Cochlear Implantation in Adults With Asymmetric Hearing Loss Clinical Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cochlear Implantation in Adults With Asymmetric Hearing Loss Clinical Trial (NCT03052920), a na na study. The primary outcome is Change in Poor Ear Alone CNC Monosyllabic Word Understanding in Quiet.

2. Clinical Question

This question concerns change in a measured speech-understanding score over time, not a randomized comparison of implantation against another treatment. The pre-implant and post-implant conditions differ in both timing and listening device: the description specifies a hearing aid before implantation and a cochlear implant alone after implantation. The primary outcome is therefore framed as a before-and-after group mean difference in this study population.

The record also lists secondary outcomes covering sound localization, speech understanding in several listening conditions, hearing handicap, health utility, and self-reported speech, spatial, and sound qualities. These measures broaden the study questions beyond the primary poor-ear word score. The record does not report results for the primary or secondary outcomes, so it does not establish the direction or size of change in any of them.

3. Trial Design

The registry identifies a completed, single-group clinical study sponsored by Washington University School of Medicine. The study began on 2017-07-28, and primary completion is recorded as 2020-11-17. Enrollment is listed as 40. The phase is recorded as NA, allocation as NA, and masking as none. The intervention is a cochlear implant, described as implantation of the poor-hearing ear.

The brief description characterizes the study as longitudinal. The primary outcome compares poor-ear-alone CNC monosyllabic word understanding in quiet before implantation with the score 6 months after implantation. The record describes the pre-implant condition as use of a hearing aid and the post-implant condition as use of the cochlear implant alone. It reports that 36 participants had scores at both time points for this primary outcome.

This is not a randomized comparison. The registry record does not list a separate untreated or alternative-treatment control arm, and the design is identified as single-group. The before-and-after assessment can describe how measured scores differ over time in the assessed participants, but it cannot by itself separate a change associated with the intervention from other influences that may also change over time. Such influences are not detailed in the record.

The registry lists 15 outcome measures and 15 analyses. Secondary outcomes include measures of localization, speech understanding under specified listening conditions, hearing handicap, health utility, and speech, spatial, and sound qualities. The record does not describe the statistical analysis plan, the handling of multiple outcomes, or the approach to missing outcome data. It also does not report the results for the primary endpoint or the secondary outcomes.

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:

Analysis population for the primary outcome, as defined in the registry: 36 participants had both pre-implant and 6-month post-implant CNC scores for the poor ear alone.

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 Change in Poor Ear Alone CNC Monosyllabic Word Understanding in Quiet, measured over Pre-implant and 6 months post-implant.

The primary endpoint is change in poor-ear-alone CNC monosyllabic word understanding in quiet. CNC refers to the word test named in the registry record; its score is expressed as the percentage of words correct. The record notes that scores range from 0% to 100% and that higher scores indicate better performance. The endpoint compares the group mean at 6 months after implantation with the pre-implant group mean.

This type of endpoint provides a continuous measure of speech understanding rather than a simple yes-or-no outcome. A group mean can describe the average score for the assessed participants, while the change in means describes how that average differs between the two assessment conditions. It does not show how every participant's score changed: individual responses may vary around the group average.

The test is specified for the poor ear alone, with the cochlear implant alone at the post-implant assessment. The pre-implant comparison is described as the poor ear with a hearing aid. This makes the endpoint relevant to the study's focus on hearing performance in the poorer ear, while also meaning that the two assessments involve different devices and different times.

The endpoint is used as the primary measure because it directly quantifies performance on a speech-understanding task. The registry record does not report the observed means, the mean change, a confidence interval, or a significance test. Consequently, the size and precision of the endpoint result cannot be assessed from the information recorded for this outcome.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous: it is a percentage-of-words-correct score, and the registry identifies the summary parameter as a mean. General statistical explanation: a mean represents the arithmetic average of measured scores in a group. It can provide a compact description of performance, but it does not show the full distribution of scores or how much participants differ from one another.

What does the standard error describe?

The registry identifies standard error as the dispersion measure for the primary outcome. General statistical explanation: the standard error describes the uncertainty in an estimated mean, rather than the spread of individual participants' measurements. It is often used to construct a confidence interval for a mean or a difference in means. A standard error does not, by itself, describe the range of individual scores. The registry record does not report the numerical standard error or a confidence interval for this endpoint.

What is the before-and-after contrast?

The stated primary comparison is the group mean CNC score in the poor ear alone at 6 months after implantation versus the pre-implant score. General statistical explanation: a before-and-after contrast describes the change between measurements taken at different times. When the same participants contribute both measurements, the two observations are related rather than independent. The registry reports that 36 participants had scores at both time points, but does not specify the statistical test, whether participant-level changes were analyzed directly, or how any incomplete records were handled.

