel-group model. The stated enrollment is 200. The posted outcome summaries give 100 participants for standard three-port TEP and 100 for LESS TEP. The trial status is completed. The record identifies Sofia Med Hospital as sponsor.

The two groups received different laparoscopic TEP approaches for inguinal hernia repair. Standard three-port TEP is described as using one 10 mm port and two 5 mm ports. LESS TEP is described as using one skin incision 2-3cm. The record describes both as procedures and identifies the randomized allocation; it does not give additional information about allocation concealment or the method used to generate the allocation sequence.

Double masking is recorded, but which people were masked and how masking was maintained are not reported in the registry record. The title calls the trial prospective and double blinded, while the registry's design fields identify randomization, double masking, and parallel groups. These labels describe intended design features, not whether masking was successful or whether all participants followed their assigned procedure.

The primary outcome was postoperative pain on a Visual Analog Scale at 24hours. Listed secondary outcomes include operating time, intraoperative complications, length of hospital stay, postoperative complications, recurrence of hernia, and patient satisfaction. Results are posted for some secondary outcomes, but outcome timing or definitions are not reported for every listed measure. The original sample-size rationale, the trial's planned analysis methods, and details of the final analysis population are not reported in the registry record. The planning illustrations based on the observed effect are separate from the trial's original design rationale.

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.

Before assignment: Before randomization, all patients underwent standard preoperative assessment, including medical history, physical examination, laboratory testing, and anesthesiology evaluation. Eligibility was confirmed according to predefined inclusion and exclusion criteria. Written informed consent was obtained from all participants prior to allocation. Only eligible and consented patients were randomized to the intervention groups.

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 Postoperative Pain, measured over 24hours.

The primary endpoint is postoperative pain assessed using the Visual Analog Scale at 24hours. The registry describes the scale as ranging from 0 to 10, where 0 means no pain and 10 means the worst imaginable pain. A higher score represents worse pain intensity. The posted group summaries report means and standard deviations, so the main comparison describes average scores and the spread of scores within each group.

A pain scale provides a structured way to record a subjective experience in numerical form. Comparing group means can help describe whether the average recorded pain differs between the two procedures at the stated time. The standard deviation adds context about variation among participants: a mean alone does not show how dispersed individual scores were.

The endpoint is time-specific. It addresses pain at 24hours, not pain over the entire recovery period or pain at other follow-up times. The registry record does not report a clinically important difference threshold, additional assessment times, or details of how the measure was collected. Without such information, the mean difference can be interpreted statistically, but its importance to patients cannot be established from the registry record alone.

7. Results Posted in the Registry

• LESS TEP: mean 4.67 versus 4.80 on control; difference -0.13 (95% CI -0.62 to 0.36), standardized effect d = -0.07; z-test p = 0.602.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Operating Time

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • LESS TEP: mean 48.93 versus 49.57 on control; difference -0.64 (95% CI -6.01 to 4.73), standardized effect d = -0.03; z-test p = 0.815.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between LESS TEP and the control. The interval gives the range of effects that remain compatible with the data.

Intraoperative Complications

• Endpoint type: Binary: the number of participants with the event, compared as proportions.
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • LESS TEP: 0.0% (0/100) versus 1.0% (1/100) on control; risk difference -1.0 percentage points (95% CI -3.0 to 1.0); unadjusted two-proportion z-test p = 0.316.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between LESS TEP and the control. The interval gives the range of effects that remain compatible with the data.

Length of Hospital Stay

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • LESS TEP: mean 1.50 versus 1.37 on control; difference 0.13 (95% CI -0.10 to 0.36), standardized effect d = 0.16; z-test p = 0.269.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between LESS TEP and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes address several different dimensions of surgery and recovery: operating time, intraoperative and postoperative complications, length of hospital stay, recurrence, and patient satisfaction. These measures can complement the primary pain comparison by describing other aspects of the procedures, but they answer different questions and should not be combined into a single overall judgment.

The registry record contains comparative result entries for operating time, intraoperative complications, and length of hospital stay. It names postoperative complications, recurrence of hernia, and patient satisfaction among the secondary outcomes, but results for those measures are not reported in the registry record. In addition, the timeframes and definitions are not stated for every listed outcome. This uneven coverage means the available secondary results cannot represent the full set of outcomes named in the record.

The secondary comparisons do not overturn or resolve the primary pain result. A finding about one outcome cannot establish the result for another: an operating measure does not determine pain, and a hospital-stay measure does not describe recurrence or satisfaction. Considered together, secondary measures may offer context, but they do not replace a precise primary comparison or fill in unreported follow-up outcomes.

