This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for LifeVest Safety and Efficacy in Real Life Settings in France (NCT03319160), a registered phase not stated study. The primary outcome is Appropriate Shock Events Per Patient.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03319160 |
| Phase | Phase not stated |
| Condition | Sudden Cardiac Death, Left Ventricular Dysfunction, Cardiac Event |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 1164 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Zoll Medical Corporation |
| Results posted | Yes |
2. Clinical Question
Population
People in France who were prescribed and used a LifeVest. The registry lists 1164 participants enrolled and identifies the study population as all LifeVest users. It does not report further eligibility details or characteristics of the participants in the posted results.
Intervention
Use of a wearable cardioverter defibrillator, identified as the LifeVest. This is a post-market observational study of device use in real-life settings, rather than a trial assigning participants to different treatments.
Comparator
No comparator group is described. The registry lists one group, All LifeVest Users, and does not state an allocation method. The study therefore does not provide a like-for-like control comparison.
Primary question
The primary endpoint is the count of participants with at least one appropriate shock event during WCD use. An event involves a therapy shock delivered during sustained ventricular tachycardia or ventricular fibrillation, under the registry’s definition. The stated timeframe is from start to end of WCD use, with a typical prescription of 3 months. The numerical primary result is not reported in the registry record, so the posted information does not establish how many participants experienced the endpoint.
3. Trial Design
This is a prospective observational post-market clinical follow-up study of LifeVest use in real-life settings in France. The registry describes the intervention as a wearable cardioverter defibrillator and lists one group: All LifeVest Users, defined as patients who were prescribed and used a LifeVest in France. Enrollment is listed as 1164. The registry does not describe a control group or state an allocation method; the design is not a randomized comparison.
The listed study dates are 2017-02-02 for the start and 2018-09-30 for primary completion. The status is COMPLETED. These dates describe the registry record’s study timeline; they do not, by themselves, specify each participant’s time under observation. The primary endpoint timeframe is start to end of WCD use, with a typical prescription of 3 months.
The registry lists Survival During WCD Use and Quality of Life Relative to Health State as secondary outcomes. It also reports 7 outcome measures and 2 analyses, without describing all their methods or results in the available record. The primary endpoint is expressed as a count of participants with appropriate shock events. Separately, its description mentions incidence per 100 patient years, for which all appropriate shock events are counted. The posted information does not give the primary event count, the participant-level primary result, or the patient-time needed to interpret an incidence rate. Consequently, the design and endpoint can be described, but the primary outcome’s magnitude cannot be assessed from this registry information.
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
| Stage | WCD Users |
|---|---|
| STARTED | 1164 |
| COMPLETED | 1157 |
| NOT COMPLETED | 7 |
Reasons for not completing this period:
| Reason | WCD Users |
|---|---|
| Data not available. | 7 |
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.
| Characteristic | Unit | All LifeVest Users |
|---|---|---|
| Participants analysed | 1157 | |
| Age, Continuous | years | 60.0 (SD 11.5) |
| Sex: Female, Male: Female | Participants | 183 |
| Sex: Female, Male: Male | Participants | 974 |
| Race and Ethnicity Not Collected | Participants | — |
| Enrollment type: Prospective enrollment | Participants | 529 |
| Enrollment type: Retrospective enrollment | Participants | 628 |
| BMI | kilograms per meter squared | 26.2 (SD 5.0) |
| Resting HR | beats per minute | 80.0 (SD 17.6) |
| Indication for use: ICD extraction due to infection | Participants | 119 |
| Indication for use: Bridge to heart transplant | Participants | 88 |
| Indication for use: Early after myocardial infarction with LVEF 30% or less | Participants | 647 |
| Indication for use: Early after coronary revascularization with LVEF 30% or less | Participants | 303 |
| LVEF (4 groups): >45% | Participants | 41 |
| LVEF (4 groups): >35% and ≤45% | Participants | 48 |
| LVEF (4 groups): >25% and ≤35% | Participants | 483 |
| LVEF (4 groups): ≤25% | Participants | 577 |
| LVEF (3 groups): ≥35% | Participants | 147 |
| LVEF (3 groups): ≥30% and <35% | Participants | 251 |
| LVEF (3 groups): <30% | Participants | 751 |
| NYHA class: Class I | Participants | 140 |
| NYHA class: Class II | Participants | 320 |
| NYHA class: Class III | Participants | 238 |
| NYHA class: Class IV | Participants | 99 |
6. Primary Endpoint
The registry lists the primary outcome as Appropriate Shock Events Per Patient, measured over start to end of WCD use (3 months typical prescription).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint, Appropriate Shock Events Per Patient, is defined as a count of participants. A participant meets the event definition if at least one WCD therapy shock is delivered during sustained ventricular tachycardia or ventricular fibrillation. Sustained rhythm is specified as lasting at least 30 seconds. Shocks delivered within 24 hours of the first shock are treated as one event. The record says that 3 cardiologists familiar with device-recorded ECG tracings adjudicated the rhythms recorded during therapy shocks.
