Cluster-randomized Controlled Trial of Mindfulness-Based Cognitive Therapy Effects on Anxiety and Stress: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cluster-randomized Controlled Trial of Mindfulness-Based Cognitive Therapy Effects on Anxiety and Stress (NCT06019299), a randomized na study. The primary outcome is State-Trait Anxiety Inventory.

2. Clinical Question

3. Trial Design

The registry record describes a randomized, cluster-randomized, parallel-group trial with no masking. Michigan State University is listed as the sponsor. The study status is completed, and its recorded start date is 2023-03-21, with primary completion on 2023-04-26. The phase is listed as NA. These design labels describe the trial structure; they do not by themselves establish how allocation was generated or concealed.

Enrollment is recorded as 289. The number and definition of the randomized clusters, the identity of the clustering unit, and the method used to allocate clusters are not reported in the registry record. The numbers assigned to each intervention group are not stated in the information. Consequently, the reported overall enrollment should not be used to infer group sizes or cluster counts.

The active intervention was a mindfulness-based cognitive therapy program delivered through a smartphone application, with daily practice encouraged over a four-week period. The positive control involved instruction in mindfulness breathing, including setting a timer for 5 minutes. The registry record does not report how adherence to either approach was measured, how much intervention participants actually completed, or whether other care was allowed or controlled.

Because randomization was clustered, observations from participants in the same cluster may be related. The registry record explicitly cautions that a simple individual-level re-analysis would be misleading and indicates that only the sponsor’s own analysis is to be used. However, the analysis output and its numerical estimates are not reported in the registry record. The trial’s design can therefore be described, but its comparative endpoint result cannot be interpreted numerically from the available record.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Analysis population for the primary outcome, as defined in the registry: All randomized participants were included in 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: All randomized participants were included in analysis.

6. Primary Endpoint

The registry lists the primary outcome as State-Trait Anxiety Inventory, measured over Change from baseline, 4 weeks..

The primary endpoint is the change from baseline at 4 weeks in the trait scale of the Spielberger State-Trait Anxiety Inventory. The record describes the measure as a scale rating and specifies that the endpoint is represented by a mean, with standard error as the measure of dispersion. Trait scores can range from 20 to 80; higher scores indicate greater levels of anxiety.

In general, a standardized anxiety measure can provide a structured way to assess a psychological outcome rather than relying only on informal descriptions. Measuring change from baseline focuses on how scores shift during the study period, while a comparison between randomized groups is needed to distinguish a group-specific pattern from changes shared across groups. Those are general reasons such endpoints may be used; the registry record does not state why this particular instrument was selected.

The registry record says all randomized participants were included in the primary analysis population. It does not give the observed baseline or follow-up means, the mean change in either group, a between-group estimate, a confidence interval, or a statistical test result. The endpoint’s definition is therefore available, but its observed result and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The trial is described as randomized and cluster-randomized, with a parallel-group structure and no masking. Randomization is intended to create groups whose outcomes can be compared without relying solely on differences that existed before the intervention. In a cluster-randomized study, allocation is made by groups or clusters rather than independently for each person. The record does not identify the cluster unit or describe how many clusters were included, so those details cannot be assessed.

Why does clustering matter?

In general, participants within the same cluster may share circumstances, environments, or experiences. Their measurements can therefore be more alike than measurements from participants in different clusters. This within-cluster similarity is called intracluster correlation. When it is present, treating each participant as an independent observation can make the analysis seem more precise than it is. Appropriate methods account for the clustered allocation and dependence in the data, often by modeling cluster effects or using cluster-level information. The registry record specifically warns that a simple individual-level re-analysis would be misleading. It does not report the sponsor’s model, its assumptions, or the method used to account for clusters.

What does the endpoint summary mean?

The primary outcome is continuous: it is a numerical scale score, and the registry record specifies a mean as the summary parameter. The recorded dispersion measure is standard error. In general, a mean describes the average score or average change in a group, while a standard error describes the precision of an estimated mean under the analysis model. Standard error is not the same as the spread of individual participants’ scores. The record does not give the values needed to interpret either quantity for the primary outcome.

The stated endpoint is change from baseline at 4 weeks. In general, change scores compare a participant’s later measurement with that participant’s baseline measurement. A treatment comparison can then estimate whether average change differs between groups. Analyses may instead model follow-up scores while adjusting for baseline, but the registry record does not say which approach the sponsor used. No group-specific changes or comparative estimate are reported, so neither approach can be reconstructed from the outcome description.

