Safety Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Renal Failure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Renal Failure (NCT01072682), a na na study. The primary outcome is 60 Day Mortality.

2. Clinical Question

3. Trial Design

This was a completed, single-group, multicenter pilot study of the selective cytopheretic device in patients with acute renal failure who were receiving continuous renal replacement therapy. The registry record lists SeaStar Medical as the sponsor, enrollment of 35 participants, a start date of 2010-02, and a primary completion date of 2011-05. The phase is recorded as NA.

The design has no listed control arm: allocation is recorded as NA, and the study model is single group. Masking is recorded as none. These features mean the registry record does not describe a randomized, blinded comparison. The SCD experimental treatment arm is the sole listed arm. Its adverse-event information is reported for 35 participants at risk.

The protocol summary identifies safety evaluation as the purpose of the study, and the official title describes it as a pilot study to assess safety and efficacy. A pilot study can provide descriptive information about conduct and observed outcomes, but the registry record does not establish a comparator-based estimate of treatment effect. It also does not report a planned sample-size justification, recruitment approach, treatment schedule, or details of follow-up beyond the primary endpoint timeframe.

The primary outcome is 60-day mortality, with the timeframe defined as day 60 following treatment end. The registry record lists two outcome measures, but identifies no analyses. It does not report the mortality result or explain whether the listed safety results use the same analysis population as the primary endpoint. Consequently, the design and outcome definitions can be described, but the posted record does not support a full account of how the study was conducted or how the primary outcome was 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

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 60 Day Mortality, measured over Day 60 following treatment end.

The primary endpoint is 60-day mortality, recorded as a count of participants. Its timeframe is day 60 following treatment end. This is a binary outcome at the participant level: each participant either died within the defined period or did not. The registry record does not provide the number meeting the endpoint, the number included in the endpoint analysis, or a statistical estimate for the outcome.

In general, mortality is used as a clear clinical endpoint because it records whether death occurred within a specified follow-up period. Defining the time origin matters: the registry record anchors the period to treatment end, not to enrollment or study start. The endpoint therefore requires reliable information about treatment end and participant status through the specified follow-up. The registry record does not describe how deaths were ascertained, how participants with incomplete follow-up were handled, or whether any cause-of-death distinction was used.

The record separately lists 11 deaths in the safety information. It does not state that this count is the primary endpoint result, nor does it specify that those deaths occurred within the endpoint timeframe. The safety count should therefore not be substituted for the unreported 60-day mortality result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record identifies the primary outcome as a participant count for 60-day mortality. It lists no analyses. As a result, the statistical methods used for the primary outcome are not reported in the registry record. General statistical concepts can clarify what would ordinarily be needed to interpret a binary outcome, but they should not be mistaken for methods documented for this study.

What does a participant count represent?

For a binary endpoint, each participant is classified according to whether the defined event occurred. A count tells how many participants had the event, while a denominator tells how many participants were assessed for that endpoint. The registry record states that 35 participants were enrolled and that 35 were at risk in the adverse-event group, but it does not report the denominator used for the mortality endpoint or its event count. Enrollment and an endpoint analysis population are not necessarily interchangeable; how they relate must be reported rather than assumed.

What would an uncertainty interval add?

General explanation: a confidence interval expresses uncertainty around an estimate under a specified statistical model and sampling framework. A narrow interval indicates greater precision under those assumptions, while a wide interval indicates less precision. An interval does not remove design limitations, and it cannot create a comparison that the study did not include. No confidence interval for mortality or the adverse-event counts is reported in the registry record.

What can a significance test establish?

General explanation: a statistical test evaluates compatibility between observed data and a stated null hypothesis under specified assumptions. A p-value is not the probability that a treatment works or that the null hypothesis is true. Its interpretation depends on the outcome, model, hypothesis, and analysis plan. No p-value, test result, or primary-outcome analysis is reported in the registry record. Because this study has no listed control group, a test of a between-group treatment difference is not described.

Why does the design matter for inference?

