This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Lung Ultrasound in PD Patients (NCT03801044), a registered phase not stated study. The primary outcome is Association Between Number of Kerley B Lines by Ultrasound and Serum VEGF-C Level (pg/ml) by Enzyme-linked Immunosorbent Assay.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03801044 |
| Phase | Phase not stated |
| Condition | Peritoneal Dialysis, Hypervolemia, VEGF Overexpression |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 23 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Sisli Hamidiye Etfal Training and Research Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Peritoneal dialysis patients at the clinic were invited to participate. The primary-outcome description says two patients were excluded because of immobility. The record does not give further eligibility criteria or describe the characteristics of the patients who took part.
Intervention
Lung ultrasound was used to assess the number of Kerley B lines. The record also lists measurements including VEGF-C, NT-BNP, echocardiography, chest radiography, and bioelectrical impedance analysis. These are assessment methods, not treatment assignments.
Comparator
There is no randomized control group. The record describes comparisons between ultrasound findings and other measurements, clinical signs, and symptoms. It does not specify an allocation process or a like-for-like treatment comparison.
Primary question
The primary question is whether the number of Kerley B lines on lung ultrasound is associated with serum VEGF-C level. The registry describes VEGF-C measurement by enzyme-linked immunosorbent assay and names the primary outcome as an association, rather than a change caused by an intervention. The direction and strength of the association, and its uncertainty, are not reported in the registry record.
The clinical motivation in the record is that assessing volume status in peritoneal dialysis patients can be difficult and may rely on clinical evaluation. Lung ultrasound is considered as a way to assess hidden congestion, with its findings compared against symptoms, physical examination, laboratory measurements, imaging, and bioelectrical impedance. This design addresses how measurements relate to one another in the enrolled patients. It cannot, by itself, establish that using one measurement improves care or changes patient outcomes.
3. Trial Design
The registry describes a completed study titled “Lung Ultrasound in PD Patients,” with the official title “Comparison of Lung Ultrasound and Other Volumetric Methods in Peritoneal Dialysis Patients.” The listed enrollment is 23. The record gives a start date of 2018-05-01 and a primary completion date of 2018-09-01. Its status is completed.
The record describes PD patients as the study arm and says that all PD patients treated in the unit were enrolled. The primary-outcome description says patients in the clinic were invited and that two patients were excluded because of immobility. These descriptions do not establish that every invited patient participated, and the record does not explain how the enrollment figure relates to the stated exclusions or to the safety denominator.
This is not a randomized treatment comparison. The registry does not state an allocation process, and its own note cautions that the arms are not a like-for-like control comparison. The listed procedures are diagnostic or measurement activities: lung ultrasound, NT-BNP and VEGF, echocardiography, chest radiography, and bioelectrical impedance analysis. They are used to compare measures of volume status rather than to assign different therapies.
The primary outcome concerns the association between ultrasound Kerley B-line count and serum VEGF-C. Secondary outcomes describe associations between the ultrasound count and dyspnea, New York Heart Association classification, physical findings, and echocardiographic measurements. The registry lists 16 outcome measures and one analysis, but gives no detailed analysis plan. The study design, sampling details beyond the clinic invitation description, timing of each assessment, and procedures for handling incomplete measurements 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.
Before assignment: Total 23 patients accepted to participate in the study, but two of them were excluded because of immobility and not being capable of proceeding with the diagnostic tests
Overall Study
| Stage | PD Patients |
|---|---|
| STARTED | 21 |
| COMPLETED | 21 |
| NOT COMPLETED | 0 |
Analysis population for the primary outcome, as defined in the registry: All peritoneal dialysis patients in the clinic invited to the study. Two patients were excluded because of immobility
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.
| Characteristic | Unit | PD Patients |
|---|---|---|
| Participants analysed | 21 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 21 |
| Age, Categorical: >=65 years | Participants | 0 |
| Sex: Female, Male: Female | Participants | 17 |
| Sex: Female, Male: Male | Participants | 4 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: Turkey | participants | 21 |
| Etiology of End-Stage Renal Disease: Unknown | Participants | 12 |
| Etiology of End-Stage Renal Disease: Hypertension | Participants | 2 |
| Etiology of End-Stage Renal Disease: Diabetes Mellitus | Participants | 2 |
| Etiology of End-Stage Renal Disease: Familial Mediterrenean Fever | Participants | 1 |
| Etiology of End-Stage Renal Disease: Focal Segmental glomerulosclerosis | Participants | 2 |
| Etiology of End-Stage Renal Disease: Ig A Nephropathy | Participants | 1 |
| Etiology of End-Stage Renal Disease: Tuberous Sclerosis | Participants | 1 |
| Duration of PD, months | Months | 22 (13 to 49.5) |
| PD modality, CAPD (%) | Participants | 17 |
| Peritoneum Transport Type: Low | Participants | 1 |
| Peritoneum Transport Type: Low-medium | Participants | 10 |
| Peritoneum Transport Type: High-medium | Participants | 7 |
| Peritoneum Transport Type: High | Participants | 3 |
6. Primary Endpoint
The registry lists the primary outcome as Association Between Number of Kerley B Lines by Ultrasound and Serum VEGF-C Level (pg/ml) by Enzyme-linked Immunosorbent Assay, measured over 4 months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | ng/ml |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the relationship between the number of Kerley B lines detected by lung ultrasound and serum VEGF-C level measured by enzyme-linked immunosorbent assay. Kerley B lines are the ultrasound feature being counted; VEGF-C is the laboratory measurement being related to that count. The stated timeframe is 4 months, corresponding to the study period described in the registry.
