Subcutaneous Immunotherapy in Patients Sensitized to Dermatophagoides Pteronyssinus (DPT): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Subcutaneous Immunotherapy in Patients Sensitized to Dermatophagoides Pteronyssinus (DPT) (NCT01489020), a randomized phase 1 study. The primary outcome is Number and Seriousness of Both Local and Systemic Adverse Reactions.

2. Clinical Question

The study asked whether three subcutaneous immunotherapy dose-escalation schedules could be assessed for safety and tolerability in people with allergic rhinoconjunctivitis, with or without asthma, who were sensitized to Dermatophagoides pteronyssinus. Its stated aim was to assess safety and tolerability, rather than to establish a treatment effect on allergic symptoms or disease control.

The study was randomized, double blind, and parallel-group. Its primary endpoint concerns reactions associated with administration, including local swelling and redness and systemic symptoms from organs distant from the injection site. The registry says reactions were classified by severity and onset using an EAACI classification. It does not provide a reported statistical comparison of the primary endpoint, so the available record does not establish how the schedules compared on that measure.

3. Trial Design

This was a multicentre, randomized, double-blind, placebo-controlled, parallel-group Phase I study. The registry lists an enrollment of 48 and a completed status. The study start is recorded as 2011-01, and primary completion as 2011-07. The sponsor is Roxall Medicina España S.A.

The active treatment was subcutaneous immunotherapy with DPT extract, and the comparator was subcutaneous depot placebo. Participants were allocated among three named schedule groups. Group A was described as 6 administrations over 5 weeks, with escalating doses from Vial 2 and then Vial 3. Group B was described as 8 administrations over 7 weeks, using Vials 1, 2, and 3. Group C was described as 8 administrations over 3 weeks, with two administrations on the same day and a 30-minute interval between paired doses. The registry gives corresponding placebo schedules for each group.

The participant counts in the adverse-event record are 12 for each active group and 4 for each placebo group. These counts indicate an imbalance in the recorded group sizes. The registry does not report the randomization ratio, the sequence-generation method, allocation concealment, or whether the group sizes were planned in this way. It also does not describe whether separate randomization occurred within each schedule group.

The primary endpoint was the number and seriousness of local and systemic adverse reactions. The stated observation period ran from informed consent signature, labelled V0, until the end of participation, depending on assigned treatment between 4 and 8 weeks. This means that the possible observation period was not identical across all schedules. The registry lists secondary outcomes for specific IgE, total IgG, and IgG 4 levels, each comparing active treatment with placebo.

The record does not report a sample-size justification, detailed statistical analysis plan, or interim-analysis plan. It lists no outcome analyses. As a result, the design features and observed adverse-event counts can be described, but the registry does not permit a full appraisal of the planned inferential analysis.

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:

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.

Only the first 6 of 7 groups are shown.

6. Primary Endpoint

The registry lists the primary outcome as Number and Seriousness of Both Local and Systemic Adverse Reactions, measured over From informed consent signature (V0) until the end of patient participation in the study (depending on the treatment assigned between 4 and 8 weeks ).

The primary endpoint is titled Number and Seriousness of Both Local and Systemic Adverse Reactions. It concerns the count and severity of reactions associated with subcutaneous immunotherapy administration. The registry describes local reactions such as swelling and redness, including early and late reactions, and systemic reactions defined as symptoms from organs distant from the injection location. It also says reactions were classified according to severity and onset using an EAACI classification.

This type of endpoint is used in a safety and tolerability study because it records unwanted reactions during exposure to the study injections. Counts can describe how many reactions occurred, while severity classifications distinguish less serious reactions from more serious ones. The registry states that proportions were compared between study arms, but does not report the results of such a comparison.

