Developing a Positive Psychology Intervention to Promote Health Behaviors in Metabolic Syndrome: Proof-of Concept Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Developing a Positive Psychology Intervention to Promote Health Behaviors in Metabolic Syndrome: Proof-of Concept Trial (NCT03473886), a na na study. The primary outcome is Number of PP-MI-Based Health Behavior Intervention Exercises Completed.

2. Clinical Question

The study also set out to assess whether participants found the exercises acceptable, using ratings of ease and helpfulness. Its stated hypothesis was that the mean rating for each exercise would be at least 7 out of 10. These are planned criteria, not reported findings.

Other aims concerned physical activity, sedentary time, diet quality, and psychological well-being. The record describes a hypothesis of improvement at 8 weeks compared with baseline, but does not report observed results for those outcomes. The registry record therefore identifies what the investigators intended to examine, but does not establish whether the feasibility or acceptability targets were met or whether any outcome changed.

3. Trial Design

This was a completed, single-group proof-of-concept trial registered as NCT03473886. The registry lists enrollment of 8 participants with metabolic syndrome. The study start date was 2018-06-01, and the primary completion date was 2019-04-15. The phase is recorded as not applicable, allocation as not applicable, masking as none, and the model as single group.

Participants were assigned to the intervention arm labeled PP-MI. The described program combined group physical activity and positive psychology over 8 weeks. It included exercises intended to increase positive emotions and physical activity during and between sessions. The study summary also describes motivational interviewing-based goal-setting and tracking activity, including steps. Further details about the exercise schedule and program delivery are not reported in the registry record.

Because the registered design has one group and no separate control arm, it cannot provide a randomized comparison of the intervention against another treatment or usual care. The registry describes an intended comparison of outcomes at 8 weeks with baseline, but does not report the results of that comparison. Changes over time in a single group can be described, but without a concurrent comparator they cannot by themselves separate intervention-related change from other explanations.

The primary aim was feasibility, with acceptability and preliminary outcomes also listed as aims. The primary outcome was the number of intervention exercises completed during 8 weeks of group sessions. The record lists 22 outcome measures and 0 analyses. The completed status indicates the study’s registry status; it does not supply the missing outcome estimates. Details of recruitment procedures, adherence to the intended program, and the analysis plan 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.

Overall 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.

6. Primary Endpoint

The registry lists the primary outcome as Number of PP-MI-Based Health Behavior Intervention Exercises Completed, measured over 8 weeks of group sessions.

The primary endpoint is the number of positive psychology and motivational interviewing-based health behavior intervention exercises completed during 8 weeks of group sessions. It is a count of completed exercises, intended to indicate whether participants could engage with the intervention as designed. The registry specifies that feasibility would be assessed by examining the number completed.

The endpoint is listed as a continuous measure summarized by a mean and standard deviation. In general, a mean describes the average number of exercises completed across participants, while a standard deviation describes how much participants’ counts vary around that average. Neither summary alone shows the full distribution: participants may complete different numbers of exercises even when the mean is similar.

The study summary states a feasibility hypothesis that most participants would complete 6/8 exercises or sessions. That target is a planned benchmark, not an observed completion result. The registry record does not report the mean, standard deviation, participant-level counts, or the proportion reaching the stated benchmark. Consequently, the endpoint’s intended meaning is clear, but the posted record does not permit an assessment of whether the intervention met its feasibility target.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the primary endpoint describe?

The primary endpoint is the number of intervention exercises completed during 8 weeks of group sessions. This is a measure of engagement with the intervention, not a direct measure of health behavior change. The registry labels the measure as continuous and specifies a mean and standard deviation. In general, the mean gives a compact description of the average count; the standard deviation describes dispersion among participants. A mean can hide differences in individual experience, so participant-level values or a distribution would add context. Those values are not reported in the registry record.

The study summary states a target that most participants would complete 6/8 exercises or sessions. Such a threshold can make a feasibility question concrete: it defines what investigators hoped would count as adequate completion. But a threshold is not itself evidence of success. Assessing it requires observed completion data, which are not reported in the registry record.

How should the single-group design be understood?

General statistical context: a single-group before-and-after study can describe how measured outcomes differ over time within the enrolled group. It does not include a concurrent comparison group that would help distinguish intervention-associated change from changes that might have occurred for other reasons. The registered model is single group, and allocation is listed as not applicable. Therefore, any intended baseline-to-8-week comparison is not a randomized treatment contrast.

The trial’s proof-of-concept and feasibility aims fit a preliminary study purpose. The primary question is whether participants completed the intervention exercises; acceptability and other outcomes were also intended for assessment. The registry record does not report the statistical plan used to analyze these measures, so details such as the exact comparison method, handling of repeated measurements, or adjustment for baseline values are not reported in the registry record.

