ShockPulse-SE vs. Trilogy Trial: Comparing the Performance of Two Intracorporeal Lithotripters for Removal of Large Renal Calculi: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for ShockPulse-SE vs. Trilogy Trial: Comparing the Performance of Two Intracorporeal Lithotripters for Removal of Large Renal Calculi (NCT03959683), a randomized na study. The primary outcome is Stone Clearance Rate Defined as the Kidney Stone Surface Area Measured by Pre-operative Computed Tomography (CT) Scan Divided by the Time to Remove the Targeted Stone Burden..

2. Clinical Question

The stated clinical aim was to compare the devices' performance in breaking up and removing stones, with the brief summary describing a hypothesis that Trilogy would increase stone-clearance rate by 25% compared with ShockPulse-SE. That hypothesis is a stated expectation, not a result. The primary result is a comparison of mean clearance rates, so the posted data describe an average outcome in each randomized arm rather than the experience of every individual participant.

The record also identifies stone-free status on postoperative CT imaging and at final follow-up as a secondary outcome. The posted stone-free result is specifically for postoperative day 1. Device malfunctions and complications are also listed among the secondary outcomes, but detailed outcome results for those measures are not reported in the registry record. The trial therefore addresses a device-performance question using a rate measure, with stone-free status and safety-related outcomes offering additional, distinct perspectives.

3. Trial Design

The study is listed as a completed, randomized, single-masked, parallel-group trial sponsored by Indiana University. Enrollment was 100. The record lists 49 participants in the ShockPulse intervention arm and 51 in the Trilogy intervention arm for the primary outcome. The study began on 2019-02-19, and primary completion is listed as 2020-07-29. The phase is listed as not applicable.

Random allocation means assignment to the device groups was intended to be determined by a chance-based process. A parallel design means participants were assigned to one device group rather than receiving both devices in sequence. The record labels masking as single, but does not state who was masked; that detail is not reported in the registry record. Additional details of allocation concealment, the randomization procedure, and how masking was maintained are not reported in the registry record.

The arm descriptions specify that both devices were used to fragment urinary tract calculi in the kidney, ureter, and bladder. The primary outcome, however, is framed around clearance of a targeted kidney stone burden. The record describes the rate as surface area measured by pre-operative CT divided by the time to remove that burden. The clock begins when the lithotripter starts fragmenting the stone and stops when all fragments are removed from the kidney by visual inspection, before final visual inspection with a flexible nephroscope.

Although the trial is marked completed, the record does not report a detailed participant flow, the number randomized but excluded from each analysis, or analysis-population definitions. Whether every randomized participant contributed to each result is not reported in the registry record. Those details matter when interpreting a randomized comparison because exclusions after assignment can affect how closely the reported groups preserve the original randomization.

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: Intention to treat - there was one patient that was recruited to the wrong arm but was maintained in that arm - and there was complete follow up with out any cross-over.

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.

Population: Participants of the Trilogy versus ShockPulse trial.

6. Primary Endpoint

The registry lists the primary outcome as Stone Clearance Rate Defined as the Kidney Stone Surface Area Measured by Pre-operative Computed Tomography (CT) Scan Divided by the Time to Remove the Targeted Stone Burden., measured over Postoperative day 1.

The primary endpoint is stone-clearance rate in cm^3/min. It is defined as the kidney stone surface area measured by pre-operative computed tomography divided by the time required to remove the targeted stone burden. The recorded timing starts when the lithotripter unit begins fragmenting the stone and ends when all fragments have been removed from the kidney based on visual inspection. This measurement precedes final visual inspection of the kidney with a flexible nephroscope.

A rate combines the amount of stone burden being addressed with the time taken to remove it. In general, such a measure is intended to describe procedural efficiency rather than simply whether a participant is stone-free at a later assessment. The endpoint's use of pre-operative imaging gives a measure of the targeted burden, while the recorded procedural interval supplies the time component. The registered timeframe is postoperative day 1, although the described timing interval itself is intraoperative.

