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 BRADYCARE: Advanced Bradycardia Device Feature Utilization and Clinical Outcomes (NCT01062126), a registered phase not stated study. The primary outcome is Complication Rate at 1-year Post-implant.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01062126 |
| Phase | Phase not stated |
| Condition | Pacemaker |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 3389 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Abbott Medical Devices |
| Results posted | Yes |
2. Clinical Question
Population
The study enrolled a general pacemaker population. The primary endpoint population is described as all subjects enrolled in the study. The registry record lists enrollment of 3389. It does not provide further eligibility criteria or a detailed description of participants’ baseline characteristics in the information available for this analysis.
Intervention
This is not a trial of an assigned treatment. The study gathered information about pacemaker feature use, device therapy choices, clinical management, and outcomes in routine practice. Features of interest included automated capture and sensing, patient alerts, algorithms intended to minimize ventricular pacing, automatic mode switching, rate-responsive pacing, advanced diagnostics, remote monitoring, and radiofrequency technology. Which features were used, and how often, are not reported in the registry record.
Comparator
No comparator group or randomized allocation is reported. The registry describes an observational study, and allocation is not stated. Feature users and non-users should therefore not be treated as randomized, like-for-like groups. The registry record does not provide a comparison of outcomes between groups defined by device-feature use.
Primary question
The primary aim was to evaluate use of advanced features and diagnostics in patients with St. Jude Medical pacemakers. The listed primary endpoint is the complication rate at 1-year post-implant, expressed as a percentage of enrolled subjects, with a 95% confidence interval and a 12-month timeframe. The registry record does not report the observed rate or interval. Secondary and tertiary aims concerned progressive clinical outcomes and the correlation between feature use and clinical outcomes, respectively; results for those aims are not reported in the registry record.
3. Trial Design
BRADYCARE is an observational study of pacemaker feature utilization and clinical outcomes. It was sponsored by Abbott Medical Devices and is listed as completed. The registry record gives a start date of 2010-02 and a primary completion date of 2012-09. Enrollment is listed as 3389. These record-level details describe the study’s registration and timeline; they do not establish how long each participant was followed or whether every participant contributed complete follow-up.
The study aimed to collect information on presenting clinical status, the indication for device implantation, use of advanced device features, device therapy choices, clinical management, and outcomes. Its stated primary aim was to assess use of advanced features and diagnostics in patients with St. Jude Medical pacemakers. Its secondary aim was to learn about progressive clinical outcomes in a general pacemaker population, and its tertiary aim was to evaluate the correlation between advanced-feature use and clinical outcomes.
No treatment assignment or randomized comparison is reported. The registry record does not state an allocation method, and it does not describe a control arm. Consequently, the study should be read as observational rather than as a randomized test of device features. Associations between feature use and outcomes, if reported, would not by themselves show that feature use caused an outcome. Differences in patients, clinical decisions, or circumstances related to device use could also be relevant, but details of any adjustment for such factors are not reported in the registry record.
The record lists one primary outcome measure: complication rate at 1-year post-implant, with a 12-month timeframe. It also lists adverse-event figures, but the primary complication result and its confidence interval are not reported in the registry record. The registry lists no analyses. The statistical approach, analysis population beyond the stated all-enrolled population, and handling of incomplete follow-up are not reported.
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 | All Subjects Enrolled in the Study |
|---|---|
| STARTED | 3389 |
| COMPLETED | 2856 |
| NOT COMPLETED | 533 |
Reasons for not completing this period:
| Reason | All Subjects Enrolled in the Study |
|---|---|
| Death | 209 |
| All Withdrawals | 324 |
Analysis population for the primary outcome, as defined in the registry: All subjects enrolled in the study.
