Evaluation of Speech-in-noise Performance in Cochlear Implant Recipients With a CROS Device on the Contralateral Ear: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of Speech-in-noise Performance in Cochlear Implant Recipients With a CROS Device on the Contralateral Ear (NCT03867396), a randomized na study. The primary outcome is Cochlear Implant: Signal to Noise Ratio (SNR) Threshold Obtained From IEEE (Speech Perception in Noise Test) Sentence in Noise Test..

2. Clinical Question

The study asks whether speech understanding in noise differs when cochlear implant recipients use a device on the ear opposite the implant. The registry describes three listening conditions: cochlear implant alone, cochlear implant with a conventional hearing aid, and cochlear implant with a CROS device. Its stated interest is whether CROS improves speech perception when speech comes from the side opposite the implant; the official title also identifies a comparison between a conventional hearing aid and CROS.

The primary outcome is a signal-to-noise ratio threshold from the IEEE Speech Perception in Noise sentence test. Testing is described for speech and competing noise arriving from different directions, including all directions, the implant side, the front, and the opposite side. The endpoint is intended to assess speech perception under those listening conditions, rather than a general measure of hearing in everyday life.

The registry identifies the study as randomized and crossover, but does not report the randomization sequence, the order of listening conditions, or whether every participant completed every condition. The posted primary outcome description compares listening with the cochlear implant alone against listening with a contralateral device. It does not report a numerical comparison for CROS versus hearing aid, or any outcome estimates for the directional conditions.

Consequently, the clinical question is clear, but the posted record does not establish what the measured differences were. The primary outcome values, uncertainty estimates, and inferential analyses are not reported in the registry record. The record also notes incomplete primary-outcome data for the no-contralateral-device condition, limiting what can be concluded from the description alone.

3. Trial Design

The registry identifies this as a randomized, unmasked crossover study with an enrollment of 40 participants. The recorded condition is sensorineural hearing loss, and the listed interventions are a CROS device, a hearing aid, and cochlear implant alone. The descriptions indicate that the hearing aid or CROS device was worn on the side opposite the cochlear implant; the hearing aid and CROS device were clinic-loaned for listening tests.

A crossover design means that comparisons can be made within participants when the same people complete more than one listening condition. In general, such designs can reduce the influence of stable differences between participants, because each participant can contribute information under multiple conditions. The registry does not state the condition order, how the order was randomized, whether there was a washout period, or how possible carryover effects were handled. It also does not specify whether all enrolled participants completed all conditions.

The study is listed as completed. Its recorded start date is 2019-01-23, and its primary completion date is 2021-02-11. The phase is recorded as NA. The sponsor is University of Colorado, Denver. The record does not report the detailed eligibility criteria, recruitment procedures, allocation concealment, or the rationale for the enrollment target.

The primary outcome description concerns an IEEE sentence-in-noise test, with testing taking about 12 minutes. Visits are described as flexible and based on participant preference, and may occur between enrollment and the end of the study. The record lists three outcome measures, but does not provide their complete numerical results or any statistical analyses. The study is unmasked, so participants and study personnel were not described as blinded to listening condition.

Although randomization and crossover are recorded, these labels alone do not explain the implementation. Details needed to evaluate sequence generation, condition completion, and analysis of within-participant measurements are not reported in the registry record.

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.

Intervention 1

Intervention 2

Intervention 3

Analysis population for the primary outcome, as defined in the registry: One participant did not have data collected while wearing the contralateral device. Data is only available for 5 participants in the "No Contralateral Device" group. The PI has left the institution and multiple attempts to contact the PI or ascertain why only 5 participants were assessed for this group have been unsuccessful. This is the only data that can be provided.

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: Demographics data and baseline measurements were only collected for participants who completed the study.

6. Primary Endpoint

The registry lists the primary outcome as Cochlear Implant: Signal to Noise Ratio (SNR) Threshold Obtained From IEEE (Speech Perception in Noise Test) Sentence in Noise Test., measured over 12 minutes.