The secondary results are unadjusted, and the registry record does not report a multiplicity strategy. When multiple outcomes are examined, the chance of observing apparently notable results can increase, particularly when each is considered separately without accounting for the number of comparisons. For that reason, unadjusted secondary findings generally carry less confirmatory weight than a clearly prespecified primary outcome analyzed under a reported plan. The record does not provide that plan, so the secondary results are best treated as descriptive and exploratory rather than as definitive evidence across outcomes.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Operating Time
• Intraoperative Complications
• Length of Hospital Stay
• Postoperative Complications
• Recurrence of Hernia
• Patient Satisfaction

9. Statistical Interpretation

10. Statistical Methods Explained

Continuous outcomes are summarized by a mean and standard deviation. The mean is the arithmetic average of the recorded scores or measurements in a group. The standard deviation describes how much the observations vary around that average. For postoperative pain, this gives a concise account of both the average score and the dispersion of individual scores. It does not describe the full shape of the score distribution or show whether particular subgroups experienced different outcomes.

What does a mean difference represent?

The primary comparison is expressed as the mean for LESS TEP minus the mean for standard three-port TEP. A negative estimate means the observed mean in the LESS TEP group is lower; a positive estimate means it is higher. Since higher pain scores represent worse pain intensity, the sign gives the direction of the observed contrast, but it does not by itself establish whether the difference is precise or clinically important. The posted estimate is -0.13.

A confidence interval gives a range of values compatible with the estimate under the statistical method used. It communicates uncertainty around the mean difference rather than only its direction. For the primary outcome, the interval runs from -0.618 to 0.358. Because zero is within this interval, the estimate does not distinguish clearly between a lower, similar, or higher mean score for LESS TEP. A wide interval can leave substantial uncertainty even when the point estimate appears close to zero.

How should the p-value be understood?

The unadjusted p-value for the primary comparison is 0.602. In general, a p-value describes how unusual data at least as discrepant as the observed data would be under a specified null model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure the probability that a result arose by chance. A p-value also does not indicate whether a difference matters to patients. The confidence interval and the clinical context are needed to understand the size and precision of the contrast.

The registry record has no reported analysis entries. The comparative estimates and p-values are unadjusted recalculations from the posted summary statistics, not descriptions of a reported adjusted or prespecified model. The record does not report an analysis plan, covariate adjustment, or a method for handling missing observations. Those details should not be inferred from the numerical summaries.

Why can variability affect precision?

When measurements vary substantially within groups, an estimated difference between group means is generally less precise than it would be with less variability, all else being equal. The standard deviations for the primary outcome are 1.71 and 1.81. The interval for the contrast incorporates uncertainty arising from the observed group summaries. This general relationship helps explain why a point estimate alone is insufficient: the amount of within-group spread and the amount of information available both matter to precision.

Some statistical methods also rely on assumptions about the distribution of measurements. If data are highly skewed or include unusual values, a mean and standard deviation may not describe the outcome fully. The registry record does not report distributional checks or alternative analyses, so it is not possible to assess those issues from the posted summaries. This is a general consideration, not a claim that the data in this trial violate an assumption.

How do binary outcomes differ?

For an outcome recorded as whether a participant experienced an event, the group result is a count of participants with the event and the group size. A risk difference compares the proportions between groups. Its sign indicates which group has the higher observed proportion, while its confidence interval describes uncertainty. Sparse event counts can yield imprecise comparisons; interpreting such outcomes requires attention to both the event counts and the interval, rather than relying on a p-value alone.

Intraoperative complications are recorded as a participant count, with a recalculated risk difference and confidence interval. The registry record does not report a formal analysis for this outcome. The simple comparison does not adjust for other factors, and the record does not state whether all relevant complications were captured using a standardized definition.

For continuous measures, a mean difference keeps the outcome in its original units, such as pain score, minutes, or days. This makes the estimate interpretable in the measurement scale, but comparisons across different outcomes are not interchangeable. A difference in operating time cannot be treated as a difference in pain, and neither alone captures all aspects of the clinical question.

All of these calculations describe the posted summaries. The registry record does not report whether the trial used an intention-to-treat population, a per-protocol population, or another analysis set. It also does not report how missing observations, withdrawals, or deviations from assigned procedures were addressed. Without these details, the analysis cannot be fully reconstructed or evaluated for sensitivity to those choices.

11. Confidence Intervals and Precision

Precision concerns how narrowly the data estimate a group difference. For postoperative pain, the estimated mean difference was -0.13, with a 95% confidence interval from -0.618 to 0.358. The interval spans zero, so the posted estimate is compatible with a lower mean pain score in LESS TEP, little or no difference, or a higher mean score, within the interval's limits. The point estimate alone should not be treated as the settled effect.

A confidence interval is not a range that contains a fixed proportion of individual participant scores. It describes uncertainty around an estimated quantity under the statistical method's assumptions. In general, greater precision corresponds to a narrower interval. The interval leaves uncertainty about both the direction and size of the mean difference. The registry record does not report a threshold for a clinically important difference, so the range cannot be classified against a trial-defined standard of meaningful change.

