Evaluation of the Nucleus Hybrid™ L24 Cochlear Implant System: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the Nucleus Hybrid™ L24 Cochlear Implant System (NCT00678899), a na na study. The primary outcome is Consonant Nucleus Consonant (CNC) Monosyllabic Word Score-Treated Ear (CO-PRIMARY).

2. Clinical Question

In plain terms, the study was intended to assess change in word recognition after implantation and activation, while also evaluating safety. The registry lists CNC Monosyllabic Words and AzBio Sentence Score as secondary outcomes, but detailed results for these outcomes are not reported in the registry record. The clinical question is therefore described by the study plan, not answered by posted efficacy estimates. Without outcome values and an analysis, the size, precision, and direction of any observed change cannot be assessed.

3. Trial Design

The registry describes a completed, single-group device study of the Nucleus Hybrid L24 cochlear implant. Enrollment is recorded as 50. The study started in 2008-04, with primary completion in 2012-06. The listed condition is sensorineural hearing loss, and the sponsor is Cochlear. The phase and allocation are recorded as NA, while masking is listed as NONE.

The only arm is Surgery, described as implantation with the Nucleus Hybrid L24 Cochlear Implant. Because there is no separate control arm, the main efficacy comparison described in the registry is a before-and-after comparison within the treated ear. The primary endpoint description specifies a preoperative unilateral acoustic CNC word score and postoperative CNC word scores in Hybrid mode for activated implant subjects. The assessment timeframe is 6 Months Postactivation.

This design can describe how scores change over time among participants with measurements, but it does not create a randomized like-for-like contrast between implant recipients and a concurrent untreated group. A preoperative score serves as a within-participant reference, rather than as a separate randomized control condition. Consequently, changes over time cannot by themselves distinguish the effect of the device from other explanations such as changes in testing conditions, participant experience, or other factors. Whether such factors were addressed in the analysis is not reported in the registry record.

The registry lists four outcome measures and zero analyses. It does not report the number of participants who completed follow-up, the analysis population, or the results for the primary or secondary outcomes. It also does not report the sample-size justification, a detailed statistical analysis plan, or whether interim analyses were planned or conducted. The stated enrollment is not evidence that every enrolled participant contributed to each outcome analysis.

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:

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 Consonant Nucleus Consonant (CNC) Monosyllabic Word Score-Treated Ear (CO-PRIMARY), measured over 6 Months Postactivation.

The named co-primary endpoint is the Consonant Nucleus Consonant (CNC) Monosyllabic Word Score in the treated ear. It is a continuous outcome measured as percentage of words correct, with the registry specifying the mean and standard deviation as the summary parameters. The comparison is between the preoperative score, obtained with unilateral acoustic hearing in the ear to be implanted, and postoperative scores in Hybrid mode. The stated timeframe is 6 Months Postactivation.

The registry describes the CNC test as consisting of 10 recorded lists, each containing 50 monosyllabic words. For this study, two lists are to be administered in quiet at 60 dBA in the sound field. The total number of words correct is expressed as a percentage. The score therefore represents performance on a word-recognition task under the described test conditions; it is not a direct measure of every aspect of hearing or everyday communication.

A continuous score can be summarized by its mean and variability, and a paired comparison can focus on within-participant change. The endpoint is relevant to the stated study question because it measures monosyllabic word recognition before and after the intervention. The registry record does not report the observed means, standard deviations, number of paired observations, estimated change, or uncertainty around that change. It also labels the endpoint co-primary without providing details of the other co-primary endpoint; those details are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a mean score describe?

For a continuous outcome such as percentage of words correct, the mean describes the average score among the observations included in an analysis. The standard deviation describes how dispersed individual scores are around that average. These summaries answer different questions: the mean concerns the group average, while the standard deviation concerns variability among participants. The registry specifies mean and standard deviation as the endpoint parameters, but does not report their observed values.

Why does the before-and-after structure matter?

General statistical explanation: when measurements are taken from the same participant at different times, a paired analysis focuses on each participant’s change and then summarizes those changes. This approach accounts for the fact that repeated measurements from one person are related. It differs from comparing the average of one independent group with the average of another independent group. The registry describes a preoperative and postoperative comparison for the treated ear, but does not report the statistical test or model used, or whether the analysis used paired observations.

A paired analysis also depends on having both measurements for a participant. If one measurement is missing, that participant may not contribute to a simple complete-pair analysis. More complex methods can use incomplete measurements under explicit assumptions, but the method and assumptions would need to be reported. The registry record does not state how missing preoperative or postoperative scores were handled, or how many participants had usable measurements at each timepoint.

What does a confidence interval add?

