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 Inferior Vena cavaCollapsibility Index in Patients With Acute Kidney Injury (NCT02165072), a registered phase not stated study. The primary outcome is Maximum and Minimum Diameters of the Inferior Vena Cava in Patients With Acute Kidney Injury.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT02165072 |
| Phase | Phase not stated |
| Condition | Acute Kidney Injury |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 30 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Texas Tech University Health Sciences Center |
| Results posted | Yes |
2. Clinical Question
Population
Patients with acute kidney injury admitted to an intensive care unit. The registry record reports enrollment of 30 participants; further eligibility details are not reported in the registry record.
Intervention
Bedside ultrasound measurement of the inferior vena cava. The study is observational, so the ultrasound assessment is a measurement procedure, not a randomized treatment assignment.
Comparator
No like-for-like control comparison is described. The registry record does not state an allocation method, and a randomized comparison is not reported.
Primary question
Can bedside ultrasound measurements of the inferior vena cava help determine the type of acute kidney injury? The listed primary outcome is maximum and minimum vena cava diameters on Day 1 of ICU admission.
The study description frames the investigation as an examination of whether bedside ultrasound can help determine the type of acute kidney injury. The primary outcome is a continuous measurement: maximum and minimum diameters of the inferior vena cava, reported in centimeters, with the mean and standard deviation specified as the summary form. The registry record does not report an outcome estimate, a comparison of diagnostic groups, or an analysis linking the measurements to an assigned type of kidney injury.
The title refers to the inferior vena cava collapsibility index, but the primary outcome description names the maximum and minimum diameters. How those measurements would be converted into an index, or how the index would be evaluated against a classification of kidney injury, is not reported in the registry record. The record also does not give the criteria used to define kidney-injury types. Therefore, the research question can be described from the study purpose, but the registry information does not establish how accurately the measurements classified participants or whether classification was assessed.
3. Trial Design
This is an observational study sponsored by Texas Tech University Health Sciences Center. Its registry status is completed, with enrollment of 30. The registry lists the condition as acute kidney injury and describes the study as examining the possibility of determining its type using bedside ultrasound machines. The study is not described as a randomized trial, and the registry record does not state an allocation method.
The primary outcome is maximum and minimum inferior vena cava diameters in patients with acute kidney injury, measured on Day 1 of ICU admission. The outcome is continuous, in centimeters, and the specified summary is mean with standard deviation. The registry record identifies two outcome measures, but details of the other measure are not reported in the registry record. The listed primary outcome description does not specify an assigned intervention or a control group.
The study began in 2014-02, and primary completion is listed as 2015-10. These dates describe the registry record and do not supply details about recruitment dates for individual participants, follow-up duration, or the timing of any analysis. The record gives no further information about the protocol, eligibility criteria, setting beyond ICU admission in the primary outcome timeframe, or how ultrasound measurements were obtained. These design details are not reported in the registry record.
Because the study is observational and no control comparison is described, its structure should not be read as a test of randomized treatment assignment. The registry record also reports no statistical analyses. Without the outcome values, analysis methods, and classification criteria, the study design alone cannot establish the relationship between the ultrasound measurements and the types of acute kidney injury.
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
| Stage | Ultrasound of Acute Kidney Injury |
|---|---|
| STARTED | 30 |
| COMPLETED | 30 |
| NOT COMPLETED | 0 |
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 | Ultrasound of Acute Kidney Injury |
|---|---|---|
| Participants analysed | 30 | |
| Age, Continuous | years | 62.4 (SD 16.0) |
| Sex: Female, Male: Female | Participants | 9 |
| Sex: Female, Male: Male | Participants | 21 |
| Region of Enrollment: United States | participants | 30 |
6. Primary Endpoint
The registry lists the primary outcome as Maximum and Minimum Diameters of the Inferior Vena Cava in Patients With Acute Kidney Injury, measured over Day 1 of ICU admission.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | cm |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the maximum and minimum diameters of the inferior vena cava in patients with acute kidney injury, measured on Day 1 of ICU admission. The unit is centimeters, and the registry specifies a mean and standard deviation as the summary statistics. This makes the endpoint a continuous measurement rather than a count or a time-to-event outcome.
