Evaluation of the Performance and Safety of Two Intradermal Delivery Devices.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Performance and Safety of Two Intradermal Delivery Devices. (NCT01943110), a na na study. The primary outcome is Proportion of Injections Delivered to the Intradermal Layer of the Skin.

2. Clinical Question

3. Trial Design

This completed study evaluated the performance and safety of two intradermal delivery devices: an autodisable ID adapter and a side-load ID adapter. The registry lists an enrollment of 30 and a single-group model. Allocation is recorded as NA, and masking is listed as none. The study is not described as a randomized comparison, so the device-and-location groupings do not establish a like-for-like control comparison.

The registered intervention description concerns saline injection with ID adapters. Each participant was to receive six injections of 0.1 ml of sterile saline solution into the skin. The arm description names the upper deltoid and suprascapular locations with each adapter and also mentions the forearm. However, the forearm description is incomplete: the remaining details of the six-injection schedule are not reported in the registry record. The order of injections and any procedure for assigning device or site are also not reported in the registry record.

The study start and primary completion are both listed as 2013-07, and the status is completed. The phase is listed as NA. PATH is named as the sponsor. The registry identifies two outcome measures and no analyses. It does not report a statistical analysis plan, a sample-size justification for the trial, or an account of how participants were included in the reported outcome analyses.

Because the design is single-group and does not specify random allocation, counts across device-and-location groups should be read as descriptive registry results, not as evidence from a controlled comparison. In particular, the record does not establish that differences in counts between groups, if any, are attributable to the device rather than to other features of the injection or measurement process.

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.

Population: Healthy adults aged 18-55 years.

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Injections Delivered to the Intradermal Layer of the Skin, measured over 1 day.

The primary endpoint is titled the proportion of injections delivered to the intradermal layer of the skin. The registered description says that delivery is assessed by measuring intradermal wheals with diameters of at least 5mm and the volume of liquid injected. The listed timeframe is 1 day, and the unit is injections.

A proportion endpoint is intended to express how often injections meet a specified criterion among the injections assessed. The wheal measurement provides a physical indication used by the study to assess whether liquid entered the target skin layer, while injected volume is also included in the assessment. This is a performance measure for delivery, rather than a measure of vaccine effectiveness: the registered injections used sterile saline.

The registry record does not report the number of injections meeting the criterion, the total number assessed for this endpoint, or the resulting proportion. It also does not explain how the wheal and volume measurements were combined to classify an injection, or how incomplete measurements were handled. Consequently, the endpoint definition can be described, but its observed value and the precision of that value cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry gives enough information to identify the endpoint concept and the design category, but not enough to reconstruct an inferential analysis. The sections below explain what the registered measure would mean statistically and why several common interpretations are not supported by the reported information.

What does a proportion endpoint represent?

In general, a proportion is a count of observations meeting a defined condition divided by the total number of observations assessed. For this study, the observation is an injection, and the condition concerns delivery into the intradermal layer as assessed by wheal diameter and injected volume. To interpret a proportion, readers need both the number of injections meeting the criterion and the denominator: the number of injections with an evaluable assessment. Neither is reported in the registry record.

The endpoint description refers to wheals with diameters of at least 5mm and to the volume of liquid injected. It does not explain the exact classification rule. For example, it does not state in the registry record whether both measures had to meet criteria, whether one measure could determine success, or how a missing measurement would be treated. These details are important because different operational rules can yield different classifications even when measurements are the same.

Why do repeated injections matter?

General statistical guidance: when a participant contributes more than one observation, those observations may be related because they come from the same person. Analyses that treat every injection as independent can understate uncertainty if within-person observations are correlated. Methods for repeated or clustered data account for that dependence, but the registry record does not report whether such methods were planned or used. It also does not report how many injections contributed to the primary endpoint or how injection-level results were grouped by participant.

The study description says each participant would receive six injections, while the location-and-device details are incomplete. This matters for both the denominator and the analysis structure: the number of injections is not interchangeable with the number of participants, and repeated injections from one participant are not automatically independent observations. Without the complete schedule and analysis details, the appropriate unit of analysis cannot be confirmed.

What does the single-group design allow?

General statistical guidance: a single-group evaluation can describe observed performance in the studied procedures, but it does not by itself estimate a causal difference between devices. A comparison requires a clearly specified contrast and an analysis that accounts for how participants, injection sites, and devices were assigned. Here, allocation is NA, the model is single group, and the registry explicitly does not characterize the groupings as a like-for-like control comparison. The listed device-and-location groups therefore support descriptive reading only.