General statistical explanation: an estimate alone gives a central value, while a confidence interval communicates uncertainty around that estimate under the method’s assumptions. A narrower interval indicates greater precision; a wider interval indicates less precision. Intervals also help readers assess which effect sizes remain compatible with the data. No confidence interval for the CNC comparison is reported in the registry record, so its precision cannot be evaluated.

What does a significance test address?

General statistical explanation: a significance test evaluates how compatible the observed data are with a specified null hypothesis under a statistical model. A test result does not measure the size or clinical importance of an effect. Interpretation also depends on the design, analysis assumptions, and the number of outcomes being tested. The endpoint description says the study endpoints concern statistically significant differences, but the specific test, significance threshold, and resulting test statistic or p-value are not reported in the registry record.

Why does the lack of a control arm matter?

General statistical explanation: random allocation to a concurrent comparison group can help balance both measured and unmeasured factors, on average, between groups. In a single-group pre-post design, the participant serves as their own reference, which controls for stable differences between people but does not control for all changes that may occur over time. Testing familiarity, changes in circumstances, or other concurrent influences can affect a before-and-after result. This is a general limitation of the design, not evidence that any particular influence occurred in this study.

The registry lists allocation as NA and identifies the study model as SINGLE GROUP. It does not report a separate control group or a randomized treatment comparison. The primary contrast is therefore best understood as a within-treated-ear comparison over time. The posted record does not establish whether the analysis used additional covariate adjustment or sensitivity analyses.

How should planning illustrations be understood?

General statistical explanation: sample-size planning uses assumptions about the effect to detect, outcome variability, significance level, allocation, and statistical method. A planning illustration based on a fraction of an observed effect asks how many participants per arm might be needed under its stated assumptions. It is not an observed result and is not a measure of the probability that this completed study found an effect. The registry record does not report the trial’s own sample-size justification. Any planning illustration should therefore be kept separate from the study’s observed enrollment and from conclusions about its actual statistical power.

The listed planning assumptions describe a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect framed as a stated fraction of the observed effect. These are assumptions for an illustration, not evidence that this single-group study used that design or analysis. The record does not provide the observed effect needed to interpret those illustrations as study-specific evidence.

What can be inferred from the posted analysis information?

The registry lists zero analyses. That is an important distinction from a reported analysis with a nonsignificant result: no analysis result is posted, so no test outcome or estimate can be evaluated. The available description identifies the intended outcome and comparison, but not the model, test, variance estimate, missing-data strategy, or analysis population. Those methods are not reported in the registry record. Statistical interpretation should remain limited to the design and outcome description until results and analysis details are available.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("6 Months Postactivation")
n   <- c(49)
m   <- c(65.4)
sp  <- c(25.4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  6 Months Postactivation  49  65.400  25.400  58.104  72.696

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies the CNC Monosyllabic Word Score as a co-primary endpoint. It does not provide details of the other co-primary endpoint in the primary outcome description. The registry also lists CNC Monosyllabic Words and AzBio Sentence Score as secondary outcomes and records four outcome measures overall. The specific multiplicity strategy—how the analysis would account for testing more than one endpoint or comparison—is not reported in the registry record. Without that information, the impact of multiple testing on interpretation cannot be assessed.

Missing-data handling is also not reported. The record does not state how many participants had preoperative and postoperative CNC scores, how many completed the 6 Months Postactivation assessment, or how incomplete observations were treated. It does not describe imputation, a complete-case approach, or sensitivity analyses. The enrolled number of 50 should not be assumed to equal the number included in every outcome analysis.

The analysis populations are not reported in the registry record. In particular, the record does not specify whether results were intended for all enrolled participants, all implanted participants, participants with activation, or participants with complete measurements. No analysis results are posted, and the registry records zero analyses. These gaps prevent assessment of the outcome denominator, potential attrition, and robustness to alternative analysis choices.

The registry record also does not report an interim-analysis plan or a detailed statistical analysis plan. Their existence or absence should not be inferred from the posted information.

12. 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

The registry reports safety counts for the Surgery group. Serious adverse events are recorded for zero of 50 participants at risk. Other adverse events are recorded for 34 of 50 participants at risk. These are counts of participants recorded as affected in the registry, not a description of the number, type, timing, severity, or duration of each event.

No serious adverse event terms are listed among the top serious terms. The registry does not report the event definitions, collection method, or observation period for these counts. The deaths value is not reported in the registry record, so it should not be interpreted as a confirmed zero. The record also does not provide details that would establish whether all participants had the same duration of safety follow-up.

These figures are descriptive safety information and should be interpreted separately from the unreported efficacy results. In particular, the recorded serious adverse event count does not establish that no safety concerns occurred, and the count for other adverse events does not by itself indicate whether events were related to implantation or the device. Attribution and event-level details are not reported in the registry record.