The unadjusted p-value of 0.602 is consistent with the interval's inclusion of zero, but the p-value does not replace the interval. It gives no direct account of whether the possible differences are clinically important. Nor does it demonstrate that the approaches are equivalent. Establishing equivalence would require a defined margin and an analysis designed to evaluate that question; neither is reported in the registry record.

The standard deviations, 1.71 and 1.81, describe variation in the observed group scores, not precision of the group difference by themselves. Precision depends on the uncertainty of the comparison as a whole. The reported interval is the most direct summary of that uncertainty for the primary outcome. It should be read alongside the measured scale, the assessment time, and the absence of a reported clinical-importance threshold.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size illustrations are planning calculations based on the observed effect, not the trial's original design justification. They use a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The original sample-size assumptions for this trial are not reported in the registry record.

For continuous outcomes, the figures are participants per arm. The primary pain comparison lists 2,880 participants per arm for 80% power and 3,855 participants per arm for 90% power when planning for 100% of the observed effect. For 75% of the observed effect, the figures are 5,120 and 6,854 participants per arm; for 50% of the observed effect, they are 11,519 and 15,420 participants per arm.

The 80% power column represents a planning target under which the assumed effect would be detected at the stated significance level in 80% of repetitions of the specified design, if its assumptions held. The 90% column uses a higher target probability of detecting that assumed effect and consequently requires more participants in these illustrations. Planning for smaller effects also requires more participants, because smaller differences are harder to distinguish from sampling variability.

The figures are not observed power. They are hypothetical planning illustrations calculated from the observed effect and stated assumptions, not evidence about the probability that this completed trial detected an effect. A curve based on these calculations should be interpreted as showing how the planning requirement changes as the assumed effect changes, not as a new analysis of trial outcomes. These illustrations should not be read as recommendations or as the trial's actual planned enrollment rationale.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = -0.130; pooled standard deviation σ = 1.761.
2. n = 2 × (1.96 + 0.842)² × 1.761² / -0.130² = 2,879.6, rounded up to 2,880 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- -0.13                      # observed difference in means
sigma <- 1.7607100840286                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(4303182)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 2,880 (80% power), 3,855 (90% power)
 75% of observed effect: n per arm = 5,120 (80% power), 6,854 (90% power)
 50% of observed effect: n per arm = 11,519 (80% power), 15,420 (90% power)
power.t.test: 2880.5 
Simulated power at n = 2,880 per arm: 0.803 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry record lists several secondary outcomes in addition to the primary pain endpoint. It does not report how the trial planned to control the overall chance of false-positive findings across multiple outcomes or comparisons. This issue is called multiplicity. In general, examining many outcomes without an adjustment or a prespecified hierarchy can make isolated nominally notable results less persuasive. No adjustment should be assumed from the posted results.

The record contains no reported analysis entries. It does not describe a statistical analysis plan, the primary analysis population, covariate adjustment, or the handling of deviations from assigned treatment. In particular, it is not reported in the registry record whether the primary comparison followed an intention-to-treat approach or used another population definition. These details matter because different analysis populations can lead to different estimates and because excluding participants after randomization can affect the comparability created by random allocation.

Missing-data methods are also not reported in the registry record. The posted summaries give group sample sizes, but those figures alone do not establish whether every randomized participant contributed a primary outcome or whether any missing scores were imputed or otherwise addressed. The record does not describe withdrawals, exclusions, or the reasons for missing observations. It is therefore not possible to assess whether missingness could have influenced the comparison.

The record also does not report interim analyses, stopping rules, or a prespecified method for handling the listed secondary outcomes. These elements should not be inferred from the completed status or from the estimates. Overall, the absence of analysis and missing-data details limits assessment of whether the posted comparisons follow the trial's planned approach and how robust they are to alternative analysis choices.

15. 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 record reports serious adverse events affecting zero participants in each group and other adverse events affecting zero participants in each group. It separately lists one death in the standard three-port TEP group and zero deaths in the LESS TEP group. These are counts as recorded; the registry record does not provide causes, timing, relatedness to the procedures, or further narrative detail.

Zero recorded events in a group does not establish that the risk is absent. It describes what was recorded in the stated group and does not rule out uncommon events or events that were not captured. Likewise, the death counts alone do not show whether a death was related to treatment. No causal attribution should be inferred from the counts.

The safety figures are limited to the adverse-event categories and counts posted in the registry record. The record does not provide event definitions, follow-up duration for safety, severity details beyond the serious-event category, or a statistical comparison of these counts. They should therefore be read as a brief descriptive account, not as a comprehensive safety assessment or a basis for attributing an event to either procedure.

