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 Mechanisms of Chronic Kidney Disease (CKD)-Induced Foam Cell Formation (NCT01671605), a registered phase not stated study. The primary outcome is In Vitro Lipoprotein Functions.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01671605 |
| Phase | Phase not stated |
| Condition | Chronic Kidney Disease, Cardiovascular Disease |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 103 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Vanderbilt University Medical Center |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled people in two groups: participants with CKD not on dialysis, described as CKD III-IV, and controls with normal kidney function. The registry record gives an enrollment of 103. It does not report further eligibility details or describe the participants’ characteristics in the outcome record.
Intervention
There was no intervention. The primary assessment used HDL isolated from participants in each group in an in-vitro cell assay. This was a measurement of HDL function, not a treatment administered to participants.
Comparator
The assay compared the cholesterol efflux capacity of HDL isolated from the CKD group with that of HDL isolated from controls. The registry record cautions that this was not a randomized comparison and that the arms are not a like-for-like control comparison.
Primary question
The primary measure was the percentage of cholesterol removed from cultured cells by HDL from each group. The underlying scientific question was whether CKD status is associated with differences in processes related to cholesterol handling and foam cell formation. The registry record’s broader rationale discusses the possible relationship between CKD severity, cholesterol processes, plasma lipids, and co-morbidities. However, it does not report numerical results for the primary measure, so the direction or size of any observed group difference is not available from the registry record.
3. Trial Design
This completed study was designed to examine mechanisms related to CKD-induced foam cell formation. It compared HDL isolated from participants with CKD not on dialysis with HDL from controls who had normal kidney function. The registry record describes the CKD group as CKD III-IV and records an enrollment of 103. It lists the study start as 2013-02 and primary completion as 2015-04.
The study was not a randomized intervention trial. The registry record states that there was no intervention and flags the arms as not being a like-for-like control comparison. Allocation is not stated. The comparison is therefore between groups defined by kidney-function status, not between randomly assigned treatments. Differences between groups could reflect CKD status or other group differences; the registry record does not provide enough information to separate those possibilities.
The primary outcome was measured once, at enrollment. HDL from each group was used in a cell-based assay of cholesterol efflux. The record describes one primary outcome measure and no analyses. It does not report the protocol’s planned statistical methods, the recruitment or analysis populations, a sample-size justification, or whether any interim analyses were planned. Those details are not reported in the registry record.
The study is marked completed, but completion status does not itself establish that outcome results were posted. The registry record gives the outcome’s definition and measurement procedure but does not include numerical group summaries or an estimated comparison. Consequently, the design can be described, while the magnitude and precision of the primary result cannot be evaluated from 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
| Stage | CKD Not on Dialysis | Controls |
|---|---|---|
| STARTED | 72 | 31 |
| COMPLETED | 72 | 31 |
| NOT COMPLETED | 0 | 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.
Population: With or without Chronic Kidney Disease
| Characteristic | Unit | CKD Not on Dialysis | Controls | Total |
|---|---|---|---|---|
| Participants analysed | 72 | 31 | 103 | |
| Age, Continuous | years | 61.9 (SD 13.5) | 49.9 (SD 10.6) | 55.9 (SD 12.0) |
| Sex: Female, Male: Female | Participants | 32 | 20 | 52 |
| Sex: Female, Male: Male | Participants | 40 | 11 | 51 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 1 | 1 | 2 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 15 | 1 | 16 |
| Race (NIH/OMB): White | Participants | 56 | 29 | 85 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 |
| Region of Enrollment: United States | participants | 72 | 31 | 103 |
| HDL Function | Percentage | 20.8 (16.1 to 23.7) | 26.5 (19.6 to 28.5) | 23.65 (16.1 to 28.5) |
6. Primary Endpoint
The registry lists the primary outcome as In Vitro Lipoprotein Functions, measured over Once, at enrollment.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | Percentage of cholesterol content |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was in-vitro lipoprotein function, measured as the percentage of cholesterol content removed by HDL. HDL was isolated from participants with CKD and controls, then introduced to cultured cells that had been loaded with cholesterol. The cells were maintained for 72 hours before the media was changed. In the assay, cells exposed to HDL were maintained for 24 hours, after which intracellular cholesterol was assessed. Additional cells received no HDL, serving as an assay reference for cholesterol content in the absence of HDL.
