Improving Cardiac Rehabilitation Outcomes Through Mobile Case Management (iCARE): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Improving Cardiac Rehabilitation Outcomes Through Mobile Case Management (iCARE) (NCT04938661), a randomized na study. The primary outcome is Change in Metabolic Equivalents of Task (METS).

2. Clinical Question

3. Trial Design

iCARE was a randomized, parallel-group clinical trial with no masking reported. The registry lists an enrollment of 206 and a completed status. The recorded study start was 2021-07-08, and the primary completion date was 2025-04-10. The registry lists Mayo Clinic as the sponsor and phase as not applicable.

Participants were assigned to one of three approaches: conventional center-based cardiac rehabilitation (CON), conventional center-based cardiac rehabilitation plus mHealth (CON+), or home-based cardiac rehabilitation plus mHealth (HOM+). The CON arm was prescribed 36 center-based sessions, described as including supervised exercise and educational and group activities. The CON+ arm had the same prescribed center-based rehabilitation and access to an mHealth platform with e-learning content. The HOM+ arm received paper educational content and access to the mHealth platform; participants were encouraged to exercise three days per week. Some arm-description text is incomplete in the registry record, so these descriptions should not be treated as a complete account of delivery.

The primary outcome is change in METS, assessed at baseline and 3 months. Secondary outcomes listed in the record are change in body mass index and change in self-reported quality of life. The primary result is reported as a median with an interquartile range. The endpoint figures use 44 participants in CON, 44 in CON+, and 37 in HOM+. Those outcome counts are not interchangeable with the enrollment figure: they describe the participants represented in the posted endpoint results.

The record does not report allocation concealment, detailed eligibility criteria, site counts, adherence, or the statistical plan. Randomization can reduce systematic differences in expectation between assigned groups, but the degree to which that occurred cannot be assessed from these descriptive results alone.

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: 10 participants in the CON arm, 9 participants in the CON+ arm and 1 participant in the HOM+ did not complete the METS measurement at the 3-month mark.

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 Change in Metabolic Equivalents of Task (METS), measured over Baseline; 3 Months.

Metabolic equivalents of task (METS) are used to express energy expenditure during activity relative to resting energy expenditure. The registry describes the primary outcome as change in METS and lists measurements at baseline and 3 months. This makes the endpoint a measure of change over the study interval, rather than a single follow-up level alone.

Exercise capacity is relevant to cardiac rehabilitation because the intervention aims to support physical activity and functional improvement. In general, an activity-related measure can help describe a change in exercise capacity, but it does not capture every aspect of rehabilitation or health. A result on this endpoint should not be treated as a direct measure of quality of life, safety, or other clinical outcomes.

The registry reports the outcome using medians and interquartile ranges. A median describes the middle of the observed distribution, while the interquartile range describes the central spread of observations. These summaries are useful when a distribution may not be well represented by a mean and standard deviation. The record gives median values of 6.48 for CON, 7.4 for CON+, and 7.43 for HOM+, with corresponding reported ranges of 5.2 to 7.6, 5.68 to 8.35, and 6.3 to 8.8. The unit is mL/kg/min. The registry does not report a comparison estimate or uncertainty interval for differences between arms.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical interpretation depends not only on the arm-level values but also on how outcomes were defined, how participants entered the analysis, and how uncertainty was estimated. The registry record supplies descriptive summaries for the primary outcome, but does not report a statistical analysis for comparing arms. The following concepts explain what the posted summaries can and cannot establish.

What does a median describe?

In general, the median is the central observation in an ordered set of values. It is less sensitive than the mean to unusually large or small observations. A median does not show the full distribution, and it does not indicate how precisely the population-level effect has been estimated. In this trial, the posted medians are 6.48 for CON, 7.4 for CON+, and 7.43 for HOM+.

The interquartile range describes the central half of the observations, bounded by the lower and upper quartiles. It conveys spread within an arm, not uncertainty about the difference between arms. The posted ranges are 5.2 to 7.6 for CON, 5.68 to 8.35 for CON+, and 6.3 to 8.8 for HOM+. Comparing these ranges visually is not a substitute for an analysis that directly estimates the between-arm contrast.

What would an interval estimate add?

In general, a confidence interval gives a range of effect values compatible with the observed data under the chosen statistical model and its assumptions. It is a way to communicate uncertainty, rather than a guarantee that the true value lies within the interval. An interval for an arm-to-arm difference would be more directly useful for assessing comparative precision than separate arm-level ranges. The registry record does not report confidence intervals for the primary comparisons.

A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under a statistical model. It does not measure the size or clinical importance of an effect, and it does not show the probability that the null hypothesis is true. No p-value for the primary comparison is reported. Without a stated test and result, the descriptive medians should not be assigned a conclusion about statistical significance.

