EASSI - Evaluation of the Safety of Self-Administration With Icatibant: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for EASSI - Evaluation of the Safety of Self-Administration With Icatibant (NCT00997204), a non-randomized phase 3 study. The primary outcome is Number of Participants With Adverse Events in Self-treatment of Acute HAE Attacks With s.c. Injections of Icatibant.

2. Clinical Question

The clinical question concerns the safety and local tolerability of self-administered subcutaneous icatibant for acute attacks of hereditary angioedema. The study also examined convenience and clinical efficacy, as described in the registry record, but the primary outcome is a safety measure: the number of participants with adverse events during the specified observation period.

The registry record also names a secondary outcome concerning time to symptom relief using a visual analogue scale for a single primary symptom, by patient cohort. Numerical results for that efficacy outcome are not reported in the registry record. The posted safety counts therefore address only part of the broader study question and cannot, on their own, establish comparative efficacy or safety.

3. Trial Design

This was a phase 3, open-label, multicenter study with non-randomized allocation and a single-group model. The registry record describes two phases: a naive treatment phase and a self-administration phase. In both, the intervention was a single subcutaneous injection of icatibant, 30 mg. During the naive phase, a health care provider administered treatment; another group is described as self-administering while naive, and a third as self-administering while non-naive.

The adverse-event results distinguish three groups: naive subjects administered icatibant by a health care provider, subjects who self-administered icatibant while naive, and subjects who self-administered icatibant while non-naive. The denominators reported for these groups are 22, 19, and 78 participants, respectively. These group counts should not be treated as randomized arms. Participants were not randomly assigned to a self-administration strategy or a control treatment, and the groups do not establish a like-for-like comparison.

The registry record lists enrollment of 151 and status as completed. The study start date is 2009-09-25, and primary completion is recorded as 2011-06-22. These dates describe the registry record, but they do not supply participant-level follow-up information or explain how all enrolled participants contributed to each analysis.

Masking was listed as none. Participants and investigators therefore were not described as blinded in the record. The protocol's detailed allocation procedures, criteria for entering each phase, and statistical analysis plan are not reported in the registry record. The design is best understood as an evaluation of treatment experience and safety in an open-label setting, rather than a randomized estimate of the difference between self-administration and an alternative.

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.

Before assignment: Patients were screened for entry based on their known medical histories (HAE attacks) and previous exposure to a treatment (naïve or not). 151 were enrolled and trained in the self-administration. 47 of these subjects did not have an acute attack of HAE treated with icatibant during this study and were included in the untreated population.

Naive Treatment Phase

Self-administration Phase

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 Number of Participants With Adverse Events in Self-treatment of Acute HAE Attacks With s.c. Injections of Icatibant, measured over 7 days from the beginning of each phase.

The primary endpoint is the number of participants with adverse events during self-treatment of acute hereditary angioedema attacks with subcutaneous icatibant. It is a count of participants with an event, not a count of all event episodes and not a rate per unit of follow-up. The registry record specifies a timeframe of 7 days from the beginning of each phase. Its description further says that adverse events are assessed through the earlier of 7 days from the start of the naive phase, study discontinuation, or the start of the self-administration phase.

The record says that safety assessment included a local tolerability tool. Participants and investigators graded erythema or reddening, swelling, burning, pruritus or itching, warm sensation, and skin pain on a 0 to 3 severity scale. This kind of assessment captures the presence and severity of local symptoms, which can be relevant when treatment involves an injection and the participant administers it.

Counting participants with adverse events gives a direct descriptive account of how many people in each reported group had at least one event. It does not show how many events each person had, establish whether an event was caused by treatment, or quantify a comparison against a control group. The registry record does not report the full instrument results or a detailed breakdown of local tolerability grades.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record reports participant counts for adverse events, not a comparative effect estimate. Reading these counts starts with the outcome definition: the result is the number of participants who experienced an adverse event in a group. This differs from counting every event, since one participant may experience multiple events. The record does not give the total event count or event-level listings.

What a participant count describes

A count paired with its group denominator describes how many participants in that group were recorded as having an event. The posted counts are 0 of 22, 0 of 19, and 0 of 78 for serious adverse events, and 7 of 22, 6 of 19, and 21 of 78 for other adverse events. These figures are descriptive observations in the listed groups. They do not by themselves provide a causal comparison or account for differences in follow-up time.

For binary outcomes such as whether a participant had at least one event, a proportion can be useful, but any calculated proportion would need to be interpreted in light of its denominator and the way outcomes were collected. No additional percentages should be inferred from the counts. The registry record does not report uncertainty intervals for the group-level results. In general, a confidence interval describes a range of values compatible with the observed data under a specified statistical model; it represents uncertainty in an estimate, not a guarantee about the true value.

Why the design matters

Randomization helps balance measured and unmeasured participant characteristics between treatment groups, on average. This study is listed as non-randomized and single-group, with no masking. Its three reported safety groups are not randomized control arms. Their counts can be compared descriptively, but differences could reflect who entered each group, their prior treatment experience, the administration setting, follow-up, or other factors. The registry record does not provide enough detail to assess those factors or establish an adjusted comparison.

