Safety and Performance Study of the ARGOS-IO (Intraocular) System in Patients With Primary Open Angle Glaucoma (POAG): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Performance Study of the ARGOS-IO (Intraocular) System in Patients With Primary Open Angle Glaucoma (POAG) (NCT02434692), a na na study. The primary outcome is Safety: Number of Patients Experiencing a Device Related SAE (SADE) and Complications During Implantation.

2. Clinical Question

The investigation concerns patients with primary open angle glaucoma (POAG) who also had indicated cataract surgery. The registry describes a pressure sensor implanted during local routine cataract-surgery procedures. Its central clinical question was whether the ARGOS-IO system could be assessed for safety and performance in this setting, with the primary endpoint focused on device-related serious adverse events and complications during implantation.

The safety question is therefore descriptive: the registry records events among participants who received the device, rather than estimating a difference between randomized treatment groups. The separate adverse-event figures report participants affected by serious and other adverse events, but the record does not establish that every reported event was device-related or part of the primary endpoint. Those distinctions matter when interpreting the available safety information.

3. Trial Design

This was a prospective, open-label, multicenter clinical investigation of the ARGOS-IO system in patients with POAG and indicated cataract surgery. The registry classifies the study as single-group, with allocation recorded as not applicable and masking recorded as none. The intervention description states that the pressure sensor was additionally implanted during local routine procedures for cataract surgery.

The registry records 24 enrolled participants and a completed study status. The recorded study start is 2014-07-09, and the primary completion date is 2017-04-11. The safety figures use a safety set with 23 participants at risk. The registry record does not explain the difference between the enrollment count and the safety-set count, so no reason for it can be inferred.

The primary outcome timeframe is Day 0 to Day 360, from implantation visit V01 to V11. It is described as the number of patients experiencing a device-related serious adverse event and complications during implantation. A secondary safety outcome is described as the incidence, nature, severity, and seriousness of observed adverse events and adverse device effects.

Because there is no concurrent control group, the study design does not support a randomized comparison of the device with another treatment or with no device. The registry explicitly cautions that the arms are not a like-for-like control comparison. The record does not report a statistical analysis plan, a sample-size justification, interim analyses, or a specific endpoint analysis. Those omissions limit what can be concluded about the study’s prespecified analytical approach.

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 Safety: Number of Patients Experiencing a Device Related SAE (SADE) and Complications During Implantation, measured over Day 0 to Day 360 (V01 [Implantation] to V11).

The primary endpoint is a count of patients who experienced a device-related serious adverse event or complications during implantation of the ARGOS-IO device. Its stated timeframe runs from Day 0 to Day 360, covering implantation visit V01 through V11. The endpoint is intended to describe safety events relevant to the device and the implantation procedure in the population studied.

Counting affected participants gives a clinically interpretable summary of how many people experienced at least one event meeting the endpoint definition. It is different from counting the total number of events: one participant can experience more than one event, while a participant-based count treats that person as affected. General statistical context: a binary participant-level outcome records whether each person did or did not meet a specified event definition during a specified period.

The registry gives the endpoint definition but does not report a specific result for this primary measure. The separate safety figures list participants affected by serious and other adverse events, but do not identify those figures as the primary endpoint result or specify that all included events were device-related or implantation complications. Those adverse-event counts should therefore not be substituted for a missing primary-endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Several statistical ideas help clarify what the registry’s safety numbers can and cannot show. The distinctions below are general explanations, not additional analyses reported by the registry.

What does a participant count represent?

The primary endpoint is expressed as a number of participants meeting an event definition. For a binary outcome, each participant is classified according to whether the specified event occurred during the stated timeframe. A participant-level count is not the same as an event count: a participant can experience multiple events and still contribute only once to a count of participants affected. The registry’s primary definition combines device-related serious adverse events and implantation complications, but a result for that endpoint is not reported in the registry record.

The adverse-event figures separately report participants at risk and participants affected for serious and other adverse events. These are useful descriptive quantities, but the record does not state that the broader serious-event count is identical to the primary endpoint. The terms listed under serious events likewise do not establish whether each event was device-related or met the implantation-complication definition. Endpoint definitions determine which observations belong in an analysis; similar wording alone is not enough to equate two measures.

Why does the study design matter?

In a randomized comparison, treatment groups can be compared under the study’s allocation scheme, subject to the usual assumptions and limitations. This investigation is classified as single-group, with allocation not applicable and no masking. The registry warns that arms are not a like-for-like control comparison. Thus, its posted safety figures describe events observed in the ARGOS-IO study group; they do not estimate a randomized treatment contrast.

General statistical context: a control group can help distinguish the experience associated with an intervention from background events, though a comparison still requires careful design and analysis. In a single-group study, no concurrent control observations are available for that purpose. It is not possible to infer from the event count alone what would have happened to similar participants under another approach.