Why does the analysis population matter?

Random assignment defines the groups at the start of a trial, but endpoint summaries may include only participants whose outcome was measured. The record notes missed 3-month METS measurements in each arm and reports endpoint counts of 44, 44, and 37. It does not state whether the primary analysis followed original assignment regardless of adherence, included only participants with observed outcomes, or used another population definition. These approaches answer different questions and can lead to different estimates.

In general, complete-case analysis uses participants with observed endpoint data. It can be biased if the chance of missing an outcome is related to the outcome itself or to other factors associated with it. Imputation or model-based methods can use additional information, but their validity depends on assumptions about why data are missing. The registry does not report a missing-data method, so the effects of missing measurements on the primary summaries cannot be evaluated from the record.

What do the sample-size illustrations mean?

The posted planning illustrations are based on the observed effect, rather than the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They consider an effect defined as a stated fraction of the observed effect. For outcomes other than time-to-event outcomes, the illustrations are participants per arm for 80% or 90% power. They are planning calculations, not evidence of the trial's observed power and not a substitute for the trial's original sample-size justification. The registry record does not report that justification.

Because the primary result is presented as a median and interquartile range, while the planning assumptions use a normal approximation, the assumptions should be read as an illustration rather than a complete account of the outcome's distribution or a reconstruction of the trial's analysis plan. The record does not report the trial's own sample-size calculation, prespecified effect, or planned statistical test.

Why are three arms not one comparison?

With three arms, there are several possible pairwise questions, as well as possible overall tests or planned contrasts. Each question has a different interpretation. The registry record does not identify a primary pairwise contrast or report an analysis accounting for multiple comparisons. In general, multiplicity procedures can control the chance of false-positive findings across a set of tests, but they depend on which tests were planned and how they were conducted. That information is not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists three treatment arms, so comparisons could address CON versus CON+, CON versus HOM+, or CON+ versus HOM+. The record does not report which contrasts were prespecified, whether an overall test was planned, or whether any adjustment for multiple comparisons was used. It also reports no analysis results for the primary endpoint. Without the analysis plan, it is not possible to determine how multiplicity was addressed or to interpret any unreported comparison as prespecified.

For the primary METS measurement, the registry states that 10 participants in CON, 9 in CON+, and 1 in HOM+ did not complete the measurement at 3 months. The endpoint summaries include 44 participants in CON, 44 in CON+, and 37 in HOM+. The record does not explain the relation between missing measurements and the endpoint analysis, describe reasons for missingness, or state whether missing values were imputed. It does not report sensitivity analyses assessing how alternative missing-data assumptions might affect results.

The analysis population is also not reported. The registry does not say whether the primary outcome was analyzed according to original randomized assignment, among participants with measured outcomes, or under another rule. In general, these choices affect the question answered and can influence results when outcomes are missing or participation differs after assignment.

Although the record lists secondary outcomes of change in body mass index and change in self-reported quality of life, it does not report statistical analyses for them. The statistical plan, outcome hierarchy, and any multiplicity strategy are not reported in the registry record. These gaps limit interpretation of both the primary endpoint and any broader set of outcome claims.

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 registry reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each of the three arms. The corresponding groups at risk are reported as 71 in CON, 67 in CON+, and 68 in HOM+. These are the registry's reported safety counts; they are distinct from the endpoint counts for the METS outcome.

A report of zero events means that no events were recorded in the listed categories for the stated groups in the registry results. It does not establish that the interventions carry no risk. In general, the ability to characterize uncommon harms depends on the amount and duration of observation, how events are defined and collected, and whether all events are reported. The record does not provide detailed event definitions, follow-up duration for safety, or a narrative explaining the absence of reported events.

The registry lists no top serious adverse-event terms. These safety summaries should therefore be read as reported counts, not as a formal comparison showing that safety is the same across approaches. The record does not report statistical tests or uncertainty estimates for safety differences.

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

The posted results describe change in METS for participants represented in the primary endpoint summaries. The medians are 6.48 in CON, 7.4 in CON+, and 7.43 in HOM+, with interquartile ranges of 5.2 to 7.6, 5.68 to 8.35, and 6.3 to 8.8. They offer a compact account of the outcome distributions in the three groups, but do not by themselves estimate the causal effect of one rehabilitation approach compared with another.

The record does not report a treatment-effect estimate, confidence interval, or p-value for an arm comparison. It therefore does not establish that one approach resulted in a greater change, nor that the approaches had equivalent results. Demonstrating equivalence or noninferiority requires a defined margin and an appropriate prespecified analysis; such details are not reported in the registry record.