Open-label assessment can also affect how symptoms are reported or assessed. The record notes that subjects and investigators graded local symptoms, but it does not report blinding or an independent adjudication process. This does not invalidate the observations; it means that the context of measurement matters when interpreting subjective symptoms such as burning, itching, warmth, or pain.

Time and outcome ascertainment

The endpoint timeframe is described as 7 days from the beginning of each phase, with the assessment ending at the earlier of 7 days from the start of the naive phase, study discontinuation, or the start of the self-administration phase. This definition makes the observation period dependent on what happened to each participant. The registry record does not report the actual follow-up duration for each person, the number with incomplete observations, or how missing outcome information was handled. If observation differs across participants, raw counts do not fully convey differences in time at risk.

General statistical methods for count outcomes can account for variation in observation time or for event counts that vary more than a simple model expects. Such approaches require adequate event-level or person-time data and a specified analysis plan. Neither a modeled rate analysis nor an analysis accounting for over-dispersion is reported in the registry record. The posted endpoint is a participant count, so event-rate methods should not be assumed to have been used.

What inferential results would add

A confidence interval around a group proportion or a between-group contrast would communicate statistical uncertainty. A hypothesis test could assess compatibility with a null hypothesis under assumptions, but a p-value would not measure the size or clinical importance of an effect. No confidence intervals, p-values, adjusted effects, or model specifications are reported in the registry record. Accordingly, there is no reported inferential result to interpret alongside the descriptive counts.

The record also names time to symptom relief as a secondary outcome. Time-to-event methods generally account for the timing of an event and can accommodate participants whose event time is not observed by the end of follow-up, subject to assumptions and a clearly defined analysis population. The registry record does not report numerical results, censoring details, or an analysis method for this outcome, so no such analysis should be inferred.

The registry record contains no reported analysis results. Any planning illustration based on an observed effect is a planning exercise, not observed power and not evidence that a hypothesis was confirmed. Sample-size planning depends on assumptions about the effect to detect, the statistical model, and the desired operating characteristics. The record does not report the trial's sample-size justification or enough analysis detail to determine whether planning assumptions guided enrollment.

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("Naive Subjects Administered Icatibant by Health Ca", "Subjects Who Self-administered Icatibant (Naive)", "Subjects Who Self-administered Icatibant (Non-naiv")
n      <- c(22, 19, 78)
events <- c(11, 6, 27)
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  Naive Subjects Administered Icatibant by Health Ca  22  11  50.0  28.2  71.8  30.7  69.3  30.6  69.4
ARM  Subjects Who Self-administered Icatibant (Naive)  19  6  31.6  12.6  56.6  15.4  54.0  15.4  54.3
ARM  Subjects Who Self-administered Icatibant (Non-naiv  78  27  34.6  24.2  46.2  25.0  45.7  25.0  45.7

11. Multiplicity, Missing Data and Analysis Populations

The registry record names a primary safety outcome and a secondary outcome concerning time to symptom relief. It also reports that there are 2 outcome measures, while no analyses are listed. A statistical plan specifying how outcomes were prioritized, tested, or interpreted is not reported in the registry record. In particular, it is not reported whether any adjustment for multiple outcomes or multiple comparisons was planned or used.

Multiplicity arises when several outcomes, subgroups, or comparisons are examined: the chance of at least one apparently unusual result can increase when many statistical tests are performed. This general concern cannot be evaluated from the outcome names alone. There are no reported p-values or inferential analyses to assess, and numerical findings for the secondary time-to-symptom-relief outcome are not reported in the registry record.

The registry record gives denominators for the three adverse-event groups but does not provide a full participant flow account, an analysis population definition, or details of missing outcome data. It is not reported how many participants completed each phase, whether all participants had outcome assessment through the specified timeframe, or how discontinuations and incomplete records were handled. Those omissions limit assessment of whether the posted counts reflect all eligible participants in each group or only those with recorded outcome information.

In general, missing outcomes can bias a result if the likelihood of missingness is related to participant characteristics or the outcome itself. Without the extent and handling of missing data, the direction and magnitude of any such effect cannot be determined. The registry record also does not report sensitivity analyses, subgroup analysis plans, or a prespecified statistical analysis plan. These details should not be inferred from the descriptive results.

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 non-serious adverse event terms

The serious adverse-event counts are 0 of 22 participants in the naive group administered icatibant by a health care provider, 0 of 19 in the naive self-administration group, and 0 of 78 in the non-naive self-administration group. The registry record lists no serious adverse-event terms. Death counts are not reported in the registry record.

A count of zero means that no participants in the stated group were recorded as affected in the posted results. It does not establish that the possibility of serious harm is absent. In general, small or limited observations leave uncertainty about the frequency of uncommon events, and interpretation also depends on how long participants were observed and how events were collected. Those details are not fully reported in the registry record.

The other adverse-event counts are 7 of 22, 6 of 19, and 21 of 78, respectively. They are separate from the serious-event counts and should not be assumed to represent a list of distinct event episodes. The registry record does not provide the names or severity breakdown of these other events. The groups are not randomized comparisons, so their counts should be read as observations within different treatment experiences, not as evidence that one administration approach caused more or fewer events.