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

The primary result describes postoperative pain scores at 24hours in the two randomized groups. The observed means were close, and the estimated difference was -0.13. However, the confidence interval from -0.618 to 0.358 includes zero and allows for differences in either direction. The result therefore does not precisely establish the direction or size of a pain-score difference between the procedures.

This finding does not prove that the procedures are equivalent. A non-significant unadjusted p-value is not an equivalence test, and the registry record does not report an equivalence margin or a design intended to establish equivalence. It also does not prove that there is no difference: the confidence interval retains a range of possible contrasts. The lack of a clinically important difference threshold further limits assessment of practical importance.

The primary outcome is one point in time and one dimension of the trial. It cannot by itself characterize longer-term pain, operating experience, complications, hospital stay, recurrence, or satisfaction. Some secondary results are posted, but other listed outcomes are not reported in the registry record. The limited safety counts do not establish cause or provide a complete safety profile.

The trial record describes randomization and double masking, but it does not report enough detail to assess masking, analysis populations, missing data, or the original analysis plan. The comparisons are unadjusted recalculations from summary statistics rather than reported analyses. Interpretation should therefore remain tied to the posted summaries and their uncertainty, without extending the result into a broader claim about overall benefit, equivalence, or safety.

17. Why This Trial Matters Statistically

This trial is a useful example of the distinction between a point estimate and the precision of an estimate. The observed mean pain scores are close, and the estimated difference is small in the outcome's units. Yet the confidence interval, rather than the point estimate alone, shows how much uncertainty remains about the group contrast. Statistical interpretation requires both the estimated direction and the range of values compatible with the data.

It also illustrates why a p-value should not be treated as a verdict. The primary unadjusted p-value does not establish equivalence, rule out a difference, or indicate clinical importance. The confidence interval makes the uncertainty more interpretable, while the missing clinical-importance threshold prevents a direct judgment about whether values in the interval would matter to patients.

The posted secondary outcomes demonstrate another recurring issue in clinical trials: multiple outcomes can describe different aspects of care, but their evidential weight depends on prespecification, analysis methods, and control of multiplicity. Those details are not reported in the registry record. Nor are all listed secondary outcomes accompanied by results. Readers should distinguish a broad list of planned outcome topics from the outcomes with posted numerical data.

Finally, the sample-size illustrations show why planning assumptions need to be kept separate from trial results. They are based on the observed effect and stated hypothetical assumptions, rather than on the original rationale for enrollment. Treating such illustrations as a retrospective measure of success would confuse a planning calculation with evidence from the trial. Clear reporting of analysis populations, missing data, outcome definitions, and the original statistical plan would make the results easier to assess.

18. 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 registry record does not report the original sample-size justification or the trial's planned statistical analysis methods. It also contains no reported analysis entries. The comparative estimates are unadjusted recalculations from posted summary statistics, so they cannot be checked against a reported prespecified model or analysis plan.

Important details about the analysis population and missing data are not reported in the registry record. The posted group summaries do not explain whether all randomized participants contributed to each outcome, how withdrawals or exclusions were handled, or whether any missing values were imputed. The record also does not specify who was masked or describe how masking was maintained.

The primary pain outcome is reported at 24hours, with no additional pain assessment times or clinically important difference threshold stated. The record does not provide further measurement details or distributional checks. The listed secondary outcomes are not all accompanied by results, and definitions or follow-up timeframes are not reported for every outcome. In particular, the recurrence outcome has no reported timeframe in the registry record.

The safety information is limited to event counts. Causes, timing, relatedness, event descriptions, and safety follow-up duration are not reported. The record also does not state how multiplicity across outcomes was addressed. These limitations restrict assessment of completeness, precision, and the robustness of the comparisons; they do not establish that an unreported method or event was absent.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: LESS TEP vs. Three Port TEP for Inguinal Hernia Repair — NCT04303182.
• Registry record last updated 2026-07-17; status last verified 2026-04.
• Results first posted 2026-07-17.
• 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.

22. Record Summary

NCT04303182 is a completed randomized, double-blind, parallel-group trial comparing LESS TEP with standard three-port TEP for inguinal hernia repair. The primary outcome is mean postoperative pain score on a Visual Analog Scale at 24hours, with higher scores indicating worse pain intensity.

The posted primary estimate is a mean difference of -0.13 for LESS TEP versus standard three-port TEP, with a 95% confidence interval from -0.618 to 0.358 and an unadjusted p-value of 0.602. The interval includes zero and leaves uncertainty about the direction and size of the difference.

Results are also posted for selected secondary outcomes and adverse-event counts. The registry record does not report analyses, the original sample-size rationale, missing-data methods, analysis populations, or a multiplicity strategy. Some listed secondary outcomes have no posted result entries.