Positive Psychology to Improve Healthy Behaviors After an Acute Coronary Syndrome: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Positive Psychology to Improve Healthy Behaviors After an Acute Coronary Syndrome (NCT02004158), a na na study. The primary outcome is Rate of Exercise Completion.

2. Clinical Question

The registry record frames this study as a proof-of-concept evaluation of a positive psychology program for people with acute coronary syndrome and less-than-optimal adherence to health behaviors. Its primary focus is the rate of completion of program exercises, rather than a randomized comparison of health outcomes.

3. Trial Design

This is a completed, single-group, proof-of-concept study of a behavioral positive psychology intervention after acute coronary syndrome. The registry lists enrollment of 23 and identifies Massachusetts General Hospital as the sponsor. The recorded start is 2013-11, and primary completion is recorded as 2014-09. The study phase is listed as NA.

Allocation is listed as NA, masking as NONE, and the study model as SINGLE GROUP. Those entries describe a design without a randomized allocation or a separate comparison arm. The positive psychology group is the only arm described. Consequently, the record does not support a randomized estimate of the intervention’s effect relative to a control condition. Any assessment of completion would be a description of participants’ experience in this group, not a between-group treatment contrast.

The stated study purpose is to assess the ease and usefulness of a positive psychology program for patients with acute coronary syndrome and less-than-optimal adherence to health behaviors. The registry summary presents the program as a possible adjunctive approach for cardiac populations, but does not establish that the study tests a clinical outcome against a control group.

The primary outcome is the rate of exercise completion, with a timeframe of 8 weeks. It is defined using the number of participants who have a good rate of completion: an average of 5 or more exercises completed per subject, from 8 exercises in total. The registry also lists a secondary outcome, Objective Psychological Impact of Exercises. Further endpoint definitions and results are not reported in the registry record.

The registry marks the study COMPLETED, but completion status does not itself indicate that all planned data were collected or that results were analyzed. Recruitment details, follow-up completeness, protocol deviations, and reasons for any missing endpoint data 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 Rate of Exercise Completion, measured over 8 weeks.

The primary endpoint is the rate of exercise completion over 8 weeks. The registry defines a good completion rate as an average of 5 or more exercises completed per subject, from 8 exercises in total. It describes the outcome in participant-count terms: the measure is the number of participants with a good completion rate. This makes the endpoint binary at the participant level: a participant either meets the stated threshold or does not.

Such an endpoint can be useful in a proof-of-concept study because it describes whether participants engage with the program’s exercises according to a prespecified threshold. In general, a completion measure addresses participation or feasibility; it does not by itself establish a change in health behavior or a clinical benefit. Interpretation also depends on how completion is recorded, how missing exercise data are handled, and whether the threshold was selected before outcomes were observed. Those details are not reported in the registry record.

The registry record defines the endpoint but does not report the observed number of participants meeting the threshold. It therefore does not allow a reader to assess the completion rate or its precision. The listed secondary outcome is Objective Psychological Impact of Exercises, but its measurement details and results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a count of participants meeting a completion threshold. Although the outcome is expressed as a number of participants, the underlying classification is binary at the participant level: each participant either meets the definition of a good completion rate or does not. The threshold is an average of 5 or more completed exercises per subject, from 8 total exercises, over 8 weeks. The record does not state the number who met this threshold.

What a binary outcome means

In general, a binary endpoint reduces a set of observations to two categories. For this study, the defined categories follow from the completion threshold. A count of participants in one category can be reported alongside the number assessed, and a proportion can then summarize the frequency of that category. The record does not report either an observed count for the primary endpoint or the endpoint’s evaluable denominator, so no observed proportion or interval estimate can be interpreted from the registry entry.

In general, a confidence interval describes a range of values compatible with the data under a specified statistical method. For a binary outcome, its width depends in part on the number of observations and the observed frequency. A small study may yield substantial uncertainty, especially when the outcome is uncommon or common. No confidence interval or other precision estimate for exercise completion is reported in the registry record.

Why the design matters

The study is listed as SINGLE GROUP, with allocation recorded as NA and masking as NONE. In general, a single-group study can describe what happened among participants who received an intervention, but it does not create a concurrent comparison for estimating what would have happened without that intervention. Changes over time, outside influences, and characteristics of participants who enroll can all affect observed outcomes. Without a comparator, those possibilities cannot be distinguished using a between-group contrast.

Randomization, when used, aims to make comparison groups similar on average with respect to measured and unmeasured baseline factors. That general rationale does not apply as a comparison method in this single-group record. The registry does not report a control arm, randomized allocation, or an adjusted comparative analysis. Accordingly, no treatment-effect estimate relative to another condition is available.

