CLinical Evaluation of Aspiration for Removal ANd ClearancE of Stones: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for CLinical Evaluation of Aspiration for Removal ANd ClearancE of Stones (NCT06615713), a na na study. The primary outcome is Stone Clearance (% Reduction in Stone Volume).

2. Clinical Question

3. Trial Design

NCT06615713 is a prospective, single-group device study of SURE using the CVAC System. The registry lists the study as completed, with enrollment of 30. Its recorded start date is 2024-09-05, and its primary completion date is 2025-01-31. The listed phase is NA, allocation is NA, and masking is NONE. These entries describe a study without a randomized allocation or masking; the record does not identify a control group.

The intervention description characterizes the CVAC System as a catheter system with integrated vision, irrigation, and aspiration. Its intended use in the study is removal of urinary stones and stone material. The brief summary states that the study purpose is to assess safety and efficacy. That purpose does not, by itself, establish that either outcome was demonstrated.

The primary endpoint is stone clearance, defined as percent reduction in stone volume at 30 days. Imaging is described as non-contrast CT with 2.0 mm slice thickness. The primary endpoint analysis population is described as all kidneys available at follow-up, rather than all enrolled participants. The number of kidneys contributing data is not reported in the registry record.

The record lists 3 outcome measures and 0 analyses. It does not report a statistical analysis plan, a sample-size justification, interim analyses, or details of how outcomes were analyzed. Planning assumptions associated with sample-size illustrations describe a hypothetical two-arm calculation; they are not the design of this single-group trial and are not a rationale for its enrollment. Numerical planning illustrations 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: All kidneys available at follow-up were analyzed.

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 Stone Clearance (% Reduction in Stone Volume), measured over 30 Days.

The primary endpoint is titled Stone Clearance, with the measure expressed as percent reduction in stone volume. It compares baseline stone volume with stone volume assessed at 30 days, using non-contrast CT with 2.0 mm slice thickness. A change in measured volume can summarize the amount of stone material remaining at the imaging assessment relative to baseline. Such an imaging measure provides a defined way to quantify change over time, rather than relying only on a general description of stone clearance.

The endpoint is specified as a mean with standard deviation. The registry record says that all kidneys available at follow-up were analyzed. It does not report the number of kidneys included, the observed mean, the standard deviation, or an interval estimate. Consequently, the posted results do not show the size or variability of the observed change.

The endpoint description gives a formula based on baseline and 30-day stone volume. Its accompanying prose says that a positive result indicates a decrease in stone volume removed during the procedure, while a negative value indicates an increase in stone volume following the procedure. The phrase about a decrease in volume removed does not align clearly with the formula's description of change in stone volume. This wording ambiguity should be kept in mind; the record does not clarify it further.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary measure is continuous: percent reduction in stone volume. A continuous outcome can take values across a range rather than being limited to categories. The registry specifies a mean and standard deviation as its summary form. The mean describes the average measured result in the analyzed observations. The standard deviation describes how dispersed individual measurements are around that average; it is not an estimate of uncertainty in the mean. The registry record does not report either statistic for the primary endpoint.

The endpoint uses an imaging comparison between baseline and 30 days. Non-contrast CT is the stated assessment method, with 2.0 mm slice thickness. Measurement-based outcomes depend on a consistent definition of what is measured and when it is assessed. The registry gives the formula and imaging details, but does not describe image reading procedures, reader masking, measurement reproducibility, or how multiple kidneys belonging to a participant were handled. These details are not reported in the registry record.

A confidence interval is a statistical way to express uncertainty around an estimate, given a model and its assumptions. It can help readers distinguish a relatively precise estimate from one that is compatible with a broader range of values. It does not show that a result is clinically important, and it does not remove limitations in study design or data collection. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be judged from the posted results.

The registry lists a mean and standard deviation but does not report a statistical test, a model, or a test result for the primary outcome. The analysis count is 0. It is therefore not possible to identify whether the sponsor used a paired analysis, a particular distributional assumption, an adjustment, or another method. The endpoint compares two time points by definition, but that fact alone does not establish which statistical method was used.

