ESP Block VS Intrathecal Opioid After Laparoscopic Colorectal Surgery: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ESP Block VS Intrathecal Opioid After Laparoscopic Colorectal Surgery (NCT05257941), a randomized phase 1, phase 2 study. The primary outcome is 24 Hour Cumulated Oral Morphine Equivalent (OME).

2. Clinical Question

The registry describes a comparison of postoperative pain-control methods, but it does not report a formal hypothesis statement or a prespecified direction of benefit. The posted primary outcome is opioid consumption rather than a direct pain score. Pain scores and other outcomes appear among the secondary measures. These outcomes address related, but distinct, aspects of postoperative recovery: medication use, reported pain, and the timing of first ambulation.

The record identifies the study as randomized and parallel, with no masking. It lists 116 participants as enrolled. The primary outcome results are posted for 56 participants in the IT Injection arm and 51 in the ESP Block arm. The registry record does not explain the difference between the enrollment figure and the outcome arm counts, or describe the population included in each analysis.

3. Trial Design

This was a randomized, open-label, parallel-group study comparing two regional analgesia approaches after laparoscopic colorectal surgery. One group received an intrathecal injection containing duramorph and bupivacaine; the other received an ESP block using bupivacaine and decadron. The registry lists the study phase as PHASE1 and PHASE2 and the sponsor as Indiana University.

The record lists 116 participants as enrolled. Results for the primary endpoint include 56 participants in the IT Injection arm and 51 in the ESP Block arm. The listed arm counts for the reported secondary results are also 56 and 51. The registry record does not explain how participants moved from enrollment to the outcome analyses, whether all randomized participants were included, or how missing outcome data were handled.

The study population was described as adults aged 18 to 80 years, with an ASA physical status of 1, 2, or 3 and BMI less than 40 kg/m², scheduled for elective laparoscopic colorectal surgery at Indiana University Hospital or Methodist Hospital. The description also says participants desired regional anesthesia. Further eligibility details are not reported in the registry record.

The study is listed as terminated. Its start date is 2022-01-27, and the primary completion date is 2024-08-26. The reason for termination and whether termination affected enrollment or follow-up are not reported in the registry record. No masking was used, so participants and clinical personnel were not described as blinded to the assigned approach. The registry record does not report the randomization method, allocation concealment, planned enrollment rationale, or details of the enhanced recovery pathway.

The primary outcome was cumulative OME consumption at 24 hours after surgery. The registry also posts secondary results for OME and visual analog scale pain scores at 1 hour after surgery, as well as time to first ambulation. It lists additional secondary outcomes, but not all are represented in the reported results. The statistical analysis plan, analysis populations, and prespecified handling of multiple outcomes are not reported in the registry record.

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: The baseline study population consists of adults aged 18 to 80 years (male or female) with an ASA physical status of 1, 2, or 3, a BMI less than 40 kg/m², and scheduled for an elective laparoscopic colorectal procedure at Indiana University Hospital or Methodist Hospital who desire regional anesthesia for postoperative pain control.

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: The baseline study population consists of adults aged 18 to 80 years (male or female) with an ASA physical status of 1, 2, or 3, a BMI less than 40 kg/m², and scheduled for an elective laparoscopic colorectal procedure at Indiana University Hospital or Methodist Hospital who desire regional anesthesia for postoperative pain control

6. Primary Endpoint

The registry lists the primary outcome as 24 Hour Cumulated Oral Morphine Equivalent (OME), measured over 24 hours after surgery.

The primary endpoint is cumulative oral morphine equivalent (OME) consumption during the 24 hours after surgery, measured in mg morphine equivalents. OME converts opioid consumption into a common morphine-equivalent scale, allowing amounts from opioid medications to be expressed in comparable units. The endpoint is reported as a mean with a standard deviation for each arm.

Opioid consumption is one way to describe postoperative analgesia and medication use. It does not, by itself, capture all dimensions of pain or recovery. A patient’s reported pain, side effects, mobility, and other experiences may not track perfectly with the amount of opioid medication used. The registry includes pain scores and ambulation among secondary outcomes, which can provide related perspectives, but the primary question remains focused on cumulative opioid consumption.

