Efficacy Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Kidney Injury: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Kidney Injury (NCT01400893), a randomized na study. The primary outcome is The Primary Clinical Efficacy Endpoint in This Trial is All Cause Mortality Through 60 Days Post-randomization..

2. Clinical Question

3. Trial Design

The study was a randomized, controlled, parallel-group trial comparing CRRT plus SCD with CRRT alone in patients with acute kidney injury who required CRRT. The registry describes the study as multi-center and identifies SeaStar Medical as the sponsor. Masking was recorded as none, so the trial was open-label. The phase was listed as not applicable.

Enrollment was 134. That figure is the registry enrollment entry; the record does not explain whether it represents the number randomized, treated, or included in each analysis. The arm-level safety entries list 69 participants at risk in the CRRT plus SCD group and 63 in the CRRT-alone group. Those values should not be added to infer another study total or assumed to describe the primary endpoint population.

The study started in 2011-08, and primary completion was recorded as 2013-09. Its status is terminated. The registry record does not report why the study was terminated, whether the planned enrollment was reached, or whether termination affected the timing or completeness of outcome collection.

The registry names all-cause mortality through Day 60 as the primary clinical efficacy endpoint. Renal replacement therapy dependency at Day 60 is listed as a secondary outcome. The registry identifies two outcome measures but contains no analysis entries. It therefore does not provide enough information to reconstruct a complete statistical analysis plan or to determine how the named outcome measures were analyzed.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Outcome data is reported for those subjects in which the calcium levels were maintained in the protocol's recommended range (≤0.4 mmol/L) for greater or equal to 90% of the therapy time.

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 The Primary Clinical Efficacy Endpoint in This Trial is All Cause Mortality Through 60 Days Post-randomization., measured over Day 60 following treatment initiation.

The primary endpoint is all-cause mortality through 60 days after randomization. All-cause mortality counts death from any cause within the defined follow-up period, rather than restricting the endpoint to a particular cause. A fixed follow-up time gives the endpoint a common clinical horizon for comparing groups, although the interpretation still depends on which participants were included and how missing outcome status was handled.

The registry also gives the timeframe as Day 60 following treatment initiation. Its outcome description says the reported mortality data concern treated subjects whose ionized calcium was maintained in the protocol-recommended range of no more than 0.4 mmol/L for at least 90% of therapy time. This qualification matters: the described outcome population is not necessarily the same as the full randomized population, and the record does not explain how this restriction was applied in the analysis.

Mortality is a binary outcome for each participant: death by the stated follow-up point or no recorded death by that point. A comparison can be reported using event counts and an effect estimate with uncertainty, but the registry record does not present a primary mortality comparison, confidence interval, or p-value. The primary endpoint is named; its comparative result cannot be determined from the available record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Random allocation is intended to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. That protection applies to the randomized groups as assigned; it does not automatically carry over to a subset defined by events during treatment. The registry records randomized allocation and a parallel-group design. It does not report the allocation procedure, any stratification factors, or the statistical analysis plan.

What does a binary endpoint represent?

For an individual participant, a binary endpoint records whether a defined event occurred by a specified time. For this trial’s primary endpoint, the event is death from any cause through Day 60. Group summaries can describe the number of participants with the event and the number whose outcome is known. A comparison may then express the difference between groups in several ways. Each measure answers a somewhat different question, so it is important to identify the reported measure and its definition rather than infer one from event counts.

A point estimate describes the observed comparison in the study population. A confidence interval describes the uncertainty around that estimate under the assumptions of the method used. A wider interval indicates less precision; an interval that includes values representing no difference is compatible with a range of possible effects, not proof that the groups are identical. The registry record does not report an effect estimate or confidence interval for the primary endpoint, so these interpretations cannot be applied to a posted mortality comparison.

Why does the analysis population matter?

An analysis of participants according to their randomized assignment preserves the original comparison created by randomization, subject to the analysis plan and available outcome data. By contrast, restricting analysis to participants who met a condition after treatment began can change the groups being compared. In this record, the mortality description refers to treated subjects who maintained ionized calcium in the recommended range for at least 90% of therapy time. The record does not explain whether that restriction was prespecified, how it was determined, or whether the reported outcome data also include an analysis of all randomized participants.

Missing outcomes can also affect interpretation. If outcome status is unavailable for some participants, the amount and pattern of missingness matter, as do the assumptions used to handle it. The registry record does not report missing-data counts, reasons for missingness, or a method for addressing missing outcomes. It is therefore not possible to judge from the record whether the mortality follow-up was complete or how incomplete observations were treated.

How should safety counts be read?