The study description gives a reason for collecting these measurements: to examine whether bedside ultrasound may help determine the type of acute kidney injury. Maximum and minimum diameters are the measurements named in the primary outcome description. Although the study title refers to a collapsibility index, the registry does not describe a formula for calculating such an index or identify it as the primary outcome measure. The method for interpreting diameter measurements as evidence about injury type is not reported in the registry record.
In general, a mean describes the average measurement in a group, while a standard deviation describes how spread out individual measurements are around that average. Neither summary alone shows whether a measurement can distinguish among diagnostic categories. That assessment would require an explicit classification or comparison method and observed results. The registry record does not report the endpoint values, the number of observations contributing to each summary, or a statistical analysis of the primary endpoint. As a result, the endpoint’s intended role is clear, but its observed distribution and its usefulness for classification cannot be evaluated from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed observational study with enrollment of 30 and a primary outcome focused on maximum and minimum inferior vena cava diameters on Day 1 of ICU admission. It does not report numerical results for those measurements. There is no reported mean, standard deviation, estimated difference, confidence interval, or p-value for the primary outcome. The registry also reports no statistical analyses. Consequently, there is no numerical result in the registry record from which to assess the size or precision of an association between ultrasound measurements and acute kidney injury type.
The study purpose concerns whether bedside ultrasound could help determine the type of acute kidney injury. However, the registry record does not give the diagnostic categories, the criteria used to assign a type, or an analysis connecting diameter measurements to those categories. It also does not report sensitivity, specificity, predictive values, classification accuracy, or another diagnostic-performance measure. These omissions mean the stated aim cannot be evaluated using the posted registry information.
The primary endpoint is expressed as a mean with standard deviation. In general, the mean locates the center of a continuous measurement distribution, while the standard deviation describes variation among observations. To interpret either statistic, readers would also need to know which participants contributed measurements and whether measurements were available for everyone. Those details are not reported in the registry record. No uncertainty interval is reported, so the precision of any estimate cannot be assessed.
The record lists two outcome measures but describes only the primary measurement in detail. The other outcome’s name, measurement procedure, timeframe, and result are not reported in the registry record. The status is completed, but completion status does not itself communicate the outcome findings. The registry’s absence of analyses should not be mistaken for evidence of no association, nor does it show that a specific association was present.
The study is observational, and no like-for-like control comparison is described. Its stated purpose is exploratory: considering whether bedside ultrasound might assist in identifying the type of acute kidney injury. Without results and a reported analysis plan, conclusions about the observed data, uncertainty, or diagnostic performance cannot be drawn from this record. Any sample-size planning illustration should be interpreted as planning information rather than observed power; it does not fill the gap left by unreported outcome results.
9. Statistical Methods Explained
The registry describes a continuous primary outcome, reports that the intended summary is mean and standard deviation, and lists no statistical analyses. The methods concepts below explain how such quantities are generally interpreted; they do not describe analyses reported for this study.
What does a mean describe?
General statistical explanation: A mean is the arithmetic average of measurements. For a continuous outcome such as diameter in centimeters, it gives a central summary of the recorded values. A mean does not show the range of observations or whether the data are clustered, skewed, or affected by unusual values. The registry record does not report the primary outcome mean.
What does a standard deviation describe?
General statistical explanation: A standard deviation describes the spread of observations around their mean. A larger standard deviation indicates more variation in the measurement values, while a smaller one indicates that values tend to lie closer to the mean. It is not a measure of uncertainty in the mean itself. A confidence interval for a mean, if calculated and reported, would address uncertainty about the estimated average; no such interval is reported for this outcome in the registry record.
How would a comparison be interpreted?
General statistical explanation: A comparison requires clearly defined groups or conditions and a stated estimand, such as a difference in average measurements. An estimate describes the observed contrast, while its confidence interval conveys the range of values compatible with the data under the method’s assumptions. A p-value addresses compatibility with a specified null hypothesis; it is not the probability that the null hypothesis is true and does not measure the size or clinical importance of an effect. The registry record does not report a comparison, an estimate, a confidence interval, or a p-value. It also does not specify diagnostic groups to compare.