What does uncertainty mean?

General statistical context: an estimate summarizes the observed data, while a confidence interval describes the range of values compatible with those data under the assumptions of the chosen method. A narrow interval indicates greater precision than a wide interval, but neither an estimate nor its interval resolves limitations in design. No confidence intervals for the trial outcomes are reported in the registry record. Without the estimates and their uncertainty, readers cannot determine the precision of the study’s observed outcomes.

Standard deviation and confidence interval answer different questions. A standard deviation describes variability among observations; a confidence interval concerns uncertainty about an estimated quantity. The primary endpoint is described using a mean and standard deviation, but neither value is posted. No calculation can therefore be interpreted as an observed estimate from the registry record.

How should the planning illustration be read?

The sample-size assumptions describe a planning illustration based on an observed effect, not 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 defined as a stated fraction of the observed effect. The illustration is not an analysis of this single-group trial and is not observed power. Its two-arm allocation assumption does not match the registered single-group design. Planning figures under those assumptions should not be read as the actual enrollment plan or as evidence about the precision of the trial’s results.

General statistical context: sample-size planning asks how much information a future study might need under specified assumptions. It depends on the target effect, variability, significance level, allocation, and analysis method. If those assumptions do not match the study design or are based on an unstable preliminary estimate, the resulting planning figure may not translate to a future study. The registry record does not report the investigators’ original sample-size justification.

Why does variability matter?

General statistical context: when participants’ responses vary substantially, a group average alone may give an incomplete picture, and an estimate based on a small group may be especially uncertain. Over-dispersion is a form of variability greater than expected under a particular statistical model; accounting for it can matter when that model is used. The registry record does not report a distribution or model for the exercise counts, so there is no basis to claim that over-dispersion was present or that a specific adjustment was used.

Overall, the registry identifies the endpoint and some intended benchmarks, but it does not report the observed summaries or analysis methods needed to evaluate them. The statistical concepts help explain what those summaries would mean; they cannot substitute for the missing results.

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("Intervention Arm: PP-MI")
n   <- c(7)
m   <- c(7)
sp  <- c(0.5)
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  Intervention Arm: PP-MI  7  7.000  0.500  6.538  7.462

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 22 outcome measures, including acceptability, physical activity adherence, and measures of psychological well-being, health behaviors, and related domains. Considering many outcomes raises a multiplicity question: when several outcomes are analyzed, the chance of finding an apparently notable result by chance can increase. General statistical practice may address this through a prespecified primary outcome, adjustment procedures, or an explicitly exploratory interpretation. The multiplicity strategy for this trial is not reported in the registry record.

The primary outcome is identified as the number of intervention exercises completed, but the record lists 0 analyses. It does not report whether secondary outcomes were analyzed, which outcomes were prioritized beyond the named primary endpoint, or whether any adjustment for multiple comparisons was planned or used. The study summary’s hypotheses are not analysis results.

Missing-data handling is also not reported in the registry record. The study hypothesis anticipated objective physical activity follow-up data from at least 80% of enrolled participants at 8 weeks. That percentage is a target, not a report of the observed follow-up rate. The record does not provide the number with available outcome data, reasons for missingness, imputation methods, or sensitivity analyses.

The analysis population is not reported in the registry record. Enrollment of 8 participants does not establish how many contributed data to any particular endpoint, whether all enrolled participants were included in an analysis, or how incomplete participation was handled. These omissions prevent assessment of attrition, outcome-specific denominators, and the robustness of any estimates.

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.

Most frequent non-serious adverse event terms

The registry’s adverse-event figures list the intervention group with 8 participants at risk for serious events and 0 participants affected. For other, non-serious adverse events, 8 participants were at risk and 1 was affected. Deaths are listed as 0 among 8 participants at risk. These counts describe the entries in the registry record; they do not provide event rates beyond the counts themselves.

No serious adverse-event terms are listed. The record does not provide details about the one participant counted for other adverse events, including the event description, timing, severity, or relationship to the intervention. It also does not report the method or period used for adverse-event collection in the information available for this analysis.

These figures should be read as limited descriptive safety reporting in a small single-group study. A count of zero serious events in this group does not establish that serious events cannot occur, and the record’s limited event detail constrains interpretation of the other adverse event. The figures do not support a comparison with another group because no comparator group was registered.

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

The registry record establishes that a completed proof-of-concept study enrolled 8 participants with metabolic syndrome in a single-group program combining positive psychology, motivational interviewing, and physical activity. It identifies feasibility as the primary aim and defines exercise completion as the primary endpoint. It also records planned assessments of acceptability and preliminary changes in physical activity, related behaviors, and psychological well-being.