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 Subjects Enrolled in the Study |
|---|---|---|
| Participants analysed | 3389 | |
| Age, Categorical: <=18 years | Participants | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 559 |
| Age, Categorical: >=65 years | Participants | 2830 |
| Age, Continuous | years | 74.8 (SD 11.1) |
| Sex: Female, Male: Female | Participants | 1546 |
| Sex: Female, Male: Male | Participants | 1843 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 185 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 3175 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 29 |
| Region of Enrollment: United States | participants | 3389 |
| Primary Indication for Pacemaker Implant: Sinus Node Dysfunction | Participants | 2427 |
| Primary Indication for Pacemaker Implant: AV Node Block | Participants | 754 |
| Primary Indication for Pacemaker Implant: Syncope | Participants | 220 |
| Primary Indication for Pacemaker Implant: Pacemaker Replacement | Participants | 329 |
| Primary Indication for Pacemaker Implant: PAVE | Participants | 55 |
| Primary Indication for Pacemaker Implant: Others | Participants | 20 |
| Cardiovascular History: Coronary Artery Disease | Participants | 1361 |
| Cardiovascular History: Angina | Participants | 156 |
| Cardiovascular History: Myocardial Infarction | Participants | 204 |
| Cardiovascular History: Heart Failure | Participants | 25 |
| Cardiovascular History: Hypertension | Participants | 2668 |
| Ejection Fraction | % of blood leaving heart at contraction | 56.8 (SD 9.9) |
| Other Medical History: Pulmonary disease | Participants | 335 |
| Other Medical History: Hepatic/Renal disease | Participants | 306 |
| Other Medical History: Diabetes | Participants | 869 |
| Other Medical History: Peripheral vascular disease | Participants | 240 |
| Medications: ACE Inhibitors/ARBs | Participants | 1659 |
| Medications: Aldosterone inhibitors | Participants | 64 |
| Medications: Anti-coagulants | Participants | 1064 |
| Medications: Antiarrhythmics - Class I | Participants | 103 |
| Medications: Antiarrhythmics - Class III | Participants | 356 |
| Medications: Antiplatelet | Participants | 1833 |
| Medications: Beta Blockers | Participants | 1653 |
| Medications: Calcium channel blockers | Participants | 936 |
| Medications: Cardiac glycosides | Participants | 239 |
| Medications: Diuretics | Participants | 1172 |
| Systolic BP | mm Hg | 130.1 (SD 19.6) |
| Diastolic BP | mm Hg | 72.2 (SD 11.3) |
| Heart Rate | beats per min (bpm) | 69.4 (SD 12.1) |
6. Primary Endpoint
The registry lists the primary outcome as Complication Rate at 1-year Post-implant, measured over 12 months.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of enrolled subjects |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is the complication rate at 1-year post-implant. The registry defines the measure as a percentage of enrolled subjects and gives a timeframe of 12 months. It also specifies a 95% confidence interval. The stated endpoint population is all subjects enrolled in the study.
A complication rate is intended to describe how frequently complications occurred in the defined population over the stated follow-up period. Reporting a percentage can make the frequency easier to interpret than a count alone, while a confidence interval conveys uncertainty around the estimated rate. In general, a confidence interval gives a range of values compatible with the data and the method used; it is not a guarantee that the true value lies within that particular interval. Its width reflects statistical precision, among other factors.
The registry record does not report the endpoint’s observed percentage, the confidence interval limits, or the number of complications contributing to this endpoint. The adverse-event figures listed elsewhere in the record cannot be substituted for the primary endpoint: the record does not establish that those figures use the same definition, follow-up window, or population rules as the complication measure. Without the endpoint result and its operational definition, the complication rate cannot be interpreted quantitatively from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The central interpretive limitation is that the registry record names a primary endpoint but does not report its result. It identifies a complication rate at 1-year post-implant, a 12-month timeframe, and a 95% confidence interval, but gives neither the rate nor the interval. Accordingly, the posted information does not establish the observed frequency of complications or how precisely that frequency was estimated.
The study’s broad purpose was to describe advanced pacemaker feature use and clinical outcomes in a general pacemaker population. The listed aims include assessment of feature use, description of progressive outcomes, and evaluation of correlations between feature use and outcomes. The registry record does not report results for those aims, nor does it list analyses. It therefore does not support a quantitative account of how often specific features were used or whether use was associated with particular outcomes.
The adverse-event entries are a separate part of the record. For the group labeled all subjects enrolled in the study, the serious-adverse-event figures list 3389 at risk and 38 affected; the other-adverse-event figures list 3389 at risk and 17 affected. The record also lists 209 deaths. These entries do not supply the primary complication-rate result. The registry record does not provide the event definitions, timing, causes, or relationship to device feature use needed to interpret these figures as the endpoint or as evidence of a causal effect.
Because the study is observational and no randomized allocation is stated, any comparison by feature use would be vulnerable to differences between people who did and did not use particular features. The registry record does not describe a comparative analysis or adjustment strategy. No effect estimate, uncertainty interval for a feature-use comparison, or statistical test is reported. Descriptive event counts alone do not show whether one device strategy changed outcomes.