The posted arm means are 44.49 mg morphine equivalents for IT Injection and 45.17 mg morphine equivalents for ESP Block. The unadjusted mean difference for ESP Block compared with IT Injection is 0.68 mg morphine equivalents, with a 95% confidence interval from -16.67 to 18.03. The interval spans values on both sides of zero, so the estimate is compatible with a range of differences in either direction. The registry record does not report a separate clinical threshold for interpreting the size of an OME difference.

The outcome timeframe is 24 hours after surgery. More detailed rules for collecting or aggregating medication use, including any protocol for missing measurements, are not reported in the registry record.

7. Results Posted in the Registry

• ESP Block: mean 45.17 versus 44.49 on control; difference 0.68 (95% CI -16.67 to 18.03), standardized effect d = 0.01; z-test p = 0.939.

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.

Oral Morphine Equivalents (OME)

• 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 errors.
• Result:
  • ESP Block: mean 11.97 versus 12.22 on control; difference -0.25 (95% CI -11.03 to 10.52), standardized effect d = -0.01; z-test p = 0.963.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ESP Block and the control. The interval gives the range of effects that remain compatible with the data.

Visual Analog Scale Pain Scores

• 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 errors.
• Result:
  • ESP Block: mean 4.41 versus 3.41 on control; difference 1.00 (95% CI -0.02 to 2.02), standardized effect d = 0.37; z-test p = 0.054.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ESP Block and the control. The interval gives the range of effects that remain compatible with the data.

First Ambulation

• 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:
  • ESP Block: mean 18.89 versus 19.66 on control; difference -0.77 (95% CI -3.35 to 1.81), standardized effect d = -0.11; z-test p = 0.558.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ESP Block and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes address several related aspects of postoperative analgesia and recovery: opioid consumption at a separate time point, reported pain, and time to first ambulation. Their overall pattern is not uniformly aligned in one direction. The arm estimates vary in direction, and the corresponding uncertainty intervals include zero. The record therefore does not present a consistent, precise separation across these secondary measures.

These outcomes provide context for the primary endpoint, but they do not replace it. OME at a different time point describes medication use over a distinct timeframe, whereas a pain score captures a participant-reported experience and ambulation reflects a recovery milestone. Similar or differing patterns across these measures could be informative, but they should not be assumed to measure the same underlying quantity. The primary result concerns cumulative OME over 24 hours; the secondary outcomes are related evidence, not independent confirmation of that result.

The registry lists many secondary outcomes and repeated measurements, but fewer results are posted than the total number listed. The record does not report why some listed outcomes are absent, whether all were assessed, or how the outcome reporting was selected. It also lists no reported analyses for these secondary outcomes. These gaps make it difficult to assess how complete the secondary evidence is.

Unadjusted secondary results carry less inferential weight when many outcomes are examined. Looking across multiple measures can produce apparently notable findings by chance, particularly when no multiplicity strategy is reported. The registry record does not describe a hierarchy of secondary outcomes, adjustment for multiple testing, or a plan distinguishing confirmatory from exploratory results. The secondary findings are therefore best treated as descriptive and hypothesis-generating rather than as separate proof of a treatment difference.

In general, agreement among outcomes can strengthen coherence, while disagreement may reflect different constructs, timeframes, measurement error, or chance. The posted results should be interpreted with those distinctions in mind, without choosing an isolated secondary result as decisive. The registry record does not provide enough methodological detail to determine whether outcome collection and analysis were consistent across all listed measures.