The amount of cholesterol remaining in cells exposed to a group’s HDL was used to reflect that HDL’s capacity to remove cholesterol. The endpoint is therefore a laboratory measure of cholesterol efflux, not a direct measure of cardiovascular events, kidney-function progression, or clinical benefit. It is relevant to the study’s mechanistic question because cholesterol removal by HDL is one process related to cellular cholesterol handling and foam cell formation.
The registry specifies a median and inter-quartile range as the summary format and gives the measurement time as once, at enrollment. It does not report the median, inter-quartile range, or a numerical comparison between groups. The observed endpoint values and their precision are therefore not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a biologically focused group comparison: HDL from participants with CKD not on dialysis was assessed in a cell-based cholesterol-efflux assay and compared with HDL from controls with normal kidney function. It reports an enrollment of 103 and describes the primary outcome as the percentage of cholesterol removed by HDL. But it does not report numerical outcome values, an estimated group contrast, a confidence interval, a p-value, or any analysis results. The direction, magnitude, and precision of the primary comparison cannot be determined from the registry record.
The endpoint is a laboratory measure. Even if a difference in cholesterol efflux were reported, its interpretation would concern the assay under the stated experimental conditions. It would not by itself establish a difference in cardiovascular outcomes or demonstrate that CKD caused a change in HDL function. The registry record’s warning that the arms are not a like-for-like control comparison is important: the groups were not randomized, and allocation is not stated. Factors that differ between groups could contribute to any observed difference. The record’s scientific rationale mentions co-morbidities and plasma lipids as relevant considerations, but numerical adjustment results are not reported.
The outcome was measured once at enrollment. The registry record does not describe repeated measurement or a change-from-baseline comparison. It explicitly says that baseline and outcome measurements are the same. This is consistent with a single assessment rather than a longitudinal treatment-effect analysis.
The primary outcome is summarized using a median and inter-quartile range. In general, the median describes the central position of observations, while the inter-quartile range describes the spread of the middle portion of the data. These summaries can be useful when data are skewed, but no actual summaries are reported in the registry record. No numerical claim about group separation or uncertainty is possible.
The registry record lists zero analyses. It therefore does not establish whether the planned or final analysis included adjustment for participant characteristics, how missing observations were handled, or what population was included in the analysis. Any numerical sample-size planning illustration should be treated as a planning scenario, not as observed power; it cannot substitute for reported outcome estimates and their uncertainty. Overall, the record supports understanding the research question and assay, but not drawing a statistical conclusion about the observed group results.
9. Statistical Methods Explained
The design is a comparison of two groups rather than a randomized trial of an intervention. One group comprised participants with CKD not on dialysis, described as CKD III-IV; the other comprised controls with normal kidney function. The registry record states that allocation is not stated and cautions that the arms are not a like-for-like control comparison. In general, random allocation helps make treatment groups comparable on average, whereas a non-randomized group comparison can remain affected by differences in participant characteristics. The record does not report an adjusted analysis that would address such differences.
The primary outcome is a single in-vitro assay of HDL cholesterol-efflux capacity. Cultured cells were loaded with cholesterol and maintained for 72 hours. The media was then changed, with HDL from CKD or control participants added to some cells and no HDL added to additional cells. After 24 hours, intracellular cholesterol was assessed. The registry describes the resulting measure as the percentage of cholesterol removed by HDL. This assay measures a cellular process under laboratory conditions; it does not directly measure a clinical event or a participant’s health outcome.
The endpoint summary format is median with inter-quartile range. In general, the median is the middle value when observations are ordered, and the inter-quartile range describes the spread from the lower to the upper quartile. These summaries can communicate the center and spread of data without assuming that observations follow a symmetric distribution. The registry record does not include the actual medians or inter-quartile ranges, so the amount of variability and the degree of overlap between groups cannot be assessed.
A group comparison would ordinarily need a clearly defined estimand: the quantity being compared, such as a difference in group summaries, together with a specification of the analysis population and any adjustment. The registry record identifies the outcome and groups, but it does not report a numerical comparison or analysis method. It also records zero analyses. No particular test, model, covariate adjustment, or confidence-interval method should therefore be inferred.
In general, a confidence interval describes the uncertainty around an estimated quantity under the assumptions of the analysis. It helps distinguish a precise estimate from one that is compatible with a broad range of values. No confidence interval is reported for this outcome, so precision cannot be assessed from the registry record. Likewise, without a reported test result, there is no basis for describing statistical evidence for or against a group difference.
