Safety and Acceptability Study of a Non-Hormonal Ring: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Acceptability Study of a Non-Hormonal Ring (NCT03598088), a na na study. The primary outcome is Changes From Baseline in the Post Coital Test Results (PCT) Due to Device Use..

2. Clinical Question

This is a question about a measured post-coital test result during device use, not a randomized estimate of the effect of Ovaprene versus a control. The study’s single-group model, open-label status, and use of both devices in the trial limit what can be concluded from differences between the adverse-event groups. The registry record does not report a separate comparative primary analysis, an analysis population, or a measure of uncertainty for the primary endpoint.

3. Trial Design

NCT03598088 is titled “Safety and Acceptability Study of a Non-Hormonal Ring.” The registry identifies Daré Bioscience, Inc. as the sponsor and lists the condition as contraception. The study is marked completed. Its recorded start date is 2018-05-23, and its primary completion date is 2019-10-17.

The registry describes a feasibility, multi-center, open-label, non-significant risk device study. Its model is single group, its masking is none, and allocation is listed as NA. The phase is also listed as NA. These labels indicate that the record does not describe a blinded, randomized, parallel-group efficacy comparison. The registry record does not report more detail about how participants were recruited, how many centers took part, or how the study visits were scheduled.

Ovaprene is the listed device intervention. The arm description says that participants received both Ovaprene and the Caya diaphragm throughout the trial. It also refers to a Caya Post Coital Test cycle, but the available description ends before fully explaining its purpose. The record lists adverse-event summaries separately for an Ovaprene Device group and a Caya Cycle group. Since the study was not randomized and the groups are not described as like-for-like controls, differences between their reported event counts cannot be interpreted as a treatment contrast.

The registry lists enrollment of 38. This number describes enrollment; it should not be assumed to be the denominator for every endpoint or safety summary. The denominators reported for safety differ by group, and the primary endpoint description does not give its own analyzed denominator. The registry record does not report a sample-size justification, a formal statistical analysis plan, or interim analyses. Its completion status does not by itself establish that every outcome was analyzed or that every enrolled participant contributed to each result.

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.

Screening/Baseline PCT Visits 1-4

Caya PCT Cycle, Visit 5 & 6

OVP Safety Cycle Visits 7-11

OVP PCT Cycle A Visits 12-16

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: All Enrolled Population are those participants that met eligibility criteria.

6. Primary Endpoint

The registry lists the primary outcome as Changes From Baseline in the Post Coital Test Results (PCT) Due to Device Use., measured over Baseline to OVP PCTa at 175 Days.

The primary endpoint is titled “Changes From Baseline in the Post Coital Test Results (PCT) Due to Device Use.” It is expressed as a count of participants. The registry gives the timeframe as baseline to OVP PCTa at 175 Days and describes the result as all participants having fewer than 5 progressively motile sperm per high power field (PMS/HPF) in all cycles during Ovaprene use.

The endpoint therefore summarizes a post-coital test finding across cycles during device use, using a threshold for progressively motile sperm per high power field. It is not described as a pregnancy outcome. A count can communicate how many participants met a specified finding, but the registry record does not report a corresponding denominator, a confidence interval, or a participant-level distribution of test results. The endpoint description also does not specify how missing or unevaluable tests were handled.

In general, a prespecified endpoint gives a study a defined outcome to assess rather than relying on an unspecified collection of observations. A post-coital test can serve as a biological measurement related to the question being studied; however, the registry record does not report validation information or explain how changes in this measure relate to other outcomes. The measure should therefore be read as the stated test result, not as direct evidence of a broader clinical outcome. The record’s wording does not provide enough detail to reconstruct a change estimate from baseline or to assess the precision of the result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count endpoint convey?

The primary endpoint is a count of participants meeting the stated post-coital test finding. A count is different from an estimated effect such as a difference between treatment groups. To interpret a count as a proportion, a denominator must also be known. The registry gives enrollment, but it does not identify the denominator used for this endpoint. It would therefore be inappropriate to treat enrollment as the endpoint denominator or to calculate a percentage from it.

In general, binary outcomes classify each participant according to whether a defined event or condition occurred. Counts are straightforward to describe, but they can omit important information if the corresponding denominator, definition, or handling of unobserved outcomes is not clear. Here, the endpoint description supplies a threshold and a statement about cycles during Ovaprene use, but the registry record does not report how participants with incomplete test data were handled.

Why does study design affect interpretation?

In general, random allocation helps make treatment groups comparable by distributing measured and unmeasured characteristics without relying on investigator choice. This study’s allocation is listed as NA, and the model is single group. The registry also says participants received both Ovaprene and Caya. Thus, the separate Ovaprene Device and Caya Cycle safety summaries do not constitute a randomized comparison. Their counts describe the listed groups, not the causal effect of one device relative to the other.