The primary endpoint is the cochlear implant signal-to-noise ratio threshold obtained from an IEEE sentence-in-noise test. The registry describes the outcome as a mean with standard deviation and gives the unit as a ratio. Testing presents sentences with competing noise from different directions, including speech or noise from all directions, the implant side, the front, and the opposite side.

In general, a signal-to-noise ratio describes the relationship between the target speech signal and background noise. A threshold summarizes the signal-to-noise condition associated with a defined level of speech understanding. The specific scoring criterion used to determine the threshold is not reported in the registry record. In general, a lower required signal-to-noise ratio can indicate that speech is understood under a less favorable speech-versus-noise balance; interpretation still depends on the test procedure and scoring definition.

This kind of endpoint is used because speech perception in noise is the study's stated concern, particularly when speech originates on the side opposite the implant. Direction-specific testing can distinguish listening situations that may be combined in a single overall measure. However, the registry does not report the numerical thresholds for any direction or listening condition, so the endpoint's observed pattern cannot be described.

The recorded testing duration is about 12 minutes. The registry notes that one participant did not have data collected while wearing a contralateral device and that data are available for 5 participants in the no-contralateral-device group. The reason for the limited data collection is not established in the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized crossover study and a continuous primary outcome summarized as a mean and standard deviation. It does not report an analysis plan, outcome estimates, or inferential tests. The explanations below are general statistical context, not a description of methods confirmed to have been used in this study.

What does a crossover design imply?

General statistical context: In a crossover study, participants may be measured under multiple conditions. Measurements from the same participant are usually related, because they share characteristics such as baseline hearing and test-taking ability. An analysis can use this pairing to compare conditions within people, rather than treating all observations as independent. The exact benefit depends on participants completing the conditions and on the model representing the repeated measurements appropriately.

Condition order can matter. Practice, fatigue, adaptation, or lingering effects from a previous condition may influence a later measurement. Crossover studies commonly need to consider order and possible carryover, but the registry record does not report condition sequence, washout procedures, or how order and carryover were addressed. No particular procedure should be assumed.

Randomization can help balance influences on condition assignment, but a registry label does not reveal how the sequence was generated or concealed. Those details are not reported in the registry record. The unmasked designation means masking is listed as none; the record does not describe any other steps to limit expectation or measurement effects.

What does the endpoint summary mean?

General statistical context: A mean is an average of observed values. A standard deviation describes the spread of individual values around that mean, not the precision of the mean itself. The precision of an estimated mean or condition contrast depends on the number of usable observations and their variability, as well as on the analysis design. The registry gives no primary endpoint means or standard deviations, so none of these quantities can be interpreted for the trial.

The endpoint is a signal-to-noise ratio threshold from a sentence-in-noise test. A condition contrast would need to specify which listening conditions and sound directions were compared. If participants contribute measurements under multiple conditions, uncertainty calculations should account for within-participant correlation. The record does not identify the model, contrast definitions, handling of direction, or whether thresholds were combined across directions.

Why do missing observations matter?

General statistical context: Missing data reduce the information available for a comparison. Their effect depends not only on how many values are absent, but also on which participants and conditions are affected and why measurements are missing. If missingness is related to performance or condition, the observed participants may not represent all enrolled participants. A complete-case analysis, for example, can be difficult to interpret when completion differs across conditions.

The primary outcome description states that one participant lacked data while wearing a contralateral device and that the no-contralateral-device group has data for 5 participants. It does not explain the reason for the latter limitation or report the analysis population. There is no information about imputation, sensitivity analyses, or how partial crossover data were used. These methods are not reported in the registry record.

How should multiplicity be considered?

General statistical context: Multiplicity arises when several outcomes, contrasts, directions, or analysis choices are examined. Repeated testing can increase the chance of finding an apparently notable result by chance if the analyses are treated as independent opportunities for discovery. A prespecified hierarchy or adjustment can address some multiplicity concerns, but the appropriate approach depends on the planned scientific questions.