Planning calculations and observed evidence

The registry’s sample-size assumptions describe a planning illustration rather than the trial’s own design. The assumptions are a two-sided significance level of 0.05, equal allocation between two arms, a normal approximation, and an effect to detect expressed as a stated fraction of the observed effect. The record also characterizes the illustration as based on the observed effect, not as a design justification for this study. These assumptions do not change the fact that the registered study is single group.

In general, sample-size planning asks how much information a proposed study might need under specified assumptions. It is not a measure of the probability that a completed study’s finding is true. A planning calculation is not observed power, and it cannot substitute for the outcome estimate and its uncertainty. The registry does not report a protocol sample-size justification or a two-arm trial design for this study. No inference about the adequacy of the study’s enrollment can be made from the planning assumptions alone.

Analyses and model choices

The registry record does not report statistical analyses for the primary or secondary outcomes. It therefore does not identify a fitted model, adjustment variables, a test used for the completion endpoint, or a method for handling repeated observations. It would be inappropriate to assume that a particular method was used merely because it could be applied to a binary outcome.

In general, analysis choices should match the outcome structure and design. A binary endpoint may be described using counts and proportions; an inferential analysis may also quantify uncertainty, if appropriate to the question and study design. A single-group estimate answers a descriptive question about the observed group, while a comparative model requires a meaningful comparator. No such comparative result is reported.

Over-dispersion is a general issue in count models: it occurs when observed variability exceeds what a model assumes, and can make standard errors too small if ignored. The primary endpoint is defined as a participant count, but the registry does not report a count-model analysis. There is therefore no basis for saying that over-dispersion was assessed or affected any result in this study.

Likewise, the registry does not report interim analyses, stopping rules, or a prespecified statistical analysis plan. Their existence, absence, or implementation cannot be inferred from the completed status. The clearest statistical reading is therefore limited to the outcome definition, design classification, enrollment, and safety counts that the record explicitly lists.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Positive Psychology")
n      <- c(23)
events <- c(17)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Positive Psychology  23  17  73.9  51.6  89.8  53.5  87.5  53.3  87.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 4 outcome measures and identifies Objective Psychological Impact of Exercises as a secondary outcome. The primary outcome is exercise completion over 8 weeks. The record does not provide the full set of outcome definitions, results, or analyses, and it does not report a multiplicity strategy.

In general, multiplicity arises when several outcomes or statistical comparisons are assessed. Conducting multiple tests can increase the chance of at least one apparently unusual result, depending on the tests and their relationship. Methods to address multiplicity may adjust significance thresholds, define an outcome hierarchy, or emphasize estimation and uncertainty. The registry does not report whether any such approach was planned or used, and no statistical analyses are reported. It is therefore not possible to evaluate how multiplicity was handled.

Missing-data methods and the analysis population are also not reported in the registry record. The enrollment of 23 does not establish how many participants completed the 8-week assessment, performed any exercise, or had sufficient information to classify the primary endpoint. The record does not explain whether participants with incomplete exercise logs were counted as not meeting the threshold, excluded, or handled in another way.

In general, missing outcome data can affect both the estimate and its uncertainty, particularly when the likelihood of missingness is related to participants’ experiences or outcomes. A transparent report would describe the number assessed, the amount and pattern of missingness, and the analysis population and assumptions used. Those details are not reported in the registry record, so the endpoint’s completeness and potential sensitivity to missing data cannot be assessed.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The serious adverse event entry lists the Positive Psychology group with 23 participants at risk and 0 affected. This is a count within the single study group, not a comparative safety estimate. Because there is no separate comparator arm, the registry record does not support a between-group comparison of serious adverse events.

The reported zero should be read narrowly: the record lists 0 participants as affected for the serious-event entry. It does not establish that participants experienced no adverse events of any kind, and it does not describe how events were collected or adjudicated. The record lists no top serious-event terms. A death count is not reported in the registry record.

In general, a zero count in a small study does not prove that an event is impossible or that risk is absent. The amount of information available depends on the number observed, the length and completeness of follow-up, and the event definitions and ascertainment methods. The registry lists 23 at risk, but does not report further safety follow-up details. The serious-event figures therefore describe what was recorded, without establishing broader safety conclusions.

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

This study addresses a focused proof-of-concept question: whether participants with acute coronary syndrome and less-than-optimal adherence to health behaviors engage with a positive psychology program’s exercises. The registry defines good completion as an average of 5 or more exercises completed per subject, out of 8, during 8 weeks. That definition makes the intended measure understandable, but the registry record does not report the number of participants who met it.