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

The study record describes an evaluation of acoustic and electric sound processing delivered by the Nucleus Hybrid L24 cochlear implant system. Its stated efficacy question concerns whether mean CNC word scores in the treated ear differ from the preoperative assessment to the postoperative Hybrid-mode assessment at 6 Months Postactivation. The record also lists AzBio Sentence Score-Treated Ear and CNC Monosyllabic Words among the secondary outcomes.

What the record does not establish is the observed change in CNC score, its precision, or the result of a statistical test. Outcome values and analysis results are not reported in the registry record, which lists zero analyses. No conclusion about the direction or magnitude of change can be drawn from the endpoint description alone. The same limitation applies to the listed secondary outcomes.

The single-group design also limits causal interpretation. A before-and-after difference, if reported, would describe change over time in the analyzed participants. Without a separate randomized control group, the comparison would not by itself determine how much of any change was due to the intervention rather than other influences over time. This is a design limitation, not a claim that a particular alternative explanation affected the study.

The safety information reports zero participants with serious adverse events among 50 at risk and 34 participants with other adverse events among 50 at risk. The registry does not provide enough event detail or follow-up information to characterize these counts fully, and the death value is not reported in the registry record.

Accordingly, the posted record supports a careful description of the study question, design, endpoint, and limited safety counts. It does not support a quantitative judgment about the efficacy endpoint or a causal claim about the device. Missing outcome results should not be treated as evidence either for benefit or for no effect.

14. Why This Trial Matters Statistically

This trial is statistically informative as an example of how a device evaluation can pose a clear within-participant question while still requiring careful attention to design and reporting. The CNC endpoint is defined as a continuous score, expressed as percentage of words correct, and the planned contrast is between preoperative and postactivation performance in the treated ear. That structure makes the measurement and timing of paired observations central to interpretation.

The registry record also illustrates why a study’s design label is important. A single-group before-and-after comparison is not a randomized comparison between intervention and control groups. Even when repeated measurements are available for the same participants, interpretation depends on who contributes data, how the paired measurements are analyzed, and whether other influences over time are considered. These details are not reported in the registry record.

Another statistical lesson is that an endpoint description is not an outcome result. The record specifies the test and the intended comparison, but reports no means, variability estimates, confidence intervals, or analysis results. The enrollment figure alone cannot supply those missing results, and planning illustrations cannot substitute for observed estimates.

Finally, the record identifies co-primary and secondary outcomes without reporting a multiplicity approach or details of the complete analysis plan. This makes it difficult to assess how the study intended to control interpretation across outcomes. The case underscores the importance of reporting outcome estimates, uncertainty, denominators, analysis populations, and methods alongside the study design. Those elements are necessary for readers to evaluate what the data show and how precisely they show it.

15. 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.

Several limitations specific to this study are apparent from the registry record. First, the study is a single-group evaluation with no separate control arm. The primary comparison is preoperative versus postoperative in the treated ear, so it does not provide a randomized between-group contrast. Any measured change would require cautious interpretation as change over time rather than, by design alone, an isolated causal effect of the device.

Second, the registry does not report efficacy results despite describing the primary endpoint. The observed CNC means, standard deviations, change estimate, confidence interval, and test result are not reported in the registry record. The number of participants with complete measurements is also not reported, so the available record does not establish how much of the enrolled group contributed to the primary comparison.

Third, the endpoint is labelled co-primary, but the other co-primary endpoint is not detailed in the primary outcome description. The registry lists four outcome measures, but it does not report how multiplicity was handled or how the listed outcomes related to the primary analysis. The statistical analysis plan and method for handling missing data are not reported.

Finally, safety reporting is limited to counts. The event-level descriptions, observation period, attribution, and death count are not reported in the registry record. These limitations concern the information available in the record; they do not establish that particular methods or data were absent from the conduct of the study.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of the Nucleus Hybrid™ L24 Cochlear Implant System — NCT00678899.
• Registry record last updated 2015-07-15; status last verified 2015-06.
• Results first posted 2014-09-29.
• 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.

19. Record Summary

The registry describes a completed, single-group device study of the Nucleus Hybrid L24 Cochlear Implant System, sponsored by Cochlear. Enrollment is recorded as 50, with study start in 2008-04 and primary completion in 2012-06. The study concerns sensorineural hearing loss, and the stated population has significant residual low-frequency hearing and profound high-frequency sensorineural hearing loss above 1500 Hz.

The co-primary CNC endpoint is a treated-ear score expressed as percentage of words correct, comparing preoperative unilateral acoustic performance with postoperative Hybrid-mode performance at 6 Months Postactivation. The record lists four outcome measures and zero analyses; efficacy results and analysis methods are not reported in the registry record.

For safety, zero of 50 participants at risk are recorded as affected by a serious adverse event, and 34 of 50 are recorded under other adverse events. The death value is not reported in the registry record.