The endpoint’s stated unit is adverse reactions number. That unit is important: a count of reactions is not necessarily the same as a count of participants who experienced at least one reaction. A participant may have more than one reaction, and the registry’s available adverse-event summary also reports the number of participants affected. Those measures should not be treated as interchangeable. The record does not provide a complete arm-by-arm result for the primary endpoint’s total reaction counts, severity categories, or local-versus-systemic breakdown. Accordingly, the listed participant counts cannot by themselves reconstruct the primary endpoint.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry supports a descriptive reading of the study, but not a detailed reconstruction of its analysis. The study is identified as randomized, double blind, and parallel group. These design features describe allocation and masking, but do not by themselves specify how outcomes were analyzed. The randomization method, allocation concealment, analysis populations, and detailed statistical procedures are not reported in the registry record.

What does a participant count describe?

The adverse-event summary gives, for each group, the number at risk and the number affected. These are participant-level counts. For example, the record lists 3 of 12 participants with serious adverse events in Group B Active. This is a descriptive count for that group; it is not a reaction count, a rate per unit of follow-up, or a treatment-effect estimate adjusted for other factors. The record also lists counts for other adverse events, which should be read separately from the serious-event counts.

In general, a proportion summarizes the number of participants with an event relative to the number assessed in the group. A confidence interval, when reported, describes the range of values compatible with the data under the interval’s method and assumptions. Narrower intervals generally indicate greater precision, while wider intervals indicate more uncertainty. No confidence intervals are reported for the adverse-event group counts in the registry record, so their precision cannot be read directly from an interval estimate.

Why do small groups matter?

In general, small groups provide limited information about uncommon outcomes. When few participants are observed, each event can have a substantial influence on the descriptive proportion. This issue is particularly relevant to the placebo arms, for which the registry lists 4 participants in each group. The absence of a recorded serious event in a small group does not show that the underlying risk is zero. It means only that none was recorded among the participants listed for that group during the stated observation context.

Comparisons between groups require more than placing their counts side by side. A statistical comparison depends on the planned estimand, the analysis population, assumptions about the data, and a method appropriate to the endpoint. For a count endpoint, the method may need to account for repeated events within a participant and variation in follow-up. The registry does not report the analysis method used for the primary endpoint, whether recurrent events were modeled, or whether exposure time was incorporated. These details are not reported in the registry record.

What is the distinction between the endpoint and the safety summary?

The primary endpoint is described as the number and seriousness of local and systemic adverse reactions. Its stated unit is adverse reactions number. The adverse-event group summary instead includes the numbers of participants affected by serious and other adverse events. A participant-level count and an event-level count answer different questions. If a participant experiences multiple reactions, the number of affected participants can remain one while the number of reactions is greater. Since the record does not provide full reaction totals by arm, the primary endpoint cannot be reconstructed from the participant-level adverse-event figures.

The registry describes the primary endpoint as comparing proportions between study arms and says reactions were classified by severity and onset using an EAACI classification. It does not give the specific analysis output, the category-level counts, or the criteria used to handle participants with more than one reaction. No outcome analyses are listed. The relationship between the stated primary endpoint and the available serious and other adverse-event counts is therefore incomplete.

How should the arm structure be understood?

The trial includes three active schedule groups and three corresponding placebo groups. Each active group has 12 participants in the adverse-event record, while each placebo group has 4. The schedule groups differ in administration pattern and duration. A pooled active-versus-placebo analysis would combine participants from schedules that are not identical, while a schedule-specific comparison would have very small groups. The registry does not report whether the intended comparison was pooled, schedule-specific, or both. It also does not report a method for accounting for the multiple treatment groups.

The observation timeframe is described as running from informed consent signature until the end of participation, depending on the assigned treatment between 4 and 8 weeks. In general, unequal time under observation can affect event counts: groups observed for different periods may have different opportunities to record events. The record does not say whether follow-up duration was standardized in the analysis or whether counts were adjusted for exposure time.

What can planning calculations tell a reader?

In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, the variability or event rate, the significance level, and the desired power. It is not a measure of the power actually achieved after a trial. The registry does not report the trial’s sample-size justification or the assumptions used to select enrollment. Any planning illustration based on observed effects is a separate hypothetical exercise, not the original trial design and not observed power.