In a randomized comparison, allocation can support interpretation of differences between groups by reducing systematic differences in expectation. This study is single group, with allocation recorded as NA, so there is no randomized control comparison. A single-group outcome count can describe what happened among enrolled participants, but cannot by itself show what would have happened to those same participants under an alternative. Masking is recorded as none; the record does not describe whether outcome assessment or event coding was conducted independently of treatment knowledge.

How should the planning illustrations be read?

The posted sample-size assumptions describe a planning illustration computed from an observed effect, not the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. For time-to-event outcomes, the stated convention is a total number of events using Schoenfeld; other outcomes use participants per arm. These are planning assumptions, not evidence that this study randomized participants between two arms or was designed with those assumptions. Sample-size illustrations are not observed power, and they do not establish that an analysis was planned or conducted. The registry record does not report a sample-size justification for the trial itself.

General explanation: over-dispersion occurs when variation in count data exceeds what a chosen model assumes. If present, it can make standard errors too small and uncertainty intervals too narrow unless the analysis accounts for it. The registry record does not report a count model, dispersion assessment, or any model for mortality. No claim about over-dispersion or model choice can therefore be made for this study.

To assess the primary endpoint statistically, readers would need the endpoint count and denominator, the handling of incomplete follow-up, and the analysis method. To assess comparative effect, a suitable comparator and a prespecified contrast would also be needed. Those details and results are not reported in the registry record.

10. Exact Estimates for Each Arm

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

R code and output

arm    <- c("SCD Experimental Treatment Arm")
n      <- c(35)
events <- c(11)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  SCD Experimental Treatment Arm  35  11  31.4  16.9  49.3  18.6  48.0  18.6  48.1

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures and identifies 60-day mortality as the primary outcome, but it reports no analyses. It does not describe a multiplicity strategy, such as how testing across multiple outcomes or repeated analyses would be controlled. Without the analysis plan and results, it is not possible to determine whether any statistical testing was performed or how the possibility of false-positive findings was addressed.

Missing-data handling is not reported in the registry record. The record does not state how participants who withdrew, could not be contacted, or lacked status at day 60 were treated. It also does not report the number of participants with complete mortality follow-up. The enrolled total and the adverse-event group at-risk total do not establish the denominator used for the primary endpoint.

Analysis populations are not described. The registry record does not specify whether the primary outcome was analyzed among all enrolled participants, among participants who received treatment, or in another defined group. It also does not give reasons for any exclusions or explain how deviations from treatment were handled. These omissions matter because population definitions and missing outcome data can affect both the estimated event count and its interpretation.

The record lists no statistical analyses and no primary endpoint result. Accordingly, there is no basis to assess whether outcome definitions, analysis populations, or missing-data methods were selected before results were known. These elements are not reported in the registry record.

12. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: sepsis (8.6%), multi-system organ failure (8.6%), pneumonia (5.7%), dic (5.7%), acute respiratory failure (5.7%).

The safety record lists 35 participants at risk in the SCD experimental treatment arm. It reports 23 participants affected by serious adverse events and 33 affected by other adverse events. It also lists 11 deaths. These are counts in the treatment arm; they are not comparative estimates and do not, by themselves, establish that the device caused any event.

The listed serious adverse event terms and reported percentages are Sepsis, 8.6%; Multi-System Organ Failure, 8.6%; Pneumonia, 5.7%; DIC, 5.7%; Acute Respiratory Failure, 5.7%; and Right Iliac Artery Injury, 2.9%. The registry record does not give event counts for each term or explain whether a participant could have multiple listed events. It also does not report the criteria for classifying seriousness, the process for determining attribution, or the observation period for these safety summaries.

The 11 deaths are reported in the safety information, but the registry record does not identify them as deaths within the primary endpoint timeframe. The primary outcome is 60-day mortality following treatment end, and its result is not reported. The safety death count should therefore be kept distinct from the unreported primary endpoint result.

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

The registry record documents a completed, single-group pilot study of a selective cytopheretic device in patients with acute renal failure receiving continuous renal replacement therapy. It reports enrollment of 35 participants and provides descriptive adverse-event information for the SCD experimental treatment arm. It identifies 60-day mortality as the primary outcome, but does not report the mortality count or any analysis of that endpoint.

