Gaining Optimism After Weight Loss Surgery (GOALS) II: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Gaining Optimism After Weight Loss Surgery (GOALS) II (NCT04868032), a randomized na study. The primary outcome is Number of Intervention Sessions Completed.

2. Clinical Question

The trial also listed changes in moderate to vigorous physical activity, steps, light physical activity, positive affect, optimism, depressive symptoms, anxiety, and exercise identity as secondary outcomes. These measures indicate that the broader research question included both activity and psychological outcomes. No results for those outcomes are reported in the registry record.

3. Trial Design

GOALS II was a randomized, parallel-group trial with single masking. It compared a behavioral PP-MI intervention with a behavioral physical activity education control among people who had recently undergone bariatric surgery. The registry lists an enrollment of 58. It does not identify who was masked, so the meaning of single masking cannot be specified further from this record.

The intervention was designed to be delivered by phone over 10 weekly sessions, each lasting 30 minutes, with a written treatment manual. Its stated purpose was to support physical activity by using positive psychology and motivational interviewing. The comparator received a Fitbit and educational materials mailed at 4 time points during the intervention period, without an intervention manual or phone calls with an interventionist. These are different levels of contact and content, so the contrast concerns the full intervention package versus the education-control package, not a single isolated component.

The trial status is listed as completed. The record gives a start date of 2022-07-01 and a primary completion date of 2025-02-03. It identifies Massachusetts General Hospital as the sponsor. The phase is listed as NA, and the condition is bariatric surgery.

The registry record does not report the randomization procedure, allocation concealment, specific masking arrangements, site count, recruitment details, or whether participants could receive other physical activity support. It also does not describe a statistical analysis plan or provide outcome results. The primary outcome is a feasibility measure in the PP-MI group, while the listed secondary outcomes concern changes in activity and psychological measures. Without posted results, the design can be described, but the study's observed outcomes and the precision of any treatment comparisons cannot be assessed from this 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

Reasons for not completing this period:

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 Intervention Sessions Completed, measured over 10 weeks.

The primary endpoint is the number of intervention sessions completed by participants assigned to PP-MI, measured over 10 weeks. It is a continuous summary expressed as a mean, with standard deviation identified as the dispersion measure. The endpoint focuses on whether participants engage with the intended intervention, rather than directly measuring physical activity or a psychological outcome.

The stated reason for measuring session completion is feasibility. The registry description sets a criterion of an average of at least 7/10 sessions completed. That threshold defines the intended benchmark; it does not establish that the benchmark was met. The registry record does not report the observed mean, its standard deviation, or a confidence interval, and it does not state how missing session records were handled.

Feasibility measures can help describe whether an intervention was delivered and taken up as intended. In this trial, session completion alone would not show whether physical activity changed, whether any change was attributable to PP-MI, or whether the intervention was acceptable to participants. Although acceptability is mentioned in the trial's brief summary, the primary endpoint listed in the record is session completion. Results for acceptability are not reported in the registry record.

The primary endpoint is specific to the intervention group, so it is not itself a comparison of mean session completion between randomized arms. The record does not report a primary endpoint estimate or inferential analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary measure as a mean with standard deviation. These are descriptive summaries of a continuous outcome: the mean locates the center of the observed values, while the standard deviation describes their spread around that center. For session completion, the mean would describe average attendance in the intervention group. The registry record provides neither summary statistic, so the distribution and typical level of completion cannot be evaluated.

What would a confidence interval add?

General statistical explanation: A confidence interval describes uncertainty around an estimate under a specified statistical procedure. A narrow interval indicates greater precision than a wide interval, given the same method and assumptions. For a mean session-completion estimate, an interval would help show how precisely the average was estimated. For a treatment contrast in a secondary outcome, an interval would describe uncertainty around the estimated difference between assigned groups. The registry record does not report confidence intervals for these outcomes, so their precision cannot be assessed.

Why distinguish the feasibility endpoint from treatment comparisons?

