Hand-carried Ultrasound to Assess Hydronephrosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Hand-carried Ultrasound to Assess Hydronephrosis (NCT03774719), a na na study. The primary outcome is Number of Participants With Absence of Hydronephrosis.

2. Clinical Question

In statistical terms, this is an assessment of a diagnostic approach rather than a comparison of clinical outcomes between treatment groups. The central issue is whether HCU classifications agree sufficiently with radiology-performed ultrasound to support the intended rule-out question. Such an assessment depends on both the number of participants and the number with and without hydronephrosis, as well as on how the reference assessment is defined and applied. Those details and the primary outcome result are not reported in the registry record. Consequently, the clinical question can be described from the study aims, but its accuracy cannot be quantified from the posted results.

3. Trial Design

The registry identifies NCT03774719, titled Hand-carried Ultrasound to Assess Hydronephrosis, as a single-group study sponsored by Washington University School of Medicine. Its official title describes HCU for ruling out hydronephrosis in acute kidney injury and acute kidney disease. Phase and allocation are listed as NA, and masking is listed as NONE. The study status is TERMINATED. The recorded start date is 2019-05-06, and the primary completion date is 2021-06-01.

The study intervention is a device, hand-carried ultrasound. The summary says trainees would undergo a short ultrasound training program and that the investigators would compare HCU assessments with radiology-performed ultrasound. The single-arm description says the intervention is HCU evaluation of the presence and degree of hydronephrosis. It also states that participants would be inpatients with a renal ultrasound ordered or performed within the past 4 hours.

There is an important discrepancy in the record’s participant counts. The enrollment field lists 6, while the single-arm description says the arm will be comprised of 154 inpatients. The record does not explain the difference, so neither figure can resolve the other. The posted serious adverse-event data list 6 participants at risk. The registry record does not report whether enrollment reflects actual enrollment, whether the arm description reflects an earlier plan, or how the discrepancy arose.

The record lists 4 outcome measures and 0 analyses. It does not report randomization, and the study has no like-for-like control comparison. That design can describe the enrolled group and may permit a diagnostic comparison if paired assessment data and suitable outcome definitions are available. It cannot, by itself, support a randomized causal comparison between HCU and another approach. No primary outcome result or diagnostic accuracy estimate is 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.

Before assignment: 18 patients were screened, 6 met inclusion criteria, agreed to participate and were enrolled in the study.

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 Number of Participants With Absence of Hydronephrosis, measured over Through study completion, up to an average of 1 day.

The primary endpoint is the number of participants with absence of hydronephrosis. More specifically, the registry defines it as the count of participants for whom none of the kidneys imaged with HCU have hydronephrosis, or dilation of the collecting system. The stated timeframe is through study completion, up to an average of 1 day.

This endpoint records a participant-level finding: it counts people meeting the no-hydronephrosis definition rather than reporting a continuous measurement. Such a count can describe how often HCU assessments found no hydronephrosis in the observed group. It does not, on its own, establish the accuracy of HCU as a rule-out test. For that, the classification from HCU needs to be compared with the reference assessment, and the relevant diagnostic measures need to be reported. The registry summary names sensitivity, specificity, positive predictive value, and negative predictive value as planned assessments, but their estimates are not reported in the registry record.

The endpoint result itself is also not reported in the registry record. Without the observed count and the total number included in the endpoint analysis, the frequency of the finding cannot be described. The enrollment discrepancy further cautions against treating the listed enrollment or arm description as the endpoint denominator.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a single-group design tell us?

General: A single-group design observes participants receiving the same study intervention or assessment. It can describe what happened in that group, but it does not create a randomized comparison between that group and a separate control group. A diagnostic study can still compare a test with a reference assessment within participants, but the paired observations and the comparison method need to be reported to interpret agreement or accuracy.

For this study, the intervention is HCU, and the registry summary describes radiology-performed ultrasound as the basis for comparison. The record does not report the paired results, the diagnostic accuracy calculations, or detailed procedures for comparing the assessments. The design description alone therefore cannot establish how HCU classifications performed relative to the reference assessment.

What does the primary count measure?

General: A count outcome records the number of participants meeting a defined condition. A count is interpretable only alongside a clearly identified analysis population and denominator. In a diagnostic setting, a count of participants with a negative finding is not enough to determine sensitivity, specificity, or predictive values, because those measures require information about test classifications in relation to the reference classification.

The registered condition is that none of the kidneys imaged with HCU have hydronephrosis. The record gives the endpoint’s timeframe as through study completion, up to an average of 1 day. It does not give the observed count, analysis denominator, or diagnostic cross-classification. The endpoint therefore cannot be converted into a reported accuracy estimate from the registry information.

Why do confidence intervals matter?