This kind of endpoint focuses on whether a participant experienced at least one qualifying event during the stated observation period, rather than on the total number of shocks alone. The grouping rule matters: multiple shocks within the specified interval count as one event under the endpoint definition. The endpoint timeframe runs from the start to the end of WCD use, with a typical prescription of 3 months. The description also discusses incidence per 100 patient years, counting all appropriate shock events for that purpose; this is a distinct way of expressing event frequency and requires patient-time information.
The registry record does not report the primary endpoint result or a patient-year incidence estimate. The endpoint definition is available, but the frequency of qualifying events in this study cannot be determined from the posted results.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record identifies the study as a prospective observational evaluation of LifeVest use in France, with one group of users and no stated comparator. That design can describe what was recorded among the people included, but it does not create a randomized comparison between device use and another strategy. The registry explicitly notes that the arms are not a like-for-like control comparison. There is therefore no controlled contrast to interpret as an estimated treatment effect.
The primary endpoint is clearly defined: participants are counted if they have at least one appropriate shock event during WCD use. However, the registry record does not report the observed primary count or proportion, nor a confidence interval or other measure of uncertainty for that endpoint. Without those results, the frequency and precision of the primary outcome cannot be assessed. The endpoint definition alone does not show how often events occurred.
The adverse-event information lists 6 participants with a serious event among 1157 at risk and 0 with other events among 1157 at risk. It separately lists 26 deaths. These entries describe counts in the registry; the record does not provide details establishing whether events were caused by the device, how the categories relate to one another, or the timing and circumstances of the deaths. Listed serious terms include Inappropriate shocks at 0.3%, Allergy at 0.1%, and Dyspnea with device alerts at 0.1%. These term-level figures should not be treated as a substitute for the unreported primary endpoint result.
As general statistical context, a point estimate describes the observed frequency, while a confidence interval describes the range of values reasonably compatible with the data under the analysis assumptions. Neither can be interpreted for the primary endpoint without a reported estimate and its uncertainty. In an observational study, descriptive results also depend on who entered the study, how long each person was observed, and how outcomes were ascertained. The registry record does not report enough detail to evaluate those factors fully.
Overall, the record establishes the study’s setting, population description, endpoint definition, and selected adverse-event counts. It does not provide the numerical primary result or enough information for a comparative effectiveness conclusion.
9. Statistical Methods Explained
What does the primary endpoint count?
The primary measure is a count of participants with at least one appropriate shock event. It is a participant-level binary outcome for analysis: a participant either meets the event definition during the stated observation period or does not. The endpoint is not simply a count of every shock. The registry groups shocks delivered within 24 hours of the first shock as one event and requires a therapy shock during sustained ventricular tachycardia or ventricular fibrillation, with sustained defined as at least 30 seconds.
That distinction is useful when interpreting event summaries. A participant with more than one shock in the grouping interval is still represented as having an event for the participant-count endpoint. The registry separately says that all appropriate shock events are counted when assessing incidence per 100 patient years. Participant counts and event rates answer different questions: one concerns how many participants had an event, and the other relates event frequency to accumulated observation time.
What does adjudication add?
The record states that 3 cardiologists familiar with device-recorded ECG tracings adjudicated cardiac rhythms recorded during WCD therapy shocks. Adjudication is a process for reviewing recorded information against outcome definitions. As general statistical context, applying an outcome definition through structured review can help make event classification more consistent. The record does not report the adjudication procedures in greater detail, the reviewers’ agreement, or how disagreements were resolved.
How should counts and rates be distinguished?
The primary parameter is described as a count of participants. A count is a direct tally within the analyzed group; a rate per patient years uses the amount of observed time as a denominator. When participants have different observation durations, a time-based rate can express event occurrence relative to accumulated follow-up. As general statistical context, a rate is not interchangeable with a participant proportion, because repeated events and different follow-up time can affect the rate. The record does not report the primary count, patient-time total, or incidence estimate, so neither primary frequency measure can be quantified from the posted information.
What do uncertainty estimates mean?
As general statistical context, a confidence interval describes uncertainty around an estimated quantity. A narrow interval indicates greater precision under the assumptions of the method, while a wide interval indicates less precision. An interval does not correct for selection bias, incomplete outcome ascertainment, or the absence of a comparator. The registry record does not report a confidence interval for the primary endpoint, so its precision cannot be assessed.