Differences between descriptive counts can arise for many reasons, including the injection location, device, measurement process, or chance. The registry record does not report randomization, masking, adjustment, or another approach that would make the groups exchangeable for a comparative estimate. Masking is listed as none; the record does not explain whether outcome assessment was conducted independently of knowledge of device or site.

What can confidence intervals and tests tell readers?

General statistical explanation: a confidence interval describes uncertainty around an estimate under the assumptions of a statistical method. Its width depends on the amount of information and the variability in the data, as well as on the method used. A hypothesis test evaluates data relative to a specified null hypothesis and model. Neither a confidence interval nor a test can be reconstructed from a description of the endpoint alone; the estimate, denominator, and analysis details are necessary.

No primary endpoint estimate, confidence interval, or hypothesis test is reported in the registry record, and the record lists no analyses. As a result, there is no basis to characterize the statistical significance or precision of the delivery result. Reporting a point estimate without an interval would also leave uncertainty unclear, but even a point estimate is absent.

How should the planning illustration be read?

General statistical explanation: sample-size calculations are design planning tools. The registry's planning illustration is described as using an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and a specified fraction of the observed effect. The illustration is explicitly not the trial's own design. It does not show that the study was designed around those assumptions, nor does a planning estimate establish the probability that this completed study detected an effect.

Such an illustration depends on the effect chosen as its starting point and on the stated assumptions. Since the primary endpoint result is not reported in the registry record, the underlying observed effect and the numeric planning outputs cannot be interpreted from the record. Planning estimates are not observed power and cannot fill the gap left by missing endpoint results.

Why does over-dispersion matter in general?

General statistical explanation: count data are sometimes more variable than a simple statistical model expects. This is called over-dispersion. If it is present and ignored, uncertainty estimates can be too small and inferential conclusions can be misleading. Whether over-dispersion is relevant depends on the outcome and its distribution; the registry record does not report a model for the primary endpoint or a dispersion assessment. The endpoint is described as a proportion of injections, so it would be inappropriate to assume that a count model was used or that over-dispersion was evaluated.

In short, the registry describes a clinically interpretable delivery measure but does not report the endpoint data or the methods needed to assess its estimate. The design and safety counts can be described, while inferential claims about the primary endpoint or device differences remain unsupported by the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, including the primary delivery endpoint and a secondary outcome titled Proportion of Injections With Safety Events. It does not report a statistical analysis plan, analysis populations, or any analyses. The timing and definition of the secondary outcome are not described in the information available in the registry record.

Multiplicity arises in general when several outcomes, time points, or comparisons are tested and the interpretation focuses on whether any result is statistically significant. Without a prespecified testing hierarchy or adjustment plan, multiple testing can increase the chance of a chance-positive finding. The registry record does not report whether multiplicity was considered, whether any adjustment was planned, or how the primary and secondary outcomes were to be interpreted together.

Missing-data methods are also not reported in the registry record. The record does not state how unmeasurable wheals, missing volume measurements, incomplete injections, or participant withdrawals would be handled. It does not report the number of participants or injections included in any endpoint analysis, or whether analysis populations were defined. Accordingly, the available information cannot establish whether all enrolled participants contributed to each outcome or how missing observations affected the results.

These omissions limit interpretation rather than demonstrate that a particular method was or was not used. The registry record does not report enough detail to determine how multiplicity, missing observations, or analysis populations were handled.

11. 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 0% reporting threshold.

Most frequent non-serious adverse event terms

For serious adverse events, each of the six listed groups has 30 participants at risk and 0 affected. These are the registry's group-level figures. The deaths field is null; deaths are not reported in the registry record.

The other adverse-event counts are 11 for ADID Deltoid, 12 for ADID Forearm, 10 for ADID Suprascapular, 10 for SLA Deltoid, 14 for SLA Forearm, and 12 for SLA Suprascapular. Each group lists 30 at risk. The record does not provide definitions or descriptions of these other events, their severity, their timing, or an assessment of whether they were related to an injection or device.

These counts should be read descriptively, not as rates or as evidence of a comparative safety difference. The registry does not clarify whether the affected counts are distinct participants or events, and participants received repeated injections according to the study description. It also does not describe an inferential comparison across the groups. Zero reported serious adverse events means none were recorded in these listed groups; it does not establish that serious events cannot occur.

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

The registry record describes a study intended to assess whether two intradermal delivery devices can safely and precisely inject liquid into the intradermal layer at different locations. Its primary endpoint is defined around saline injections, wheal measurement, and injected volume. The posted results do not include the endpoint estimate, so the record does not show how many injections met the delivery criterion or how precise that estimate was.

