DEfibrillators To REduce Risk by MagnetIc ResoNance Imaging Evaluation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for DEfibrillators To REduce Risk by MagnetIc ResoNance Imaging Evaluation (NCT00487279), a randomized na study. The primary outcome is All-cause Mortality.

2. Clinical Question

3. Trial Design

The registry describes a prospective, multicenter, randomized study with a parallel-group design. Allocation was randomized, and masking was listed as none. The two treatment groups were the ICD Group and the Control Group. The ICD Group received an implantable cardioverter defibrillator, while the Control Group received medical therapy. The stated study objective compared ICD therapy plus medical therapy with medical therapy alone.

The registry reports enrollment of 81 and lists the study status as terminated. It records a start date of 2007-06 and a primary completion date of 2010-12. The reason for termination is not reported in the registry record. A phase designation is listed as NA. The sponsor is Abbott Medical Devices.

The registry describes a separate, non-investigational registry of non-randomized patients in addition to the two-arm randomized study. The posted primary comparison concerns the two randomized groups; outcomes for the non-randomized registry are not reported in the registry record. The primary outcome population is identified as intent to treat. That label indicates the intended analysis population, but the record does not describe participant-level inclusion, exclusions, or handling of incomplete outcome information.

The stated primary outcome is all-cause mortality. Its timeframe is described as evaluating total survival 2 years after the last patient is randomized. The registry also lists arrhythmic mortality as a secondary outcome. It reports two outcome measures, while the number of posted analyses is zero. The reason for the terminated status, any changes to the study design, the timing of termination relative to recruitment, and whether the planned follow-up was completed are not reported in the registry record.

The design creates a randomized comparison, but the lack of masking means that participants and study personnel were not blinded according to the registry listing. All-cause mortality is less dependent on subjective assessment than many outcomes, but the absence of masking remains relevant to understanding how the trial was conducted. Further details about allocation procedures, concealment, follow-up, and protocol deviations 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.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent to Treat

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 All-cause Mortality, measured over Total survival will be evaluated 2 years after the last patient is randomized..

All-cause mortality counts deaths from any cause. It is a clinically important endpoint because it captures fatal outcomes without requiring the cause of death to be classified as cardiac, arrhythmic, or otherwise. This can make the outcome less vulnerable than cause-specific endpoints to disagreement about how a death should be categorized. The registry identifies the primary measure in participants and labels its population intent to treat.

The stated timeframe is evaluation of total survival 2 years after the last patient is randomized. That description indicates the intended time point for assessing survival, but the posted numerical result is presented as event counts and an unadjusted risk difference. It is not a hazard ratio or a comparison of survival curves. The registry record does not provide individual follow-up times, censoring information, or details about how deaths were ascertained.

All-cause mortality is distinct from the listed secondary outcome of arrhythmic mortality. The primary result should therefore be interpreted as a comparison of deaths from any cause, not as a direct estimate of arrhythmic death or of a specific mechanism of effect. Although the study objective refers to long-term survival, the available comparison is a summary of recorded events in each group. Without additional time-to-event results, it does not describe when deaths occurred or how survival experience developed during follow-up.

7. Results Posted in the Registry

• ICD Group: 2.3% (1/44) versus 0.0% (0/37) on control; risk difference 2.3 percentage points (95% CI -2.1 to 6.7); unadjusted two-proportion z-test p = 0.356.

8. Statistical Interpretation

9. Statistical Methods Explained

The posted primary comparison uses a risk difference. In general, a risk difference subtracts the event risk in one group from the event risk in another. Here, the contrast is defined as the ICD Group minus the Control Group. A positive value indicates a higher observed event risk in the ICD Group, while a negative value indicates a lower observed event risk in that group. The reported estimate is 0.023. This is an absolute difference on the risk scale, not a relative risk, odds ratio, or time-to-event effect.

The posted counts are one event among 44 participants in the ICD Group and no events among 37 participants in the Control Group. The registry identifies the outcome unit as participants and the result type as a number. These counts are sparse. With so few events, a single event contributes substantially to the comparison, and estimates can be sensitive to small changes in the observed counts. The estimate should not be treated as a stable measure of a long-term effect merely because it is reported numerically.