Why does the observational design matter?
General statistical explanation: Observational data describe measurements collected without reported random assignment. Associations in such data may reflect differences between participants or other factors, as well as the relationship of interest. Randomization is one way to support causal comparisons, but it is not described in this study. The registry record characterizes the study as observational and does not report an allocation method or a control comparison. It therefore does not support interpreting a hypothetical group contrast as an effect caused by an assigned intervention.
What do sample-size illustrations mean?
General statistical explanation: A sample-size calculation depends on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. A planning illustration is conditional on those assumptions; it is not a summary of observed outcomes or a measure of observed power. The planning assumptions stated for this record describe 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. The record is observational and does not describe a randomized two-arm comparison, so these assumptions should not be mistaken for the study’s design. The numerical planning results and an observed effect estimate are not reported in the registry record.
Why can over-dispersion matter?
General statistical explanation: Over-dispersion occurs when the variability in data exceeds what a statistical model assumes. If a model underestimates variability, standard errors may be too small and confidence intervals too narrow. Appropriate modeling depends on the outcome type and its distribution. The primary outcome is continuous, but the registry record does not report a distributional assessment, model, or variance adjustment. It is therefore not possible to determine whether over-dispersion was considered or relevant to any analysis.
What information is needed to judge the analysis?
General statistical explanation: Readers need to know the analysis population, the number of observed measurements, how missing observations were handled, the model or summary procedure, and the uncertainty estimates. If a study evaluates classification, it also needs a defined reference classification and a stated performance measure. The registry record does not report these details for the primary outcome. No analysis should be inferred from the study title or intended purpose alone.
10. Multiplicity, Missing Data and Analysis Populations
The registry record identifies two outcome measures, but it describes only the primary outcome in detail. The other measure’s name and analysis are not reported in the registry record. No statistical analyses are listed, and the registry does not report a statistical plan, an order of testing, or any adjustment for testing multiple outcomes. Therefore, it is not possible to determine whether multiplicity was considered or how it would have been handled.
Missing-data handling is also not reported in the registry record. The entry does not state whether all enrolled participants had the primary measurement, how missing or unusable measurements were treated, or whether an analysis population differed from the enrolled group. Enrollment of 30 is reported, but the number contributing to each outcome is not. These distinctions matter because an outcome summary based on fewer participants may represent a different subset of the enrolled group.
The record does not describe an intention-to-treat population, a per-protocol population, or another analysis population. In general, analysis-population definitions clarify which observations contribute to each estimate and help readers understand how exclusions affect interpretation. Since no analysis is reported, no specific population can be identified for the primary endpoint. The registry also does not state whether interim analyses were planned or performed. That information is not reported in the registry record and should not be inferred from the completed status.
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 |
|---|---|---|---|
| Ultrasound of Acute Kidney Injury | 0 | 30 | 0.0% |
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 |
|---|---|
| Ultrasound of Acute Kidney Injury | 0 of 30 |
The registry lists one group, titled Ultrasound of Acute Kidney Injury. For that group, 30 participants are recorded as at risk for serious adverse events and 0 as affected. The record also lists 30 at risk for other adverse events and 0 as affected. Deaths are recorded as null, which is not a numerical zero; the death count is not reported in the registry record.
These entries should be read as registry reporting fields, not as proof that no adverse events occurred. The record does not list serious adverse-event terms, and the top serious-event terms list is empty. It does not provide definitions of the observation period, event-collection procedures, or further detail about ascertainment. The term “other” is not explained in the record.
In general, an adverse-event count describes events recorded under a specified collection and reporting process. A zero in a registry field means zero affected participants are recorded in that field; it cannot establish the completeness of event collection. Because this is an observational study and the registry does not describe a randomized comparator, these figures do not support a comparative safety assessment.
12. What the Result Does, and Does Not, Mean
The registry record establishes that a completed observational study enrolled 30 participants and focused on bedside ultrasound measurements in patients with acute kidney injury. Its primary endpoint was maximum and minimum inferior vena cava diameters on Day 1 of ICU admission. The study description states an aim of examining whether ultrasound could help determine the type of acute kidney injury.