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

• Oral Morphine Equivalents (OME)
• Oral Morphine Equivalents (OME)
• Oral Morphine Equivalents (OME)
• Oral Morphine Equivalents (OME)
• Oral Morphine Equivalents (OME)
• Visual Analog Scale Pain Scores
• Visual Analog Scale Pain Scores
• Visual Analog Scale Pain Scores

9. Statistical Interpretation

10. Statistical Methods Explained

The registry posts continuous outcomes as means or least-squares means, with a measure of spread, and gives unadjusted mean differences for the arm comparisons. A mean describes the arithmetic average of observed values. A standard deviation describes how dispersed individual observations are around their group mean; it is not the uncertainty in the estimated mean itself. A standard error, used for some secondary outcomes, describes uncertainty in an estimated quantity under the method used to obtain it. The registry record does not explain the models used to produce the least-squares means or their standard errors.

What does a mean difference represent?

A mean difference is the estimated average outcome in one group minus the average in the reference group, with the direction stated for each comparison. For the primary outcome, the estimate is given for ESP Block compared with IT Injection. A positive value indicates a higher estimated mean in the ESP Block arm under that convention; a negative value indicates a lower estimated mean. The estimate is a point estimate, not a certainty about the true difference in the population.

For the primary endpoint, the posted arm summaries are means with standard deviations. The reported mean difference and interval are unadjusted recalculations from those summaries. A recalculation of this kind is useful for describing the posted group summaries, but it cannot reproduce a model-based analysis whose details are absent. The registry record does not report covariate adjustment, a test statistic, a model specification, or an analysis population for the primary comparison.

How should the p-value be read?

A p-value describes how unusual data at least as inconsistent with a specified null hypothesis would be under the assumptions of a statistical test. It is not the probability that the null hypothesis is true, nor does it measure the clinical importance of an effect. The primary unadjusted p-value is 0.939. Because the registry does not report the test or model used by a sponsor analysis, this value should be read as part of the posted unadjusted comparison rather than as a complete account of the trial’s statistical analysis.

A p-value by itself does not show the range of effects compatible with the data. The confidence interval adds that information by displaying uncertainty around the estimated difference. A broad interval can include the null value and still leave substantial possibilities on either side. Failure to distinguish a difference from zero is not the same as demonstrating equivalence; an equivalence conclusion requires a prespecified margin and an analysis designed for that question. Such a margin and analysis are not reported in the registry record.

Why do standard deviations and standard errors differ?

A standard deviation describes variation among individual outcome values. A standard error describes uncertainty in an estimate, such as a group mean. The posted primary outcome is reported as a mean with a standard deviation. Some secondary outcomes are reported as least-squares means with standard errors. These summaries are not interchangeable: the standard error does not directly show the spread of individual patients’ outcomes, and the standard deviation does not directly give the uncertainty of the difference between group means.

Least-squares means are model-based averages, often adjusted for terms in an analysis model. The registry does not report which terms, if any, were included for these outcomes. It also does not describe the estimation method, assumptions, or adjustments used. Consequently, the secondary least-squares means should be treated as posted estimates whose model context is unavailable in the registry record.

What does an unadjusted comparison leave out?

An unadjusted comparison uses the posted group summaries without accounting for other variables. Randomization is intended to balance prognostic characteristics across groups over repeated assignments, but chance imbalances can remain in a particular trial. An adjusted model may account for prespecified characteristics and can change an estimate or its precision. No adjusted analysis is reported in the registry record, so there is no basis for describing the primary result as adjusted or for assessing sensitivity to covariates.

Interpretation also depends on how participants were analyzed. An intention-to-treat analysis generally retains participants in their assigned groups, while other analysis populations may use different eligibility or outcome-availability rules. The registry record does not identify an analysis population or explain how crossovers, withdrawals, or missing measurements were handled. The displayed outcome counts alone do not establish which analysis principle was used.

Why does multiplicity matter?

The registry lists multiple outcome measures, including repeated OME and pain-score outcomes. When many outcomes or time points are examined, the chance of observing a seemingly notable result by chance can increase if each is interpreted separately. A multiplicity strategy might define a hierarchy, adjust inference, or designate results as exploratory. The registry record does not report a multiplicity plan. The secondary p-values are therefore unadjusted, and their interpretation should be more cautious than that of a single prespecified primary outcome. It is also not reported whether all listed outcomes were planned in the same way or whether any analysis decisions were made after observing the data.