General: A confidence interval describes the uncertainty around an estimate under the assumptions of the statistical method. It helps distinguish a relatively precise estimate from one that could plausibly vary widely because the observed data are limited. For diagnostic accuracy, intervals around sensitivity, specificity, and predictive values are useful because a point estimate alone does not communicate how uncertain the estimate is.

No confidence interval or diagnostic estimate is reported in the registry record. It is consequently not possible to assess the precision of the intended accuracy measures. The small posted safety denominator is not a substitute for a diagnostic analysis denominator, and the record does not establish that the same participants contributed to each outcome.

Why does the participant-count discrepancy matter?

The enrollment field lists 6, while the arm description states that the group will be comprised of 154 inpatients. The registry record does not resolve the discrepancy. General: A difference between a recorded enrollment figure and an arm description makes it difficult to identify the number of participants actually observed, the number eligible for analysis, and the denominator used for each outcome. These distinctions matter for both estimates and their uncertainty. No denominator should be inferred by choosing one of the two figures without further documentation.

The posted adverse-event data list 6 participants at risk. That information describes the safety record’s denominator, not necessarily the number included in the primary endpoint analysis. It should not be used to fill in a missing primary outcome denominator.

What can sample-size planning illustrations show?

General: A sample-size illustration shows how an assumed effect and statistical design choices relate to a hypothetical recruitment target. It is a planning exercise, not an analysis of observed participants and not a measure of the probability that a completed study found a true effect. An illustration based on an observed effect is especially dependent on that effect estimate and should not be read as evidence that the study was adequately powered.

The registry record describes planning assumptions using a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect expressed as a stated fraction of the observed effect. It says that the illustration is computed from the observed effect, not from the trial’s own design. This study is identified as a single-group study, so those two-arm planning assumptions do not describe its registered design. No numerical sample-size illustration result is reported in the registry record, and such an illustration would not establish observed power.

What analysis details are unavailable?

The record lists 0 analyses. It does not report the statistical procedures used to summarize the primary endpoint, how missing or indeterminate assessments were handled, whether any adjustment was planned, or how the radiology assessment was used as a reference. The record also does not report an analysis population, an interim analysis plan, or a sample-size justification for the registered single-group design. General: These details help readers understand which observations contributed to an estimate and whether the analysis matches the stated question. Their absence limits interpretation, but does not establish what procedures were or were not carried out outside the registry record.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Hand-carried Ultrasound Arm")
n      <- c(6)
events <- c(4)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Hand-carried Ultrasound Arm  6  4  66.7  22.3  95.7  30.0  90.3  29.0  90.1

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 4 outcome measures and 0 analyses. The primary outcome is a count of participants with absence of hydronephrosis. The record also names Direct Costs of Hand-carried Ultrasound as a secondary outcome, and the study summary describes sensitivity, specificity, positive and negative predictive value, and potential cost savings as measures of interest. The registry record does not report results for these measures.

Multiplicity is the issue that arises when several outcomes or analyses are considered: the chance of at least one apparently notable result can depend on how many tests are performed and how they are handled. The registry record does not report a multiplicity adjustment, a hierarchy among the diagnostic measures, or a prespecified strategy for interpreting multiple outcomes. It is therefore not possible to determine how multiplicity was addressed, if at all.

Missing-data handling is not reported in the registry record. The record does not state how missing, incomplete, technically inadequate, or indeterminate HCU or radiology assessments would be treated. It also does not identify the analysis population for the primary endpoint or explain whether every enrolled participant contributed to each outcome. These omissions matter because incomplete paired assessments can change which participants contribute to a diagnostic comparison.

The enrollment field lists 6, while the arm description states 154 inpatients; the record does not reconcile them. This makes the intended and observed analysis denominators unclear. The status is TERMINATED, but the reason for termination and its consequences for missing data or analysis are not reported in the registry record. No conclusions about attrition, exclusions, or unreported data should be inferred from the status alone.

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.

The posted serious adverse-event data list 6 participants at risk and 0 participants affected in the hand-carried ultrasound arm. The record lists 0 deaths. It also lists 6 at risk and 0 affected for other adverse events. No serious adverse-event terms are listed.

These figures describe the safety counts recorded in the registry; they do not provide a detailed account of event definitions, collection procedures, follow-up completeness, or causal assessment. The study timeframe for the primary endpoint is through study completion, up to an average of 1 day, but the registry record does not specify whether the adverse-event observation period was identical.

Zero recorded events in the posted data should not be read as proof that an event could not occur or as a broad assessment of safety. The safety denominator is limited, and the discrepancy between the enrollment field and arm description remains unresolved. The data report no affected participants in the listed categories; they do not establish the absence of all possible harms in other settings or populations.