The serious adverse-event information gives, for each group, a count of participants at risk and a count of participants affected. These are descriptive quantities. A count does not itself measure uncertainty or establish that an observed difference between groups is more than chance variation. A comparative safety analysis would need a clearly defined event unit, follow-up period, analysis population, and statistical method. Those details and an inferential comparison are not reported in the registry record.

The registry also lists percentages for serious adverse-event categories. Such percentages need a denominator and a definition of whether they refer to participants, events, or another unit. The available record does not state the denominator for the category percentages. They should therefore be read as listed descriptive percentages, not converted into counts or treated as directly comparable event rates.

What do planning calculations mean?

Sample-size planning uses assumptions about the outcome, the effect a future study aims to detect, the allocation, and the statistical method. The stated planning approach uses a two-sided significance level of 0.05, equal allocation, and a normal approximation; it frames the effect to detect as a stated fraction of the observed effect. Such calculations illustrate planning under assumptions. They do not show the probability that this completed trial found a true effect, and they are not observed power. The record does not report a primary-endpoint effect estimate or the trial’s own design justification, so planning illustrations should not be mistaken for evidence about the trial result.

Finally, multiplicity concerns arise when several outcomes, time points, or comparisons are tested. Repeated testing can increase the chance of at least one apparently unusual result if no adjustment or hierarchy is specified. The record lists the primary mortality endpoint and renal replacement therapy dependency at Day 60 as a secondary outcome, but does not report the analysis hierarchy or any multiplicity adjustment. No unadjusted or adjusted inferential results are available in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry names all-cause mortality through Day 60 as the primary clinical efficacy endpoint and renal replacement therapy dependency at Day 60 as a secondary outcome. It also records two outcome measures but no analysis entries. The record does not provide the complete set of analyses, the ordering of hypotheses, or a multiplicity strategy. It is therefore not possible to determine whether the recorded outcomes were tested under a prespecified hierarchy or whether any adjustment was used.

Multiplicity is a general statistical concern when investigators assess several outcomes, time points, or comparisons. If many tests are considered, the chance of seeing at least one result that appears unusual under a no-effect assumption can rise. A prespecified hierarchy or adjustment can address this issue, but the choice depends on the design and analysis plan. The registry record does not report such a plan; no particular approach should be assumed.

The registry’s mortality description refers to treated participants who kept ionized calcium within the recommended range for at least 90% of therapy time. The record does not state whether this was the intended analysis population for the primary endpoint or whether results for all randomized participants were also analyzed. It also does not report the number of participants meeting the condition, the number with known Day 60 status, or missing-data methods. Thus, the completeness and population basis of the mortality outcome cannot be assessed.

Missing-data handling is important because participants without known outcome status may differ from those with observed outcomes. Appropriate interpretation depends on the amount and reasons for missingness and the analysis assumptions. Those details are not reported in the registry record. The reported information does not establish whether missing data were absent, excluded, or handled by a statistical method.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: cardiac disorders (17.4%), infections and infestations (17.4%), respiratory, thoracic and mediastinal disorders (15.9%), blood and lymphatic system disorders (11.6%), general disorders and administration site conditions (11.1%).

The serious adverse-event entries list 45 affected participants among 69 at risk in the CRRT plus SCD group, and 40 affected among 63 at risk in the CRRT-alone group. These are descriptive registry counts. They should be interpreted within the recorded groups and should not be turned into a comparative effect by calculating a difference or ratio.

The record does not report confidence intervals, p-values, or an adjusted safety comparison for these entries. It also does not provide enough detail to establish the event-collection rules, the precise follow-up window for these safety counts, or whether the participants represented are the same population described for the primary mortality outcome. A difference between descriptive counts alone does not establish a treatment effect or its precision.

The listed serious adverse-event categories include cardiac disorders and infections and infestations, each at 17.4%; respiratory, thoracic and mediastinal disorders at 15.9%; blood and lymphatic system disorders at 11.6%; general disorders and administration site conditions at 11.1%; and vascular disorders at 10.1%. The registry record does not identify the denominator or statistical uncertainty for these percentages. They should be read as category summaries, not as evidence of a between-group difference. The death counts listed in the group information do not replace the missing primary endpoint analysis.

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

The record establishes that a randomized, open-label, parallel-group study compared CRRT plus SCD with CRRT alone in patients with acute kidney injury requiring CRRT. It identifies all-cause mortality through Day 60 as the primary clinical efficacy endpoint and lists renal replacement therapy dependency at Day 60 as a secondary outcome. It also gives selected arm-level safety information and describes the calcium condition associated with the mortality data.

Those details do not establish whether the groups differed in Day 60 mortality, how large any difference was, or how precisely it was estimated. The registry record contains no primary mortality estimate, confidence interval, or p-value, and it records no analyses. The death counts in the adverse-event group entries cannot be assumed to be the primary endpoint counts, because the record does not clarify whether their population and definitions match the primary outcome description.