For a binary participant outcome, an analysis might report the number of participants with an event alongside the number assessed, and an estimate of the event frequency with uncertainty. This is a general description of reporting practice, not a claim that this study used a particular model. The registry does not identify a model for the primary result, and it does not report an adjusted or unadjusted effect estimate.
What is the role of the planning illustrations?
The record describes planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. For time-to-event illustrations, the reported quantity is the total number of events; for other illustrations, it is participants per arm. These are planning assumptions, not evidence that the observational study enrolled participants according to those assumptions. Sample-size illustrations are not observed power and do not establish that the study had adequate precision for its primary endpoint.
As general statistical context, power is a design quantity tied to an assumed effect, variability, allocation, and analysis. It is not a measure of whether a result is true after data collection. A planning calculation based on an observed effect can be especially dependent on that particular estimate. The registry record does not report the original sample-size justification or state that these illustrations were part of the study’s own design.
What analysis details remain unknown?
The registry lists 7 outcome measures and 2 analyses, but does not describe the statistical methods for the primary endpoint in enough detail to identify model choice, covariate adjustment, or handling of incomplete follow-up. The record also does not report the primary estimate or its uncertainty. These absences limit independent assessment of how the endpoint was analyzed and how sensitive the result might be to different reasonable choices.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 7 outcome measures and 2 analyses. It identifies one primary endpoint and names Survival During WCD Use and Quality of Life Relative to Health State as secondary outcomes. However, the record does not describe a multiplicity procedure, such as an adjustment to account for evaluating multiple outcomes or analyses. It also does not state whether a hierarchy or prespecified testing sequence was used. The handling of multiplicity is therefore not reported in the registry record.
As general statistical context, when several outcomes or analyses are examined, the chance of finding at least one apparently notable result can increase if each is assessed separately without an appropriate plan. Adjustments or a prespecified hierarchy can address that issue, but the registry does not provide enough information to determine whether either approach was used. The existence of multiple listed outcomes alone does not establish that a multiplicity problem occurred.
The record does not report how missing outcome data were handled, whether all enrolled participants contributed to each analysis, or whether any analysis population differed from the enrolled group. It lists enrollment as 1164, while the adverse-event group lists 1157 at risk. The record does not explain this difference, so it should not be interpreted as a particular exclusion, loss to follow-up, or analysis rule.
It is also not reported in the registry record whether follow-up was complete for the primary endpoint, how participants without an observed event were classified, or how any unavailable device recordings were treated. These details matter because missingness and unequal follow-up can affect estimates of event frequency. Without the analysis population, missing-data methods, and outcome results, the completeness and robustness of the primary analysis cannot be evaluated from the posted information.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| All LifeVest Users | 6 | 1157 | 0.5% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| All LifeVest Users | 26 of 1157 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| All LifeVest Users | 0 of 1157 |
Most frequent serious adverse event terms
| Event term | Organ system | All LifeVest Users |
|---|---|---|
| Inappropriate shocks | Product Issues | 4 of 1157 |
| Allergy | Skin and subcutaneous tissue disorders | 1 of 1157 |
| Dyspnea with device alerts | Respiratory, thoracic and mediastinal disorders | 1 of 1157 |
Serious events with the highest arm-level rate: inappropriate shocks (0.3%), allergy (0.1%), dyspnea with device alerts (0.1%).
The adverse-event group is All LifeVest Users. The record lists 1157 participants at risk for serious events, with 6 affected, and 1157 at risk for other events, with 0 affected. It separately records 26 deaths. The listed serious terms are Inappropriate shocks at 0.3%, Allergy at 0.1%, and Dyspnea with device alerts at 0.1%.
These are registry summaries, not a causal comparison. The record does not state whether the deaths were related to device use, provide their timing, or explain how deaths overlap with the adverse-event categories. It also does not give event-level descriptions or a comparison group’s corresponding counts. The term percentages should be read as the registry’s reported values, not converted into estimates of comparative risk.
As general statistical context, an event count describes what was recorded in the stated group; it does not alone establish cause. Interpreting safety comparatively would require appropriate information about event definitions, follow-up, ascertainment, and a valid comparison. The registry record does not report enough detail to make such a comparison. These entries therefore describe recorded counts and terms, rather than establishing a causal relationship or a rate relative to an alternative.
12. What the Result Does, and Does Not, Mean
The registry record documents a prospective observational study of LifeVest users in France and defines the primary outcome as participants with at least one appropriate shock event during WCD use. It also gives selected adverse-event counts and names secondary outcomes. Those details help identify what the study set out to monitor and how the primary event was defined.