The primary endpoint is a continuous measure, and the registry reports its mean and standard deviation in each arm. An average rate can provide a compact comparison between randomized groups, but does not convey the full range of individual rates. The standard deviations help describe variability around the arm means. The record does not report further details about how surface area was calculated, how timing was recorded, or whether the endpoint was assessed by a masked evaluator.

7. Results Posted in the Registry

• Trilogy Intervention Arm: mean 0.77 versus 1.22 on control; difference -0.45 (95% CI -0.95 to 0.05), standardized effect d = -0.36; z-test p = 0.080.

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.

Number of Participants With Stone Free Status as Defined by the Presence or Absence of Stone Material on Postoperative CT Imaging and at Final Follow up

• 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:
  • ShockPulse-SE: 89.8% (44/49) versus 90.2% (46/51) on control; risk difference -0.4 percentage points (95% CI -12.2 to 11.4), risk ratio 1.00 (0.87–1.13); unadjusted two-proportion z-test p = 0.947.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between ShockPulse-SE and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes broaden the assessment beyond the primary procedural rate. Stone-free status on postoperative day 1 is a binary status measure, while the primary endpoint is a continuous rate describing stone burden cleared over time. Device malfunctions and complications concern device use and surgical events rather than clearance rate itself. These domains are related to procedural performance, but they are not interchangeable outcomes.

The posted stone-free counts are relatively close between the two arms in the observed trial, and the reported risk-difference interval includes zero. That result does not establish a clear between-arm difference in stone-free status. It should not be treated as confirmation or contradiction of the primary endpoint: a participant's stone-free status at an imaging assessment does not directly measure the rate at which the targeted stone burden was removed during the procedure.

Detailed results for device malfunctions and complications as named secondary outcomes are not reported in the registry record. The safety summaries give counts of participants with serious and other adverse events, but those summaries do not provide the full event-level descriptions or establish whether events were caused by a device or procedure. Interpretation should keep those reporting formats and outcome definitions distinct.

Unadjusted secondary results carry less weight for claims about a single confirmatory question when many outcomes may be examined. In general, evaluating multiple outcomes increases the opportunity for apparently notable findings to arise by chance. Adjustment procedures or a prespecified hierarchy can address this issue, but a multiplicity strategy is not reported in the registry record. The secondary results are therefore best read as additional descriptive evidence, with the primary outcome remaining the registered main comparison and the uncertainty in each result kept in view.

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

• Device Malfunctions During Intraoperative Device Use as Described by Surgeon Completing the Device Questionnaire.
• All Complications Measured by the Clavien Classification of Surgical Complications
• Number of Participants With Stone Free Status as Defined by the Presence or Absence of Stone Material on Postoperative CT Imaging and at Final Follow up

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous, and the registry reports an arithmetic mean and standard deviation for each device group. A mean describes the group average on the measured scale, here cm^3/min. A standard deviation describes how dispersed individual observations are around that average. It is not the uncertainty interval for the mean, nor is it a range that contains every participant's result.

What does the mean difference express?

The posted comparison expresses the Trilogy mean relative to the ShockPulse mean. Its estimate is -0.45 cm^3/min. A negative value indicates that the observed mean in the named Trilogy group is lower than the observed mean in the ShockPulse group under that comparison's direction. The sign depends on which arm is subtracted from which; reversing the order would reverse the sign while leaving the underlying group results unchanged.

In general, a difference in means retains the endpoint's original units, which can make it easier to relate the estimate to the measure itself than a standardized effect. The reported primary result is an unadjusted comparison. The record does not report an adjusted model, covariates, or a rationale for any adjustment. It also does not report whether the analysis followed an intention-to-treat principle or another analysis population.

What does the p-value say?

The unadjusted p-value for the primary comparison is 0.08. In general, a p-value describes how compatible the observed data, and data at least as extreme under a specified test, are with a null model. It is not the probability that the null hypothesis is true, and it does not quantify the chance that the result will replicate. A p-value should be read with the effect estimate, uncertainty interval, outcome definition, and analysis plan.