The findings also do not describe all dimensions of cardiac rehabilitation. The registry lists changes in body mass index and self-reported quality of life as secondary outcomes, but no analyses for those outcomes are reported. The METS summaries do not resolve questions about attendance, adherence, longer-term outcomes, patient experience, or safety beyond the adverse-event counts recorded.

Missing 3-month measurements are reported in each arm, and the record does not explain how they were handled in the analysis. If participants with missing outcomes differ systematically from participants with measured outcomes, observed summaries may not represent the randomized groups in the same way. Because the analysis population and missing-data methods are not reported, that possibility cannot be assessed.

In general, randomized assignment supports a comparative interpretation when analysis follows the design and accounts appropriately for missingness and other prespecified features. Here, the registry record confirms randomization and reports descriptive endpoint and safety summaries, but does not provide the inferential analysis needed to make a firm comparative conclusion. Readers should distinguish the observed medians from evidence about between-arm effects.

13. Why This Trial Matters Statistically

This trial is statistically informative as a three-arm comparison of center-based rehabilitation, center-based rehabilitation with mHealth, and home-based rehabilitation with mHealth. That structure raises more than one possible comparative question. For example, a contrast involving CON+ and CON addresses the addition of mHealth to the center-based approach, whereas a contrast involving HOM+ and CON compares broader differences in delivery. The registry record does not report which contrast was the principal target, so the summaries should not be used to infer a single intended comparison.

The primary endpoint also illustrates why descriptive statistics and comparative inference are different. Arm-level medians and interquartile ranges communicate central tendency and spread, but do not quantify uncertainty in differences between arms. A direct contrast with an interval estimate would help readers understand both the direction and precision of an estimated effect. No such result is reported in the registry record.

Missing 3-month METS measurements matter to interpretation, and the number reported as missing varies across arms. The record does not describe how these observations were handled. This makes transparency about the analysis population and missing-data assumptions especially important when interpreting randomized trials.

Finally, the posted planning assumptions should not be confused with the trial's original design justification or observed power. Planning calculations based on an observed effect can illustrate what future studies might require under stated assumptions, but they do not replace a prespecified analysis or address whether the observed effect is estimated precisely. The registry record does not report the trial's own sample-size rationale or statistical plan.

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 endpoint summaries are descriptive, and the registry record reports no statistical comparison among the three arms. There is no reported effect estimate for an arm-to-arm contrast, confidence interval, or p-value. As a result, the size and precision of comparative differences cannot be judged from the posted results.

The registry reports missing 3-month METS measurements in all arms, but does not state how missing outcomes were addressed, identify reasons for missingness, or report sensitivity analyses. It also does not define the analysis population. These omissions limit assessment of whether the arm summaries reflect the randomized groups or only those with observed outcomes.

The record does not report the planned statistical model, baseline adjustment, prespecified contrasts, or a strategy for multiplicity. With three arms, those details are important for knowing which comparisons were intended and how their uncertainty should be interpreted. The registry record also does not report the trial's own sample-size justification or an analysis plan.

The arm descriptions are incomplete in the registry record, particularly for the delivery details of the mHealth and home-based approaches. Information on adherence, actual rehabilitation participation, and treatment fidelity is not reported. The record lists conditions but does not give detailed eligibility criteria or participant characteristics, limiting assessment of how broadly the findings may apply.

Safety results are counts without accompanying event definitions, uncertainty estimates, or a detailed account of safety follow-up. Secondary outcomes are listed, but analyses are not reported. Together, these limitations mean that the registry supports a descriptive account of the posted results, but a more complete assessment of comparative effectiveness and precision requires analysis details not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Improving Cardiac Rehabilitation Outcomes Through Mobile Case Management (iCARE) — NCT04938661.
• Registry record last updated 2026-04-27; status last verified 2026-04.
• Results first posted 2026-04-27.
• 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

iCARE (NCT04938661) is a completed, randomized, parallel-group trial sponsored by Mayo Clinic, with no masking reported. The registry lists an enrollment of 206 and a study start of 2021-07-08; the primary completion date was 2025-04-10.

The three groups were conventional center-based cardiac rehabilitation (CON), center-based rehabilitation plus mHealth (CON+), and home-based rehabilitation plus mHealth (HOM+). The primary outcome was change in METS at baseline and 3 months, reported as medians with interquartile ranges. The posted medians were 6.48, 7.4, and 7.43, respectively. The record reports missed 3-month measurements and does not report inferential comparisons, a statistical plan, or a missing-data method.

Secondary outcomes listed were change in body mass index and change in self-reported quality of life. The registry reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each arm. These results provide descriptive outcome and safety counts, but do not establish comparative effects or equivalence among the rehabilitation approaches.