The registry specifies a median and inter-quartile range as the summary format for the endpoint. Such summaries describe the central value and spread of a measurement without requiring a symmetric distribution. This can be useful when measurements are skewed or when a few values are unusually high or low. That general rationale does not establish why this particular summary was selected; the reason is not reported in the registry record.
An association endpoint is intended to describe whether two measurements vary together in the patients assessed. It does not establish that one measurement causes the other, nor does it establish that either measurement is a more accurate or useful clinical decision tool. To interpret the result, readers would need the observed summaries or association estimate, an uncertainty interval, and details of the analytic method. Those numerical results and details are not reported in the registry record.
There is a unit-label inconsistency in the endpoint description: the outcome title and description refer to VEGF-C in pg/ml, while the stated outcome unit is ng/ml. The registry does not explain this difference, so the intended reporting unit cannot be determined from the record alone.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the primary question but does not report a numerical estimate for the association between Kerley B-line count and VEGF-C level. It also does not report the endpoint’s median, inter-quartile range, a test statistic, a p-value, or a confidence interval. Consequently, the direction, magnitude, and precision of the primary association cannot be judged from the registry record. The absence of a reported estimate should not be read as evidence that the association was absent or that it was present.
The listed secondary outcomes cover several kinds of comparison: ultrasound findings against symptoms and clinical examination, and ultrasound findings against echocardiographic measurements. The registry names associations involving dyspnea, functional classification, third heart sound, pretibial edema, ventricular dimensions and volumes, septal and posterior wall thickness, and ejection fraction. It does not give estimates or uncertainty for these outcomes. Their results therefore cannot be interpreted from the registry record either.
Even if an association estimate were available, its meaning would depend on the method used, the scale of the estimate, and the uncertainty around it. A confidence interval, in general, describes a range of values compatible with the data and the assumptions of the analysis. A narrow interval can indicate greater precision than a wide one, but neither the interval nor the underlying estimate is reported. A p-value alone, if one were reported, would not convey the size or clinical importance of an association.
The study compares measurements within a clinical population rather than assigning treatments. Any observed relationship would therefore be descriptive or associational. It would not show that VEGF-C changes cause ultrasound findings, that ultrasound findings cause changes in another measure, or that acting on ultrasound findings improves outcomes. Differences in patient characteristics, measurement timing, or other factors could also affect an association; the registry record does not provide enough analysis detail to assess such possibilities.
The record reports completion and an enrollment of 23, but these registry entries do not substitute for outcome results. The safety figures are also not evidence about the primary association. The appropriate reading is that the registry documents a planned clinical measurement question and a completed study, while leaving the primary result and its precision unreported in the registry record.
9. Statistical Methods Explained
What does an association answer?
An association analysis asks whether values of one measure tend to vary with values of another. In this study, the named primary relationship is between the count of Kerley B lines on lung ultrasound and serum VEGF-C level. The question is not whether one group received a treatment and had a better outcome than a control group. The record describes measurements in PD patients and does not describe random assignment.
Association can be represented in different ways. A correlation coefficient can describe the direction and strength of a particular kind of relationship; a regression model can describe how an outcome relates to a predictor under stated assumptions; and a rank-based measure can focus on ordering rather than raw distances. These methods answer related but not identical questions. The method used for the primary analysis is not reported in the registry record, so no specific interpretation of an association statistic can be attached to this study.
Why report a median and inter-quartile range?
The primary endpoint is designated for summary by median and inter-quartile range. In general, the median is the middle of an ordered set of observations, while the inter-quartile range describes the spread across the central half of the observations. These summaries are less sensitive to extreme observations than the mean and standard deviation. They can be useful for skewed measurements or data with outliers. That general explanation does not establish the distribution of VEGF-C or Kerley B-line counts in this study. The registry does not report distributions, plots of individual values, or the reason for choosing this summary.