The primary endpoint is a one-arm measure of sessions completed among participants assigned to PP-MI. Its purpose is to assess intervention engagement against the stated average-completion criterion. It is not a between-arm treatment effect. The listed physical activity and psychological outcomes, by contrast, are framed as changes and could be used to examine differences between the randomized groups if results and an analysis were reported. No such estimates appear in the registry record.

What can randomization support?

General statistical explanation: Randomization is intended to make assigned groups comparable on average with respect to factors known and unknown at allocation. It provides a basis for estimating the effect of assignment to the compared intervention packages when the trial's outcomes, follow-up, and analysis are adequately described. It does not guarantee that every measured characteristic will be balanced in a particular trial, and it does not remove the need to report missingness, outcome definitions, and analysis methods. The record states that allocation was randomized and the model was parallel, but the randomization procedure and analysis details are not reported in the registry record.

How should the sample-size illustrations be understood?

General statistical explanation: The planning assumptions in the record describe illustrations based on a fraction of an observed effect, a two-sided significance level of 0.05, equal allocation, and a normal approximation. Such illustrations ask what sample size might be required under stated assumptions; they are not a description of the trial's original design justification. The record explicitly distinguishes the illustration from the trial's own design. It also does not report the observed effect estimate needed to assess the assumptions or reproduce a particular planning scenario. Any sample-size figure derived from that approach is a planning illustration, not observed power.

Power is a design-stage probability defined relative to a specified effect, variability, significance level, and analysis. It is not a retrospective measure of whether a trial's findings are true or whether an effect exists. In particular, a calculated sample size under an assumed effect does not reveal the power of this completed trial. The registry record does not report a sample-size justification or the statistical plan used to select enrollment.

What does over-dispersion mean in general?

General statistical explanation: Over-dispersion occurs when the variability in count data is greater than a statistical model expects. If a count outcome is over-dispersed and the model does not account for it, standard errors and uncertainty estimates can be misleading. Session completion is bounded by the planned number of sessions and is summarized in the record as a mean with standard deviation, but the record does not report a model for analyzing it. It is therefore not possible to determine whether a count model was used or whether over-dispersion was assessed.

The registry's listed analysis count is zero, and no outcome analysis is described. There are consequently no reported test statistics or p-values to interpret. Without the analysis plan, estimates, and uncertainty measures, the statistical methods used to evaluate the trial's secondary outcomes cannot be reconstructed from this record.

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("Positive Psychology-Motivational Interviewing Inte")
n   <- c(29)
m   <- c(9.6)
sp  <- c(1.5)
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  Positive Psychology-Motivational Interviewing Inte  29  9.600  1.500  9.029  10.171

11. Multiplicity, Missing Data and Analysis Populations

The record lists multiple secondary outcomes: changes in moderate to vigorous physical activity, steps, light physical activity, positive affect, optimism, depressive symptoms, anxiety, and exercise identity. It also lists 26 outcome measures overall. When a study evaluates multiple outcomes, the chance of at least one apparently notable result can increase if each is tested separately without accounting for multiplicity. General statistical explanation: A prespecified hierarchy, adjustment procedure, or clear distinction between confirmatory and exploratory analyses can help readers interpret a collection of tests. The registry record does not report a multiplicity plan, outcome hierarchy beyond identifying the primary endpoint, or secondary outcome results.

The record does not describe missing-data procedures, the extent or pattern of missing outcome measurements, or how participants with incomplete follow-up were handled. These details matter because the consequences of missingness depend on how much information is absent and why it is absent. A method that assumes missing observations are unrelated to unobserved outcomes may be inappropriate if missingness is related to outcome status. No particular missing-data assumption or method can be attributed to this trial from the registry record.

The record also does not define an analysis population for the secondary outcomes. It does not say whether analyses followed randomized assignment regardless of intervention attendance, included only participants with observed outcomes, or used another population. The randomized design is stated, but the analysis approach is not reported in the registry record. As a result, neither the handling of deviations from assigned intervention nor the impact of missing observations can be assessed. No adjustment for multiple testing, missing-data sensitivity analysis, or analysis-population definition is reported.

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 serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: abdominal pain and constipation (3.4%), cancer (3.4%).