The registry record does not report the test used to obtain the p-value, whether assumptions were checked, or whether the analysis was prespecified. The sample-size planning illustration uses a two-sided significance level of 0.05, but that planning assumption is not evidence that the same decision threshold or method was used for the trial's primary analysis.

Why does variability matter?

The observed standard deviations differ between arms: 1.67 in ShockPulse and 0.68 in Trilogy. In general, greater dispersion can make the mean difference less precise, particularly when sample sizes are limited. It can also signal that individual outcomes vary substantially within a group. The registry record does not report distribution plots, checks for skewness or unusual values, or methods intended to address unequal variability.

For some outcome types, a few large observations can strongly influence a mean. General statistical approaches may include robust methods or transformations when assumptions are unsuitable, but the record does not say whether any such methods were used. No such method should be inferred from the posted summary statistics alone.

How should the interval be understood?

In general, a confidence interval gives a range of values reasonably compatible with the data under the method used and communicates uncertainty in an estimate. It is not a guarantee that the true value lies within the particular calculated interval, nor does a wide or narrow interval speak directly to clinical importance. For the mean difference, the interval includes zero, so the posted estimate does not rule out no average difference. The registry record does not report the interval-construction method.

These methods explanations describe general statistical concepts. Specific details of the trial's statistical analysis plan, including model choice, assumptions, handling of outliers, missing-data methods, and prespecified subgroup analyses, are not reported in the registry record. The absence of a reported detail does not establish that the investigators did or did not perform a particular procedure.

11. Confidence Intervals and Precision

The primary mean-difference estimate is -0.45 cm^3/min. Its confidence interval extends across zero, so the posted interval is compatible with no average difference as well as with values on either side of zero. This is important because a single point estimate cannot show how uncertain the comparison is. The interval makes clear that the estimated direction should not be treated as settled.

In general, a confidence interval describes uncertainty around an estimate under the assumptions of the statistical method used. A narrower interval indicates greater precision than a wider interval on the same scale, but precision does not by itself establish importance. The registry record does not define a clinically important difference for the clearance-rate endpoint, so the practical importance of values within the interval cannot be determined from the record alone.

The arm standard deviations also help put precision in context. The ShockPulse standard deviation is 1.67 and the Trilogy standard deviation is 0.68. These values describe observed variation among participants, not uncertainty in the treatment comparison. Greater observed variability generally makes it harder to estimate an average difference precisely, all else being equal. The registry record does not report the confidence-interval method or adjusted estimates that might further inform precision.

The secondary stone-free result also has uncertainty: the posted risk-difference interval includes zero. This means the data do not precisely distinguish a difference from no difference on that measure. The primary and secondary outcomes use different scales and definitions, so their intervals should not be compared as though they quantify the same clinical quantity.

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 planning figures are illustrations based on the observed effect, not the trial's original design justification. The stated assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The assumed effect to detect is a stated fraction of the observed effect. For the continuous primary outcome, the figures are participants per arm. The registry record does not report the original trial's sample-size assumptions or justification.

The 80% power column means the illustrative number of participants per arm associated with an 80% chance of detecting the selected effect if that effect were the true one and the planning assumptions held. The 90% power column uses a higher target chance of detection under the same general framework. Neither column describes what happened in the completed trial or the chance that its result is correct.

The rows consider planning for 100%, 75%, and 50% of the observed effect. The smaller the effect one aims to detect, the more participants are generally needed, because a modest difference is harder to distinguish from random variation. The listed participant counts should therefore be read as planning illustrations for the specified assumed effects and methods, not as recommended enrollment numbers for a future study.

This is not observed power. Observed power calculated after seeing results does not provide a useful substitute for reading the effect estimate and its confidence interval. These figures instead show how sample-size requirements change under a set of stated planning assumptions. They do not establish that those assumptions were used when this trial was designed.