In general, a confidence interval is useful because a point estimate alone can obscure uncertainty. In this case, however, the interval itself is not reported. The available record supports a description of study purpose, design, endpoint specification, and selected adverse-event entries, but not a numerical conclusion about the primary outcome or the relationship between advanced features and clinical outcomes.
9. Statistical Methods Explained
The registry describes BRADYCARE as observational. That design means the record concerns feature use and outcomes in clinical practice rather than a randomized assignment of participants to competing device strategies. Observational studies can characterize practice and describe associations. They cannot, without additional design and analytic safeguards, separate the effect of a feature from differences that may influence both feature use and outcomes. The registry record does not report an analysis addressing those possible differences.
What does the endpoint estimate?
The primary outcome is a complication rate at 1-year post-implant, expressed as a percentage of enrolled subjects. The stated timeframe is 12 months, and the stated population is all enrolled subjects. A rate or proportion is interpretable only when its numerator and denominator are defined consistently. The registry record does not report the observed endpoint value or the number of complications used to calculate it. It also does not provide an operational definition of a complication in the information. The adverse-event counts should not be assumed to be the numerator for this endpoint.
What does a confidence interval add?
The registry specifies a 95% confidence interval for the complication rate. In general, a confidence interval communicates the precision of an estimate under a particular statistical method and its assumptions. A narrower interval indicates greater precision than a wider one, while an interval that is not reported cannot be used to assess precision. A confidence interval is not itself a test of clinical importance, and it does not correct for selection bias, incomplete follow-up, or inconsistent outcome definitions. The registry record does not report the interval limits or the method used to calculate them.
Why does observational design matter?
Feature use was not described as randomized. In routine practice, clinical characteristics and treatment decisions may be related to whether a feature is enabled or used. If outcomes differ across feature-use groups, those differences may reflect the feature, differences among patients, clinical management, or a combination of factors. An adjusted analysis may address measured differences, but the registry record lists no analyses and does not report whether any adjustment was planned or performed. It is therefore not possible to assess the strength of any feature-outcome association from this record.
Randomization, when used, is intended to make groups comparable on average, including on factors that may not be measured. No randomized allocation is stated for BRADYCARE. The record also does not provide a comparator group definition. A comparison between device-feature users and non-users should not be interpreted as though the groups were assigned randomly or otherwise guaranteed to be comparable.
How should the adverse-event entries be read?
The adverse-event record lists an all-subjects group, with 3389 at risk for serious adverse events and 38 affected, and 3389 at risk for other adverse events and 17 affected. It also lists 209 deaths. These are registry entries, not a reported analysis of the primary complication endpoint. The record does not explain event ascertainment, whether affected refers to people or events, how repeated events were handled, or how the entries relate to the 12-month endpoint timeframe. No causal attribution to a device feature is reported.
General event-rate interpretation depends on knowing the observation window, event definition, and whether the analysis counts people with events or all events. For time-to-event outcomes, the timing of events and censoring can also matter. The registry record does not provide these details for the adverse-event entries. The figures should therefore be read as recorded safety information, without assuming a specific rate calculation or follow-up structure.
What do the planning assumptions mean?
The record describes a planning illustration based on the observed effect, rather than the study’s own design. It specifies a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event illustrations, the stated quantity is the total number of events; other illustrations are expressed as participants per arm. These are planning conventions, not observed study outcomes, and the registry record does not report the numerical planning outputs in the information.
In general, a sample-size illustration asks how much information a future comparison might require under chosen assumptions. Its result depends on the assumed effect, allocation, significance threshold, statistical method, and outcome type. It is not observed power, and it does not show that the completed observational study had a particular probability of detecting an effect. Moreover, a hypothetical equal-allocation comparison does not describe BRADYCARE’s actual design: the registry record does not state randomized allocation or two treatment arms.
The record lists no analyses. It does not report a statistical analysis plan, interim analyses, the method for estimating the primary endpoint, adjustments for multiple testing, or procedures for missing data. These absences limit what can be inferred about the reliability and completeness of any result beyond the results themselves not being reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one primary outcome measure and describes secondary and tertiary aims in the study summary. It does not list analyses or report how many statistical tests or outcome comparisons were conducted. A plan for controlling multiplicity—the increased chance of false-positive findings when many hypotheses are tested—is not reported in the registry record. No correction method or hierarchy among outcome tests is specified.
The primary endpoint population is described as all subjects enrolled in the study. That identifies the intended population for the measure, but it does not explain how participants with unavailable follow-up or incomplete endpoint information were handled. The amount and pattern of missing outcome data, reasons for missingness, and any imputation or sensitivity analysis are not reported in the registry record. It is therefore not possible to assess whether the endpoint estimate, if reported elsewhere, would be affected by incomplete observation.