How should event frequency and uncertainty be considered?

A count of affected participants is a direct summary of observed experience. An estimated proportion can also describe the share affected, but this explanation does not calculate a new proportion from the posted counts. When data arise from a sample, the observed frequency is subject to uncertainty about the underlying frequency in a broader population. General statistical context: a confidence interval gives a range of values compatible with the data under a specified statistical method; it communicates uncertainty and is not a guarantee that the underlying value lies within that range.

No confidence interval for the adverse-event figures is reported in the registry record. No unadjusted recalculation or adjusted analysis is reported either. As a result, there is no interval or model-based estimate to interpret alongside the observed counts. The raw counts remain descriptive rather than a fully quantified estimate of precision.

General statistical context: over-dispersion matters when variation in event counts is greater than a statistical model assumes. A model that underestimates variation can produce uncertainty intervals that are too narrow. The registry does not report a model for recurrent event counts, and the endpoint is described as participants affected rather than total events. There is therefore no basis in this record for claiming that an over-dispersion adjustment was used or needed in a particular analysis.

What do the planning assumptions mean?

The registry’s sample-size assumptions describe a planning illustration based on a stated fraction of an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The illustration is not the trial’s own design: the study itself is single-group, and there is no like-for-like control comparison. The record does not report the study’s sample-size justification or a calculation used to set enrollment.

General statistical context: power is a design-stage probability of detecting an effect of a specified size under stated assumptions if that effect exists. A planning calculation can help illustrate how sample size relates to an assumed effect and analysis approach. It does not establish the probability that a completed study’s finding is true. The sample-size illustrations are not observed power, and they should not be read as evidence that the study was adequately or inadequately powered for its primary endpoint.

The stated planning method assumes equal allocation between two arms, whereas the registry describes a single-group study. This mismatch means the illustration does not directly describe the enrolled design. No numerical planning results are included in the registry record details used for this interpretation, so none are inferred or reproduced.

What can be concluded about the analysis plan?

The record lists 0 analyses. It does not report the statistical plan, any prespecified model, interim analyses, multiplicity adjustments, or confidence intervals. General statistical context: a prespecified analysis plan helps readers distinguish planned analyses from exploratory ones and clarifies how outcomes, populations, and missing observations are handled. Without that information, the analytic choices behind the posted safety figures cannot be fully evaluated.

Overall, the appropriate statistical reading is descriptive. The adverse-event counts communicate recorded experience among participants in the safety set. They do not establish causality, provide a controlled comparison, or supply a reported result for the specifically defined primary endpoint. Any stronger interpretation would require information not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 0 analyses. It identifies a primary safety endpoint and a secondary safety outcome describing the incidence, nature, severity, and seriousness of observed adverse events and adverse device effects. However, the registry record does not report a multiplicity plan or explain whether any adjustment was intended for testing or interpreting multiple outcomes.

General statistical context: multiplicity arises when several outcomes or comparisons are examined. If each is treated as a separate opportunity to find a statistically notable result, the chance of at least one apparent finding can increase. Methods for addressing multiplicity depend on the study questions and analysis plan. No particular method can be attributed to this investigation because it is not reported in the registry record.

The record does not report an analysis plan for missing data, an imputation method, or a description of how participants with incomplete follow-up were handled. It reports 24 enrolled participants and a safety set with 23 at risk, but does not explain the difference. No reason for the safety-set size or information about missing observations should be inferred from these figures.

The registry names a safety set, but further details about the analysis population, eligibility for that set, and any exclusions are not reported in the registry record. The primary endpoint result is also not reported. Without these details, it is not possible to determine how missing data or population definitions affected an endpoint analysis. These gaps limit reproducibility and make it important to keep the available adverse-event counts separate from the unreported primary-endpoint result.

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: anterior chamber fibrin (8.7%), intraocular pressure increased (8.7%), abnormal visual field test (4.3%), amaurosis fugax (4.3%), corneal decompensation (4.3%).

The safety figures report 9 participants affected by serious adverse events among 23 at risk, and 23 participants affected by other adverse events among 23 at risk. The reported deaths count is 0. These are descriptions of the safety set; the registry does not say that the serious-event count is equivalent to the primary endpoint count.

The serious-event terms include anterior chamber fibrin and increased intraocular pressure, each listed at 8.7%. Abnormal visual field test, amaurosis fugax, corneal decompensation, and cataract operation in the fellow eye are each listed at 4.3%. These percentages describe the listed terms as recorded, not a comparative risk or an estimate of device-attributable harm.

General statistical context: adverse-event summaries depend on definitions, ascertainment, follow-up, and whether the unit is participants or events. The registry record does not report participant-level overlap between event terms, event timing, or a causal assessment for each term. It also does not report confidence intervals for these figures. The counts should therefore be read as descriptive observations, not as evidence that the device caused or prevented an event.