The stated statistical plan, including model choice, handling of missing data, multiplicity adjustment, and prespecified analysis populations, is not reported in the registry record. Without those details and without the outcome analyses, the appropriate interpretation is descriptive: the adverse-event counts are observations in the recorded groups, while uncertainty about comparative effects remains unresolved.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary safety endpoint and secondary outcomes for specific IgE, total IgG, and IgG 4 levels. It does not report the statistical plan for these outcomes, whether each secondary outcome had multiple time points, or whether adjustments for multiple comparisons were planned. It also does not report a hierarchy of hypotheses or identify which comparisons were intended to be confirmatory. The multiplicity strategy is therefore not reported in the registry record.

In general, testing multiple outcomes or comparisons can increase the chance of obtaining an apparently noteworthy result by chance if each is interpreted separately. An analysis plan can address this through a prespecified hierarchy or another multiplicity strategy. Since the registry does not report such a plan or any outcome analyses, no conclusion about multiplicity-adjusted evidence can be drawn.

Missing-data handling is also not reported in the registry record. The adverse-event summary lists participants at risk in each group, but does not explain whether all randomized participants completed follow-up, whether any data were incomplete, or how incomplete observations were handled. The registry does not report an intention-to-treat, per-protocol, or safety analysis population definition.

The study schedules had different stated durations, and the primary endpoint timeframe varied by assigned treatment between 4 and 8 weeks. The record does not explain how differences in exposure or observation time were handled in analysis. This matters for event counts because participants may have different periods in which reactions could be recorded. No adjustment method or exposure-time analysis is reported.

These omissions do not show that particular procedures were or were not used; they mean the procedures are not reported in the registry record. Consequently, the available information permits description of the recorded counts, but does not support appraisal of missing-data assumptions, multiplicity control, or the population used for each analysis.

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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: broncoconstriction (16.7%), otitis (8.3%), pyrosis (8.3%), facial edema (8.3%), urticaria (8.3%).

The serious adverse-event summary lists participants affected and participants at risk in each group. Group A Active has 1 of 12 affected, Group B Active has 3 of 12, and Group C Active has 3 of 12. Each placebo group has 0 of 4 affected. The record lists 0 deaths in every group. These figures are counts during the study, not estimates adjusted for follow-up duration or other factors.

The registry also gives serious-event terms with percentages: broncoconstriction, 16.7%; Otitis, 8.3%; pyrosis, 8.3%; Facial edema, 8.3%; urticaria, 8.3%; and Edema in upper extremities, 8.3%. The record does not identify the group associated with each term or state the denominator for these percentages. They therefore cannot be assigned to a particular schedule or compared across arms on the available information.

These serious-event counts should be kept distinct from the primary endpoint’s number and seriousness of adverse reactions and from the separate counts for other adverse events. The registry does not provide the full reaction-level data needed to connect those measures. A zero count in a group means no event was recorded among the listed participants; it does not establish the absence of risk beyond those observations.

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

The results support a limited descriptive statement: adverse events were recorded in the active and placebo groups, and serious adverse events were listed among participants in the active groups but not among the small placebo groups. The record also lists no deaths. These findings describe what was recorded for the trial groups; they do not provide a precise comparative estimate or an inferential conclusion.

The registry does not report the primary endpoint results in the form of reaction counts by arm, nor does it provide the complete severity and local-versus-systemic breakdown. Although it states that proportions were compared between arms, it lists no analyses. There are no reported confidence intervals or statistical tests for the group counts. Thus, the record cannot show how uncertain a between-group difference is, or whether the observed counts are compatible with a wide range of underlying values.

The groups are small and unbalanced in size, with 12 participants in each active group and 4 in each placebo group. The active schedules also differ in dose escalation and administration timing. This limits direct comparison among schedules and makes a pooled active-versus-placebo interpretation dependent on an analysis approach that is not reported. Variation in the stated participation duration, from 4 to 8 weeks, is another consideration because the time available to observe reactions may differ.

The study’s stated purpose was safety and tolerability assessment. The listed secondary outcomes concern immunoglobulin levels, but their results are not included in the registry record. The information therefore does not establish effects on symptoms, disease control, or other clinical outcomes. Nor can the safety counts establish that a treatment schedule works or does not work.