These data can describe the adverse-event counts and the serious adverse event terms recorded for the group. They cannot show how those counts compare with what would have occurred without the device or with a different treatment, because no comparator group is listed. They also cannot establish that an event was caused by the device. The registry record does not include the methods for attribution or enough information to account for the participants' underlying illness and other care.

The absence of a reported primary result is not evidence that no deaths occurred or that the endpoint was not measured. It means the registry record does not report the result. Likewise, the absence of a reported analysis does not establish what analyses may have been conducted outside the registry record; those details are not reported in the registry record.

In general, a treatment-effect conclusion needs an interpretable outcome estimate, a suitable comparison, and information about uncertainty and study limitations. The posted record lacks a control comparison and a reported primary outcome analysis. It therefore cannot establish a comparative mortality effect or resolve the official title's efficacy question. The available information supports a descriptive account of the registered design and safety counts, not a conclusion about whether the device changes clinical outcomes.

14. Why This Trial Matters Statistically

This study illustrates the difference between an outcome being named and an outcome being reported. The registry record designates 60-day mortality as the primary endpoint, with a defined timeframe following treatment end, but does not provide the endpoint result or any analysis. Without the event count, denominator, and an uncertainty estimate, readers cannot assess the observed mortality level or its precision from the registry record.

The single-group design is central to the statistical interpretation. The adverse-event counts describe the enrolled SCD group, but there is no listed control group to provide a reference for comparison. This matters especially in acute renal failure, where the registry record identifies a population receiving CRRT and the safety record includes serious clinical events. Descriptive counts can document events without separating the contribution of the device from other influences.

The record also shows why endpoint definitions and analysis populations need to be read separately. The primary endpoint has a stated time origin and follow-up period, while the safety data include a death count whose relationship to that endpoint timeframe is not specified. Assuming those figures are identical would go beyond what the registry record reports.

For statistical education, the trial is a useful example of how a protocol's stated aims, a study's design, and its posted results answer different questions. The record identifies an intended safety and efficacy assessment, but the results available for interpretation are limited to adverse-event descriptions. Transparency about absent analyses and endpoint results is necessary to keep descriptive observations from being mistaken for comparative evidence.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The main trial-specific limitation is the absence of a comparator. The study is listed as single group, with allocation recorded as NA. The safety counts therefore have no concurrent control group for comparison, and they cannot estimate a relative treatment effect. The record also lists masking as none, while not describing whether outcome assessment or event classification was otherwise independent.

The primary outcome result is not reported in the registry record, and no analyses are listed. The mortality count, analysis denominator, uncertainty interval, and statistical method are all not reported in the registry record. The safety record lists 11 deaths, but does not establish that these are the primary endpoint events within the defined follow-up timeframe.

Details that would help interpret the population and conduct are also not reported in the registry record. These include eligibility criteria, treatment delivery and duration, follow-up procedures, missing-data handling, analysis populations, event attribution, and the approach to sample-size justification. The record describes a multicenter pilot study but does not give the number or characteristics of participating centers.

With enrollment of 35 participants, the study's scope is limited to the enrolled group, and the registry record does not provide precision estimates that would help characterize uncertainty. The adverse-event terms are accompanied by percentages, but event counts by term and information about overlapping events are not reported. These limitations do not show that the study was conducted improperly; they define what can and cannot be concluded from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Safety Study of a Selective Cytopheretic Device (SCD) in Patients With Acute Renal Failure — NCT01072682.
• Registry record last updated 2022-03-31; status last verified 2022-03.
• Results first posted 2022-03-09.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT01072682 is a completed, single-group, multicenter pilot study sponsored by SeaStar Medical. It enrolled 35 participants with acute renal failure receiving continuous renal replacement therapy and evaluated a selective cytopheretic device. The listed study dates are 2010-02 for start and 2011-05 for primary completion. Phase is recorded as NA, allocation as NA, and masking as none.

The primary outcome is 60-day mortality, measured as a participant count at day 60 following treatment end. The registry record does not report that outcome's result or any analyses. Safety information lists 23 participants with serious adverse events, 33 with other adverse events, and 11 deaths among 35 participants at risk. These descriptive data do not provide a control comparison or establish event attribution.