Mindfulness, Group Therapy and Psychosis; Training Decreases Anxiety and Depression: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Mindfulness, Group Therapy and Psychosis; Training Decreases Anxiety and Depression (NCT04711460), a registered phase not stated study. The primary outcome is Change in Generalized Anxiety Disorder-7 Pre/Post Test at Week 5.

2. Clinical Question

The study's objective was to evaluate adding mindfulness as a technique within an outpatient group therapy program, alongside CBT. The primary outcome is a pre/post change in GAD-7 score at week 5. The registry describes comparisons between TAU and TAU plus mindfulness practice, as well as between younger and older participants. These are not equivalent questions: the first concerns the addition of group practice to the described TAU program, while the second concerns age-group differences among participants receiving mindfulness practice.

The record labels the study a non-randomized, within-group comparison and notes that allocation was not stated. It also cautions that the arms are not a like-for-like control comparison. Consequently, the clinical question is descriptive and comparative rather than a clean randomized estimate of the effect of mindfulness. The registry record does not report numerical GAD-7 changes, uncertainty intervals, or a test of whether groups differed. The study title asserts that training decreases anxiety and depression, but the title alone does not establish the size, precision, or credibility of an outcome difference.

3. Trial Design

The registry record describes a completed, non-randomized study with a within-group comparison. Enrollment is listed as 116. The stated objective was to assess adding mindfulness practice to an outpatient group therapy program for participants diagnosed with a psychotic spectrum disorder, alongside CBT. The record lists the University of Minnesota as sponsor and gives the study dates as 2017-01-01 and 2019-08-30 for start and primary completion.

The intervention descriptions distinguish younger and older participants, and TAU from TAU plus mindfulness practice. Younger participants are described as adults ages 19 to 29 years; older participants are described as adults ages 30-54 years. Both descriptions include CBT and 10 minutes of mindfulness training and practice in group therapy. The TAU description includes CBT and education about the mindfulness process, but no group practice of the mindfulness technique. The TAU plus mindfulness description includes CBT and 10 minutes of mindfulness practice in group sessions.

These labels describe more than one contrast. TAU versus TAU plus mindfulness practice compares the described group programs. Younger versus older compares age groups who received CBT and mindfulness practice; it is not a comparison of mindfulness against no mindfulness. The registry cautions that the arms are not a like-for-like control comparison. The allocation method is not stated, and random assignment is not described. It would therefore be inappropriate to interpret these groups as exchangeable treatment arms or to attribute any difference solely to mindfulness.

The record lists four outcome measures and nine analyses, and identifies CAGE-AID and the Columbia Suicide Severity Rating Scale as secondary outcomes. It does not give a detailed account of recruitment, eligibility criteria, treatment attendance, the timing of every assessment, or the statistical analysis plan. Details of allocation, masking, and sample-size justification are not reported in the registry 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.

Before assignment: All participants assessed and enrolled had a DSM-V diagnosis that included psychosis. They participated twice a week for 5 weeks. Pre/post-test scores were collected and compared.

Overall Study

Analysis population for the primary outcome, as defined in the registry: The Generalized Anxiety Disorder 7 number of participants for two studies: Treatment as usual vs TAU + Mindfulness study and the Younger versus older 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.

Population: The number of participants in each study: Treatment as usual (TAU) versus TAU + Mindfulness and the Younger versus Older study.

6. Primary Endpoint

The registry lists the primary outcome as Change in Generalized Anxiety Disorder-7 Pre/Post Test at Week 5, measured over Five weeks.

The primary endpoint is change in GAD-7 score from baseline to approximately five weeks, reported as a mean with standard deviation and expressed in units on a scale. The GAD-7 is a seven-item survey asking how often a person is bothered by symptoms of anxiety. Each item is rated from 0 (not at all) to 3 (nearly every day), and the item scores are summed. The registry describes the total score as ranging from 0 to 27.

As a general measurement point, a continuous score can represent degrees of symptom burden and can capture changes that would be obscured by reducing scores to broad categories. A pre/post change focuses on how scores move over the study interval. Reporting a mean gives a measure of the group's average score change, while the standard deviation describes variation among individual scores around that average. Neither statistic by itself shows how precisely the mean change has been estimated; that requires an uncertainty measure such as a confidence interval, which is not reported in the registry record.