For that reason, no quantitative conclusion about the observed completion rate can be drawn from the posted results. The record also does not report a primary outcome estimate, confidence interval, p-value, or analysis. Enrollment of 23 is study context, not a substitute for an endpoint result or confirmation that all enrolled participants contributed outcome data.

The single-group design means there is no control-group contrast. A descriptive result, if reported, would characterize participants in this study and would not by itself establish that the program caused an outcome. The record does not provide a comparative estimate of the intervention’s effect on exercise completion, health behaviors, or clinical outcomes.

The registry’s stated aim is to assess ease and usefulness, and its secondary outcome is Objective Psychological Impact of Exercises. No result for that secondary outcome is reported in the registry record. The record therefore does not establish psychological impact or improvement in health behaviors.

The serious adverse event entry records 0 affected among 23 at risk in the Positive Psychology group. That entry is limited to the reported serious-event information and should not be interpreted as evidence that no adverse events occurred. Taken together, the record supports describing the study design, intended endpoint, enrollment, and listed serious-event count. It does not support a conclusion about efficacy, comparative effectiveness, or the frequency of primary endpoint completion.

14. Why This Trial Matters Statistically

This trial matters statistically because it illustrates the difference between specifying an outcome and reporting evidence about that outcome. A threshold-based completion endpoint can be clearly defined, but readers still need the observed count, the number assessed, and an account of missing data to understand what the study found. The registry gives the threshold and timeframe, but does not report the primary result.

It also demonstrates why design labels are essential to interpretation. This is a single-group study, not a randomized comparison. The absence of a comparator does not make descriptive information meaningless, but it limits the question that can be answered: a single group can be characterized, while a comparative treatment effect cannot be estimated from the registered design.

The proof-of-concept framing is relevant. Questions about whether a program is usable or whether participants complete its exercises differ from questions about whether it changes clinical outcomes. The registry describes an interest in ease and usefulness and defines exercise completion as the primary endpoint. The record does not report results that would quantify completion or establish changes in health behaviors.

Finally, the entry shows why planning assumptions and study results must be kept distinct. A sample-size planning illustration with specified assumptions is not a report of this study’s analysis and is not observed power. The study itself is registered as single group, and the registry does not provide a statistical analysis result. Reading each item according to its role helps prevent planning language, endpoint definitions, and safety counts from being mistaken for evidence of a comparative effect.

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.

Several limitations are specific to what the registry record reports. First, it defines the primary completion endpoint but does not report the number of participants who met its threshold. The primary result and its precision therefore cannot be assessed. The record also does not report how many of the 23 enrolled participants had evaluable endpoint data, so the enrolled count cannot be assumed to be the endpoint denominator.

Second, the study is single group, with allocation recorded as NA and no separate comparator arm. This prevents a like-for-like comparison and limits interpretation to the design’s descriptive scope. The registry does not report a randomized contrast or an adjusted comparative analysis.

Third, the entry lacks details needed to evaluate endpoint measurement and data completeness. Further information about how exercises were recorded, how the average was calculated when observations were incomplete, and how missing data were handled is not reported in the registry record. The analysis population and protocol deviations are also not reported.

Fourth, although the registry lists 4 outcome measures and a secondary outcome, the posted results do not include statistical analyses or a multiplicity approach. The measurement details and findings for the secondary outcome are not reported. Interim analyses and a statistical analysis plan are not reported either, so their status cannot be inferred.

Finally, the serious-event entry is limited to 23 at risk and 0 affected in the Positive Psychology group. Safety ascertainment details and the death count are not reported in the registry record. These gaps prevent the serious-event count from serving as a comprehensive safety assessment.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Positive Psychology to Improve Healthy Behaviors After an Acute Coronary Syndrome — NCT02004158.
• Registry record last updated 2017-07-24; status last verified 2017-05.
• Results first posted 2017-07-24.
• 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 describes a completed, single-group proof-of-concept study of a behavioral positive psychology intervention after acute coronary syndrome. Enrollment is listed as 23. The primary endpoint is the number of participants with a good exercise-completion rate over 8 weeks, defined as an average of 5 or more of 8 exercises completed per subject.

The registry does not report the primary endpoint result, statistical analyses, or the secondary outcome result. It lists a serious adverse event count of 0 affected among 23 at risk in the Positive Psychology group. With no comparator arm, these entries do not provide a comparative treatment-effect estimate.