Multiplicity concerns arise when several outcomes, comparisons, time points, or analyses are tested: multiple opportunities to find an apparently unusual result can affect how evidence is interpreted. The registry lists one primary outcome measure and zero analyses. It does not report a multiplicity plan, a hierarchy of outcomes, or whether additional exploratory outcomes were assessed. The existence or absence of any adjustment cannot be determined from the registry record.
The sample-size assumptions describe a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is described as a stated fraction of the observed effect. For non-time-to-event outcomes, the planning quantities are participants per arm; time-to-event illustrations instead use total events. In general, such calculations show what sample sizes correspond to specified assumptions. They are not observed power and do not show that an analysis had a particular probability of detecting an effect. The registry record does not report the numerical observed effect or the numerical planning outputs in the information available for interpretation.
Over-dispersion is a general concern when observed variability exceeds what an assumed statistical model allows; if unaccounted for, uncertainty estimates can be too narrow. The record does not state that an over-dispersion issue arose or identify a model for this endpoint, so this is a general methodological consideration, not a reported feature of this study. More broadly, the missing numerical results and analysis details prevent assessment of model fit, assumptions, or robustness.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure, in-vitro lipoprotein function, and zero analyses. It does not describe a multiplicity strategy, such as prioritizing outcomes, adjusting for multiple comparisons, or distinguishing confirmatory from exploratory analyses. The brief study description discusses several processes and possible relationships, but it does not specify which, if any, were tested as additional outcomes. The extent of any multiplicity is therefore not reported in the registry record.
Missing-data procedures are also not reported. The record does not state how many participants contributed usable assay results, whether any samples were unavailable or excluded, how missing observations were handled, or whether any sensitivity analysis was planned. The enrollment count alone does not establish the analysis count for the primary outcome.
The analysis population is not reported in the registry record. It does not state whether all enrolled participants were intended to be included, whether eligibility or assay-quality criteria affected inclusion, or whether analyses were adjusted for participant characteristics. The record also does not give a statistical analysis plan or interim-analysis details. These omissions limit the ability to evaluate how the reported design translated into an analysis. Because no outcome analyses or numerical estimates are reported, it is not possible to assess whether missingness, multiple testing, or analysis-population choices influenced a result.
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 |
|---|---|---|---|
| CKD Not on Dialysis | 0 | 72 | 0.0% |
| Controls | 0 | 31 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| CKD Not on Dialysis | 0 of 72 |
| Controls | 0 of 31 |
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 |
|---|---|
| CKD Not on Dialysis | 0 of 72 |
| Controls | 0 of 31 |
The serious adverse-event record lists 72 participants at risk in the CKD Not on Dialysis group and 31 in the Controls group. It records zero serious adverse events and zero deaths in each group. The record also lists zero other adverse events for each group. These figures describe the adverse-event entries in the registry; they are separate from the primary in-vitro cholesterol-efflux endpoint.
The denominators indicate the numbers listed as at risk for the adverse-event summaries, not necessarily the number with an evaluable primary assay result. The registry record does not provide additional information on adverse-event collection, definitions, monitoring period, or completeness. The study involved no intervention and assessed the primary outcome once at enrollment, but those design details do not fill in the unreported safety-collection methods.
Zero recorded events should be read as the counts entered in the registry, not as proof that no event could occur or as a comparison of safety between groups. The study was not a randomized treatment comparison, and the groups are flagged as not like-for-like controls. The adverse-event entries do not establish a causal safety effect.
12. What the Result Does, and Does Not, Mean
The study addresses a mechanistic question about cholesterol handling: whether HDL from participants with CKD not on dialysis differs from HDL from controls in its capacity to remove cholesterol from cultured cells. The registry record provides a description of the assay, including the cell preparation and measurement process, and defines the endpoint as a percentage of cholesterol removed by HDL. That information clarifies what the investigators intended to measure.
The registry record does not report the numerical primary outcome, group summaries, an estimated difference, confidence intervals, p-values, or analyses. It therefore cannot establish whether the assay results differed between groups, how large any difference was, or how precisely it was estimated. Study completion and an enrollment of 103 do not answer those statistical questions.