What can a confidence interval tell a reader?

Generally, a confidence interval communicates uncertainty around an estimated effect. Its width reflects how precisely the effect is estimated under the statistical model and the available data. A narrow interval indicates greater precision than a wide interval, but interpretation also depends on the effect scale and the range of values that would matter scientifically. No interval for the primary endpoint is reported in the registry record. Therefore, the precision of the trial’s estimated effect cannot be assessed.

How should significance tests be read?

In general, a significance test assesses how compatible the observed data are with a specified null hypothesis, given the model assumptions. A p-value is not the probability that the null hypothesis is true, nor does it measure the size of an effect. For a cluster-randomized trial, valid inference also depends on accounting for the clustered design. The registry record does not report a test statistic, p-value, significance threshold for the outcome analysis, or the sponsor’s model specification. No claim of statistical significance can be made from the posted information.

What do the planning assumptions represent?

The registry record describes planning illustrations using a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is specified as a fraction of the observed effect. In general, a sample-size illustration estimates the number of participants per arm needed for a stated target power under chosen assumptions. It is conditional on the assumed effect and analysis framework; it is not an observed result and does not show the trial’s observed power.

The record also notes that time-to-event planning tables use a total event count, while other planning tables use participants per arm. The primary endpoint in this trial is a continuous measure, not a time-to-event outcome. The numerical planning estimates are not reported in the information available for this analysis, and the observed effect needed to assess such illustrations is also not reported. No new planning values can be inferred from the enrollment figure alone.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures, identifies trait anxiety change at 4 weeks as the primary endpoint, and lists zero analyses. The identity and results of the other outcome measure are not reported in the registry record. The record also does not report whether an adjustment for multiple outcomes or multiple statistical tests was planned or used.

In general, testing multiple outcomes or multiple hypotheses can increase the chance of a false-positive finding if each test is interpreted separately. Multiplicity procedures can control that risk, but the appropriate approach depends on which outcomes and comparisons were prespecified. Since the analysis results and multiplicity plan are not reported, it is not possible to evaluate how multiple testing was handled or whether any reported result would have been adjusted.

The record states that all randomized participants were included in the primary analysis population. It does not describe how missing baseline or follow-up measurements were handled, whether any participants lacked outcome data, or whether imputation or another method was used. The phrase “all randomized participants” identifies the intended population, but does not by itself establish that every randomized participant contributed a measured endpoint.

For a clustered trial, missingness can also relate to the cluster structure: an entire cluster or individual participants might lack follow-up data. The registry record does not report missingness by group or cluster, reasons for missing data, or sensitivity analyses. These details matter because conclusions may depend on the assumptions used to handle absent measurements. As no numerical primary analysis is posted, neither missing-data handling nor multiplicity can be evaluated against an observed result.

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 record reports zero serious adverse events and zero deaths for each listed group. It also reports zero other adverse events for each group. The corresponding at-risk counts are 139 for the Positive Control group and 150 for the Mindfulness-Based Cognitive Therapy Intervention group. These are the recorded safety figures; no additional arithmetic or event rates are needed to read them.

These entries should be interpreted as registry-reported counts, not as proof that no adverse experiences occurred. The record does not report the adverse-event collection period, event definitions, severity criteria, ascertainment procedures, or whether events were judged related to an intervention. It also does not list serious adverse-event terms. Without those details, the scope and completeness of the safety reporting cannot be assessed.

In general, adverse-event counts describe events recorded under a study’s collection and reporting procedures. A zero count means no events are listed in that category in the record; it does not establish that an intervention is free of risk. Safety findings also need to be considered alongside the duration of observation and the completeness of follow-up, neither of which is described for adverse-event collection in the registry record.

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

The registry record establishes that a completed, cluster-randomized, parallel-group study compared a four-week smartphone mindfulness-based cognitive therapy program with mindfulness breathing instruction in college students. It identifies trait anxiety change at 4 weeks as the primary endpoint and describes the scale’s range and interpretation. Those details explain the question the study was designed to address.

However, the record does not report numerical results for the primary endpoint or a sponsor analysis. It therefore does not show whether the groups’ average changes differed, in which direction any difference went, or how precisely a difference was estimated. No conclusion about an intervention effect can be drawn from the intervention descriptions, enrollment, or outcome definition alone.