The registry record also does not describe analysis populations for the secondary or tertiary aims, or whether analyses were restricted to participants with particular device features or follow-up information. It does not report how repeated outcomes or multiple events per person were handled. Those details matter because different analysis rules can change the population represented by a result and the uncertainty attached to it.
In general, multiplicity procedures address the interpretation of a family of statistical tests, while missing-data methods address incomplete information. Neither can be inferred from the study’s aims or from its enrollment figure. The record does not report these methods, so no claim about multiplicity adjustment, complete follow-up, or a particular analysis population beyond the stated all-enrolled endpoint population is justified.
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 Subjects Enrolled in the Study | 38 | 3389 | 1.1% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| All Subjects Enrolled in the Study | 209 of 3389 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0.05% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| All Subjects Enrolled in the Study | 17 of 3389 |
Most frequent serious adverse event terms
| Event term | Organ system | All Subjects Enrolled in the Study |
|---|---|---|
| Lead dislodgement or migration | Product Issues | 14 of 3389 |
| Infection | Infections and infestations | 6 of 3389 |
| Lead fracture | Product Issues | 4 of 3389 |
| Elevated pacing thresholds | Product Issues | 3 of 3389 |
| Mid-sternal pain at the location of RA and RV leads | Injury, poisoning and procedural complications | 2 of 3389 |
| Pericardial effusion | Injury, poisoning and procedural complications | 2 of 3389 |
| Atrial Fibrillation | Cardiac disorders | 1 of 3389 |
| Bleeding/Hematoma | Gastrointestinal disorders | 1 of 3389 |
| Diaphragmatic/Phrenic Nerve Stimulation | Product Issues | 1 of 3389 |
| Dehisence | Injury, poisoning and procedural complications | 1 of 3389 |
Most frequent non-serious adverse event terms
| Event term | Organ system | All Subjects Enrolled in the Study |
|---|---|---|
| Elevated pacing thresholds | Product Issues | 6 of 3389 |
| Oversensing | Product Issues | 3 of 3389 |
| Hematoma | Vascular disorders | 3 of 3389 |
| Atrial Arrhythmia | Cardiac disorders | 2 of 3389 |
| Inappropriate device interaction | Product Issues | 2 of 3389 |
| Loss of capture | Product Issues | 2 of 3389 |
| Syncope | Vascular disorders | 2 of 3389 |
Serious events with the highest arm-level rate: lead dislodgement or migration (0.4%), infection (0.2%), lead fracture (0.1%), elevated pacing thresholds (0.1%), mid-sternal pain at the location of ra and rv leads (0.1%).
The safety entry for the group labeled all subjects enrolled in the study lists 3389 at risk and 38 affected for serious adverse events. For other adverse events, it lists 3389 at risk and 17 affected. The record also lists 209 deaths. These figures describe the entries in the registry; they do not provide a complete account of event timing, severity criteria, causes, or relationship to pacemaker features.
The serious adverse-event terms with listed percentages are lead dislodgement or migration at 0.4%, infection at 0.2%, lead fracture at 0.1%, elevated pacing thresholds at 0.1%, mid-sternal pain at the location of RA and RV leads at 0.1%, and pericardial effusion at 0.1%. The registry record does not state whether these terms are mutually exclusive, how the percentages were calculated, or whether they represent participants or events. They should not be added together or treated as a complete breakdown of the serious-adverse-event figures.
The adverse-event entries are not interchangeable with the primary complication endpoint. The registry record does not establish that they share its definition or 12-month timeframe. Nor does the observational design establish that a listed event was caused by a device feature or by the study. Without definitions and timing, these figures are best read as recorded safety information rather than as comparative or causal estimates.
12. What the Result Does, and Does Not, Mean
The registry record establishes that BRADYCARE was an observational study of advanced pacemaker feature use and clinical outcomes, with enrollment listed as 3389. It identifies a primary endpoint of complication rate at 1-year post-implant, expressed as a percentage of enrolled subjects, over a 12-month timeframe. It also specifies a 95% confidence interval and identifies all enrolled subjects as the endpoint population.
Those details describe what the primary outcome was intended to measure, but they do not give the outcome. The observed complication rate, confidence interval limits, and the count underlying the endpoint are not reported in the registry record. Consequently, the posted information does not show the magnitude or precision of the primary result. The listed adverse-event figures do not fill that gap because the record does not establish that they correspond to the primary endpoint’s definition and timeframe.