General statistical context: if outcome variability is greater than a model assumes, standard errors and confidence intervals from that model may be unreliable. The outcomes are presented as continuous measures, but the registry record does not provide enough detail to assess model diagnostics, distributional assumptions, or whether alternative methods were considered. No claim about those checks can be made from the posted record.

11. Confidence Intervals and Precision

Precision concerns how tightly the data estimate a quantity. For the primary outcome, the estimated mean difference for ESP Block compared with IT Injection is 0.68 mg morphine equivalents, with a 95% confidence interval from -16.67 to 18.03. The interval includes zero and values on either side of it. It therefore does not isolate a single direction of difference, and its range indicates uncertainty about the size and direction of the group difference.

In general, a confidence interval is a range generated by a statistical procedure that, under its assumptions, would contain the target parameter at the stated coverage rate over repeated studies. It is not a range containing a known proportion of individual patient outcomes, and it is not a guarantee that the true value lies within this particular interval. The interpretation also depends on the analysis method and assumptions. The registry record does not report a sponsor analysis model for the primary comparison; the posted comparison is an unadjusted recalculation from the arm summaries.

The primary arm standard deviations are 55.39 for IT Injection and 34.67 for ESP Block, while the group means are 44.49 and 45.17. These standard deviations describe variation in participant outcomes, not the precision of the estimated contrast. Precision of a group comparison depends on the amount of information in both groups and the variability of the outcome. The record does not report a prespecified clinically important difference, so the confidence interval cannot be classified against a clinical threshold using the registry alone.

The interval should be read alongside the point estimate and the outcome’s scale. A p-value of 0.939 does not replace the interval or resolve its breadth. The posted data do not establish equivalence, because no equivalence margin or corresponding analysis is reported in the registry record. The interval instead communicates that the estimated group difference remains uncertain across values on both sides of zero.

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 display is a planning illustration based on the observed effect, not the trial’s original design calculation. For continuous outcomes, the figures are participants per arm, not a total across both arms. The registry’s planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set at the stated percentage of the observed effect. The original design assumptions and sample-size justification are not reported in the registry record.

The 80% power column gives the number of participants per arm indicated by those assumptions for an 80% chance of detecting the specified effect if that effect were the true one. The 90% power column gives the corresponding planning number for a 90% chance. These are planning targets under a statistical model, not guarantees about a future study’s result. The sample-size figures in the display refer to participants per arm; the event-total convention applies to time-to-event planning displays, not these continuous outcomes.

The rows use the full observed effect and planning for 75% or 50% of the observed effect. Smaller target effects require more participants because a subtler difference is harder to distinguish from random variation. The displayed numbers can become very large when the observed effect is small, as in the primary OME comparison. Such estimates are sensitive to the observed effect and variability in this trial, and should not be treated as a standalone recommendation for a future study without a clinical target and a design justified for that question.

This is not observed power. It is a prospective planning illustration computed from the observed effect and the stated assumptions, not a measure of how likely the completed trial was to detect its true effect.

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 = 0.680; pooled standard deviation σ = 46.685.
2. n = 2 × (1.96 + 0.842)² × 46.685² / 0.680² = 73,989.3, rounded up to 73,990 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 <- 0.68                      # observed difference in means
sigma <- 46.6846880679308                     # 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(5257941)
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 = 73,990 (80% power), 99,051 (90% power)
 75% of observed effect: n per arm = 131,537 (80% power), 176,091 (90% power)
 50% of observed effect: n per arm = 295,958 (80% power), 396,203 (90% power)
power.t.test: 73990.2 
Simulated power at n = 73,990 per arm: 0.797 (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 lists multiple secondary measures, including repeated OME and visual analog scale pain assessments, but does not report a plan for controlling multiplicity. When multiple outcomes or time points are tested, interpreting each p-value as if it were the only test can overstate the strength of the evidence. A prespecified hierarchy or adjustment method can address this issue, but no such approach is reported in the registry record. The primary outcome remains the main posted endpoint, while secondary results warrant more cautious, descriptive interpretation.