The record does not establish whether the measurements differed across injury types or whether they classified participants accurately. It reports no primary outcome values, no analysis, and no diagnostic-performance estimates. The endpoint’s title and intended purpose are not substitutes for observed results. The absence of reported results also does not show that measurements had no relationship to injury type; it leaves that question unanswered in this registry record.
The entry does not describe a randomized comparison or a like-for-like control group. It therefore cannot be read as evidence that an assigned treatment caused a change in an outcome. More broadly, the available registry entries do not establish how measurements were linked to clinical categories, how many measurements were analyzed, or how uncertainty was quantified.
The serious and other adverse-event fields record 0 affected among 30 at risk in each category, while deaths are not reported as a numerical value. These entries describe what is recorded, but the registry does not provide enough information about event collection to establish the completeness of safety reporting. Taken together, the record documents the study’s aim, primary measurement, enrollment, and status, but leaves the numerical findings and their statistical interpretation unreported.
13. Why This Trial Matters Statistically
This study raises a statistical question about measurement and classification: whether continuous ultrasound measurements can help distinguish types of acute kidney injury. That question requires more than a mean and standard deviation. It requires a clearly defined classification target, a method that links measurements to that target, and estimates of how well the resulting classification performs. The registry record states the motivation but does not report those analytical details or results.
The design information also matters. An observational study can describe measurements and associations, but the absence of a randomized comparison limits causal interpretation. The registry does not state an allocation method or identify control groups. This distinction helps prevent an exploratory measurement study from being read as a treatment comparison.
Reporting is essential for statistical interpretation. The record gives enrollment and identifies the primary measurement, but it does not give outcome values, uncertainty intervals, analysis populations, or missing-data procedures. Without these, readers cannot judge the magnitude, variability, precision, or robustness of any result. The record’s completed status does not substitute for those findings.
The case also illustrates why a study title, a stated scientific aim, and a reported endpoint should be read separately. The title names a collapsibility index, while the primary outcome description names maximum and minimum diameters. The registry does not explain the relation between them. Clarifying that measurement pathway would be important to understanding what was analyzed and how it answers the stated question.
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 registry record contains limited detail for evaluating the study’s methods and findings. It reports enrollment of 30 and a completed status, but it does not report numerical results for the primary endpoint or any statistical analyses. The mean and standard deviation are specified as the intended summary form, but their values are not reported in the registry record.
The relationship between the study title and the primary outcome is not explained. The title refers to an inferior vena cava collapsibility index, while the primary outcome names maximum and minimum diameters. The formula, measurement protocol, and analysis connecting these quantities are not reported. The criteria used to classify acute kidney injury types are also not reported, so the intended diagnostic question cannot be evaluated from this entry.
The registry does not describe eligibility criteria, participant characteristics, measurement quality procedures, the number of measurements available, or handling of missing values. It reports two outcome measures but does not describe the second measure in detail. There is no reported analysis population, model, uncertainty estimate, or multiplicity approach. These omissions limit assessment of both the primary measurement and the broader study aims.
The observational design and absence of a described control comparison further limit causal interpretation. The safety fields record zero affected participants for serious and other adverse events, but event ascertainment details are not reported; deaths are not given as a numerical result. These limitations reflect what is absent from the registry record and do not determine what may have been included in other study materials.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Inferior Vena cavaCollapsibility Index in Patients With Acute Kidney Injury — NCT02165072.
- Registry record last updated 2016-06-23; status last verified 2016-06.
- Results first posted 2016-06-23.
- 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
The registry record describes a completed observational study sponsored by Texas Tech University Health Sciences Center, with enrollment of 30. The condition is acute kidney injury, and the study aim is to examine whether bedside ultrasound can help determine its type. The listed primary outcome is maximum and minimum inferior vena cava diameters in centimeters on Day 1 of ICU admission, summarized as mean and standard deviation.
The record lists two outcome measures but does not describe the second in detail. It reports no statistical analyses or numerical primary outcome results. A randomized comparison and allocation method are not reported. Serious and other adverse-event fields each list 30 participants at risk and 0 affected; deaths are not reported as a numerical value. The study start is listed as 2014-02 and primary completion as 2015-10.