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

The registry record documents a study intended to evaluate trainee use of hand-carried ultrasound for identifying hydronephrosis in hospitalized adults with acute or subacute kidney dysfunction. It describes a single-group design, a comparison with radiology-performed ultrasound, and a primary count of participants with no hydronephrosis detected in any kidney imaged with HCU. It also records a terminated status and a small set of safety counts.

The posted record does not report the primary endpoint result, diagnostic accuracy estimates, cost results, confidence intervals, or analyses. Consequently, the information does not establish how often HCU found absence of hydronephrosis, how its classifications compared with radiology-performed ultrasound, or how precisely any diagnostic estimate was measured. It also does not establish potential cost savings.

The record’s enrollment field lists 6 participants, while the arm description says the group will be comprised of 154 inpatients. Because this difference is unexplained, the number of participants intended, enrolled, or analyzed for the primary outcome cannot be determined from these entries alone. The 6 participants listed in the safety data should not be assumed to define the endpoint denominator.

General: Diagnostic accuracy is a property estimated by comparing test results with a reference classification in an appropriate set of participants. A study’s aim or endpoint definition is not itself an accuracy result. Similarly, the absence of a randomized control arm does not make a paired diagnostic comparison impossible, but the paired data and analysis details are needed to interpret one.

The record therefore supports a description of the research question and its registered endpoint, not a conclusion about the test’s performance or clinical consequences. The termination status does not explain why the study ended, whether planned observations were completed, or why results are not listed.

14. Why This Trial Matters Statistically

This study raises a useful statistical distinction between defining a diagnostic question and demonstrating diagnostic performance. The registry describes HCU as an approach trainees would use to assess hydronephrosis and identifies radiology-performed ultrasound as the intended comparator. It also names sensitivity, specificity, and predictive values as planned measures. Those measures require comparison data; a count of participants meeting the primary endpoint definition cannot replace them.

The record also illustrates why denominators and analysis populations matter. The enrollment field lists 6, while the arm description refers to 154 inpatients. Without an explanation, readers cannot know which figure represents the participants who contributed observations or whether the figures refer to different stages of the study. A denominator is essential for interpreting a count and for understanding its precision.

Another statistical issue is the difference between a planning illustration and an analysis of observed data. The registry describes a hypothetical sample-size exercise based on an observed effect and assumptions for a two-arm allocation. Those assumptions do not match the registered single-group design, and a planning illustration is not observed power. It cannot supply the missing outcome estimates.

Finally, the record shows how a registered outcome and study status can be informative without resolving the research question. The primary endpoint is clearly named, and the status is TERMINATED, but the primary result and reason for termination are not reported. Clear endpoint definitions, transparent denominators, paired diagnostic data, and analysis details are all important for judging what a diagnostic study can establish. In this record, those missing result details prevent a quantitative assessment of the intended question.

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 most direct limitation is that the registry record does not report the primary outcome value or any analysis. It also does not report diagnostic accuracy estimates, confidence intervals, cost findings, or results for the named secondary outcome. The number of outcome measures is listed as 4, but the record does not provide outcome-level results that would allow those measures to be interpreted.

The participant counts are inconsistent: the enrollment field lists 6, and the arm description states 154 inpatients. The record does not clarify whether one figure reflects a plan and the other actual enrollment, nor does it identify the denominator for the primary outcome. Although 6 participants are listed as at risk in the adverse-event data, that count does not resolve the primary analysis population.

Important diagnostic-study details are not reported in the registry record, including the method for matching HCU and radiology assessments, the handling of missing or indeterminate findings, and the analysis population. The record does not report how trainee training was standardized or how trainee performance was evaluated. Such details may affect interpretation, but their absence from the registry does not establish what occurred in practice.

The single-group design does not include a randomized control arm. The summary describes a reference assessment, but the paired results are unavailable, so the intended diagnostic comparison cannot be assessed. The registry also does not explain the TERMINATED status, report a sample-size justification for the registered design, or describe an analysis plan. These limitations constrain interpretation to the stated aims, design description, and posted safety counts.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Hand-carried Ultrasound to Assess Hydronephrosis — NCT03774719.
• Registry record last updated 2024-07-24; status last verified 2024-07.
• Results first posted 2024-07-24.
• 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

NCT03774719 is a terminated, single-group study sponsored by Washington University School of Medicine. It evaluates hand-carried ultrasound for assessing hydronephrosis in adults hospitalized with acute or subacute kidney dysfunction. The study summary describes trainee training and a comparison with radiology-performed ultrasound. The primary outcome is the number of participants for whom none of the kidneys imaged with HCU have hydronephrosis.

The registry lists enrollment of 6, while the arm description refers to 154 inpatients; this discrepancy is not explained. It lists 4 outcome measures and 0 analyses. The primary outcome result, diagnostic accuracy estimates, cost results, and reason for termination are not reported in the registry record. The posted safety data list 6 participants at risk, 0 affected by serious adverse events, and 0 deaths.