There are also limits to what can be inferred about missing data. The registry lists 116 participants as enrolled, while the primary outcome is posted for 56 participants in IT Injection and 51 in ESP Block. It does not explain the participant flow, state whether the outcome counts represent everyone randomized, or describe withdrawals, exclusions, or unavailable measurements. The reason for the difference between enrollment and the listed outcome counts is not reported in the registry record; it should not be attributed to a particular cause.

The analysis population is not identified. The record does not state whether analyses followed assigned groups, included only participants who received the assigned intervention, or used another rule. It also does not report an imputation method, a sensitivity analysis for missing outcomes, or how partial outcome measurements were treated. These details matter because the estimated group contrast can depend on which participants and measurements are included.

The record lists zero reported analyses, and no statistical analysis plan is included. Details such as the primary test, covariate adjustment, handling of protocol deviations, and prespecified treatment of secondary outcomes are not reported in the registry record. This absence does not show that no analysis was conducted; it means the registry record does not document those methods. As a result, the posted summary estimates can be described, but their relationship to a prespecified analysis strategy cannot be assessed.

The study is listed as terminated, but the reason and any consequences for planned follow-up or outcome reporting are not reported. Without that context, it is not possible to determine whether termination affected missingness, the number of analyzed participants, or the completeness of posted outcomes.

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.

Most frequent non-serious adverse event terms

The registry reports zero serious adverse events in each arm and zero deaths in each arm. The serious-event counts are reported among 56 participants at risk in the IT Injection arm and 51 in the ESP Block arm. These are observed counts in the posted record; they do not establish that serious events could not occur or that the approaches have identical safety profiles.

Other, non-serious adverse events are reported for 7 participants in the IT Injection arm and 2 in the ESP Block arm, with 56 and 51 participants at risk, respectively. The registry does not provide the event descriptions, severity details, timing, relatedness assessments, or methods used to collect and classify these events. The counts should therefore be read as registry summaries rather than as a complete characterization of safety.

Differences in adverse-event counts do not by themselves establish that one approach caused more events. The record does not report a comparative statistical analysis of adverse events, and the counts should not be interpreted as adjusted rates. Small event counts can be uncertain, and the registry does not give enough detail to assess whether event ascertainment was equally complete in both groups. These figures describe what was posted, not a clinical safety recommendation.

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

The posted primary result estimates a mean difference of 0.68 mg morphine equivalents for ESP Block compared with IT Injection in cumulative OME 24 hours after surgery. The 95% confidence interval ranges from -16.67 to 18.03, and the unadjusted p-value is 0.939. The estimate is near zero, but the interval includes possible differences in either direction. The results therefore do not establish that the groups are equivalent, nor do they establish a clear difference in primary outcome.

The interpretation is limited by what the registry reports. It does not give the original sample-size justification, a sponsor-reported statistical analysis, an analysis population, or a missing-data strategy. The registry lists 116 participants enrolled but posts primary outcome results for 56 and 51 participants by arm without explaining the participant flow. It also lists the study as terminated without reporting the reason. Each of these omissions leaves uncertainty about the context and completeness of the results.

Randomization supports a comparative design, but this study was not masked. Participant and clinician expectations may matter for outcomes involving reported pain or clinical decisions, and the record does not say whether outcome assessment was masked. OME consumption, pain scores, and ambulation measure different dimensions of postoperative care; no one measure should be treated as a complete account of recovery.

The secondary outcomes add descriptive context but are numerous, unadjusted, and not accompanied by a reported multiplicity plan. They should not be used to select a favorable isolated finding or to override the primary result. The posted results do not establish that either regional approach is clinically preferable, and they do not establish that the approaches have the same effect. They describe estimates and uncertainty in this particular record.