The study’s aims included describing advanced-feature use and clinical outcomes and evaluating their correlation. The registry record does not report feature-use frequencies, outcome analyses, or estimates of association. It therefore does not establish whether feature use was associated with better or worse outcomes, or whether a feature caused any observed outcome. The absence of randomized allocation and of a reported comparative analysis is especially important when interpreting any apparent difference between groups.
In general, an observational study can describe clinical practice and generate evidence about associations, but causal interpretation requires careful consideration of group comparability and other sources of bias. The registry record does not report methods that would allow those issues to be evaluated. The record supports understanding the study’s goals and selected safety entries; it does not support a quantitative conclusion about the primary complication rate or a causal conclusion about advanced device features.
13. Why This Trial Matters Statistically
BRADYCARE addresses a practical statistical question: how advanced pacemaker features are used in routine care and how that use relates to clinical outcomes. The study summary describes a range of features, including automated functions, pacing algorithms, diagnostics, remote monitoring, and radiofrequency technology. Understanding real-world utilization can be valuable because device capabilities and clinical practice may not map directly onto one another.
Statistically, the study illustrates the distinction between describing use and evaluating an effect. Descriptive information can characterize which features are used and the outcomes recorded in a population. An association analysis can examine whether outcomes vary with feature use. A causal claim requires more: the comparison must address why some patients receive or use a feature while others do not. Because this is observational and no randomized allocation is stated, the design and analysis would need to address potential differences among groups before causal interpretations could be considered.
The primary endpoint also highlights why reporting estimates with uncertainty matters. A complication rate alone would describe an observed frequency, while its confidence interval would convey precision. The registry record names both but does not report either result. Without them, the primary clinical outcome cannot be quantitatively assessed from the record.
The adverse-event entries show another general reporting issue: event counts and percentages are interpretable only in the context of clear definitions, observation periods, and analysis rules. Those details are not reported for the listed entries. The study’s aims are relevant to real-world device care, but the registry information available for this analysis leaves the main outcome and feature-outcome findings unresolved.
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 interpreting this trial record is that the stated primary endpoint has no reported result. The complication rate at 1-year post-implant and its 95% confidence interval are not reported in the registry record, despite the endpoint being described with a 12-month timeframe and an all-enrolled population. The endpoint definition and the number of complications contributing to it are also not reported.
The record identifies an observational design but does not state an allocation method or describe a comparator group. It lists no analyses. As a result, the registry record does not support evaluation of any adjusted or unadjusted association between feature use and outcomes, nor does it allow assessment of possible differences between people with different feature-use patterns.
Details needed to interpret follow-up and safety reporting are also absent. The registry record does not report how missing endpoint information was handled, whether each participant had complete follow-up, or how adverse events were defined and ascertained. It does not describe event timing, the handling of repeat events, or how the listed safety entries relate to the primary endpoint. The study’s reported aims do not substitute for outcome estimates or analytic methods.
The record lists 3389 enrolled subjects and adverse-event figures, but these do not establish the number contributing to the primary endpoint or the endpoint result. It also does not report baseline characteristics in the information available for this analysis. These limitations mean the study’s goals and selected safety entries can be described, while its primary complication result and its conclusions about advanced feature use cannot be evaluated quantitatively from the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: BRADYCARE: Advanced Bradycardia Device Feature Utilization and Clinical Outcomes — NCT01062126.
- Registry record last updated 2020-10-14; status last verified 2020-09.
- Results first posted 2020-10-14.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
BRADYCARE is an observational study sponsored by Abbott Medical Devices, listed as completed, with enrollment of 3389. The registry record gives a start date of 2010-02 and a primary completion date of 2012-09. Its aims concern advanced pacemaker feature use, clinical outcomes, and the relationship between the two.
The primary endpoint is complication rate at 1-year post-implant, expressed as a percentage of enrolled subjects over 12 months, with a 95% confidence interval. The registry record does not report the endpoint result or the interval. It also lists adverse-event figures for the enrolled group, including 38 affected by serious adverse events, 17 affected by other adverse events, and 209 deaths, but does not provide the detail needed to link these entries to the primary endpoint or attribute them to a device feature.
No analyses are listed. Randomized allocation, comparator details, missing-data procedures, and multiplicity methods are not reported in the registry record. The record therefore describes the study’s purpose and selected safety information but does not provide a quantitative primary outcome result or an analysis of feature-outcome relationships.