The absence of a reported analysis is not evidence that the groups had identical outcomes. It is also not evidence that one approach had a larger effect. Both interpretations would require observed results and a suitable analysis. The cluster-randomized design makes this especially important: a comparison must account for the way participants were allocated and for potential dependence among participants in the same cluster.

The safety entries report no serious adverse events, other adverse events, or deaths in the listed groups, but the registry record does not supply the collection and assessment details needed to judge the completeness of those counts. These entries should not be expanded into a general claim about safety.

In general, a useful interpretation of a trial combines its design, outcome estimate, uncertainty, missing-data approach, and safety reporting. Here, the design and intended endpoint are described, but the comparative estimate and analysis details are not reported in the registry record. The appropriate reading is therefore limited: the study’s question and structure are documented, while its primary numerical result remains unavailable.

13. Why This Trial Matters Statistically

This trial is statistically notable because it uses cluster randomization. Cluster allocation changes the structure of the data: participants within a cluster may not provide fully independent information. Analyses that ignore this feature can give misleading uncertainty estimates. The registry record recognizes this issue and cautions against a simple individual-level re-analysis, making the design detail central to interpretation rather than a minor technical note.

The primary endpoint is a continuous anxiety scale, defined as change from baseline at 4 weeks and summarized by a mean with standard error. Such an endpoint calls for attention to both the estimated group contrast and its uncertainty. A scale’s direction and range help readers understand what higher or lower scores mean, but they cannot replace the observed comparison. The record gives the scale interpretation while omitting the numerical endpoint result.

The study also illustrates a distinction between a registered outcome and a posted analysis. The registry identifies two outcome measures but lists zero analyses. Without estimates, confidence intervals, or tests, there is no basis for assessing the magnitude or precision of the primary result. This is a limitation of what can be learned from the registry record, independent of the intervention question itself.

Finally, planning calculations and observed findings answer different questions. The record describes assumptions for planning illustrations, including a fraction of an observed effect, but those illustrations are not observed power or evidence of an outcome. Keeping design, planning, and analysis distinct helps prevent an enrollment figure or a sample-size assumption from being mistaken for a result. In this case, the design can be discussed, but the registered primary comparison cannot be quantitatively interpreted.

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 principal limitation for interpreting this trial is that numerical primary outcome results are not reported in the registry record. There is no group-specific change, between-group estimate, confidence interval, or test result. This prevents assessment of the direction, size, and precision of the anxiety comparison. The record lists zero analyses, so there is no sponsor analysis to interpret or compare with an alternative calculation.

Several design details needed to evaluate a cluster-randomized analysis are also not reported in the registry record. These include the unit of clustering, number of clusters, allocation procedure, and statistical model. The record itself cautions that an individual-level re-analysis would be misleading. Without the sponsor’s analysis output and these methodological details, the handling of within-cluster dependence cannot be assessed.

The registry record says all randomized participants were included in the analysis population, but does not report outcome availability, missing-data methods, or follow-up completeness. Participant characteristics, detailed eligibility criteria, intervention adherence, and the identity of the second outcome measure are not reported in the information available for this analysis. The record also does not explain the rationale for the sample-size design or state whether interim analyses occurred.

Safety interpretation is limited by the absence of event definitions, collection procedures, assessment period, and attribution information. The reported zero counts are therefore descriptive entries, not a complete characterization of possible harms. In combination, these omissions mean that the trial’s question and general design are documented, but the comparative effectiveness, statistical uncertainty, analysis robustness, and completeness of safety reporting cannot be determined from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cluster-randomized Controlled Trial of Mindfulness-Based Cognitive Therapy Effects on Anxiety and Stress — NCT06019299.
• Registry record last updated 2026-06-12; status last verified 2026-05.
• Results first posted 2026-06-12.
• 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

NCT06019299 is a completed cluster-randomized, parallel-group trial sponsored by Michigan State University. Enrollment is recorded as 289. The study compared a smartphone-delivered mindfulness-based cognitive therapy program with a positive control involving mindfulness breathing instruction. The primary endpoint was change from baseline at 4 weeks in the trait scale of the Spielberger State-Trait Anxiety Inventory, for which higher scores indicate greater anxiety.

The registry record lists two outcome measures and zero analyses. It does not report numerical primary outcome results, a comparative estimate, or its precision. Safety entries list zero serious adverse events, zero other adverse events, and zero deaths in each group. The record cautions that a simple individual-level re-analysis would be misleading because of the cluster-randomized design.