Clinical Trial in Patients Diagnosed With Immune Thrombocytopenic Purpura: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Clinical Trial in Patients Diagnosed With Immune Thrombocytopenic Purpura (NCT00699140), a na phase 3 study. The primary outcome is Responder Patients.

2. Clinical Question

3. Trial Design

This was a phase 3, single-group study of IGIV3I Grifols in patients diagnosed with immune thrombocytopenic purpura. The registry record identifies the study as completed, with enrollment of 18. Its start is recorded as 2008-02 and its primary completion as 2013-12. The sponsor was Instituto Grifols, S.A.

The treatment group was open label and non-randomized. As a result, participants and study personnel were not masked to treatment, and the design did not include a randomized control group. The allocation field is NA. These features mean the study describes outcomes in treated patients but cannot, by design, separate the treatment experience from other influences as a controlled comparison could.

All patients received a total dose of 2 g/kg of IGIV3I Grifols, infused intravenously in divided doses over either 2 days or 5 days. The registry record does not say how many participants received each schedule or how the schedule was determined. It also does not report additional details about treatment adherence, concomitant care, or the visit schedule beyond the platelet measurement times listed for the primary endpoint.

The registry identifies an intent-to-treat population of all 18 subjects who received at least one infusion, at any dose. That population was used for efficacy and safety analysis. Although the record lists several secondary outcomes, including platelet response over time, regression of hemorrhages, adverse reactions, vital signs, laboratory changes, renal function, and viral safety, numerical results for those outcomes are not reported in the registry record. The record lists no analysis entries.

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

Analysis population for the primary outcome, as defined in the registry: All 18 subjects received at least one infusion (at any dose) of IGIV3I Grifols and were included in the intent-to-treat (ITT) population for efficacy and safety analysis.

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 Responder Patients, measured over At any time during the study period (The platelet count was measured at Days 1-6, 10, 14. 21, 30, 60, 90)..

The primary endpoint was the proportion of patients who reached a platelet count of at least 50x10^9/L at any time during the study period. The registry describes the result as a percentage of subjects and lists a 95% confidence interval as its measure of uncertainty. It gives the measurement timeframe as the study period, with platelet counts measured at Days 1-6, 10, 14, 21, 30, 60, 90.

This endpoint turns a series of platelet measurements into a responder classification: a patient counts as a responder if at least one recorded count reaches the specified threshold. It is therefore different from an endpoint based on the average platelet count, the maximum change from baseline, or the time until a response. The registry separately lists maximum platelet level and time to reach the threshold as secondary outcomes.

As a general statistical point, a binary response endpoint can be easy to interpret as a proportion of participants meeting a defined criterion. But it also compresses the underlying measurements: it does not, by itself, describe how high counts rose, how long a response lasted, or whether a response occurred at a particular scheduled measurement. Those questions require other outcomes. The primary endpoint result and its confidence interval are not reported in the registry record, so the response proportion and its precision cannot be described from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes the primary result as a percentage of subjects with a 95% confidence interval. It does not report the interval itself or explain the statistical procedure used to calculate it. General explanations below describe the meaning of these methods, not a claim about undocumented analysis choices.

What does a responder percentage represent?

A percentage for a binary endpoint expresses the share of the analysis population meeting a defined condition. In this study, the condition was reaching a platelet count of at least 50x10^9/L at any time during the study period. Each participant is classified according to whether that threshold was reached, rather than contributing a value proportional to the size or duration of the platelet change. The resulting proportion would describe the frequency of responders in the analyzed group; it would not, on its own, describe an average platelet count or the duration of response.

The record identifies all 18 participants who received at least one infusion as the intent-to-treat population for efficacy and safety analysis. The primary result is not reported, so the observed responder percentage cannot be stated. The registry also does not report a participant-level account of which scheduled measurements were available or how a participant with no usable measurement was classified.

How should a confidence interval be understood?

In general, a confidence interval communicates statistical uncertainty around an estimate. For a responder percentage, it would indicate a range of values compatible with the observed data under the interval procedure's assumptions. A wider interval generally signals less precision than a narrower interval. The interval does not replace the point estimate, and it does not resolve limitations in study design, measurement, or missing data.

The registry names a 95% confidence interval for the primary endpoint but does not give its limits or specify how it was calculated. Without the responder estimate and interval limits, neither the magnitude of the result nor its precision can be assessed. No particular interval method should be inferred from the record.

What does the single-group design allow?

As a general statistical principle, a single-group study can describe outcomes observed among participants who received the intervention. A randomized comparison is designed to contrast outcomes between groups while reducing systematic differences in treatment assignment. This study is described as open label and non-randomized, and no control group is listed. Thus, a response observed in this group would not by itself estimate what would have happened to comparable participants under a different treatment or no study treatment.

