Trial Assessing the Effectiveness of Ivabradine Started at Discharge From the Observation Unit: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Trial Assessing the Effectiveness of Ivabradine Started at Discharge From the Observation Unit (NCT03168529), a randomized phase 4 study. The primary outcome is Change in Heart Rate.

2. Clinical Question

3. Trial Design

NCT03168529 was a phase 4, randomized, parallel-group trial comparing ivabradine with placebo. The registry record identifies the masking as quadruple; the specific roles masked are not reported. The official title describes the trial as double-blind and placebo-controlled, while the registry design fields separately identify quadruple masking. The record does not explain how those masking labels relate to one another.

The trial was intended to study ivabradine initiated at discharge from an observation unit, a setting the registry background distinguishes from longer inpatient stays. The background says that patients discharged after emergency-department treatment for worsening heart failure may represent an opportunity to begin treatment, while also noting uncertainty about starting or increasing beta blockers immediately after an exacerbation. That context explains the setting of the question, but it does not establish a specific protocol rationale beyond what is stated in the record.

Enrollment was 19. The reported arm sizes were 13 for Ivabradine (Corlanor) and 6 for placebo. The trial status is terminated. Its recorded start date is 2018-07-01, and its primary completion date is 2020-07-31. The reason for termination is not reported in the registry record. The record does not report a target enrollment or explain whether enrollment stopped according to a prespecified rule.

The intervention descriptions state that both groups would have the same number of follow-ups, possible dose titrations, and study procedures, with active drug in one group and placebo in the other. The actual dose, treatment duration details, adherence, and departures from assigned treatment are not reported in the registry record. Although randomization is specified, the method used to generate or conceal the allocation is not reported. These omissions limit how fully the conduct of the trial can be reconstructed from the registry entry.

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

Analysis population for the primary outcome, as defined in the registry: Only 19 patients were enrolled. Sample size was too small to perform a formal analysis.

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.

Population: Same as participant flow

6. Primary Endpoint

The registry lists the primary outcome as Change in Heart Rate, measured over Heart rate to be recorded at baseline, day 14 (+/-1), and day 28 (+/-2)..

The primary endpoint is titled “Change in Heart Rate.” The registry describes it as change in heart rate from the final visit to baseline, measured using a 12-lead ECG and Zio® patch. Measurements were scheduled at baseline, day 14 (+/-1), and day 28 (+/-2). The unit is beats per minute. The registry identifies the summary measure as a median and the dispersion as the full range.

Heart rate is a direct physiological measurement, so the endpoint describes a change in a measured characteristic rather than a clinical event such as hospitalization or death. In general, measuring change from baseline can help describe how an outcome differs over the course of follow-up while accounting for the starting measurement. It is important, however, to know exactly how the change was calculated and which visit posted the final value. The registry record gives the endpoint description and scheduled measurements but does not provide further calculation details.

The endpoint is relevant to the trial’s stated question about starting ivabradine at discharge, but the registry record reports no formal statistical analysis because only 19 patients enrolled and the sample was considered too small. It lists median values of 88 bpm for ivabradine, with a full range of 81 to 97, and 85 bpm for placebo, with a full range of 81 to 91. The record does not include a confidence interval or a formal between-group estimate. These summaries should therefore be read as descriptive information, not as a precise estimate of a treatment effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies this as a randomized, parallel-group comparison of ivabradine and placebo. Randomization is generally intended to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. In an individual trial, however, random assignment does not guarantee that groups will look alike, particularly when the number enrolled is small. Here, the registry reports enrollment of 19, with 13 in the ivabradine arm and 6 in the placebo arm. It does not report baseline characteristics or the allocation method, so the balance achieved by randomization cannot be assessed from this record alone.

What does a median with a full range describe?

General statistical explanation: the median is the middle value after observations are ordered. It is less influenced by unusually high or low values than the arithmetic mean. The full range gives the lowest and highest observed values, so it indicates the span of the observations but not how densely values cluster within that span. A range is not a confidence interval: it describes observed data, whereas a confidence interval describes uncertainty in an estimate under a statistical model.

For the primary outcome, the registry reports a median of 88 bpm and a full range of 81 to 97 for ivabradine, and a median of 85 bpm and a full range of 81 to 91 for placebo. Those summaries can be read as descriptions of the recorded values in each arm. They do not provide a formal estimate of the difference between groups, nor do they show how uncertain such an estimate would be. The registry does not report the individual observations or a dispersion measure beyond the full range.

Why does a small sample matter?

General statistical explanation: estimates from small samples tend to be imprecise because each observation can exert considerable influence on a summary. Small samples also make it harder to distinguish a genuine group difference from random variation. This does not mean that an effect is absent; it means that the data may not estimate it with useful precision. The registry itself states that the sample was too small to perform a formal analysis, so the posted summaries should not be treated as a definitive test of the treatment comparison.