In general, a null-compatible confidence interval can reflect limited precision as well as a small underlying difference. Distinguishing those possibilities requires an adequately justified design, complete follow-up, and a transparent analysis plan. Those elements are not fully documented in the registry record. The appropriate statistical reading is therefore cautious: the primary estimate is close to zero, but its uncertainty and the available reporting do not support a definitive equivalence or superiority conclusion.

17. Why This Trial Matters Statistically

This trial is statistically interesting because it compares two distinct regional analgesia approaches in a randomized parallel design and posts a clinically interpretable primary outcome: cumulative OME during the first 24 hours after surgery. The primary estimate is close to zero, but its confidence interval covers differences in both directions. This illustrates why a point estimate alone is not enough to judge what the data can establish.

The record also illustrates the difference between a randomized design and a fully documented statistical analysis. Random allocation is an important design feature, yet the registry does not report the allocation method, concealment procedures, analysis population, or model used for the posted outcomes. These details help readers evaluate how the comparison was conducted and whether the analysis reflects the randomized assignment.

Multiplicity is another relevant issue. Several secondary outcomes and time points are listed, but no adjustment or outcome hierarchy is reported. The pattern across secondary outcomes can be described, but multiple unadjusted findings do not carry the same inferential weight as a clearly defined primary endpoint. Transparent reporting of how secondary analyses were planned would help distinguish confirmatory evidence from exploratory observations.

Finally, the enrollment figure, outcome counts, and terminated status make participant flow and completeness especially important to assess. The registry does not explain the relation among these details. Reporting participant disposition, missing-data handling, and reasons for study termination would make the posted estimates easier to interpret. These are general reporting considerations, not claims about why the trial ended or why outcomes are absent.

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.

Several trial-specific reporting limitations constrain interpretation. The study is listed as terminated, but the reason for termination is not reported in the registry record. It is therefore not possible to determine whether termination affected recruitment, follow-up, or the planned outcome reporting. The record gives a total enrollment of 116, while the primary outcome arm counts are 56 and 51; the participant flow and explanation for these counts are not reported.

The registry identifies the study as randomized and unmasked, but does not describe the randomization sequence, allocation concealment, or whether outcome assessors were masked. The lack of masking is relevant to participant-reported pain and care decisions, although the registry does not provide information about how those outcomes were collected or standardized.

The statistical analysis plan is not reported. The record does not identify the analysis population, primary test, model specification, covariates, or missing-data methods. No sponsor-reported analyses are listed. The primary comparison is therefore available as an unadjusted recalculation from posted summaries, rather than as a documented full trial analysis.

Many secondary outcomes are listed, but fewer results are posted, and a multiplicity strategy is not reported. The registry does not clarify whether unposted outcomes were not measured, not analyzed, or omitted for another reason. The adverse-event summaries also lack event descriptions and collection or classification details. These limitations do not prove that the study methods were inadequate; they identify information that is not available in the registry record and that limits independent assessment.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: ESP Block VS Intrathecal Opioid After Laparoscopic Colorectal Surgery — NCT05257941.
• Registry record last updated 2026-03-02; status last verified 2026-02.
• Results first posted 2026-03-02.
• 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

NCT05257941 is a randomized, open-label, parallel-group study comparing intrathecal injection with an erector spinae plane block for postoperative analgesia after laparoscopic colorectal surgery. The listed sponsor is Indiana University. The registry lists PHASE1 and PHASE2, enrollment of 116, study start on 2022-01-27, primary completion on 2024-08-26, and status as terminated.

The primary endpoint is cumulative OME 24 hours after surgery. The posted arm means are 44.49 mg morphine equivalents for IT Injection and 45.17 mg morphine equivalents for ESP Block. The unadjusted mean difference is 0.68, with a 95% confidence interval from -16.67 to 18.03 and an unadjusted p-value of 0.939. The interval includes differences in either direction and does not establish equivalence.

The registry also posts secondary outcome summaries and adverse-event counts, but does not report a statistical analysis plan, multiplicity strategy, analysis population, missing-data approach, or reason for termination. These gaps, along with unexplained participant flow, limit how fully the estimates can be assessed.