The endpoint description contains an internal labeling inconsistency: it identifies the instrument as the GAD-7, a survey of anxiety symptoms, but describes the score range using the phrases “minimal depression” and “severe depression.” The registry record does not clarify that wording. It also does not specify whether change was calculated as follow-up minus baseline or baseline minus follow-up. Without that direction convention and the numerical results, the sign and magnitude of any reported change cannot be interpreted from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a continuous measure and says it is reported as a mean with standard deviation. The following points are general explanations of those statistical concepts; they do not imply that a particular test or model was used in this study. The exact statistical test, model, and variance assumptions are not reported in the registry record.

What does a mean change represent?

A mean change summarizes the average difference between measurements taken at two times for the people included in an analysis. For a pre/post outcome, it is important to know the subtraction order. A positive mean could indicate improvement or worsening depending on whether change was defined as follow-up minus baseline or the reverse, and on what higher scores represent. The registry record does not state the subtraction convention. It also does not provide the numerical mean change, so no direction or magnitude can be interpreted.

A within-person change can account for the fact that the two measurements come from the same participant. A comparison of average changes between groups asks a different question: whether the change over time differs across groups. Comparing post-treatment averages alone is not necessarily equivalent to comparing changes, particularly when baseline scores differ. The record says that pre/post scores were compared, but does not describe the precise analysis used or whether the primary test was within-group, between-group, or both.

What does the standard deviation describe?

As a general statistical point, a standard deviation describes how spread out individual observations are around their mean. A large standard deviation indicates more variation in observed scores; it is not the same as uncertainty in the estimated mean. Uncertainty in a mean or difference is commonly represented by a standard error or confidence interval, which depends on the observed variation and the amount of information available under the analysis. The registry provides no numerical standard deviation or interval for the primary endpoint.

In a pre/post setting, the variation in individual changes depends not only on the variation at each time but also on how strongly each person's measurements are related across time. A method that treats paired measurements as independent can misrepresent that structure. The record does not state how the repeated measurements were handled, so it is not possible to determine whether the analysis accounted for within-person pairing.

Why does the non-randomized design matter?

As a general design principle, random allocation can help balance measured and unmeasured baseline characteristics across groups, though it does not guarantee balance in every realized study. In a non-randomized comparison, group membership may be associated with characteristics that also relate to outcome change. Differences in baseline symptom levels, age, treatment participation, or other factors could therefore complicate interpretation. This is a general concern, not evidence that any particular imbalance occurred in this study.

The registry states that allocation was not stated and cautions that the arms are not a like-for-like control comparison. It does not report group-level baseline characteristics or an adjustment strategy. Thus, an unadjusted difference between groups, if one were available, could not automatically be interpreted as an effect of adding mindfulness practice. The younger-versus-older comparison is also not a treatment contrast because both groups are described as receiving mindfulness practice.

How should uncertainty and significance be read?

Generally, a confidence interval communicates the range of effect values reasonably compatible with the data under a specified statistical model. Its width conveys precision, while its position relative to a null value can inform a test of statistical significance. A p-value is not the probability that the treatment has no effect, and statistical significance does not by itself establish that an effect is large enough to matter clinically. These interpretations depend on a suitable design and analysis. No confidence interval or p-value for the primary endpoint is reported in the registry record.

The record lists nine analyses and four outcome measures. That makes it important to know which outcome and comparison were designated primary, whether other analyses were confirmatory or exploratory, and how multiple testing was handled. The primary endpoint is identified by name, but the multiplicity procedure and a complete analysis plan are not reported. A count of analyses alone does not show whether or how results were adjusted for multiple comparisons.

What do planning illustrations mean?

The registry describes sample-size calculations as planning illustrations based on an observed effect, not as part of the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect defined as a stated fraction of the observed effect. The record says that time-to-event calculations use a total number of events, while other calculations use participants per arm.

As a general statistical point, such calculations ask what sample size might be needed under specified assumptions to detect a target effect with a chosen probability. They do not describe the power actually achieved by a completed study. An illustration based on an observed effect is especially dependent on the stability of that estimate; if the observed effect is imprecise, a planning calculation based on it may also be unstable. The actual calculation values and detailed inputs are not reported in the registry record. Any sample-size values should therefore be read as hypothetical planning scenarios, not evidence that the study was designed or powered in that way.