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

The result does show that the registry records adverse events in the safety set during the investigation. It reports 9 participants affected by serious adverse events among 23 at risk, 23 affected by other adverse events among 23 at risk, and 0 deaths. It also lists several serious-event terms and their reported percentages. These registry entries describe what the registry records for this study group.

The result does not provide a specific posted result for the primary endpoint, which concerns device-related serious adverse events and complications during implantation over Day 0 to Day 360. It also does not establish that the serious adverse events in the safety summary were device-related, or that they met the primary endpoint definition. The record does not report a separate participant count for implantation complications.

Because the study is single-group and has no like-for-like control comparison, the event figures cannot show how the observed experience compares with an alternative intervention or with no device. General statistical context: causal attribution requires more than observing an event after an intervention. Timing can be relevant, but a temporal sequence alone does not prove that the intervention caused the event.

The registry’s figures also do not establish the frequency of events in a broader population. General statistical context: observed data from a study group are subject to sampling uncertainty, and estimates of population frequency require attention to study design and precision. Confidence intervals for these safety figures are not reported in the registry record. No conclusion about the precision of an underlying event rate should be drawn from the counts alone.

Nor do these safety data answer whether the system was effective or improved clinical outcomes. The study purpose includes evaluation of safety and performance, but the registry entries do not include a posted performance result. The defensible interpretation is limited to the reported safety observations and the clear distinction between those observations and the unreported primary-endpoint result.

13. Why This Trial Matters Statistically

This investigation is statistically informative because it illustrates the difference between a prespecified safety question and a broader adverse-event summary. The primary endpoint is defined around device-related serious adverse events and complications during implantation. The available safety figures describe serious and other adverse events more generally. Keeping those measures distinct prevents a broader safety count from being mistaken for a result on the narrower primary endpoint.

The study also highlights the limits of a single-group design. The registry describes 24 enrolled participants and a safety set with 23 at risk, but no concurrent control group is available for a like-for-like comparison. General statistical context: a single-group event count can document observed experience, but it does not estimate a treatment difference or separate intervention-related events from background events.

There is also a useful distinction between enrollment and the population used for safety reporting. The registry gives both figures but does not explain their relationship. Transparent reporting of analysis populations and follow-up can help readers understand how participants contribute to each outcome. Here, that explanation is not reported in the registry record.

Finally, the registry’s planning assumptions are described for a two-arm illustration, while the actual study is single-group. The illustration is not observed power and is not a substitute for a reported design justification. This makes the record a practical example of why statistical assumptions must be interpreted in the context of the study that was actually conducted, rather than treated as evidence about its precision or success.

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 central limitation is that the primary endpoint result is not reported in the registry record. The available adverse-event figures cannot be assumed to be the primary result because the record does not establish that the same event definition was used. The reported serious-event count does not specify which events were device-related, and a separate count for implantation complications is not reported.

The study is open-label and single-group, with no concurrent control comparison. As a result, the registry’s safety figures cannot identify a comparative effect. The record also does not report a statistical analysis plan, confidence intervals, interim analyses, or a sample-size justification. These omissions limit assessment of the intended analysis and the precision of the findings.

The registry reports 24 enrolled participants and 23 at risk in the safety set, but does not explain the difference. Details about the safety-set definition, follow-up completeness, missing data, and handling of incomplete observations are not reported in the registry record. Event timing, recurrence, overlap among event terms, and causal assessments are also not given in the registry record for interpretation.

Finally, the listed sample-size assumptions describe a two-arm planning illustration, while the trial is single-group. Without the numerical planning outputs or a reported justification for the actual design, those assumptions do not resolve the limitations of the observed safety summary.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Performance Study of the ARGOS-IO (Intraocular) System in Patients With Primary Open Angle Glaucoma (POAG) — NCT02434692.
• Registry record last updated 2024-12-12; status last verified 2024-10.
• Results first posted 2024-12-12.
• 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 registry describes a completed, prospective, open-label, multicenter, single-group investigation of the ARGOS-IO system in patients with POAG and indicated cataract surgery. The sensor was implanted during cataract surgery. The record lists 24 enrolled participants; the safety figures report 23 at risk.

The primary endpoint concerns participants with device-related serious adverse events and complications during implantation over Day 0 to Day 360. A specific result for that endpoint is not reported in the registry record. The safety figures list 9 participants affected by serious adverse events among 23 at risk, 23 affected by other adverse events among 23 at risk, and 0 deaths.

There is no like-for-like control group. The record does not report a statistical analysis plan, confidence intervals, missing-data methods, or a sample-size justification. The adverse-event figures should be interpreted descriptively and kept distinct from the unreported primary-endpoint result.