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 = -0.450; pooled standard deviation σ = 1.266.
2. n = 2 × (1.96 + 0.842)² × 1.266² / -0.450² = 124.2, rounded up to 125 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 <- -0.45                      # observed difference in means
sigma <- 1.26566591329688                     # 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(3959683)
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 = 125 (80% power), 167 (90% power)
 75% of observed effect: n per arm = 221 (80% power), 296 (90% power)
 50% of observed effect: n per arm = 497 (80% power), 665 (90% power)
power.t.test: 125.1 
Simulated power at n = 125 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 one primary outcome and three secondary outcomes. It also reports zero analyses. The listed secondary outcomes cover device malfunctions, complications measured by the Clavien Classification of Surgical Complications, and stone-free status. The record does not report a complete analysis plan describing how results across these outcomes were intended to be interpreted.

In general, testing multiple outcomes creates a multiplicity issue: the more comparisons examined, the more likely at least one may appear notable by chance if each is considered in isolation. Common approaches include adjusting significance thresholds, specifying a hierarchy of outcomes, or treating secondary findings as exploratory. Which approach, if any, was used is not reported in the registry record. The posted p-values are unadjusted, and the record does not report a multiplicity adjustment.

Missing-data methods are also not reported in the registry record. The result summaries identify arm sizes, but do not state whether any randomized participants lacked primary or secondary outcome data, how missing observations were handled, or whether sensitivity analyses were performed. A reported arm size alone does not resolve whether all randomized participants contributed to a particular endpoint.

Analysis-population definitions are not reported in the registry record. It is therefore unclear from the posted results whether analyses included all randomized participants, only participants who received the assigned device, or another subset. The record also does not describe protocol deviations, crossovers, or exclusions after randomization. These details are relevant because excluding participants after random assignment can weaken the protection that randomization provides against systematic differences between groups.

The record identifies the study as randomized and single-masked, but does not specify the masked party, allocation-concealment method, or statistical-analysis plan. These unreported details limit assessment of whether outcome assessment, analysis choices, and missing-data handling were planned in a way that protects against bias. They should be treated as reporting gaps, not as evidence that a particular method was or was not used.

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 adverse-event summaries report zero serious adverse events in each device group and zero deaths in each group. For other adverse events, the record reports six affected participants among 51 at risk in the Trilogy group and five among 49 at risk in the ShockPulse-SE group. These are participant counts, not event counts, and the record does not supply detailed descriptions of the other events in this summary.

In general, zero reported serious events in a group does not establish that the risk is absent; it describes what was recorded among the participants at risk during the reporting period. The registry record does not specify the adverse-event observation period or provide event-level detail for the serious-event listing. It also does not report a statistical comparison of these safety counts. The groups are modest in size, so these summaries alone cannot characterize uncommon harms or establish a difference between devices.

Adverse-event counts should be interpreted separately from the primary performance outcome. The registry record does not state whether the other adverse events were considered related to the device, procedure, or neither. The listed counts therefore support a description of reported events, not a causal conclusion.

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

The posted results describe average stone-clearance rates in two randomized groups and show a mean difference of -0.45 cm^3/min for Trilogy compared with ShockPulse. The observed means are lower in the Trilogy arm, while the confidence interval for the difference includes zero and the unadjusted p-value is 0.08. Taken together, these results show uncertainty about the size and direction of the average difference in the trial.

That interpretation is narrower than saying one device is better or worse. The registry result does not establish that the observed difference would recur in another group of participants, nor does it describe every participant's outcome. The record also does not define a threshold for a clinically important difference in clearance rate, so the clinical importance of the estimate cannot be settled from the posted statistical result alone.

The stone-free status result is a separate secondary measure, assessed on postoperative day 1. Its counts and interval do not substitute for the primary rate outcome. Likewise, the adverse-event summaries are limited descriptions of reported participant counts and do not provide a comprehensive comparison of safety. Each outcome speaks to a different question and has its own uncertainty and reporting limitations.