Over-dispersion is a general concern when count data vary more than a simple statistical model expects; it can make model-based uncertainty too small if ignored. The primary endpoint is continuous, and the registry does not state that a count model or an over-dispersion adjustment was used. No inference about the study's analysis should be made from general explanations of methods.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Treatment as Usual", "TAU + Mindfulness Training", "Younger Participants", "Older Participants")
n   <- c(32, 32, 26, 26)
m   <- c(4.68, 6.28, 3.96, 7.38)
sp  <- c(5.4, 5.59, 5.39, 5.13)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Treatment as Usual  32  4.680  5.400  2.733  6.627
CARM  TAU + Mindfulness Training  32  6.280  5.590  4.265  8.295
CARM  Younger Participants  26  3.960  5.390  1.783  6.137
CARM  Older Participants  26  7.380  5.130  5.308  9.452

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and nine analyses, while identifying GAD-7 change at week 5 as the primary outcome. The record also names CAGE-AID and the Columbia Suicide Severity Rating Scale as secondary outcomes. These registry entries indicate that more than one outcome or analysis is listed, but they do not reveal the full testing structure. The statistical plan, including any hierarchy of tests or multiplicity adjustment, is not reported in the registry record.

As a general statistical point, testing multiple outcomes, time points, or group comparisons can increase the chance that at least one result appears noteworthy by chance. Methods for handling that issue may include defining a primary endpoint in advance, controlling an error rate across tests, or treating secondary analyses as exploratory. Which approach is appropriate depends on the study question and plan. It cannot be determined from the number of analyses alone whether multiplicity was addressed or how it would affect interpretation.

Missing-data handling is also not reported in the registry record. The record does not describe how many participants completed the baseline and follow-up GAD-7, whether any observations were excluded, or how incomplete measurements were treated. It does not state whether the analysis used complete cases, imputation, a model that used available repeated measures, or another method. Those approaches rely on different assumptions about why data are missing, so the missingness mechanism and analysis choices matter for interpretation.

The analysis populations are not defined. The record does not say whether the primary analysis included everyone enrolled, only participants who attended a specified amount of therapy, or another subset. Without participant flow and analysis-population definitions, it is not possible to assess attrition, adherence-related exclusions, or how closely the analyzed group corresponds to the enrolled population. These gaps also limit the ability to reproduce or critically assess the reported analysis.

12. 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 entries list zero participants affected by serious events, zero affected by other events, and zero deaths in each reported group. The entries give 32 as the number at risk for each of the TAU and TAU plus mindfulness practice groups, and 26 as the number at risk for each of the younger and older participant groups. These are the registry's group-specific figures; they should not be added together because the record does not establish that the listed comparisons represent separate, non-overlapping populations.

As a general statistical point, observing zero events in a group does not demonstrate that the underlying risk is zero. It means that no events were recorded in the specified group and observation context. The precision of a safety estimate depends on factors including the amount of observation and how events were collected. The registry record does not report event-monitoring procedures, follow-up duration for safety, or confidence intervals for the event counts.

The serious-event list contains no terms, and the displayed figures do not identify a serious or other event among the groups. These entries should be read as the posted safety counts, not as proof that no safety concerns could occur. The record does not describe whether adverse-event ascertainment was systematic or whether events occurring outside the stated observation period were captured.

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

The registry record documents a completed, non-randomized study of mindfulness practice within outpatient group therapy for participants with a psychotic spectrum disorder. It describes CBT in the relevant groups and specifies a primary endpoint based on pre/post GAD-7 scores over approximately five weeks. It also records the planned comparison contexts and group descriptions. These details help define what the study set out to examine.

However, the registry record does not report the numerical primary outcome results. There is no mean change, standard deviation, confidence interval, or p-value from which to judge the size or precision of any change. The title's claim that training decreases anxiety and depression should not be treated as a substitute for those results. The score-range description also contains inconsistent wording about depression in a description of the GAD-7, and the record does not clarify the change-score direction.

The design constrains causal interpretation. This is described as a non-randomized, within-group comparison, with allocation not stated and an explicit caution that the arms are not like-for-like controls. The younger-versus-older comparison is between age groups receiving mindfulness practice, not a comparison of practice with no practice. If differences were observed, the registry information would not by itself show that mindfulness caused them.

As a general distinction, evidence that a score changed during a program is not necessarily evidence that the program caused the change. Symptoms may change over time for several reasons, and non-randomized groups may differ in relevant ways. Conversely, the absence of a reported numerical result in the registry record does not establish that no change occurred. It means that the size, direction, and uncertainty of the outcome cannot be assessed from the information recorded.

The safety entries report zero serious events, zero other events, and zero deaths in the listed groups. Those observations are relevant descriptive information, but they do not establish that risk is absent. Missing details about follow-up and event ascertainment limit further interpretation.