The confidence interval gives a range of values compatible with the observed data under the statistical method and assumptions used. In general, a confidence interval is not a guarantee that the true value lies in the particular interval, nor is it a range containing a stated percentage of individual outcomes. Repeated use of a method with its assumptions would produce intervals that cover the true value at the method’s nominal rate. The interval reported for this risk difference runs from -0.021 to 0.067. Its inclusion of zero indicates that no difference is among the values compatible with the interval. The interval also includes positive and negative values, so direction is not determined precisely.

The unadjusted p-value is 0.356. In general, a p-value assesses the compatibility of the observed data with a null hypothesis under a specified statistical model. A larger p-value is not proof of no effect, and a smaller p-value is not a measure of clinical importance. The registry record does not report the exact test used, its assumptions, whether it was prespecified, or a statistical analysis plan. The label “unadjusted” indicates that the comparison is not presented as adjusted for covariates; details of any adjusted analyses are not reported in the registry record.

The outcome timeframe refers to total survival evaluated 2 years after the last patient is randomized. A survival analysis generally uses information about the time until an event and may account for participants whose event has not been observed by the end of their follow-up. The posted result does not include event times, censoring details, a hazard ratio, or a survival curve. It is therefore best described as a risk-difference summary of event counts, rather than as a time-to-event analysis. The record does not explain how the stated survival timeframe was operationalized in the posted counts.

The stated intent-to-treat population ordinarily refers to retaining participants in the groups to which they were assigned, regardless of treatment received. This is a general explanation of the concept, not confirmation of the exact procedures used in this trial. The registry record does not describe whether the analysis followed that principle in practice, how participants with missing endpoint data were handled, or whether any participants were excluded from the reported comparison. It also does not report the number of participants with complete outcome information.

The trial’s sample-size assumptions are described as a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. The stated effect to detect is a fraction of the observed effect. Such illustrations are prospective planning calculations in general: they show how assumed effects and design choices relate to a target level of power under a model. They are not observed power and do not establish that the trial was designed using those assumptions. The record does not report the trial’s own sample-size justification or planned target enrollment rationale. Any planning figures should therefore be read as illustrations based on the specified assumptions, not as evidence about the study’s original design.

Over-dispersion is a general concern when observed variability exceeds what a statistical model assumes. It is especially relevant in outcomes such as counts when a simple model assumes a particular mean-variance relationship. The primary measure is a binary participant outcome, and no dispersion estimate is reported. No extra dispersion adjustment or model specification is described in the registry record. More broadly, sparse binary outcomes can make conventional approximations less dependable, so the exact method and its assumptions matter; those details are not reported.

The registry includes a non-investigational, non-randomized registry alongside the randomized trial. A randomized treatment comparison and a non-randomized registry serve different inferential purposes: random allocation helps balance prognostic factors on average, while non-randomized comparisons may be affected by differences between people who receive different care. No outcome results for the non-randomized registry are reported in the registry record for this analysis. Its presence should not be taken as evidence that its participants contributed to the randomized comparison.

The secondary outcome listed is arrhythmic mortality. The record reports two outcome measures and zero posted analyses. It does not provide a multiplicity strategy, a hierarchy for outcome testing, or details about the analysis of the secondary outcome. In general, testing multiple outcomes can increase the chance of at least one apparently notable result unless the analysis accounts for that possibility. That general concern cannot be quantified for this trial from the registry record. The available primary result should consequently be interpreted on its own terms, without assuming how secondary outcomes were handled.

10. Confidence Intervals and Precision

The risk-difference estimate is 0.023, with a 95% confidence interval from -0.021 to 0.067. The interval is the main guide to precision: it shows that the estimate is compatible with values below zero, zero itself, and values above zero. The point estimate alone gives a single value, but the interval makes clear that the data do not pin down the underlying difference closely.

In general, a confidence interval reflects both the observed data and the method used to calculate it. Its width is affected by the amount of information in the data and by assumptions of the analysis. Here, the comparison is based on only one event in the ICD Group and none in the Control Group. Sparse events limit how much the observed data can establish about the difference in event risk. The registry record does not describe the interval calculation method, so its exact assumptions cannot be assessed from the information reported.

The confidence interval crossing zero does not prove that the groups have identical risks. It indicates that the posted data, under the interval method, do not exclude zero difference. The interval also allows for a negative difference and a positive difference. As a result, the direction and magnitude of the underlying difference remain uncertain. The reported p-value, 0.356, is consistent with the lack of a sharply separated result, but it is not a substitute for reading the interval or assessing the limitations of the analysis.