The device condition also differs between assessments: the pre-implant poor-ear score is described as being with a hearing aid, and the post-implant score as being with the cochlear implant alone. Thus, the endpoint combines a time comparison with a comparison of listening conditions. General statistical explanation: an observed within-group change can reflect the measured intervention period as well as other changes over time; without a suitable control group, those influences cannot be separated by the comparison alone.

How would uncertainty and a p-value be read?

General statistical explanation: a confidence interval gives an estimated range for an effect under the assumptions of the analysis. Its width conveys precision, and whether it includes no difference can help describe compatibility with that possibility. A p-value measures how unusual the observed data, or more extreme data, would be under a specified null model. It is not the probability that the null hypothesis is true, nor does it measure clinical importance. The registry record does not report a confidence interval or p-value for the primary outcome, so neither significance nor precision can be assessed from the recorded results.

What do the planning assumptions mean?

The record describes sample-size planning illustrations based on a stated fraction of the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It distinguishes participant-per-arm outputs from total-event outputs for time-to-event calculations. These are planning assumptions, not evidence that the trial used a two-arm design; the actual study is identified as single-group. The record does not report numerical planning results in the registry record describing this trial. A planning calculation is not observed power, and the stated assumptions do not establish that the completed study had a particular probability of detecting an effect.

General statistical explanation: planning illustrations ask what sample size might be needed under specified assumptions about an effect and analysis. Their relevance depends on whether those assumptions suit the intended design and outcome. Here, the record's planning description refers to equal allocation between two arms, whereas the listed trial model is single-group. No further explanation of this distinction is reported in the registry record.

Why does over-dispersion matter?

General statistical explanation: over-dispersion arises when observed variability is greater than a statistical model assumes. If it is ignored, standard errors may be understated and confidence intervals may be too narrow. This is a general consideration for count outcomes and other data models that impose a particular variance structure. The primary endpoint in this record is a continuous mean score, and the registry does not report an over-dispersion assessment or a model for the primary analysis. The general concept should not be taken as evidence that over-dispersion occurred in this study.

Because the outcome estimates and analysis details are not reported, the statistical methods that were actually used to estimate change cannot be reconstructed. General methods explain how such results are commonly interpreted, but they do not substitute for the analysis plan or numerical results missing from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 15 outcome measures and 15 analyses. The primary outcome is change in poor-ear-alone CNC monosyllabic word understanding in quiet. The listed secondary outcomes cover sound localization, AzBio sentence scores under several listening conditions, BKB-SIN sentence understanding with noise to the better ear, hearing handicap, health utility, and speech, spatial, and sound qualities.

When many outcomes are assessed, the chance of at least one apparently unusual result can increase if each is tested separately without adjustment. General statistical explanation: multiplicity procedures can control or otherwise account for this issue, but the choice depends on the questions and analysis plan. Whether an adjustment was used, which outcomes were designated primary or secondary for testing purposes, and how results were interpreted across outcomes are not reported in the registry record. No outcome results are stated, so the consequences of multiplicity for this study cannot be evaluated.

The record states that 36 participants had both pre-implant and 6-month post-implant scores for the primary endpoint, while enrollment is listed as 40. It does not report reasons for unavailable scores, whether additional participants contributed partial outcome data, or how missing observations were handled. The analysis population and missing-data method are not reported in the registry record.

General statistical explanation: missing outcome data can affect both precision and interpretation, particularly if participants with unrecorded measurements differ in relevant ways from those with complete measurements. The record does not provide enough information to assess whether missingness could have influenced the estimated change. It also does not report whether an intention-to-treat principle, a complete-case analysis, or another population definition was used.

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: stroke (2.5%), infection (2.5%), coronary angioplasty and stint (2.5%), gall bladder removal (2.5%), nausea (2.5%).

The registry record lists 40 participants at risk in the cochlear implantation group. It reports 8 under serious adverse events affected and 11 under other adverse events affected, with 0 deaths. These are registry safety entries; the record does not provide further detail about timing, duration, severity beyond the serious-event classification, or the relationship of each event to the intervention.

The listed serious-event terms are Stroke, Infection, Coronary angioplasty and stint, Gall bladder removal, Nausea, and Kidney stone removal. Each is accompanied by 2.5% in the registry record. These entries describe the reported terms and percentages; they do not establish that the intervention caused the events. The record does not provide event-level narratives or enough information to determine whether a term represents an event, a participant, or more than one occurrence.

General statistical explanation: adverse-event counts or affected-participant counts are interpreted in relation to how they were defined and collected. In a single-group study without a control group, these entries cannot provide a like-for-like comparison of safety between treatments. The reported figures should therefore be read as safety observations recorded for this group, not as a comparative estimate of risk. The registry record does not report a separate causal assessment for the listed events.