The results description applies to treated subjects who maintained ionized calcium in the recommended range for at least 90% of therapy time. This condition may define a subgroup that differs from the full randomized population. Without information on how the subgroup was formed and whether an analysis by randomized assignment was also performed, its results cannot be taken as a complete account of the randomized comparison.

The serious adverse-event counts and category percentages are descriptive. Without a reported comparative analysis, uncertainty estimates, and clear denominators for the category percentages, they do not establish whether safety outcomes differed between groups. They also do not answer the primary efficacy question.

In general, a registry entry can describe a study’s design and selected outcomes without giving a complete statistical report. Conclusions about effect size, precision, missing outcomes, or consistency across analyses require details not reported in this record. The available information supports a cautious account of what the study set out to compare and which selected counts were recorded; it does not support a claim that the device did or did not change mortality or other clinical outcomes.

13. Why This Trial Matters Statistically

This trial raises several statistical issues that matter when reading clinical research. Randomization is central to comparing interventions because it aims to create groups that are comparable before treatment. But interpreting a randomized trial still requires knowing which participants were analyzed and whether the analysis retained the randomized comparison. The mortality description’s restriction to treated subjects meeting a calcium-maintenance condition makes the analysis population especially important.

The distinction between a named endpoint and a reported endpoint result is also important. The registry clearly names Day 60 all-cause mortality, but does not record an analysis estimate or its uncertainty. An endpoint label alone does not tell readers the observed comparison, its precision, or whether the analysis followed the original assignment. This trial therefore illustrates why a statistical interpretation needs more than an outcome title and descriptive event information.

The safety entries provide another useful distinction: descriptive counts are not the same as an inferential comparison. Counts can show what the registry recorded, but they do not quantify uncertainty or establish whether differences are compatible with chance variation. Category percentages also require a clearly stated denominator to be interpreted as rates or risks.

Finally, the record’s terminated status and lack of analysis entries limit what can be learned from the registry record. The reason for termination and its relationship to outcome collection are not reported. Statistical planning assumptions, if used for illustrative calculations, should not be confused with observed power or with a result. These limitations are not reasons to infer a favorable or unfavorable outcome; they identify why a complete analysis report is needed to assess the trial’s clinical comparison.

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 leaves important trial-specific details unresolved. Although it names a Day 60 mortality endpoint, it does not report an arm-specific primary result, an effect estimate, a confidence interval, or a p-value. It records no analyses. The primary endpoint’s comparative magnitude and precision therefore cannot be assessed from the recorded information.

The population description requires particular caution. Mortality data are described for treated subjects whose ionized calcium was within the recommended range for at least 90% of therapy time. The record does not explain how many participants met this criterion, whether it was prespecified, or whether a full analysis by randomized assignment was also performed. Because this condition is assessed during treatment, it does not necessarily preserve the comparability created by randomization.

The record does not provide missing-outcome counts, reasons for missingness, follow-up completeness, or the method used to address missing data. It also does not report the detailed statistical plan, allocation procedures, or multiplicity handling. These omissions prevent assessment of whether the analyses matched the intended plan and how robust the results would be to alternative assumptions.

Safety information is limited to the listed counts and category percentages. The record does not specify the denominator for the category percentages or provide inferential comparisons. The listed death counts are not clearly tied to the primary endpoint population and should not be assumed to represent its analysis.

The study is marked terminated, but the reason is not reported. Nor does the registry record explain whether termination affected enrollment, follow-up, or reporting. Enrollment is listed as 134, while the relationship of that entry to the analysis populations is not explained. These gaps mean the registry record alone cannot support a complete assessment of the trial’s conduct or outcome results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Efficacy Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Kidney Injury — NCT01400893.
• Registry record last updated 2021-04-27; status last verified 2021-04.
• Results first posted 2017-08-29.
• 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.

18. Record Summary

The registry describes a randomized, controlled, multi-center, open-label, parallel-group study of CRRT plus SCD versus CRRT alone in patients with acute kidney injury requiring CRRT. SeaStar Medical is listed as sponsor. Enrollment was 134; the study started in 2011-08, primary completion was 2013-09, and status is terminated. The reason for termination is not reported in the registry record.

All-cause mortality through Day 60 is the named primary clinical efficacy endpoint. Renal replacement therapy dependency at Day 60 is listed as a secondary outcome. The mortality description refers to treated subjects whose ionized calcium remained within the recommended range for at least 90% of therapy time. No analysis entries or primary endpoint comparison are recorded. Selected serious adverse-event counts and category percentages are listed, but the record does not provide a comparative safety analysis or the denominator for the category percentages.