The arm sizes also differ. In general, unequal allocation can result in less information for a comparison than equal allocation at the same total enrollment, especially when the smaller group is very small. No numerical power calculation or formal sample-size justification is reported in the registry record. The enrollment figure should not be interpreted as evidence that the study had adequate power to detect a particular effect.

What would an inferential comparison add?

General statistical explanation: an inferential comparison estimates the difference between groups and quantifies uncertainty around that estimate. A confidence interval presents a range of values compatible with the data and the assumptions of the method. A p-value, when used, describes how unusual data at least as incompatible with a specified null model would be under that model. Neither measure is reported for this primary outcome in the registry record. The absence of these results prevents readers from assessing statistical precision through those usual summaries.

The registry reports a median summary, but it does not report a method for comparing medians or a model-based analysis. It also does not report an adjusted analysis. No particular statistical test, regression model, or variance assumption should be attributed to the trial on the basis of the available entry. The general distinction is that a descriptive summary characterizes observed outcomes, while an inferential method attempts to generalize a comparison beyond those observations with explicit assumptions.

What is the role of the scheduled visits?

The registry lists heart-rate recording at baseline, day 14 (+/-1), and day 28 (+/-2). Repeated measurements can describe how an outcome changes over time, but an analysis must specify how measurements across visits are used. For example, an analysis might focus on a selected visit, a change from baseline, or a pattern across visits. The registry’s primary endpoint description says that the outcome is change from the final visit to baseline, but the record does not report additional details about the calculation or analysis of repeated measurements.

General statistical explanation: the timing of measurements and the definition of the final value matter because different choices can yield different summaries. Missing visits can also affect a change score if participants do not contribute measurements at all scheduled times. The registry does not report how incomplete follow-up measurements were handled. No assumptions about imputation, exclusion, or use of the last available measurement can be made from the entry.

How should planning calculations be distinguished from trial results?

General statistical explanation: a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, significance level, allocation, and analysis method. A planning illustration based on an observed effect is not an observed power result and does not show that a trial was adequately designed. The registry record describes assumptions for planning illustrations: a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a stated fraction of the observed effect. Those assumptions do not replace a trial-specific design justification, which is not reported in the registry record. No formal analysis result or sample-size justification should be inferred from such planning assumptions.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one secondary outcome: change in heart rate in self-identified African Americans. It also reports five outcome measures overall, but no analyses are listed. The record does not provide a multiplicity plan, including whether outcomes or subgroup analyses were designated as confirmatory or exploratory. Without that information, the handling of multiple outcomes or potential subgroup comparisons cannot be assessed.

The primary outcome entry states that the sample was too small to perform a formal analysis. The registry record does not report an analysis population, such as whether all randomized participants were included in the primary analysis or whether a different population was used. It does not report how missing measurements, withdrawals, protocol deviations, or incomplete follow-up were handled. The number of participants with an observed primary outcome at each visit is not reported in the registry record.

These omissions matter because the interpretation of a trial depends not only on the outcome definition but also on which participants contribute to each analysis and how incomplete data are addressed. General statistical explanation: excluding participants with missing outcomes can change the composition of the groups being compared, while imputation requires assumptions about the unobserved values. The registry does not report which approach, if any, was used. No missing-data method or analysis population should be assumed from the arm enrollment counts alone.

The registry reports one secondary outcome but does not post results for it in the information available in the record. Its analysis and any subgroup interpretation are therefore not reported in the registry record. The record also does not describe a prespecified statistical analysis plan or whether any outcome definitions changed during the study.

11. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event entry lists 13 patients at risk in the ivabradine group and 6 in the placebo group. It reports zero serious adverse events affecting patients in either group, zero other adverse events affecting patients in either group, and zero deaths in either group. No serious adverse-event terms are listed.

These figures describe events recorded in this trial; they do not establish that either treatment has no risk. With only 19 patients enrolled, the trial has limited ability to characterize uncommon events or differences in event rates. Zero recorded events means none were reported in the listed categories for these participants, not that the possibility of such events is ruled out.

The registry record does not provide further detail about adverse-event definitions, the period of safety observation, event collection procedures, withdrawals due to adverse events, or a formal comparison between groups. The figures should therefore be read as a limited descriptive account rather than as a comprehensive estimate of safety. They also do not support a claim that one group had a more favorable safety profile.

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

The trial addresses a defined clinical setting: initiating ivabradine at discharge from an observation unit after treatment for heart failure. It was randomized and placebo-controlled, and the intervention descriptions indicate that both groups were intended to have the same follow-up and study procedures. These features make the question relevant to a group that the registry background distinguishes from patients observed in hospital for days before discharge.

The posted primary-outcome summaries are median values of 88 bpm for ivabradine and 85 bpm for placebo, with full ranges of 81 to 97 and 81 to 91, respectively. The registry states that only 19 patients enrolled and that this sample was too small for formal analysis. No formal treatment-group estimate, confidence interval, or p-value is reported. The summaries therefore describe the enrolled participants but do not establish the size or precision of a treatment effect.

