A Positive Psychology Intervention for Patients With Multiple Sclerosis: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for A Positive Psychology Intervention for Patients With Multiple Sclerosis (NCT03637699), a randomized na study. The primary outcome is Percentage of PP Exercises Completed by Subjects.

2. Clinical Question

The central question concerns feasibility, particularly whether participants complete the exercises, rather than a definitive test of clinical benefit. The registry describes the study as a pilot and names tolerability and efficacy as areas of evaluation. Completion is the posted primary outcome; ratings of exercise ease and utility are also identified as outcomes of interest. Secondary outcomes include changes in affect, trait optimism, depression, anxiety, health-related quality of life, work productivity, and perceived stress.

The design compares participants assigned to positive psychology training with participants assigned to a waitlist control during the intervention phase. Because the waitlist group was scheduled to receive training later, this comparison applies to the initial phase rather than to a permanently untreated group. The registry record does not report a primary between-group inferential analysis, and the posted completion percentages do not by themselves establish whether training changed any psychological or functional outcome.

3. Trial Design

The registry record identifies a randomized, parallel-group trial with no masking. Its official title describes it as a Phase I randomized controlled trial, while the recorded phase designation is NA. The study enrolled 30 participants with multiple sclerosis and is marked completed. The recorded start date is 2018-03-12, and the primary completion date is 2019-04-09.

Participants were assigned to an intervention arm or a waitlist control arm, with 15 listed in each. During the intervention phase, the intervention arm was scheduled to complete five weeks of positive psychology exercises, one exercise per week. The study description also says participants in the intervention group would have weekly calls with the study trainer. The waitlist control group had no study activities during that phase. During the extension phase, described as weeks 6-10, the waitlist group was scheduled to complete the same five-week training.

The program used activities intended to encourage positive emotional experiences. Examples in the registry description include recalling positive life events and performing acts of kindness. The record does not provide further details about how the exercises were delivered, how assignment was generated or concealed, or whether any procedures beyond the recorded absence of masking were used.

The primary outcome is the percentage of positive psychology exercises completed over five weeks. The record also lists secondary outcomes related to affect, optimism, depression, anxiety, health-related quality of life, work productivity, perceived stress, and ease of completing the exercises. Arm-level completion values are 93.0 for both groups. The registry record does not report a sponsor analysis comparing those values. Secondary arm summaries are available for three outcomes, with unadjusted recalculated comparisons based on the posted summary statistics.

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 Percentage of PP Exercises Completed by Subjects, measured over Five weeks.

The primary endpoint measures the percentage of positive psychology exercises completed by participants over five weeks. It is a count-based measure expressed as a percentage, rather than a rating of mood or a direct measure of health-related quality of life. The registry describes completion as a way to examine tolerability. Completion can indicate whether participants engaged with the assigned activities, but it does not by itself measure how participants felt about the exercises or whether their emotional or functional outcomes changed.

The registry lists a value of 93.0 for the intervention arm and 93.0 for the waitlist control arm, with 15 participants in each. The waitlist group was scheduled to receive training during the extension phase, so its training occurred later than the intervention arm's training. The outcome timeframe is listed as five weeks. The registry record does not report an inferential comparison for the primary endpoint, a measure of uncertainty around the arm values, or details of how exercise completion was collected and handled when information was unavailable.

Completion is useful in a pilot because it addresses whether participants carried out the program activities. It should not be treated as evidence that the program changed positive affect, depression, anxiety, quality of life, or work functioning. Those are distinct outcomes, and the registry record lists them separately among the secondary measures.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry record gives arm-level summary statistics but does not list sponsor-reported analyses for the posted outcomes. The secondary comparisons described in the record are recalculated from those summaries. They are unadjusted comparisons, so they do not account for other measured outcomes or possible differences in participant characteristics. The registry record does not report whether the sponsor used a different model or analysis approach.

What a mean difference represents

For a continuous outcome, a mean difference expresses the contrast between the average change in the intervention arm and the average change in the waitlist control arm. A positive or negative result depends on the scale's scoring direction and on which group is subtracted from the other. The registry record does not give enough information to assign a favorable direction to each scale. The recalculated mean differences should therefore be read as numerical contrasts, not as a direct statement that one group improved more.

For trait optimism, the recalculated mean difference is 3.4, based on an intervention mean of 2.1 and a waitlist control mean of -1.3. The interval bounds are 1.189 and 5.611. For depression, the recalculated mean difference is -2.1, with bounds -5.665 and 1.465. For perceived stress, the recalculated mean difference is 0.7, with bounds -1.338 and 2.738. These recalculations use the posted means, standard deviations, and participant counts; they are not reported sponsor estimates.