Open-label conduct can also influence aspects of outcome assessment and care. The primary endpoint is based on a platelet count, a laboratory measurement, but the registry does not state whether laboratory assessment or other study procedures were masked. It would be inappropriate to assume additional safeguards that are not recorded.

How do the planning illustrations differ from observed results?

General sample-size planning asks how many participants might be needed under chosen assumptions to detect a specified effect with a chosen level of statistical error. The planning description associated with the record specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It also describes the effect to detect as a stated fraction of the observed effect. These are planning assumptions, not a description of this trial's design: the trial is a single-group study and does not list two allocated arms.

Any sample-size figures based on such assumptions are planning illustrations, not observed power and not evidence that the study had a particular probability of detecting an effect. The registry does not report a sample-size justification for the trial, and the numerical planning outputs are not reported in the registry record.

Why do analysis details matter?

Statistical interpretation depends on the analysis population, outcome definition, missing-data rules, and any adjustments made for multiple outcomes or repeated looks at the data. The registry identifies the intent-to-treat group and the endpoint definition, but it does not report a detailed statistical analysis plan or the method used for the confidence interval. It lists no analysis entries. Consequently, no adjustment strategy, imputation method, or interim-analysis procedure should be attributed to this study based on this record.

For safety outcomes, event counts and participant counts answer related but distinct questions. A participant can experience more than one event, and an event category can include multiple occurrences. The summary reports affected participants for serious and other adverse events, but does not provide event-level totals or detailed attribution. General interpretation should therefore distinguish the number of participants affected from the number and nature of all event episodes.

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("1 Treatment Group With IGIV3I")
n      <- c(18)
events <- c(13)
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  1 Treatment Group With IGIV3I  18  13  72.2  46.5  90.3  49.1  87.5  48.8  87.4

11. Multiplicity, Missing Data and Analysis Populations

The record lists a primary endpoint and multiple secondary outcomes, but it does not report a multiplicity strategy. In general, when several outcomes are tested, the chance of finding at least one apparently unusual result can increase if each is assessed independently. Statistical plans may address this through prespecified testing sequences or other adjustments, but such procedures are not reported in the registry record. No conclusion about adjusted or unadjusted secondary-outcome findings can be drawn because outcome results are not reported.

The registry identifies all 18 participants who received at least one infusion as the intent-to-treat population for efficacy and safety analysis. It does not report whether all scheduled platelet measurements were available, how missing measurements were handled, or whether participants were excluded from any particular endpoint analysis. The number of analysis entries is listed as 0. The registry also does not describe a per-protocol population or other analysis population.

Missing data can matter for an endpoint defined as reaching a threshold at any time: fewer observed measurements may mean fewer opportunities to record a response. As a general matter, methods for handling missing observations rely on assumptions about why data are missing and how missingness relates to the outcome. No such assumptions or methods are reported, so it is not possible to assess their influence.

Interim analyses, stopping rules, and a detailed statistical analysis plan are not reported in the registry record. This absence should not be interpreted as proof that a procedure was or was not used; it means the registry record does not document it. The same caution applies to any adjustment for baseline factors or repeated measurements.

12. Safety Results

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

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: thrombosis (5.6%), haemoglobin decreased (5.6%), leukopenia (5.6%).

The safety summary lists one treatment group with 18 participants at risk. It records 2 participants affected by serious adverse events and 12 affected by other adverse events. These are participant counts, not necessarily counts of every event occurrence: one participant may experience more than one event. The registry record does not provide event-level totals in this summary.

The serious adverse event terms listed are Thrombosis, Haemoglobin decreased, and Leukopenia, each recorded as 5.6%. These terms should be read as the listed serious-event categories, not as a complete account of all safety findings. The summary does not describe their timing, duration, severity beyond their serious classification, clinical course, or relationship to IGIV3I Grifols. The registry record does not report the death count.

As a general statistical point, adverse-event counts in a small treated group are descriptive. They do not establish that treatment caused an event, and they do not provide a controlled comparison of risk. The other adverse-event count should not be conflated with the serious-event count; the registry reports these separately. Further details on adverse reactions during and after infusions were listed as secondary outcomes, but numerical results for those outcomes are not reported in the registry record.

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

The study record documents an investigation of IGIV3I Grifols 10% in patients diagnosed with immune thrombocytopenic purpura. It specifies an open-label, non-randomized, single-group design; a total dose of 2 g/kg; and a primary endpoint based on whether platelet counts reached at least 50x10^9/L at any time during the study period. It also identifies the intended efficacy and safety population as all 18 participants who received at least one infusion.