Open-label means masking is not described; the registry lists masking as none. In general, knowledge of the device being used can affect reporting, observation, or assessment, depending on the outcome and study procedures. The registry record does not describe procedures to reduce such effects. This limitation is especially relevant when interpreting subjective outcomes, though the primary endpoint is described as a test measure. No assumptions about the conduct or blinding of laboratory assessment should be made from the record.

What can uncertainty measures add?

In general, a confidence interval gives a range of values compatible with the observed data under a specified statistical method. It conveys precision, not a guarantee that the true value lies in that range. A p-value, when used, quantifies how unusual data at least as extreme as those observed would be under a specified null model. Neither quantity alone establishes clinical importance or causation.

The registry record does not list analyses for the study and does not report a confidence interval or p-value for the primary endpoint. There is consequently no reported inferential estimate to interpret. The descriptive endpoint statement should not be treated as evidence that uncertainty is absent; rather, uncertainty is not quantified in the registry record.

How should planning illustrations be read?

In general, sample-size calculations are planning tools. The record describes a planning illustration based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. For time-to-event tables, it describes totals of events; for other tables, it describes participants per arm.

Such illustrations do not report observed power and do not change the design of this completed study. The registry record does not report that these assumptions were the study’s original design assumptions or that the study was planned as a two-arm randomized comparison. Any planning values should therefore be understood as hypothetical illustrations under their stated assumptions, not as a retrospective demonstration that the study had adequate power.

What does over-dispersion mean in general?

For count outcomes, a statistical model may assume a particular relationship between the average count and its variability. Over-dispersion occurs when observed variation is greater than that assumption allows. In general, ignoring over-dispersion can make uncertainty appear smaller than it is. That concept does not imply that over-dispersion occurred in this study: the primary outcome is reported as a participant count, and the registry record does not describe a count regression model or a dispersion estimate.

More broadly, statistical methods depend on the outcome definition, analysis population, missing-data rules, and design. The registry record does not report a formal analysis plan, so it is not possible to identify a model, adjustment strategy, or diagnostic procedure for the primary result. The descriptive interpretation should remain anchored to what is actually reported rather than to a model that is not described.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 14 outcome measures and no analyses. It does not identify a multiplicity adjustment or explain whether the primary endpoint was selected from a prespecified hierarchy. In general, when many outcomes are tested, the chance of at least one apparently unusual result can increase if each is interpreted as an independent confirmatory test. Adjustment methods or a clear prespecified hierarchy can address that concern, but the registry record does not report either for this study. Since no inferential analyses are listed, there are no reported p-values for which an adjustment can be evaluated.

The registry record does not report how missing endpoint observations were handled, whether participants were excluded from an analysis, or how the primary analysis population was defined. It also does not give a participant flow showing assessment completion. These details matter because a count of participants meeting the endpoint can depend on which participants had evaluable tests and how incomplete observations were classified.

Enrollment was 38, while the safety summaries use denominators of 33 and 35 for their respective groups. The record does not explain the difference between these denominators and enrollment, so no reason for it should be inferred. The endpoint description says “all participants,” but its analyzed denominator is not stated. The registry record also does not report sensitivity analyses for missing data or a comparison of included and excluded participants. As a result, the completeness and robustness of the endpoint result cannot be assessed from the registry record.

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 0% reporting threshold.

Most frequent non-serious adverse event terms

The registry reports serious adverse-event counts separately for the Ovaprene Device and Caya Cycle groups. There were 0 serious adverse events among 33 participants in the Ovaprene Device group and 0 among 35 participants in the Caya Cycle group. Deaths were 0 in each group. The registry lists 21 participants with other adverse events among 33 in the Ovaprene Device group and 0 among 35 in the Caya Cycle group.

These are descriptive counts, not estimates of a randomized safety contrast. The study was not randomized, participants received both devices during the trial, and the record does not explain the construction or timing of the two safety groups. The counts should not be interpreted as proving that one device caused or prevented events. The registry record does not provide the event terms for the other adverse events, their severity, timing, or attribution. It also does not report whether adverse-event collection was identical across the listed groups.

In general, zero observed serious events does not establish that the underlying risk is zero; the interpretation depends on the number followed, follow-up duration, and completeness of event ascertainment. The registry provides group denominators but does not report enough follow-up detail to quantify risk over time. The adverse-event figures therefore describe what the registry records, without establishing comparative safety or ruling out uncommon events.

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

The result describes a post-coital test finding during Ovaprene use: the registry states that all participants had fewer than 5 PMS/HPF in all cycles. It is a statement about the specified test measure and its stated threshold. Because the endpoint’s analyzed denominator and a numerical count are not reported, the registry does not allow a reader to quantify the proportion meeting the finding or the precision of that estimate.