The trial was randomized, which is a design feature intended in general to support fair comparisons between groups. However, the record does not provide enough detail to verify allocation procedures, analysis populations, missing-data handling, or adherence to a prespecified statistical plan. The enrolled trial results should therefore be interpreted with attention to these reporting gaps as well as to the confidence interval.

Nothing in the posted results warrants a medical recommendation. The findings are a statistical description of this completed trial's registered outcomes. They do not establish the best choice for an individual, and the record does not report enough information to generalize confidently to populations or procedural settings beyond those represented.

17. Why This Trial Matters Statistically

This trial illustrates why an outcome's definition matters. Stone-clearance rate is a continuous measure combining stone burden and removal time, while stone-free status is a yes-or-no assessment at a specified postoperative time. Those outcomes can complement one another, but they do not measure identical aspects of a procedure. A numerical difference on one should not automatically be translated into a difference on the other.

The primary estimate also demonstrates why uncertainty matters as much as direction. The observed means differ, yet the confidence interval includes zero. Reading the point estimate alone could make the comparison seem more definitive than the data support. Reading the estimate alongside its interval preserves both the observed direction and the uncertainty around it.

The unequal standard deviations are another useful statistical feature. The observed spread is greater in ShockPulse than in Trilogy. Such variability can affect precision and can make averages less representative of individual results. A mean-only account would obscure that variation; reporting dispersion provides important context, even though it does not reveal the full outcome distributions.

Finally, the record distinguishes a post hoc planning illustration from the original trial design only indirectly through its stated assumptions. The planning figures use the observed effect and are not a record of the original sample-size rationale. This is a useful reminder that sample-size calculations made from observed results answer a different question from prospective design planning. The original assumptions and statistical plan are not reported in the registry record.

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 gaps limit interpretation. The registry record does not report detailed eligibility criteria, the randomization method, allocation concealment, or who was masked. It also does not provide participant flow or explain whether all randomized participants contributed to each outcome. Without those details, the balance and completeness of the analyzed groups cannot be fully assessed from the posted summaries.

The primary endpoint is described as a rate based on pre-operative CT-measured kidney stone surface area and procedural time. Further operational details, such as how surface area was calculated and how time was recorded, are not reported in the registry record. The stated postoperative day 1 timeframe is also not the same as the intraoperative measurement interval described for the rate, and the record does not explain this timing relationship further.

The record does not report the primary analysis method, assumptions checks, adjustment strategy, clinically important difference, missing-data methods, or statistical analysis plan. The unadjusted primary comparison can be read descriptively, but the absent plan limits assessment of whether it matches a prespecified analysis. Detailed results for device malfunction and complication outcomes are not reported in the registry record.

The adverse-event summaries lack event-level descriptions and do not report the observation period or attribution to device or procedure. The posted data also come from a trial with 100 participants, which limits how much can be learned about uncommon outcomes. These limitations do not invalidate the reported numbers, but they constrain the strength and breadth of conclusions that can be drawn from them.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: ShockPulse-SE vs. Trilogy Trial: Comparing the Performance of Two Intracorporeal Lithotripters for Removal of Large Renal Calculi — NCT03959683.
• Registry record last updated 2023-04-12; status last verified 2023-03.
• Results first posted 2023-04-12.
• 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

The completed study was a randomized, single-masked, parallel-group comparison of the Trilogy Lithotrite and ShockPulse-SE Lithotripsy System for removal of large renal calculi. Enrollment was 100, with 51 participants in the Trilogy arm and 49 in the ShockPulse arm for the primary result.

The primary endpoint was mean stone-clearance rate in cm^3/min. The observed means were 0.77 for Trilogy and 1.22 for ShockPulse; the reported mean difference was -0.45, with an unadjusted p-value of 0.08 and a confidence interval spanning zero. The posted secondary stone-free outcome and adverse-event summaries provide additional descriptive information, but they do not resolve the uncertainty in the primary comparison.

Key details about the analysis plan, missing data, analysis populations, and several secondary results are not reported in the registry record. The findings are best understood as estimates from this trial, with uncertainty and reporting limitations considered alongside the observed values.