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

The posted results establish that the registry record contains adverse-event counts for three groups of participants receiving a single subcutaneous injection of icatibant, 30 mg, in different treatment experiences. Serious adverse events affected 0 participants in each group, with denominators of 22, 19, and 78. Other adverse events affected 7, 6, and 21 participants in those respective groups. These observations describe what was recorded for the stated groups and endpoint period.

They do not show that self-administration is safer or less safe than administration by a health care provider. The study is non-randomized, open-label, and listed as single-group; there is no randomized control comparison. Differences in counts between groups cannot be attributed to administration method or prior treatment experience on the basis of these data alone. The record does not report adjusted comparisons or uncertainty intervals.

The findings also do not establish that serious adverse events cannot occur. A zero count in the observed groups is limited to the participants and observation recorded. The registry record does not provide enough information about individual follow-up, event ascertainment, or missing data to determine how completely the observation period was captured for every participant.

The primary endpoint concerns adverse events, while the registry record also names a secondary outcome about time to symptom relief. Numerical results for that secondary outcome are not reported in the registry record. Thus, the posted safety counts do not answer whether symptoms improved or how quickly relief occurred, nor do they demonstrate comparative efficacy.

The most defensible interpretation is descriptive: the posted record reports no serious adverse events in the three listed groups and reports other adverse events in each group. The precision and generalizability of those observations cannot be fully assessed from the registry information because event details, analysis methods, participant flow, and uncertainty estimates are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of the distinction between describing treatment experience and estimating a comparative effect. A non-randomized, open-label study can collect useful safety observations, including participant-reported local tolerability. But group counts alone do not isolate the effect of self-administration from differences between the people in each group or their treatment histories.

The endpoint is a participant count with an observation period tied to treatment phases and early stopping points. That makes clear definitions of denominators, follow-up, and missing data especially important. The registry record provides group denominators and the endpoint timeframe, but does not report a complete participant flow account or the handling of missing assessments. Without those details, readers cannot fully assess the scope of the observed data.

Zero serious adverse events can be reported plainly without treating zero as proof of zero risk. Statistical interpretation requires attention to the amount of observation and the uncertainty around any estimate. The registry record does not include confidence intervals or inferential analyses, so the safety counts should not be presented as precise population estimates.

The record also illustrates why outcome labels and numerical results need to be distinguished. A secondary outcome for time to symptom relief is named, but numerical findings are not reported in the registry record. The availability of a named outcome alone does not support a conclusion about efficacy.

For clinical researchers and biostatisticians, these features make transparent reporting of group definitions, analysis populations, follow-up, missingness, and prespecified methods central to interpreting a trial. The posted results offer a bounded descriptive account, not a randomized estimate of the relative safety or efficacy of different treatment approaches.

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 design limitation is the absence of randomization and a control group. Although the registry lists three adverse-event groups, they do not constitute like-for-like randomized arms. Their results cannot identify the causal effect of self-administration compared with administration by a health care provider. Masking was listed as none, and the registry record does not describe blinded outcome assessment.

The reported group denominators are smaller than the overall enrollment of 151. The registry record does not explain the relationship between enrollment and the analyzed groups, provide a full participant flow, or state the number of participants with incomplete assessments. It is therefore not possible to determine from the record whether all enrolled participants contributed to the posted safety counts or how discontinuation affected observation.

The endpoint timeframe has phase-specific stopping conditions, but actual observation time by participant is not reported. The posted counts do not describe event frequency over time, and the record does not give event-level totals or detailed descriptions of the other adverse events. Serious-event counts are available, but death counts are not reported in the registry record.

The local tolerability assessment covered symptoms graded on a 0 to 3 scale, but results by symptom and grade are not reported in the registry record. Numerical results for the secondary time-to-symptom-relief outcome are also not reported. No confidence intervals, p-values, adjusted analyses, missing-data methods, or detailed statistical analysis plan are reported in the registry record.

These limitations restrict interpretation to the descriptive counts and prevent a full assessment of precision, generalizability, or comparative effects. They do not negate the observations, but they define what can reasonably be concluded from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: EASSI - Evaluation of the Safety of Self-Administration With Icatibant — NCT00997204.
• Registry record last updated 2021-06-11; status last verified 2021-05.
• Results first posted 2014-07-28.
• 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 identifies NCT00997204 as EASSI, a phase 3, completed, open-label, multicenter study of subcutaneous icatibant for acute hereditary angioedema attacks. It lists non-randomized allocation and a single-group model, with enrollment of 151. The intervention was a single injection of icatibant, 30 mg, in a naive treatment phase and a self-administration phase.

The primary outcome is the number of participants with adverse events during a specified phase-based observation period. Posted serious adverse-event counts are 0 of 22, 0 of 19, and 0 of 78 across the three named groups; other adverse events affected 7 of 22, 6 of 19, and 21 of 78. The record names time to symptom relief as a secondary outcome but does not report its numerical results.

No statistical analysis results are listed. Details of participant flow, missing-data handling, confidence intervals, and a statistical analysis plan are not reported in the registry record. The safety counts are descriptive and do not provide a randomized comparison.