How to read an interval estimate

In general, an interval estimate represents uncertainty around an estimated effect under the assumptions of the calculation. A narrower interval indicates greater precision than a wider one, while an interval that includes no difference is compatible with no difference as well as with effects in either direction, depending on its bounds. The confidence level for the recalculated intervals is not reported in the registry record, so it should not be inferred from the displayed limits alone. The intervals also do not account for unreported design features, missing outcomes, or multiplicity.

How to read an unadjusted p value

In general, a p value measures how unusual the observed data, or data more extreme, would be under a specified null model. It does not measure the probability that the null hypothesis is true, the size or importance of an effect, or the probability that a result will repeat. The posted recalculated p values are unadjusted: they do not incorporate the fact that several outcomes are considered. The registry record does not report a multiplicity procedure or a prespecified analysis hierarchy.

The recalculated unadjusted p values are 0.003 for trait optimism, 0.248 for depression, and 0.501 for perceived stress. These values should be interpreted alongside the mean differences, interval bounds, sample sizes, outcome definitions, and missing analysis details. They are not sponsor-reported p values, and they do not establish that any outcome was the primary basis for a formal conclusion.

Why sample-size illustrations are not trial power

The planning illustrations use the observed effects as reference points and show hypothetical participants per arm for 80% power and 90% power at different fractions of those effects. The stated assumptions are a two-sided significance level of 0.05, equal allocation, and a normal approximation. These calculations are planning illustrations, not the trial's own design justification and not observed power. They do not show the probability that this completed study detected a true effect. The trial's sample-size justification is not reported in the registry record.

In general, a planning calculation depends on assumptions about the effect worth detecting, variability, significance threshold, allocation, and analysis method. Using an effect observed in a small study as the planning target can produce unstable illustrations because that estimate is itself uncertain. The registry record does not report whether these planning values informed the trial or whether a different sample-size approach was used.

Why outcome type matters

The primary endpoint is a percentage of exercises completed, while the posted secondary comparisons concern mean changes in scale scores. Count-based or percentage outcomes and continuous scale outcomes have different distributions and may require different analytic methods. General statistical practice considers the outcome's distribution, its denominator, and the assignment structure when choosing a model. The registry record does not report the sponsor's model for the primary endpoint, a distributional assessment, or an inferential method for the posted secondary outcomes. Accordingly, the primary completion values are best treated as descriptive, and the secondary comparisons as recalculations from summary statistics.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 10 outcome measures and nine posted secondary results. It names several distinct secondary domains, including affect, optimism, depression, anxiety, health-related quality of life, work productivity, and perceived stress, as well as ratings of exercise ease. No reported analyses are listed. The record does not state which outcomes were prespecified for formal inference, whether any outcome hierarchy was used, or whether the sponsor adjusted for multiple comparisons.

Multiplicity matters because interpreting many separate tests at a conventional threshold can increase the chance of at least one apparently notable result. In general, a prespecified hierarchy or adjustment procedure can help control this issue. The registry record does not report such a procedure. The recalculated secondary p values are unadjusted and should not be interpreted as confirmatory findings in isolation.

Participant counts in the posted secondary summaries are not identical across outcomes: the trait optimism and perceived stress summaries list 14 participants in each arm, while the depression summaries list 14 in the intervention arm and 12 in the waitlist control arm. The reasons for these counts, including whether they reflect missing observations, exclusions, or another analysis population, are not reported in the registry record. Missing-data methods, imputation procedures, and sensitivity analyses are also not reported.

The registry record does not describe an intention-to-treat, per-protocol, or other analysis population for these outcomes. It does not report how participants with incomplete outcome data were handled or whether all randomized participants were included in any sponsor analysis. The primary endpoint lists 15 participants per arm, but the record does not explain the relationship between those counts and the posted completion percentages. These omissions limit assessment of potential bias from unavailable measurements and make it difficult to determine how representative each result is of the randomized groups.

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 lists 15 participants at risk in each arm for serious adverse events and for other adverse events. It reports zero serious adverse events and zero other adverse events in the intervention arm, and the same counts in the waitlist control arm. The death count is zero in both arms. No serious adverse event terms are listed.

These figures describe what was recorded among the participants included in the registry safety summaries. They do not establish that no adverse events could occur, and they do not provide a precise estimate of event risk. With 15 participants at risk in each arm, uncommon events could remain unobserved. The registry record does not provide additional detail about event definitions, collection procedures, severity grading beyond the serious-event category, duration of safety follow-up, or how events were attributed to the intervention.

The zero counts should therefore be read as an absence of recorded events in these small groups, not as proof of safety or as a comparison showing equal safety. The registry record also does not report a formal statistical safety analysis.

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

The registry results describe a completed, randomized pilot in which 30 people with multiple sclerosis were assigned to a five-week positive psychology program or a waitlist control arrangement. The primary endpoint is exercise completion. Both arms have a posted completion value of 93.0, but the registry record does not report an inferential comparison or an uncertainty estimate for that outcome. The result is descriptive evidence about completion in this study, not a demonstration of an effect on health or emotional outcomes.