The registry lists three outcome measures, and the primary endpoint description includes multiple sound directions and device conditions. It does not report the complete analysis plan, prespecified contrasts, or any adjustment for multiple comparisons. The record lists zero analyses. Thus, it is not possible to determine which comparisons were treated as primary or how multiplicity was handled.

What can a sample-size illustration tell the reader?

General statistical context: A sample-size calculation is a planning exercise based on assumptions about an effect, variability, significance level, allocation, and analysis. A calculation based on an observed effect is not evidence that a study had adequate power, and a retrospective planning illustration is not observed power. The registry record describes a planning illustration using a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. It also states that non-time-to-event illustrations are expressed as participants per arm.

Because the registry record does not report the observed primary endpoint effect or its variability, a reader cannot evaluate the assumptions against the study results from this record. The enrollment of 40 is not by itself a justification of statistical precision or power. The study's own sample-size justification is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three outcome measures, while the primary outcome description includes several listening conditions and sound directions. These features create potential multiplicity: different outcomes or contrasts could yield different estimates, and examining many comparisons can complicate interpretation. The registry record does not report which contrasts were prespecified, whether a hierarchy was used, or whether any adjustment for multiple testing was planned. It also lists zero analyses, so the handling of multiplicity in actual analyses is not available.

Missingness is a particular concern for the primary endpoint. The record states that one participant did not have data collected while wearing the contralateral device. It also states that data are available for 5 participants in the no-contralateral-device group. The principal investigator left the institution, and multiple attempts to contact the investigator or ascertain why only 5 participants were assessed for this group are noted. A reason is not reported in the registry record.

The record does not identify the analysis population, the number of participants contributing to each device condition, or the number with complete crossover measurements. It does not report whether partial observations were retained, whether missing values were imputed, or whether sensitivity analyses assessed the impact of missingness. Consequently, the influence of incomplete data on any condition comparison cannot be evaluated.

In general, missing outcome values do not automatically invalidate a study, but interpretation depends on how and why the values are missing and on the analysis used. Here, those details and numerical results are not reported in the registry record. No conclusion about the consequences of missingness or multiplicity can be reached from the posted information.

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.

The registry lists serious adverse event counts of 0 and other adverse event counts of 0 for each of the three intervention groups. It also lists 0 deaths in each group. The recorded at-risk count is 25 for serious adverse events and 25 for other adverse events in each group.

These figures describe the adverse-event entries in the registry; they do not establish that no adverse experiences occurred outside the events captured or reported there. The record does not provide event definitions, collection procedures, follow-up duration for safety, or narrative descriptions of adverse events. No serious adverse event terms are listed.

The at-risk counts should be read as the counts recorded for each group, not as a verified account of unique participants across the crossover conditions. The study enrollment is 40, and the registry lists three intervention groups, but it does not explain how the repeated-condition design relates to the adverse-event denominators. The counts should therefore not be combined or treated as independent groups without further information.

Zero events in a registry entry do not prove that the risk is absent. In general, rare events may not appear in a study's recorded results, and the meaning of a zero count depends on the amount and completeness of observation. The registry figures alone do not support a comparative safety conclusion between the hearing aid, CROS, and cochlear implant alone conditions.

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

The record documents a study designed to assess speech-in-noise performance in cochlear implant recipients using different contralateral listening conditions. It identifies a randomized, unmasked crossover design and describes an IEEE sentence-in-noise threshold as the primary outcome. It also records incomplete data for the no-contralateral-device condition and lists adverse-event counts.

What the record does not provide is the outcome information needed to say whether the measured thresholds differed by device condition. No means, standard deviations, estimated contrasts, confidence intervals, or p-values are reported. There is therefore no reported result from which to characterize the size, direction, or precision of an observed difference. The absence of a reported analysis is not evidence that conditions produced the same performance, and it is not evidence that one condition performed better.

The result also cannot establish whether any measured difference would be clinically meaningful. That interpretation would require the numerical effect, its uncertainty, the test's scoring definition, and a basis for judging the importance of a threshold change. Those items are not reported in the registry record.