The record includes general assumptions for sample-size illustrations: a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect defined as a stated fraction of the observed effect. These are planning assumptions, not the trial's own design. The study is single-group, and the record does not give the observed effect needed to interpret such illustrations. Any sample-size figures based on those assumptions would be hypothetical planning quantities, not observed power and not evidence about the trial's result. Sample-size justification for the actual study is not reported in the registry record.

In a two-arm planning calculation, equal allocation means assigning the same planned number of participants to each hypothetical arm. A normal approximation uses a mathematical distribution to approximate the behavior of an estimator or test statistic. Such assumptions can make a planning calculation tractable, but their relevance depends on the proposed design, outcome distribution, and analysis. They do not turn a single-group study into a controlled comparison. No conclusion about the adequacy of the trial's enrollment can be drawn from the listed assumptions alone.

Over-dispersion is a general concern when observed variability exceeds what a chosen statistical model assumes. If a model understates variability, uncertainty estimates can be too narrow and tests can appear more informative than warranted. This is a general statistical issue, not a reported feature of this study: the registry provides no primary endpoint distribution or analysis from which to assess over-dispersion.

Missing-data methods also matter for a follow-up imaging endpoint. If some kidneys lack 30-day imaging, the analyzed observations may not represent all enrolled participants or all kidneys eligible for assessment. The registry says that all kidneys available at follow-up were analyzed, but gives neither the number missing nor the reason for any missing imaging. It does not describe imputation, sensitivity analyses, or other handling of unavailable outcomes. Thus, the impact of missing follow-up data cannot be evaluated.

Finally, the single-group design supports descriptive reporting of outcomes in the treated group but does not provide a randomized treatment contrast. Statistical adjustment, if any, is not reported in the registry record. The absence of analysis details means readers cannot check model choices, assumptions, or the link between the endpoint definition and the reported estimate. In this record, no numerical primary estimate is available to interpret in the first place.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Steerable Ureteroscopic Renal Evacuation (SURE) Wi")
n   <- c(26)
m   <- c(96.2)
sp  <- c(6.5)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Steerable Ureteroscopic Renal Evacuation (SURE) Wi  26  96.200  6.500  93.575  98.825

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. It does not identify a multiplicity strategy, such as a prespecified hierarchy among outcomes or an adjustment for testing several outcomes. A multiplicity plan matters when several hypotheses are tested because interpreting each test at its nominal threshold can increase the chance of a chance-positive finding across the set. That is a general statistical concern; the registry record does not report whether formal hypothesis tests were conducted or how they were handled.

The primary endpoint has a stated timeframe of 30 days and a stated analysis population of all kidneys available at follow-up. The number of kidneys with baseline and follow-up measurements is not reported in the registry record. The record also does not describe the number of participants who completed follow-up imaging, the reasons for missing measurements, or how missing data were handled. The phrase “all kidneys available at follow-up” does not establish that every enrolled participant or kidney contributed data.

The record does not report whether there were prespecified subgroup analyses, sensitivity analyses, interim analyses, or adjustments for other variables. It does not provide an analysis plan or a statistical methods description. These omissions make it difficult to assess whether the reported endpoint analysis, if any, followed a prospectively specified approach. Because no primary estimate or analysis is posted, neither multiplicity nor missing-data handling can be evaluated against observed results.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 30 participants at risk in the SURE with CVAC System group. It reports 2 participants affected by other adverse events among 30 at risk, and 0 deaths. These are the recorded counts for the listed safety categories; they do not give a comparative risk estimate because the study has no separate control group.

The record does not provide terms for the serious events, and no top serious-event terms are listed. It also does not describe the other adverse events, their severity, timing, relatedness to the device or procedure, or duration of safety follow-up. The counts should therefore be read as a limited registry summary, not as a complete account of the clinical details or a basis for comparing safety with another treatment.

Zero recorded serious events does not establish that the risk is absent. In general, safety interpretation depends on the amount and duration of observation, the completeness of reporting, and the size and characteristics of the group studied. Those details are not fully reported in the registry record. The posted counts describe what is recorded, without resolving those broader uncertainties.

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

The registry record establishes that a prospective, completed, single-group study enrolled 30 participants and evaluated SURE using the CVAC System. It specifies a primary imaging endpoint based on change in stone volume from baseline to 30 days, measured by non-contrast CT with 2.0 mm slice thickness. It also records safety counts for serious adverse events, other adverse events, and deaths.