Precision is different from clinical importance. The interval does not by itself determine whether any particular value would matter in practice, and the registry record does not specify a threshold for a meaningful difference. Nor does this risk-difference interval describe the timing of events. Because event times and censoring are not reported, it cannot provide the precision of a time-to-event comparison or show how survival changed through follow-up.

Overall, the result is imprecise: the estimated difference is accompanied by an interval that permits effects in both directions. The limited event count and absent details about the statistical method, missing outcomes, and follow-up further restrict assessment of precision. The registry record does not report an adjusted estimate or an alternative analysis that could be used to evaluate robustness.

11. Multiplicity, Missing Data and Analysis Populations

The registry lists all-cause mortality as the primary outcome and arrhythmic mortality as a secondary outcome. It also reports two outcome measures and zero posted analyses. These registry entries do not establish how many statistical tests were planned or conducted, or whether the primary outcome had a prespecified testing hierarchy. The multiplicity strategy is not reported in the registry record.

In general, when researchers test multiple outcomes or make repeated comparisons, the chance of at least one result appearing notable can increase. Statistical plans may address this through prespecification, adjustment, or a structured testing hierarchy. These are general methods, not descriptions of what this trial did. Without a reported plan, the primary p-value should be read as the unadjusted result stated for the comparison, and it is not possible to determine whether or how multiplicity was considered.

The primary outcome population is labeled intent to treat. That label identifies the intended population, but it does not explain the handling of missing data. The registry record does not report how many participants lacked outcome information, whether follow-up was incomplete, whether any observations were imputed, or how deaths were verified. It also does not describe exclusions or deviations from the assigned group in the analysis.

In general, missing outcome information can affect estimates if participants with unobserved outcomes differ systematically from those with observed outcomes. The direction and extent of any such effect depend on who is missing and why. Since those details are not reported, the potential influence of missingness cannot be assessed. The stated evaluation point of 2 years after the last patient is randomized does not by itself establish complete follow-up for every participant.

The registry record does not report a statistical analysis plan, the exact method used for the confidence interval or p-value, or sensitivity analyses. It also does not explain whether the posted event counts reflect all randomized participants under the intent-to-treat principle. These gaps limit reproducibility and make it difficult to judge whether other reasonable analysis choices would change the result.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: lead dislodgment or migration (100.0%).

The posted safety figures list serious adverse events for the ICD Group: 3 participants at risk and 3 affected for serious events. For other adverse events, the record lists 44 at risk and 2 affected. The Control Group has zero participants at risk and zero affected in both categories in these safety entries. This means the record does not offer a usable safety comparison between the randomized groups; zero at risk is not evidence that no safety events occurred among control participants.

The listed top serious-event term is “Lead Dislodgment or Migration,” with 100.0% recorded for that term. The registry record does not explain the denominator or the precise meaning of this percentage, so it should not be interpreted as a rate among all participants or as the proportion of all serious events without further information. The record also does not provide death counts in the safety summary.

Safety summaries require attention to both the event count and the population used as the denominator. The ICD Group has separate entries for serious and other adverse events, and those categories should not be combined or treated as interchangeable. The available entries do not report event timing, severity details beyond the category, relatedness to the device, or whether one participant could contribute more than one event. These limitations prevent a complete assessment of comparative safety from the posted figures.

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

The result answers a narrow statistical question: what unadjusted difference in recorded all-cause mortality risk was observed between the ICD Group and the Control Group in the posted comparison? The estimate is 0.023 in the direction of a higher event risk in the ICD Group, with a 95% confidence interval from -0.021 to 0.067 and an unadjusted p-value of 0.356. The counts behind it are one event in the ICD Group and none in the Control Group.

The result does not establish that ICD therapy increased mortality, nor does it establish that the two approaches have identical mortality. The interval includes zero and values in both directions, and the event count is sparse. The estimate therefore leaves substantial uncertainty about the direction and size of any underlying difference. It should not be converted into a treatment recommendation or interpreted as proof of benefit or harm.

The result also does not directly report a hazard ratio or a comparison of survival curves. Although the trial objective refers to long-term survival and the registry specifies an evaluation 2 years after the last patient is randomized, the posted measure is a risk difference based on event counts. Without event times and censoring information, the result cannot describe when deaths occurred or how survival evolved across follow-up.

The registry’s terminated status adds context, but the reason for termination and its effect on recruitment or follow-up are not reported. It is not possible to infer that termination caused the small event count or to determine whether the planned endpoint assessment was completed. Similarly, the registry’s intent-to-treat label does not by itself confirm how missing outcomes or treatment deviations were handled.