Summary statistics and association estimates serve different purposes. A median and inter-quartile range describe the observed distribution of a variable. They do not, on their own, quantify how two variables are related. To assess the primary question, a reader would need a reported estimate of association or another stated comparison, together with its uncertainty and method. These are not reported in the registry record.
What does uncertainty add?
Statistical estimates based on a study sample are subject to sampling variability. A confidence interval is a general way to express this uncertainty: it indicates which values are reasonably compatible with the observed data under the method’s assumptions. Its width is informative about precision. A point estimate without an interval can conceal substantial uncertainty, while an interval without the estimate’s context may also be difficult to interpret. The registry record does not report a confidence interval for the primary association.
Uncertainty is especially relevant when interpreting results from a study with a limited enrollment. An estimate can be unstable even when its point value appears large, and a modest estimate can be estimated precisely in a different setting. No new precision assessment can be made from enrollment alone. The actual analysis population, missing measurements, and observed association are not reported in the registry record.
What are the planning calculations?
The record describes sample-size planning illustrations based on the observed effect, not the study’s own design. In general, such calculations ask how many participants per arm might be needed to detect an effect under selected assumptions. The stated assumptions are 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. For time-to-event calculations, the record says the quantity is the total number of events; other calculations are expressed as participants per arm.
Those calculations are planning illustrations, not observed power and not evidence that the study was designed with those group sizes. In this record, the study is not a randomized two-arm comparison, and the primary question is an association between measurements. A hypothetical two-arm planning framework should not be mistaken for the actual design. No numerical planning result should be interpreted as an observed study finding.
Why can over-dispersion matter?
In general, over-dispersion occurs when the variability in observed counts exceeds what a statistical model assumes. If count data are analyzed using a model that assumes too little variation, uncertainty can be understated and inference may be misleading. This is a general consideration for count outcomes such as counts of ultrasound findings; it does not establish that over-dispersion occurred in this study or that a count model was used. The registry does not report the model, diagnostic checks, or any adjustment for over-dispersion.
For this record, the central methodological point is the distinction between the clinical measurement question and the analysis actually documented. The registry names an association endpoint and a median/inter-quartile-range summary, but does not report the analysis method or numerical findings. Without those details, readers can identify the intended comparison but cannot reproduce or independently evaluate its statistical result.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 16 outcome measures, including the primary association and secondary associations involving clinical features and echocardiographic measurements. When many outcomes are assessed, the chance of at least one apparently notable result can increase if each is tested separately. This is the general multiplicity concern. It does not imply that any particular result in this study is false or that a specific correction was required.
The record does not report whether the outcomes were assigned a hierarchy for analysis, whether any multiplicity adjustment was planned, or how secondary findings were to be interpreted. It also does not describe a statistical analysis plan or identify which analysis corresponds to the listed count of one analysis. These details are not reported in the registry record.
The primary-outcome description states that two patients were excluded because of immobility. The record does not explain whether these patients are included in the enrollment figure, whether any other participants lacked measurements, or how missing outcome data were handled. The number of patients with an available primary endpoint and the analysis population are not reported in the registry record.
Likewise, there is no description of how incomplete laboratory, ultrasound, clinical, or imaging measurements were addressed, or whether each secondary analysis used the same set of patients. No imputation method, complete-case rule, or sensitivity analysis is specified. These gaps limit assessment of selection and missing-data effects, but they do not establish that missingness occurred beyond the stated exclusions.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| PD Patients | 0 | 21 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| PD Patients | 0 of 21 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| PD Patients | 0 of 21 |
The adverse-event record lists the PD Patients group with 21 at risk for serious adverse events and zero affected. It also reports 21 at risk for other adverse events and zero affected, with zero deaths. No serious adverse-event terms are listed.
These figures are counts as recorded for the safety outcomes. They do not demonstrate that no events of any kind occurred outside the registry’s reporting definitions or observation period. The record does not describe event-collection procedures, the exact safety follow-up period, or whether the figures cover all enrolled patients. The safety denominator also differs from the enrollment figure of 23; the reason for that difference is not reported in the registry record.
Safety counts do not answer the primary question about the association between lung ultrasound findings and VEGF-C. Nor do zero reported events establish that a measurement method is beneficial or that an intervention is safe in other populations. They describe only the recorded event counts and their stated denominator in this registry entry.
12. What the Result Does, and Does Not, Mean
The study addresses whether lung ultrasound findings, specifically Kerley B-line counts, are associated with VEGF-C and other indicators related to volume status in PD patients. Its design is a comparison among measurements and clinical findings, not a randomized comparison of treatments. The registry record identifies the question and outcome measures, but does not report the numerical primary result.