The result does not establish a randomized treatment effect. The study is described as single group and open-label, allocation is listed as NA, and participants received both Ovaprene and Caya. The Caya Cycle safety group is not a like-for-like randomized control. Consequently, differences in the recorded adverse-event counts cannot be interpreted as a causal comparison between devices.

The registry record does not report a pregnancy endpoint, a formal inferential analysis of the primary outcome, or a confidence interval. The post-coital test finding should not be substituted for an unreported outcome. Nor does the descriptive result establish long-term performance, acceptability, or comparative effectiveness; those conclusions require relevant outcomes and methods that are not reported in the registry record.

In general, feasibility studies can contribute information about whether procedures and measurements can be carried out and can describe observed results. Their descriptive findings may help frame later research questions, but a feasibility label does not itself establish that a device is effective or safe. In this record, the supported interpretation is narrow: the registry reports the stated test finding and the listed adverse-event counts in a completed device study. The absence of reported comparative analyses and endpoint uncertainty limits stronger conclusions.

13. Why This Trial Matters Statistically

This trial illustrates why a result has to be read alongside its design. The registry reports a post-coital test finding and adverse-event counts, but the study is single group, open-label, and not randomized. Those design features determine whether the numbers can support a causal comparison. Separate group labels do not by themselves create a control group, particularly when participants received both Ovaprene and Caya.

It also shows why the endpoint denominator matters. Enrollment is reported, but the registry does not state the analyzed denominator for the primary endpoint. Without that information, a count cannot be converted into a participant-level proportion or assessed for completeness. The same principle applies to safety results: each count needs to be read with its group denominator and with awareness that the registry does not report event timing or attribution details.

Statistically, descriptive outcomes and inferential comparisons answer different questions. A statement about the observed post-coital test finding tells readers what the registry records. A comparative estimate with uncertainty would require an analysis suited to the design and clearly defined populations. No such analysis is listed. This distinction prevents an untested description from being mistaken for evidence of a treatment difference.

The record also demonstrates the limits of registry reporting. Important context for interpreting missing observations, multiplicity, outcome procedures, and analysis choices is not reported. Recognizing those gaps is part of statistical interpretation, not a reason to invent explanations. The study matters as an example of how a feasibility result can be described carefully while keeping its scope separate from claims the design and reported analyses cannot support.

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 leaves several trial-specific details unclear. It does not report the analyzed population for the primary endpoint, its denominator, or how incomplete post-coital tests were handled. Although enrollment is listed as 38, that number cannot establish how many participants contributed to each endpoint. The differing safety denominators are reported, but the reason for the differences is not given.

The arm description says participants received both Ovaprene and the Caya diaphragm throughout the trial, and it mentions a Caya Post Coital Test cycle. The description is incomplete, so the sequencing, duration, and exact purpose of the Caya cycle are not fully reported in the registry record. This limits interpretation of the separate safety summaries and prevents treating one group as an untreated or randomized comparator.

The record does not report a statistical analysis plan, a sample-size justification, interim analyses, or a formal analysis for the primary endpoint. It also does not report a confidence interval, a p-value, or an adjustment for multiple outcomes. Event-level details for the other adverse events, adverse-event attribution, follow-up duration, and methods of event ascertainment are not reported in the registry record.

Finally, the primary endpoint is a post-coital test measure, while the record does not report a pregnancy endpoint or a comparative efficacy analysis. The described result is therefore limited to that test finding. The single-group, open-label design and the missing analysis details further restrict causal and precision claims. These limitations concern what can be concluded from the registry record; they do not establish that unreported procedures or analyses were not conducted.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Acceptability Study of a Non-Hormonal Ring — NCT03598088.
• Registry record last updated 2022-06-08; status last verified 2022-06.
• Results first posted 2022-06-08.
• 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.

18. Record Summary

NCT03598088 is a completed, open-label, multi-center feasibility device study sponsored by Daré Bioscience, Inc. The registry lists enrollment of 38 and describes a single-group study of the non-hormonal ring Ovaprene, with participants also receiving the Caya diaphragm. Its primary endpoint concerns changes in post-coital test results from baseline to OVP PCTa at 175 Days.

The registry states that all participants had fewer than 5 PMS/HPF in all cycles during Ovaprene use, but does not report the endpoint denominator or an inferential analysis. It records 0 serious adverse events among 33 participants in the Ovaprene Device group and 0 among 35 in the Caya Cycle group; other adverse events are reported for 21 and 0 participants, respectively. These descriptive counts are not a randomized comparison. The record does not report missing-data handling, a formal statistical plan, or a pregnancy endpoint.