These details establish what the study set out to measure and how the treatment was administered. They do not establish the observed primary response rate: that result and its 95% confidence interval are not reported in the registry record. The listed secondary outcomes likewise do not come with numerical results in this record. Therefore, the record does not allow readers to quantify the frequency, timing, or durability of platelet responses from the primary outcome.

Even if a response estimate were available, a single-group study without a control group would describe the treated participants rather than provide a randomized comparison. The design cannot by itself show how outcomes would compare under another treatment or no study treatment. Open-label conduct and unreported details about measurement availability and missing-data handling add further uncertainty to interpretation.

The safety summary reports affected participants and several serious-event terms, but it does not establish whether the events were caused by the intervention. Nor does it supply the detailed event descriptions needed to characterize their course. The listed planning assumptions are not a substitute for an observed comparison or for a trial-specific sample-size justification.

In short, the registry record is informative about the study's stated question, design, dosing, endpoint definition, and selected safety counts. It does not report the efficacy result needed to answer the primary question numerically, and it does not support a causal treatment-effect conclusion. These boundaries describe the available record, not the full set of possible study documents or results.

14. Why This Trial Matters Statistically

Statistically, this study illustrates the difference between defining an outcome and reporting its result. The registry carefully identifies a binary primary endpoint: the proportion of participants whose platelet count reached at least 50x10^9/L at any time during the study period. It also states that a 95% confidence interval was intended to accompany the percentage. Yet the response estimate and interval are not reported in the registry record. Without them, readers cannot assess either the observed frequency or its precision.

The design also matters when interpreting an outcome. This was a single-group, open-label, non-randomized study, not a like-for-like comparison. A descriptive response proportion could summarize the experience of the participants, but it would not by itself isolate the intervention's contribution to that experience. Recognizing this distinction is essential when reading clinical results: an endpoint may be clinically interpretable while the design limits causal interpretation.

The registry's safety summary offers another useful statistical distinction. It reports participants affected by serious and other adverse events, while separately listing serious-event terms and percentages. Participant counts and event counts are not interchangeable. The record also leaves important details, such as timing and event attribution, undocumented in the summary. Careful reading avoids making those counts carry more meaning than they can support.

Finally, the record lists planning assumptions that describe hypothetical two-arm calculations, although the actual study was single-group. Such illustrations can help explain how sample-size requirements depend on assumptions, but they are not observed power and do not represent the trial's actual design or its sample-size justification. Keeping design, endpoint, estimation, safety description, and planning assumptions distinct is the central statistical lesson of this study record.

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 most consequential limitation of the registry record is that it does not report the primary efficacy estimate or its 95% confidence interval. Although it defines the responder threshold and measurement timeframe, it does not state how many participants met the threshold. Numerical results for the listed secondary outcomes are also not reported in the registry record.

The single-group, non-randomized, open-label design has no listed concurrent control group. It can describe outcomes among treated participants, but it cannot provide a controlled contrast. The record does not report why allocation is listed as NA or whether any external comparison was planned. No such comparison should be presumed.

The enrolled population is described as 18 participants, all of whom received at least one infusion and entered the intent-to-treat efficacy and safety population. The registry record does not provide detailed baseline characteristics, eligibility criteria, the distribution of the 2-day and 5-day administration schedules, or participant-level follow-up and measurement completeness. It also does not report missing-data handling, a detailed statistical analysis plan, multiplicity procedures, or interim analyses.

Safety reporting is limited in the available summary. It gives affected participant counts and lists three serious adverse-event terms, each recorded as 5.6%, but does not provide event narratives, timing, duration, causal attribution, or a reported death count. The registry lists additional safety outcomes, but their numerical results are not reported. The planning assumptions described in the record are illustrative and do not constitute a documented trial-specific sample-size justification.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Clinical Trial in Patients Diagnosed With Immune Thrombocytopenic Purpura — NCT00699140.
• Registry record last updated 2016-02-08; status last verified 2016-01.
• Results first posted 2016-02-08.
• 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

The registry record describes a completed phase 3 study sponsored by Instituto Grifols, S.A., with enrollment of 18 patients diagnosed with immune thrombocytopenic purpura. The study evaluated IGIV3I Grifols 10% in an open-label, non-randomized, single-group design. Each patient received a total dose of 2 g/kg intravenously in divided doses over either 2 days or 5 days.

The primary endpoint was the proportion of patients reaching a platelet count of at least 50x10^9/L at any time during the study period. All 18 participants who received at least one infusion were included in the stated intent-to-treat efficacy and safety population. The primary response estimate and its 95% confidence interval are not reported in the registry record.

The safety summary records 2 participants with serious adverse events and 12 with other adverse events. Serious-event terms listed are Thrombosis, Haemoglobin decreased, and Leukopenia, each recorded as 5.6%. The registry lists additional secondary outcomes but does not report their numerical results.