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

The record establishes that the study examined cochlear implantation of the poor-hearing ear in adults with asymmetric hearing loss and continued hearing-aid use in the better-hearing ear. It defines a primary measure of poor-ear-alone speech understanding and specifies assessments before implantation and 6 months after implantation. It also identifies the number of participants with both scores for that endpoint.

The record does not state the observed primary outcome means or change. It therefore cannot show whether poor-ear CNC scores changed, the size of any change, or the precision of an estimate. The listed secondary outcomes likewise have no reported results in the registry record describing this record. No conclusion about the direction or magnitude of measured change can be drawn from the outcome descriptions alone.

The study's single-group before-and-after design can describe change among assessed participants, but it does not provide a randomized control comparison. General statistical interpretation: without a concurrent comparison group, change over time cannot be uniquely attributed to the intervention, because other influences may also operate during the same period. The registry record does not identify or measure those possible influences.

The endpoint is a test score, not a complete account of hearing experience or functioning. The listed secondary measures indicate that other aspects were also considered, but their results are not reported. The study record also does not state how the primary analysis handled missing data, how multiplicity was addressed, or what statistical model or test was used.

Accordingly, the information recorded supports understanding of the study question, its design, and the outcome definitions. It does not establish the observed effect, its uncertainty, or a comparative treatment effect. Those distinctions matter when interpreting a registry entry: a clearly described endpoint is not itself evidence of a particular result.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of a clinically focused before-and-after question in a single-group design. The primary endpoint is a continuous speech-understanding score measured in the poor ear alone, and the comparison is explicitly tied to two assessment times and two listening-device conditions. That detail helps define what a reported change would represent.

The design also illustrates the distinction between describing change and estimating a comparative effect. A within-group comparison can summarize scores before and after implantation among participants with both measurements. Without a separate control group, it cannot offer the same contrast as a randomized comparison between intervention and control groups. The registry record does not report an analysis that would address this limitation.

The record lists a broad set of secondary measures alongside the primary endpoint. This reflects the fact that hearing-related outcomes can involve speech understanding, localization, perceived handicap, health utility, and self-reported sound qualities. Statistically, multiple outcomes make clear reporting of endpoint hierarchy and analysis choices important. The record lists the outcomes and analyses but does not report multiplicity procedures or numerical results.

Finally, the enrollment and primary-outcome population figures are not identical in the record: 40 are listed as enrolled, and 36 are described as having both endpoint scores. This makes missing-data reporting relevant to interpretation. The reasons for unavailable endpoint measurements and their handling are not reported. These design and reporting features are important to understanding what the record can answer, even though it does not contain the primary result.

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 for interpreting the primary question is that the registry record does not report the outcome result. The primary endpoint is defined, but its means, mean change, confidence interval, standard error, and p-value are not stated. The direction, magnitude, and precision of any observed change therefore cannot be assessed.

The study is identified as single-group, with no randomized comparison. A before-and-after difference, if available, would not by itself distinguish intervention-related change from other influences over time. The record does not describe a strategy for addressing that limitation or identify measured factors that might explain changes in scores.

Outcome completeness also requires context. The record states that 36 participants had both primary endpoint assessments, while enrollment is listed as 40. Reasons for missing measurements, the handling of incomplete observations, and the analysis population are not reported. The impact of missing data on the result is therefore unknown.

The record lists multiple outcomes and analyses but does not report the statistical plan or any multiplicity approach. It also does not state the specific test or model used for the primary comparison. Masking is recorded as none; the registry does not describe how outcome assessment or analysis accounted for this. These are reporting limitations, not evidence that a particular bias occurred.

Finally, the listed safety information is not comparative, and the registry record does not provide detailed event narratives or causal assessments. These limitations restrict interpretation of both the clinical outcomes and the safety entries to what is explicitly recorded.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cochlear Implantation in Adults With Asymmetric Hearing Loss Clinical Trial — NCT03052920.
• Registry record last updated 2026-03-11; status last verified 2026-03.
• Results first posted 2021-10-18.
• 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 record describes a completed, single-group longitudinal study sponsored by Washington University School of Medicine. It lists enrollment of 40 and cochlear implantation of the poor-hearing ear as the intervention. The primary endpoint is change in poor-ear-alone CNC monosyllabic word understanding in quiet, comparing the pre-implant assessment with the assessment 6 months post-implant.

The record states that 36 participants had both primary endpoint scores. It lists secondary measures of localization, speech understanding, hearing handicap, health utility, and speech, spatial, and sound qualities. Safety entries include 8 serious adverse events affected, 11 other adverse events affected, and 0 deaths among the group with 40 at risk.

Numerical primary and secondary outcome results, analysis methods, missing-data handling, and multiplicity procedures are not reported in the registry record. The study is not a randomized comparison, so the design describes change over time in one group rather than a controlled treatment contrast.