General statistical context: A study's design and its results answer different questions. A randomized crossover design describes how listening conditions were intended to be assigned and compared; it does not substitute for reporting the measurements and analysis. Likewise, an enrollment count does not establish how many participants contributed usable outcome data under each condition or how precise the comparison is.

The registry describes a clinically focused question about speech arriving opposite the implant, but the available information supports only a description of the intended assessment and its documented data limitations. It does not support claims about effectiveness, equivalence, superiority, or absence of an effect for CROS, a conventional hearing aid, or cochlear implant alone.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of why a design label and a research question are not enough to interpret a clinical comparison. The registry identifies randomization and crossover, but the value of a crossover comparison depends on information about condition order, repeated measurements, completion, and the analysis of within-participant data. Those details are not reported in the registry record.

The study also highlights the importance of linking an endpoint to its analysis population. A speech-in-noise threshold can be relevant to a focused listening question, but interpretation requires knowing how many observations contributed under each condition and how incomplete data were handled. The record notes limited data for the no-contralateral-device condition without explaining why. This makes transparent reporting of data availability and analysis decisions especially important.

Multiplicity is another statistical consideration. The listed outcome measures and the multiple directions and listening conditions create several possible contrasts. Without prespecified comparisons or an analysis plan, readers cannot tell which contrasts were central to the study question or how many were examined.

Finally, a registry record can describe a completed study without reporting analyzable outcome results. In this case, the design, endpoint, enrollment, and some safety entries are recorded, while primary numerical results and analyses are absent. This distinction matters: lack of a posted estimate is not a null estimate. Clear reporting of effect estimates and their uncertainty is needed to judge what the observations show.

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 primary limitation for interpretation is that numerical primary outcome results and statistical analyses are not reported in the registry record. The mean and standard deviation are identified as the intended summary, but no values, condition contrasts, confidence intervals, or p-values are posted. The observed speech-in-noise pattern therefore cannot be described.

Data completeness is also unclear. The registry states that one participant did not have data collected while wearing a contralateral device and that data are available for 5 participants in the no-contralateral-device group. It notes the principal investigator's departure from the institution and multiple attempts to establish why this group had data for only 5 participants, but does not report the reason. The number of participants with usable measurements in each condition and the analysis population are not reported.

Although the study is identified as randomized and crossover, the registry does not report the condition sequence, the method for generating or concealing randomization, whether all participants completed all conditions, or how order and possible carryover effects were handled. The statistical model and treatment of repeated measurements are not reported. These omissions prevent assessment of whether the analysis reflected the design.

The primary outcome description includes different sound directions, and the registry lists three outcome measures. Prespecified contrasts, the multiplicity strategy, and the full analysis plan are not reported. The record does not state the specific threshold-scoring criterion or any clinically meaningful difference used for interpretation.

The adverse-event entries list zero events, but event definitions, safety follow-up, and the relation between the recorded at-risk counts and crossover participation are not explained. These registry limitations do not establish that the study was conducted improperly; they restrict what can be concluded from the information recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Evaluation of Speech-in-noise Performance in Cochlear Implant Recipients With a CROS Device on the Contralateral Ear — NCT03867396.
• Registry record last updated 2022-05-16; status last verified 2022-04.
• Results first posted 2022-05-16.
• 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 randomized, unmasked crossover study of cochlear implant recipients with sensorineural hearing loss. Enrollment is listed as 40. The interventions are cochlear implant alone, cochlear implant with a conventional hearing aid, and cochlear implant with a CROS device.

The primary outcome is a mean signal-to-noise ratio threshold from an IEEE sentence-in-noise test, with standard deviation as the dispersion measure. The test is described for speech and noise from different directions and takes about 12 minutes. The registry lists three outcome measures and zero analyses.

The primary outcome description notes that one participant lacked data while wearing a contralateral device and that data are available for 5 participants in the no-contralateral-device group. The reason for the limited data is not reported in the registry record. Adverse-event entries list zero serious events, zero other events, and zero deaths in each intervention group. Numerical primary results and inferential analyses are not reported.