In general, early-phase safety data can help characterize events observed during exposure and may inform later research questions. Such data need to be interpreted with attention to group size, follow-up, endpoint definition, and uncertainty. Here, the missing analysis details and incomplete primary endpoint results leave the evidence descriptive rather than comparative.

13. Why This Trial Matters Statistically

This trial is statistically notable because it combines three active dose-escalation schedules with three corresponding placebo groups in a small randomized study. The schedule differences are relevant to interpretation: administration patterns and durations vary, so the groups do not represent a single uniform exposure. A comparison across all active participants would answer a different question from comparisons within each schedule.

The imbalance in recorded group sizes is also important. Each active group lists 12 participants, while each placebo group lists 4. In general, smaller comparison groups yield less precise estimates, particularly when outcomes are uncommon. A zero serious-event count in a small group remains compatible with uncertainty about the event pattern beyond the observed participants. The registry does not report confidence intervals to quantify that uncertainty.

There is also an important distinction between the endpoint as described and the safety summary available. The primary endpoint is a number and seriousness of reactions, while the group summary reports participants affected by serious and other adverse events. Those measures can differ when a participant has more than one reaction. The registry does not provide enough reaction-level detail to bridge the distinction.

Finally, the record illustrates why an analysis plan matters. The study says proportions were compared between arms, but reports no analyses, confidence intervals, or method for handling the different group schedules and observation periods. Without those details, readers can describe the observed counts but should not treat them as precise evidence of a schedule difference. The statistical significance of the trial record lies as much in recognizing these interpretive boundaries as in noting the event counts themselves.

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 does not report the sample-size justification, randomization method, allocation concealment procedure, detailed statistical plan, or interim-analysis plan. It also lists no outcome analyses. This prevents evaluation of whether the enrollment was selected to answer a specific statistical question and how the planned comparisons were to be conducted.

The group sizes are small and differ between active and placebo groups. The record lists 12 participants in each active group and 4 in each placebo group. No confidence intervals or tests accompany the adverse-event counts, so comparative precision is not available. A lack of recorded events in a small group should not be treated as proof that events could not occur.

The three active schedules differ in administration pattern and duration, and the observation period is stated as between 4 and 8 weeks depending on assigned treatment. The registry does not report whether analyses accounted for this variation in exposure or observation time. Schedule-specific comparisons would also rely on small groups, while any pooled comparison would require a stated rationale and method that are not reported.

The primary endpoint is described as reaction counts and seriousness, but the available safety summary gives participant counts affected. Full reaction counts, category-level severity results, and the local-versus-systemic breakdown are not reported. The serious-event term percentages are not accompanied by an arm assignment or denominator. Secondary immunoglobulin results are not reported in the registry record.

Finally, the record does not describe missing-data handling or define the analysis populations. It is therefore unclear whether all randomized participants contributed to each endpoint and how incomplete follow-up, if any, was addressed. These limitations constrain interpretation to a description of the recorded adverse-event counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Subcutaneous Immunotherapy in Patients Sensitized to Dermatophagoides Pteronyssinus (DPT) — NCT01489020.
• Registry record last updated 2019-05-06; status last verified 2019-01.
• Results first posted 2019-05-06.
• 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

NCT01489020 is a completed multicentre Phase I randomized, double-blind, placebo-controlled parallel-group study sponsored by Roxall Medicina España S.A. The registry lists 48 participants enrolled. The recorded study start is 2011-01 and primary completion is 2011-07.

The study evaluated subcutaneous immunotherapy with DPT extract using three active dose-escalation schedules and corresponding subcutaneous depot placebo schedules. Its stated aim was to assess safety and tolerability in people with allergic rhinoconjunctivitis, with or without asthma, sensitized to Dermatophagoides pteronyssinus.

The primary endpoint concerned the number and seriousness of local and systemic adverse reactions. The adverse-event record lists participant counts affected by serious and other adverse events, as well as no deaths in the listed groups. However, no outcome analyses are listed, and the full primary endpoint results, confidence intervals, and detailed statistical methods are not reported in the registry record.