The record does not report the numerical result for the primary endpoint. It therefore does not show the number of participants with an appropriate shock event, the event frequency, or the precision of an estimate. The description of an incidence measure per 100 patient years does not itself supply an incidence result. The posted information also does not establish the result for the named secondary outcomes.
As general statistical context, observational findings describe outcomes in the population studied and can be affected by selection, follow-up, and outcome ascertainment. Without a comparator, an observed event count cannot quantify how outcomes would differ under another strategy. In this record, no control group is described and allocation is not stated. The registry explicitly cautions that the arms are not a like-for-like control comparison.
The adverse-event entries show that 6 participants were recorded with a serious event among 1157 at risk, 0 with other events among 1157 at risk, and 26 deaths were listed. These are descriptive registry entries; they do not establish attribution or explain overlap among categories. The listed term percentages likewise do not provide a causal contrast.
Accordingly, the posted record supports a description of the study design, endpoint definition, and selected safety counts. It does not, by itself, support a conclusion about comparative effectiveness, quantify the primary endpoint, or establish that a recorded event was caused by the device.
13. Why This Trial Matters Statistically
Statistically, this study illustrates the importance of separating an outcome definition from an outcome result. The registry provides a detailed definition of an appropriate shock event, including sustained rhythm criteria, a rule for grouping shocks, and cardiologist adjudication. Yet the numerical primary result is not reported in the registry record. A precise definition is essential for interpreting a result, but it cannot substitute for the estimate itself.
The distinction between a count of participants and a rate per patient years is also important. The primary parameter counts participants with an event, while the endpoint description separately refers to incidence per 100 patient years and counting all appropriate shock events. These measures can represent different aspects of event occurrence. The record does not provide the numerical primary results needed to compare those interpretations.
The observational design makes the comparison question especially important. The record describes one group of LifeVest users and no like-for-like control group. Descriptive results from such a group do not create a controlled estimate of what would have happened under an alternative. This is a design limitation for comparative inference, not a reason to disregard descriptive follow-up information.
The registry also shows why transparent reporting of analysis populations and missing-data handling matters. Enrollment is listed as 1164, while 1157 participants are listed as at risk in the adverse-event group; the record does not explain the difference. Without further information, readers cannot determine how that distinction arose. The lack of reported primary results, uncertainty estimates, and analysis details limits the statistical conclusions that can be drawn.
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 the registry record does not report the numerical result for the primary endpoint. It also does not give a confidence interval or another measure of uncertainty for that endpoint. The definition and adjudication description are available, but the event frequency and its precision cannot be assessed.
The study is observational and lists one group of LifeVest users, with no comparator group described. The registry states that the arms are not a like-for-like control comparison and that allocation is not stated. Comparative effects therefore cannot be estimated from the design information presented. The record does not report participant characteristics or detailed eligibility criteria, limiting assessment of who the findings represent.
The listed enrollment is 1164, while the adverse-event group has 1157 participants at risk. The record does not explain the difference. It also does not report the primary analysis population, missing-data handling, completeness of follow-up, or the number of participants contributing to each outcome. These omissions prevent assessment of whether the analyzed populations varied across outcomes or how incomplete information was addressed.
The primary endpoint description refers to incidence per 100 patient years, but the record does not report an incidence estimate or the patient-time denominator. It lists 7 outcome measures and 2 analyses without describing multiplicity handling or all analysis methods. Finally, the adverse-event information includes 26 deaths but does not give timing or attribution. These limitations constrain interpretation of both the primary endpoint and the safety summaries.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: LifeVest Safety and Efficacy in Real Life Settings in France — NCT03319160.
- Registry record last updated 2024-12-09; status last verified 2024-10.
- Results first posted 2024-12-09.
- 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.
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18. Record Summary
NCT03319160 is a completed prospective observational post-market follow-up study of LifeVest use in real-life settings in France, sponsored by Zoll Medical Corporation. The registry lists enrollment of 1164, a start date of 2017-02-02, and primary completion on 2018-09-30. Its single listed group is All LifeVest Users.
The primary endpoint counts participants with at least one appropriate shock event during WCD use. The registry defines the event and describes cardiologist adjudication, but does not report the numerical primary result. Secondary outcomes include Survival During WCD Use and Quality of Life Relative to Health State.
The adverse-event group lists 6 serious events among 1157 at risk, 0 other events among 1157 at risk, and 26 deaths. The record does not provide a like-for-like comparator or explain event attribution, the difference between enrollment and the at-risk count, or the primary analysis methods. These limitations restrict interpretation to the design, endpoint definition, and posted descriptive safety information.