Even if the numerical assay results were available, this outcome would be evidence about an in-vitro functional measure, not direct evidence about cardiovascular disease events, kidney disease progression, or the effect of a treatment. The study did not administer an intervention. The registry’s broader rationale concerns processes that may relate to foam cell formation and vascular integrity, but a laboratory measure alone cannot establish those downstream clinical relationships.
The comparison also has important limits for causal interpretation. Participants were not randomly allocated, and the record warns that the arms are not a like-for-like control comparison. Group differences in characteristics may contribute to an observed contrast. The registry does not report adjustment results that could help evaluate this issue.
In general, estimates should be interpreted alongside their uncertainty and the design that produced them. Neither the estimate nor its uncertainty is reported for the primary outcome. The defensible conclusion is therefore about the study’s question and measurement approach, not about the presence, absence, size, or clinical importance of a group difference.
13. Why This Trial Matters Statistically
This study is statistically interesting because it focuses on a biological process rather than a clinical event. Its primary endpoint is an in-vitro measure of HDL-mediated cholesterol efflux, which makes the link between the scientific question and the measured quantity explicit. Careful distinction between a mechanistic assay and a patient-level outcome is essential when interpreting research on disease processes.
The comparison also illustrates why design information matters. The registry describes a CKD group and a normal-kidney-function control group, but it does not describe random allocation and explicitly cautions that the arms are not a like-for-like control comparison. Statistical adjustment, if used and appropriately reported, can sometimes help account for measured differences, but it cannot be assumed. The registry record reports no analyses.
Equally important is the distinction between a defined endpoint and a reported result. The assay procedure and summary format are described, but numerical outcomes are not reported. Without estimates and measures of uncertainty, readers cannot judge the size, direction, or precision of a group contrast. Descriptions of a study’s rationale and methods do not substitute for outcome data.
The record also provides a useful example of how planning calculations differ from observed evidence. A sample-size illustration based on an assumed fraction of an observed effect is a planning tool. It is not observed power and does not establish the certainty of an unreported result. Statistical interpretation depends on the actual estimate, its uncertainty, the analysis, and the study design together.
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 statistical interpretation is that the registry record does not report numerical results for the primary endpoint. There are no group medians or inter-quartile ranges, no estimated contrast, and no confidence interval or p-value. Consequently, the direction, size, and precision of a possible difference in cholesterol efflux cannot be assessed.
The study is a non-randomized comparison of CKD and control groups, with allocation not stated. The record specifically cautions that the arms are not a like-for-like control comparison. The registry describes co-morbidities and plasma lipid profiles as relevant to the study’s rationale, but it does not report participant characteristics or adjusted analyses. Potential group differences therefore cannot be evaluated from the record.
The endpoint is measured once at enrollment in an in-vitro assay. It reflects cholesterol removal under the assay conditions and is not a direct clinical outcome. The registry does not report assay-result distributions, assay quality-control details, or the number of participants with evaluable endpoint data. Missing-data handling and the analysis population are not reported.
The registry lists one primary outcome measure and zero analyses, but does not report a statistical analysis plan or a multiplicity approach. It also does not report a sample-size justification for the study’s design. Planning illustrations are not a substitute for observed estimates or evidence about their precision. These limitations prevent a complete assessment of the statistical analysis and the strength of any group comparison.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Mechanisms of Chronic Kidney Disease (CKD)-Induced Foam Cell Formation — NCT01671605.
- Registry record last updated 2017-04-21; status last verified 2017-03.
- Results first posted 2017-04-21.
- 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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Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes a completed study of mechanisms related to CKD-induced foam cell formation, sponsored by Vanderbilt University Medical Center. The recorded enrollment is 103, with groups described as CKD not on dialysis, CKD III-IV, and controls with normal kidney function. The study start is listed as 2013-02 and primary completion as 2015-04.
The primary outcome is in-vitro cholesterol efflux, expressed as the percentage of cholesterol removed by HDL and summarized as median with inter-quartile range. The assay used HDL isolated from participants in each group and cultured cells loaded with cholesterol. The assessment was performed once at enrollment, with no intervention.
The record cautions that this was not a randomized, like-for-like control comparison. It lists zero analyses and does not report numerical primary outcome results, uncertainty estimates, or analysis methods. The adverse-event entries list zero serious events and zero deaths in both groups. These registry entries describe the study and its posted record, but they do not establish the magnitude or clinical meaning of a cholesterol-efflux difference.