The safety listing reports zero serious adverse events in each of six groups, each with 30 at risk. It also reports group-level counts for other adverse events. These figures are descriptive and lack accompanying event definitions and analysis. They do not establish a difference between devices, nor do the other-event counts indicate severity or causation. The record's null entry for deaths does not provide a reported death count.

The design information also limits comparative interpretation. This is registered as a single-group study with allocation listed as NA and no masking. The record does not describe a randomized comparison or a separate control group. It is therefore not appropriate to interpret the listed groups as if they were randomized treatment arms or to attribute differences among them to a device alone.

In general, a study can provide useful descriptive evidence even when it does not support a controlled causal comparison. Here, however, the missing primary result means the central delivery-performance outcome cannot be characterized from the registry record. The available information documents the study's purpose, design labels, endpoint definition, and safety counts, but does not establish an observed level of delivery performance or a statistical comparison of the adapters.

This interpretation is limited to the registry information. It does not imply that unreported outcomes were favorable or unfavorable; those results are not reported in the registry record.

13. Why This Trial Matters Statistically

This trial is statistically interesting because its primary measure is defined at the injection level, while the study description says each participant would receive repeated injections. That distinction affects how the endpoint denominator should be understood and how uncertainty should be estimated. In general, several observations from the same participant may be correlated, so treating them as unrelated observations can give an overly optimistic impression of precision. The registry record does not report the analysis method used to address this issue.

The study also illustrates the difference between evaluating performance descriptively and estimating a comparative effect. A single-group design can describe outcomes under the procedures used, but a credible device contrast requires a clearly specified comparison and information about allocation and analysis. Allocation is listed as NA, and the record does not present a randomized like-for-like control comparison. Counts across device-and-location groupings should therefore not be treated as a causal comparison.

Another important statistical point is that a defined endpoint is not the same as a reported result. The registry explains how intradermal delivery was to be assessed, but it does not report the proportion achieved, the denominator, or its uncertainty. Without those quantities, readers cannot evaluate the central performance outcome, even though the endpoint itself is described.

The safety counts similarly show why denominators and event definitions matter. The record lists 30 at risk in each group and reports the number affected, but it does not clarify whether counts represent participants or events or provide detail about the events. That limits both descriptive interpretation and any attempt at comparison.

These features make the registry record useful for understanding the intended measurement and the limits of the available evidence. They also show why statistical interpretation depends on transparent outcome reporting, clear units of analysis, and methods aligned with the design.

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 has important gaps for interpreting this particular study. Most centrally, it does not report the primary endpoint result: the number of injections meeting the delivery criterion, the number assessed, or the resulting proportion. No confidence interval or other statistical analysis of that endpoint is reported.

The injection schedule is not fully described. The record says that each participant would receive six injections of 0.1 ml of sterile saline, and it names the deltoid, suprascapular, and forearm locations. The listed device and location details stop partway through the forearm description, so the complete allocation of injections across sites and devices is not reported in the registry record. The order of injections and the approach to measurement are also not described.

The record does not describe eligibility criteria or participant characteristics. It does not explain how the primary endpoint was classified from wheal diameter and injected volume, or how missing or unevaluable measurements were handled. Because multiple injections were planned for each participant, the absence of an analysis description also leaves unclear how within-participant dependence was addressed.

Safety reporting is limited to group-level counts. Definitions and descriptions of other adverse events, event timing, severity, and attribution are not reported in the registry record. The record also does not clarify whether the affected counts represent distinct participants or events, and the deaths field is null.

Finally, the registry lists no analyses and does not report a statistical analysis plan, a trial-specific sample-size justification, or the handling of multiplicity and analysis populations. These limitations prevent reconstruction of the primary analysis and restrict the interpretation of group-level safety counts.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of the Performance and Safety of Two Intradermal Delivery Devices. — NCT01943110.
• Registry record last updated 2016-03-02; status last verified 2015-04.
• Results first posted 2015-06-19.
• 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 completed study evaluated an autodisable ID adapter and a side-load ID adapter for intradermal saline delivery. The registry lists 30 participants, a single-group model, allocation as NA, and no masking. The study start and primary completion are both recorded as 2013-07.

The primary outcome concerns the proportion of injections delivered to the intradermal layer, assessed using wheal diameter of at least 5mm and injected volume, with a listed timeframe of 1 day. The primary result and its statistical analysis are not reported in the registry record. The record lists two outcome measures and no analyses.

For serious adverse events, each of six device-and-location groups lists 30 at risk and 0 affected. Other adverse-event counts are reported by group, but event definitions and comparative analyses are not. The registry does not support a causal comparison between devices or a conclusion about the primary delivery outcome.