Finally, the primary result concerns all-cause mortality. It does not provide a separate estimate for arrhythmic mortality, despite that outcome being listed as secondary. The registry record does not report a posted analysis for that secondary outcome. The findings should be confined to the reported primary comparison and its uncertainty, without extending them to unreported outcomes, mechanisms, or broader patient groups.

14. Why This Trial Matters Statistically

This trial illustrates how a randomized design and a very sparse outcome can coexist with substantial uncertainty. Random allocation is intended to support a fair comparison of groups, but the amount of information available for estimating an outcome also depends on how many events are observed. Here, the primary comparison has one event in the ICD Group and none in the Control Group. That makes the numerical estimate sensitive to the small number of observed events and leaves a broad range of values compatible with the data.

The example also highlights why a point estimate should not be read alone. The reported risk difference is 0.023, but the confidence interval extends from -0.021 to 0.067. The interval communicates uncertainty about both direction and magnitude that the single estimate cannot. The p-value of 0.356 is another summary of the comparison, but it does not establish whether the effect is absent or clinically unimportant.

There is also a distinction between the study’s stated survival objective and the form of the posted result. Survival is naturally a time-to-event concept, yet the available comparison is an unadjusted risk difference in event counts. Without event times and censoring information, readers cannot reconstruct a survival analysis from the summary. This makes clear why endpoint labels and statistical estimands matter: results that refer to the same clinical outcome may answer different statistical questions.

The terminated status and lack of reported analysis details are reminders that registry results need context. The reason for termination, missing-data handling, multiplicity plan, and exact statistical method are not reported in the registry record. These are not grounds for assuming a particular flaw, but they limit how fully the result can be evaluated and reproduced. The example underscores the value of interpreting estimates alongside their uncertainty, event counts, outcome definitions, and the analysis information actually reported.

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.

The primary comparison is based on sparse events: one event in the ICD Group and none in the Control Group. The resulting risk-difference estimate has a confidence interval that includes values below and above zero. This limits precision and makes the direction of any underlying difference uncertain. The record does not report the statistical method used to calculate the interval, so its assumptions cannot be checked.

The registry describes an intended survival assessment 2 years after the last patient is randomized, but the posted comparison does not include event times, censoring information, or a survival curve. It is therefore not possible to evaluate the timing of deaths or reconstruct the survival experience from the reported risk difference. The record also does not report whether all participants completed the intended follow-up.

The study is listed as terminated, but the reason for termination and its effects on recruitment, follow-up, or analysis are not reported in the registry record. The record does not report a sample-size justification for the original trial, a statistical analysis plan, or the exact inferential procedures used. The planning assumptions described for an illustration are not evidence of the trial’s original design rationale.

Although the primary outcome population is labeled intent to treat, participant-level analysis details are absent. Missing outcome information, exclusions, treatment deviations, and sensitivity analyses are not reported. The multiplicity approach is also not reported, and no analysis of the listed secondary outcome is described in the registry record for this analysis.

The safety entries do not provide a comparable control-group denominator, and their event-term percentage lacks an explained denominator. The non-randomized registry is mentioned but no outcomes for it are reported. Taken together, these gaps mean the posted result can be described, but the full conduct, completeness, and robustness of the trial’s analyses cannot be assessed from the registry record alone.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: DEfibrillators To REduce Risk by MagnetIc ResoNance Imaging Evaluation — NCT00487279.
• Registry record last updated 2019-02-05; status last verified 2019-02.
• Results first posted 2012-03-26.
• 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 prospective, multicenter, randomized, parallel-group study comparing an implantable cardioverter defibrillator plus medical therapy with medical therapy alone in patients with coronary artery disease and mild to moderate left ventricular dysfunction. Enrollment is listed as 81, and the study status is terminated. The stated primary outcome is all-cause mortality, with total survival to be evaluated 2 years after the last patient is randomized; arrhythmic mortality is listed as a secondary outcome.

The posted primary comparison reports one event among 44 participants in the ICD Group and none among 37 participants in the Control Group. The unadjusted risk difference is 0.023, with a 95% confidence interval from -0.021 to 0.067 and an unadjusted p-value of 0.356. The interval indicates substantial uncertainty, including values in either direction. The registry record does not report the reason for termination, the statistical analysis plan, missing-data procedures, or time-to-event results.