The record does not report the numerical primary endpoint result. There is no posted mean or standard deviation, and no confidence interval or analysis result. As a result, readers cannot tell from the record how much stone volume changed on average, how variable the measurements were, or how precisely the mean was estimated. The study's completed status does not supply those missing outcome statistics.

The design also does not support a direct comparison with another treatment or with no intervention. A single-group observation can describe what was recorded after the intervention, but it cannot isolate the intervention's contribution from other possible influences. The registry record does not provide a comparator group or a comparative estimate.

The safety counts are similarly descriptive. The record reports 0 serious adverse events, 2 participants affected by other adverse events, and 0 deaths, but does not supply detailed event descriptions or a comparison group. These counts do not determine how safety would compare across treatments.

Accordingly, the registry entry conveys the study's purpose, design, endpoint definition, and limited safety counts, but does not provide enough numerical outcome information to judge the primary endpoint's magnitude or precision. It does not establish a comparative effect or resolve the missing-data and analysis questions.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between a well-defined endpoint and a reported result. The registry identifies a continuous imaging measure, its baseline-to-follow-up definition, the assessment timeframe, and the imaging method. Those details help clarify what the investigators intended to measure. Yet without the observed mean, standard deviation, or an uncertainty interval, the endpoint cannot be quantitatively interpreted from the registry record.

The design is equally important to interpretation. A single-group study can describe outcomes among participants receiving the device-based intervention, but it does not create a randomized comparison. Recognizing that distinction prevents a within-group change from being mistaken for a comparative treatment effect. No control group or comparative analysis is reported.

The record also illustrates why the analysis population and missing follow-up information matter. The primary endpoint applies to kidneys available at follow-up, while enrollment is given as participants. Without the number of kidneys analyzed or information about unavailable imaging, readers cannot assess how the analyzed observations relate to the enrolled group.

Finally, the safety counts are useful as registry-reported descriptive information, but their interpretation depends on details not recorded, including event descriptions and observation context. The main statistical lesson is that endpoint definitions and completion status do not replace outcome estimates, analysis methods, or a suitable comparison. The registry leaves those elements unreported.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main limitation for statistical interpretation is that the registry record does not report the primary endpoint estimate or its variability. Although the measure is defined as percent reduction in stone volume at 30 days, there is no mean, standard deviation, or confidence interval. The record therefore does not permit assessment of the magnitude or precision of the observed outcome.

The single-group design has no concurrent comparator. Any observed change would be descriptive of the treated group and could not be attributed to the intervention by comparison with another group. The registry does not report a comparative estimate or a randomized treatment contrast.

The primary analysis population is described as all kidneys available at follow-up, but the number of kidneys assessed and the extent of missing imaging are not reported. The record does not state how missing outcomes were handled. It also does not describe how multiple kidneys per participant were treated statistically, image-reading procedures, or measurement reproducibility.

Further limitations are the absence of reported statistical methods, multiplicity handling, interim-analysis information, and a sample-size justification. The endpoint description's prose about a positive result is not fully clear in relation to its formula. Safety reporting gives aggregate counts but not event details or a comparison group. These limitations concern what can be evaluated from the registry record; they do not establish what was or was not done outside the posted information.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: CLinical Evaluation of Aspiration for Removal ANd ClearancE of Stones — NCT06615713.
• Registry record last updated 2026-04-28; status last verified 2026-04.
• Results first posted 2026-04-28.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT06615713 is a completed prospective, single-group study of SURE using the CVAC System, sponsored by Calyxo, Inc. Enrollment was 30. The record lists a study start date of 2024-09-05 and a primary completion date of 2025-01-31. Allocation is NA, masking is NONE, and phase is listed as NA.

The primary endpoint is percent reduction in stone volume at 30 days, assessed by non-contrast CT with 2.0 mm slice thickness. The analysis population is described as all kidneys available at follow-up. The registry lists 3 outcome measures and 0 analyses, but does not report a numerical primary endpoint result or statistical analysis details.

Safety counts are 0 serious adverse events among 30 at risk, 2 affected participants for other adverse events among 30 at risk, and 0 deaths. Detailed descriptions of the other adverse events and further safety context are not reported in the registry record.