What the record does not establish is whether participants completed the intended number of exercises, whether they found the program acceptable, or whether measured outcomes changed. The stated thresholds and hypotheses are prospective expectations, not observed results. Because the record lists 0 analyses and does not report observed outcome summaries, neither the magnitude nor the precision of any outcome can be evaluated.

Even if within-group changes were available, the design would not provide a randomized comparison with a control group. A baseline-to-follow-up difference in a single group can be useful descriptively, but it cannot by itself establish that the intervention caused the difference. The absence of a comparator is especially important when interpreting preliminary outcomes as opposed to feasibility measures.

The small enrollment and unreported outcome denominators further limit interpretation. The registry does not report how many participants contributed data to each measure, how missing data were handled, or confidence intervals for estimates. Thus, there is no basis for judging outcome precision or whether results would generalize beyond the enrolled group.

The appropriate reading is narrow: this record documents a feasibility-focused intervention study and its intended assessments, alongside limited adverse-event counts. It does not provide posted findings sufficient to determine whether its targets were reached or to estimate intervention effects.

14. Why This Trial Matters Statistically

Feasibility studies address questions that precede a definitive test of an intervention: can participants engage with the program, can assessments be completed, and do participants find the activities acceptable? This trial made those questions central. Its primary endpoint was exercise completion, and its summary specified targets for completing exercises and obtaining objective physical activity follow-up data. Those targets clarify what investigators intended to learn, even though observed results are not reported in the registry record.

The trial also illustrates why endpoint labels and hypotheses must be distinguished from findings. Naming a primary outcome and a target does not show that the target was achieved. The registry identifies the intended measure, but does not post the observed mean, variability, or analyses. This makes transparent reporting of outcome data particularly important for a preliminary study: readers need the actual participation and follow-up results to judge whether a larger study is practicable.

Statistically, the design also demonstrates the difference between descriptive change and a treatment comparison. A single-group study can inform how outcomes moved over time in its participants, but it cannot supply a randomized contrast against a separate group. That distinction matters when interpreting any preliminary outcome hypothesis and when considering a future controlled evaluation.

Finally, this record shows the limits of planning illustrations based on a preliminary effect. Planning assumptions can be useful for considering future research, but they are not observed power and do not replace a design-specific sample-size justification. In this case, the stated two-arm planning assumptions differ from the registered single-group model. Keeping those purposes separate helps prevent an exploratory planning calculation from being mistaken for evidence about intervention performance.

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 most immediate limitation is that observed outcome values and analyses are not reported in the registry record. The primary endpoint is defined, but the number of exercises completed, its mean and standard deviation, and the proportion meeting the stated feasibility benchmark are absent. Acceptability ratings and results for the other intended outcomes are also not reported. As a result, the stated hypotheses cannot be evaluated from the posted results.

Enrollment was 8 participants, and the registry does not report how many participants contributed data to individual outcomes. Without follow-up denominators, missingness reasons, or a description of missing-data methods, the completeness of the outcome data cannot be assessed. The hypothesis about obtaining objective physical activity follow-up data at 8 weeks should not be treated as the achieved follow-up rate.

The single-group design has no concurrent comparator. Therefore, any within-group change, if it had been reported, would not isolate the intervention’s contribution from other changes over time. The registry also records no masking. The analysis plan, including methods for repeated measures, outcome prioritization, multiplicity, and analysis populations, is not reported in the registry record.

The intervention description indicates an 8-week group program but does not report complete delivery and adherence details in the record. The adverse-event information is limited to counts, without descriptions for the participant affected by an other adverse event. Finally, the sample-size planning assumptions describe a two-arm illustration, whereas the registered trial is single group; those assumptions should not be used to characterize the trial’s design or evidential strength.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Developing a Positive Psychology Intervention to Promote Health Behaviors in Metabolic Syndrome: Proof-of Concept Trial — NCT03473886.
• Registry record last updated 2020-05-12; status last verified 2020-04.
• Results first posted 2020-05-12.
• 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.

19. Record Summary

This completed proof-of-concept trial evaluated a group-based positive psychology and motivational interviewing program intended to promote physical activity and related health behaviors among participants with metabolic syndrome. The registry reports enrollment of 8, a single-group model, no masking, and a primary completion date of 2019-04-15.

The primary endpoint was the number of intervention exercises completed during 8 weeks of group sessions. Planned aims also included acceptability, physical activity, related health behaviors, and psychological outcomes. The registry lists 22 outcome measures and 0 analyses, but does not report observed outcome values or analysis results.

Adverse-event entries list 0 participants affected by serious events, 1 affected by other adverse events, and 0 deaths. The single-group design does not provide a randomized comparison. The posted record therefore documents the study’s aims and limited event counts, but does not support conclusions about whether feasibility targets were met or whether the intervention changed outcomes.