Three secondary outcomes have posted arm summaries and recalculated unadjusted comparisons. The optimism comparison has an interval that does not include no difference and an unadjusted p value of 0.003. The depression and perceived stress interval bounds include no difference, with unadjusted p values of 0.248 and 0.501. These comparisons are based on summary statistics, not sponsor-reported analyses, and the record does not report scale direction, a multiplicity plan, or missing-data methods. The patterns should be understood as exploratory rather than as a definitive evaluation across outcomes.

In general, a pilot can help characterize whether a program can be delivered and can inform future research questions. It is not automatically sized or analyzed to provide precise estimates of effects. The registry does not report a sample-size justification, so the purpose and precision intended by the trial's design cannot be assessed from the record. The planning illustrations based on observed effects are not evidence of observed power or proof that the trial was adequate for a particular effect.

The results do not establish that positive psychology training improves or fails to improve any clinical outcome. They also do not establish equivalence between the randomized groups, generalizability beyond the enrolled participants, or the safety of the program in a broader population. The registry record offers a limited descriptive account and several exploratory secondary comparisons; fuller interpretation would require a reported analysis plan, outcome definitions, and details about missing data and measurement.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of why different outcome types and study aims need separate interpretation. The primary outcome measures exercise completion, a feasibility-oriented measure, while the secondary outcomes concern psychological and functional changes. A high completion value does not answer whether those other measures changed, and an exploratory change-score contrast does not replace a primary endpoint analysis.

The record also illustrates the distinction between descriptive results and inferential evidence. The completion values are reported by arm, but no primary comparison or interval estimate is reported. Secondary mean differences, intervals, and p values are recalculated from the posted summaries rather than listed as sponsor analyses. Keeping those sources distinct prevents a reconstructed comparison from being mistaken for the trial's official analysis.

Small pilot groups can yield imprecise effect estimates, and the number of participants represented in secondary summaries varies. The recalculated intervals make uncertainty visible, while the unadjusted p values do not account for the several outcomes under consideration. The record does not report a multiplicity strategy, missing-data procedures, or the analysis populations, all of which affect how confidently results can be interpreted.

The planning illustrations can help readers understand how sample-size calculations depend on assumed effects, but they are not evidence that the trial was powered for its observed results. Their assumptions are explicitly presented as a planning exercise rather than the trial's own design. Taken together, the record supports careful distinctions among feasibility, outcome estimation, and confirmatory inference. It also shows why a registry entry with numerical summaries may still leave important questions about precision and analysis unanswered.

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.

Several limitations specific to this record constrain interpretation. The primary outcome has arm-level completion values but no reported between-group analysis or interval estimate. The registry does not explain how the completion percentage was defined in practice, how missing completion information was handled, or whether the same collection procedures were applied during the intervention and extension phases.

The waitlist group received the program later, so its role as a comparator applies to the initial intervention phase. The registry does not report whether outcomes were measured at comparable times relative to training in both groups or how timing was handled in the analyses. No masking was recorded, and the record does not describe any procedures to reduce assessment or reporting bias.

The secondary comparisons are recalculated from arm summaries and are unadjusted. The record does not report sponsor analyses, scale scoring directions, multiplicity handling, analysis populations, or missing-data methods. Secondary participant counts vary, and the reasons are not reported. Results are posted for only some of the named secondary domains, limiting conclusions about the broader outcome set.

The total enrollment was 30, with 15 participants per arm. The registry record does not report the trial's sample-size justification or a prespecified effect size. Planning illustrations based on observed effects are not a substitute for those design details. Safety summaries record zero events in groups of 15, but the record does not provide further information about event ascertainment or follow-up. These limitations mean the results are best read as descriptive and exploratory, with substantial unanswered questions about estimation and analysis.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: A Positive Psychology Intervention for Patients With Multiple Sclerosis — NCT03637699.
• Registry record last updated 2021-08-16; status last verified 2021-07.
• Results first posted 2021-08-16.
• 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

NCT03637699 is a completed randomized, parallel-group trial of a positive psychology intervention for people with multiple sclerosis. It enrolled 30 participants, with 15 assigned to the intervention and 15 to a waitlist control. The registry marks masking as none and the phase designation as NA; the official title describes a Phase I randomized controlled trial.

The intervention involved five weeks of positive psychology exercises, one exercise per week. The waitlist group was scheduled to receive the training during the extension phase. The primary outcome was the percentage of exercises completed over five weeks, with a posted value of 93.0 in each arm. No primary inferential comparison is reported.

Three secondary outcomes have arm summaries and recalculated unadjusted comparisons. Sponsor-reported analyses, a multiplicity plan, missing-data methods, and analysis populations are not reported in the registry record. Safety summaries list zero serious adverse events, zero other adverse events, and zero deaths in both arms.