Overall, the record supports describing the study's question, intervention descriptions, endpoint, design, and posted safety counts. It does not support a numerical estimate of benefit, a claim of statistical significance, a causal conclusion, or a complete assessment of missing data and analysis choices.

14. Why This Trial Matters Statistically

This study raises a useful statistical issue: the intervention question and the comparison structure need to match. TAU versus TAU plus mindfulness practice is framed as a program comparison, while younger versus older participants is an age-group comparison among people receiving mindfulness practice. Distinguishing those contrasts prevents an age comparison from being misread as an estimate of the effect of mindfulness.

The record also illustrates why design labels matter. A non-randomized, within-group comparison can describe changes and group differences, but interpretation depends on how groups were formed and whether relevant differences were measured and addressed. Here, allocation is not stated, and the registry warns that the arms are not like-for-like controls. Those details are central when considering what a comparison can establish, not merely technical qualifications.

Endpoint definition is another important issue. The GAD-7 is identified as the primary anxiety measure, but the description uses depression language for the score range and does not specify the direction convention for change. Clear definitions of outcome, timing, and subtraction order help readers interpret both the sign and the clinical meaning of an estimate. In this record, the primary measure and timeframe are identified, but the numerical result needed to interpret change is not reported.

The record lists multiple outcome measures and analyses, yet does not report the multiplicity approach, missing-data method, or analysis populations. These omissions make it harder to assess the reliability and reproducibility of any outcome claim. The example also shows why safety counts should be interpreted as observed counts within their stated groups and follow-up context, rather than as proof of no risk.

These are broadly relevant lessons for clinical research: a clear comparison, transparent analysis plan, complete outcome reporting, and explicit accounting of missing observations all contribute to sound interpretation. For this study, the available registry information is enough to identify these questions, but not enough to resolve them or quantify the primary outcome.

15. 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 the primary endpoint is that its numerical results are not reported in the registry record. The mean change, standard deviation, confidence interval, and p-value are unavailable, so the size, direction, and precision of the GAD-7 change cannot be evaluated. The change-score subtraction convention is also not stated. In addition, the endpoint description identifies an anxiety measure but uses wording about depression when describing the scale range; the record does not explain this inconsistency.

The design is non-randomized, and the allocation method is not stated. The record itself cautions that the arms are not a like-for-like control comparison. No group-level baseline characteristics or adjustment strategy are described, so comparability between groups cannot be assessed. The younger-versus-older contrast is not a no-practice control comparison, since both groups are described as receiving CBT and mindfulness practice.

The record does not provide the detailed statistical analysis plan, exact test or model, multiplicity procedure, or definition of analysis populations. Missing-data methods, participant flow, and the number of participants contributing to the primary endpoint are not reported in the registry record. These omissions limit evaluation of attrition, assumptions, and reproducibility.

Intervention descriptions are available, but treatment attendance, adherence, and consistency of delivery are not reported. The registry gives limited information about eligibility and recruitment, so the applicability of the enrolled group to other settings cannot be judged from these details alone. Safety figures are posted, but event-collection procedures and safety follow-up details are not reported. These limitations do not show that any particular bias or safety issue occurred; they identify questions the registry information does not resolve.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Mindfulness, Group Therapy and Psychosis; Training Decreases Anxiety and Depression — NCT04711460.
• Registry record last updated 2024-02-02; status last verified 2023-05.
• Results first posted 2024-02-02.
• 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.

19. Record Summary

The registry record describes a completed, non-randomized, within-group study sponsored by the University of Minnesota. Its objective was to evaluate mindfulness practice added to outpatient group therapy alongside CBT for participants with a psychotic spectrum disorder. Groups included TAU, TAU plus mindfulness practice, and younger and older participants receiving mindfulness practice.

The primary outcome is change in GAD-7 score from baseline to approximately five weeks, reported as a mean and standard deviation. Numerical primary outcome results are not reported in the registry record. The record lists four outcome measures and nine analyses, and identifies CAGE-AID and the Columbia Suicide Severity Rating Scale as secondary outcomes. Allocation, detailed statistical methods, missing-data handling, and analysis populations are not reported.

Posted adverse-event entries show zero serious events, zero other events, and zero deaths in the listed groups. The record cautions that the arms are not like-for-like control comparisons. Accordingly, the design and available results do not permit a quantitative or causal conclusion about the effect of mindfulness practice.