As a result, the record does not establish whether the primary association was positive, negative, strong, weak, or precisely estimated. It also does not show whether ultrasound findings aligned with symptoms, physical examination, laboratory measures, chest radiography, echocardiography, or bioelectrical impedance. Although these comparisons are named as outcomes or measurement methods, their results are not reported in the registry record.
More generally, an association between two measures does not prove that one causes the other. Nor does agreement between two measurements necessarily show that either is accurate against a definitive reference standard. To establish diagnostic performance, a study would need to report suitable measures and a clearly described reference approach; those results and details are not reported.
The findings, if available, would apply first to the patients studied and the methods used. The record does not provide enough information about patient characteristics, measurement procedures, or analysis to judge how broadly results would apply. The stated exclusion because of immobility also means that the record does not describe the primary-outcome population as including those patients.
The key distinction is between a completed study and a reported result. Completion and a registered endpoint do not convey the direction, size, or reliability of an association. The registry record supports understanding what was investigated, but not a conclusion about the observed relationship or its clinical importance.
13. Why This Trial Matters Statistically
This study is statistically interesting because it frames volume assessment as a relationship among different kinds of measurements rather than as a direct treatment comparison. Lung ultrasound findings are considered alongside laboratory markers, imaging, physical signs, symptoms, and bioelectrical impedance. Such questions require clear definitions of the measurements and careful interpretation of association, agreement, and diagnostic performance, which are related but distinct statistical ideas.
The primary endpoint also illustrates the difference between describing a variable and estimating a relationship. A median and inter-quartile range summarize the distribution of a measurement, while an association estimate addresses how two measurements vary together. Without the latter estimate and its uncertainty, descriptive summaries alone would not answer the primary question.
The registry lists multiple secondary associations. In general, assessing many outcomes raises questions about multiplicity, outcome hierarchy, and the distinction between primary and exploratory findings. The record does not report how these issues were handled. Transparency about analysis methods and missing measurements would help readers judge the stability and interpretability of findings.
Finally, a completed registry entry is not necessarily a complete account of results. Here, the study question and outcome list are documented, but numerical endpoint findings and analysis details are not reported in the registry record. This makes the entry useful for understanding the intended measurement question while leaving its statistical answer unresolved.
14. 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 principal limitation for interpreting this particular record is the absence of numerical results for the primary and secondary outcomes. No association estimates, confidence intervals, p-values, or observed outcome summaries are reported. The record therefore does not allow assessment of effect direction, magnitude, or precision.
The statistical method for the primary association is not specified. The record names a median and inter-quartile range summary but does not say how the relationship between the two measures was estimated or tested. Details about model assumptions, outlier handling, or checks of fit are not reported in the registry record.
The study population is described as PD patients invited at the clinic, with two patients excluded because of immobility. Further eligibility criteria and participant characteristics are not reported. The relationship between the stated enrollment of 23, the exclusion description, and the safety denominator of 21 is not explained. The number included in each outcome analysis is not reported.
The outcome list contains multiple associations, but the record does not describe a prespecified hierarchy beyond identifying a primary outcome, or any adjustment for multiple testing. Procedures for missing data and the timing of individual measurements are also not reported. A unit discrepancy appears in the VEGF-C endpoint labeling: the title and description use pg/ml, while the stated outcome unit is ng/ml. The record does not resolve that discrepancy.
Because there is no randomized comparator, the study cannot establish causal effects of a treatment. The record also does not report diagnostic accuracy against a reference standard. These are limits on what this design can answer, not evidence that the measurements were invalid or that an association was absent.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Lung Ultrasound in PD Patients — NCT03801044.
- Registry record last updated 2020-04-08; status last verified 2020-03.
- Results first posted 2020-03-31.
- 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.
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18. Record Summary
NCT03801044 is a completed study of lung ultrasound and other volume-assessment methods in peritoneal dialysis patients. The registry lists enrollment of 23, with a start date of 2018-05-01 and a primary completion date of 2018-09-01. The primary outcome is the association between ultrasound Kerley B-line count and serum VEGF-C level, summarized by median and inter-quartile range, with a stated timeframe of 4 months.
The registry also lists clinical, laboratory, imaging, and echocardiographic associations as secondary outcomes. This is not a randomized treatment comparison. Numerical outcome results, the primary analysis method, missing-data procedures, and multiplicity methods are not reported in the registry record. The VEGF-C unit is labeled inconsistently, and the safety record reports zero affected for serious and other adverse events, with zero deaths, among the stated at-risk group.