The result does not show that ivabradine did or did not change heart rate relative to placebo. It also does not answer whether the intervention affects hospitalization, mortality, or other outcomes discussed in the background; no such conclusion follows from the primary endpoint summaries. The registry’s background context is not itself evidence that a treatment produces a particular outcome in this trial.

The record also does not permit a thorough assessment of the primary analysis because it does not report the analysis population, missing-data handling, or further details of how change was calculated. The trial’s terminated status is recorded, but the reason is not reported. Those gaps limit interpretation of both the results and the process that led to them.

In general, an inconclusive or descriptive result from a small study should not be treated as proof of no effect, just as a difference between observed medians should not be treated as proof of an effect. The appropriate reading is narrower: the registry reports arm-specific summaries, notes that the sample was too small for formal analysis, and does not provide enough inferential information to establish a reliable between-group conclusion.

13. Why This Trial Matters Statistically

This trial is statistically important as an example of the difference between conducting a randomized comparison and obtaining a precise estimate from it. Randomization defines the intended comparison, but the amount of information available for estimating an effect depends on the number of observations, the outcome variability, and the analysis. The registry reports only 19 enrolled patients, with 13 assigned to ivabradine and 6 to placebo, and explicitly states that a formal analysis was not feasible because the sample was too small.

The posted median and range summaries remain useful as descriptions of the recorded outcomes. They show the values reported for each arm and the span of those values. But descriptive information and inferential evidence answer different questions. The summaries do not provide an uncertainty interval around a treatment contrast, and the record does not report a formal comparison. Readers should avoid treating the apparent difference between two arm medians as if it were a precise estimate.

The setting also highlights the importance of defining a target population and outcome clearly. The question concerns treatment started at discharge from an observation unit, whereas the background contrasts that setting with longer hospital stays. Whether the enrolled participants represent the intended clinical population cannot be evaluated because detailed eligibility and baseline characteristics are not reported in the registry record.

Finally, the record illustrates why completeness of statistical reporting matters. A clear analysis population, missing-data strategy, endpoint calculation, and prespecified analysis plan help readers understand how results were produced and how much confidence to place in them. Those details are not reported in the registry record. In this case, the main statistical conclusion is about limited information: the posted data are descriptive and do not support a precise treatment-effect estimate.

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 sample was small: the registry reports enrollment of 19 and explicitly says it was too small for formal analysis. The reported arm sizes were 13 for ivabradine and 6 for placebo. This limits the precision of group summaries and the ability to assess outcome variability or subgroup patterns. The record does not report a formal sample-size justification or target enrollment.

The trial status is terminated, but the reason for termination is not reported in the registry record. It is also not reported whether enrollment ended according to a prespecified rule, whether any interim review occurred, or whether the endpoint or analysis plan changed. These details cannot be inferred from the status field.

The primary endpoint is described as change from the final visit to baseline, measured using 12-lead ECG and Zio® patch, with planned recordings at baseline, day 14 (+/-1), and day 28 (+/-2). The registry does not provide further details about how the change was calculated, how measurements from the two methods were reconciled, or how incomplete visit data were treated. The displayed arm summaries are medians with full ranges, but no inferential comparison is reported.

Important design and analysis details are also absent. The registry does not report detailed eligibility criteria, baseline characteristics, the randomization procedure, the specific roles masked, the analysis population, missing-data handling, adherence, or the reason for termination. It does not report a formal statistical analysis plan. As a result, readers cannot fully assess the comparability of the enrolled groups, the handling of incomplete data, or the conduct of the planned analysis.

The adverse-event figures are limited to the counts reported in the registry. Event definitions and the safety observation period are not reported. The small enrollment also limits what can be learned about uncommon outcomes. These limitations do not invalidate the descriptive summaries, but they constrain the conclusions that can be drawn from them.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Trial Assessing the Effectiveness of Ivabradine Started at Discharge From the Observation Unit — NCT03168529.
• Registry record last updated 2026-09-11; status last verified 2026-08.
• Results first posted 2025-06-08.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

18. Record Summary

NCT03168529 is a phase 4 randomized, parallel-group trial comparing ivabradine with placebo for treatment initiated at discharge from an observation unit. The registry identifies the trial as quadruple-masked and reports a terminated status. Enrollment was 19, with 13 patients in the ivabradine arm and 6 in the placebo arm.

The primary outcome was change in heart rate from the final visit to baseline, measured by 12-lead ECG and Zio® patch. The registry reports median values of 88 bpm for ivabradine and 85 bpm for placebo, with full ranges of 81 to 97 and 81 to 91. It states that the sample was too small for formal analysis. A formal between-group estimate, confidence interval, and p-value are not reported in the registry record.

The record lists one secondary outcome and reports zero serious adverse events, zero other adverse events, and zero deaths in both groups. The reason for termination, missing-data methods, analysis population, and further details of the statistical plan are not reported in the registry record. The posted outcome summaries are descriptive and do not establish a precise treatment effect.