The registry lists safety counts separately for the two randomized groups. For the PP-MI intervention, it reports 2 serious adverse events, 1 other adverse event, and 1 death. For the Physical Activity Education Control, it reports 0 serious adverse events, 3 other adverse events, and 0 deaths. The registry lists 29 participants at risk for each group for the serious and other adverse-event entries.

These figures are descriptive. The registry record does not report event timing, individual-level overlap between event categories, severity details beyond the serious-event classification, or a statistical comparison. It does not state whether any event was judged related to the intervention or study procedures. The listed deaths should not be interpreted as caused by either assigned condition on the basis of these counts alone.

The record identifies Abdominal pain and constipation and Cancer as the most frequent serious adverse-event terms, each listed as 3.4%. It does not report enough detail to connect these terms to a particular arm or to clarify their relationship to the total serious-event counts. Adverse-event listings can identify events recorded during a study, but they do not by themselves establish causation or quantify comparative risk. The counts should therefore be read as registry-reported safety information, not as evidence of a treatment effect.

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

The record establishes that GOALS II was conducted as a randomized, parallel-group trial comparing a PP-MI intervention with a physical activity education control after bariatric surgery. It also establishes the intended delivery formats, the primary feasibility measure, the stated completion benchmark, and the secondary outcomes the investigators planned to examine. These details clarify the study question and the kinds of outcomes considered relevant.

The record does not establish whether participants completed an average of at least 7/10 sessions. No observed primary endpoint estimate or analysis is reported. It likewise does not establish whether the intervention changed physical activity, steps, psychological measures, or any other listed outcome relative to control. Without outcome estimates and uncertainty measures, the magnitude and precision of any between-group difference cannot be described.

A trial's completion status is not the same as public reporting of its findings. The registry lists the trial as completed, but the outcome analyses are not present in the registry record. The description of intervention content is also not a substitute for evidence about adherence, acceptability, or impact. The brief summary says the trial examines those topics, but the corresponding results are not reported.

The safety entries document adverse-event counts in both groups and a death recorded in the intervention group. They do not identify causation or provide a statistical comparison. Interpreting them as evidence that either intervention package caused or prevented an event would go beyond what the record reports.

Overall, this record supports a description of the trial's design and planned questions, not a conclusion about whether PP-MI changed outcomes or met its feasibility criterion. Those conclusions would require reported outcome data, analysis methods, and measures of uncertainty.

14. Why This Trial Matters Statistically

This trial is statistically notable for separating a feasibility question from questions about clinical or behavioral outcomes. The primary measure is the average number of intervention sessions completed in the PP-MI group. That measure addresses engagement with the intervention, while the listed secondary outcomes concern physical activity and psychological changes. Keeping these questions distinct helps prevent an attendance measure from being mistaken for evidence of a change in activity.

The comparison also involves two packages with different components. PP-MI includes a manual and scheduled phone sessions; the control includes a Fitbit and mailed educational materials. Any reported randomized comparison would estimate the contrast between these packages as delivered, rather than isolate the contribution of one component such as positive psychology, motivational interviewing, phone contact, or a Fitbit. The registry record does not report results that would quantify that contrast.

The trial's intended outcomes cover several domains, from moderate to vigorous physical activity and steps to affect, optimism, and symptoms. That breadth makes clear why reporting multiplicity decisions and analysis populations matters: readers need to know which outcomes were emphasized, how comparisons were handled, and how missing measurements affected estimates. Those details are not reported in the registry record.

Finally, the record illustrates why planning calculations and observed trial findings should be kept separate. A planning illustration based on an assumed fraction of an observed effect is conditional on its assumptions; it is not an observed result or a measure of observed power. Since outcome analyses are not reported, the registry record supports careful interpretation of the design but not conclusions about effect size or precision.

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 of interpretation follow from the information in the registry record. Most importantly, outcome results and analyses are absent. The primary mean and standard deviation are not reported, and there are no estimates for the listed secondary outcomes. The registry record therefore cannot show whether the feasibility criterion was met or quantify any between-group difference.

The intervention description is incomplete: it states that sessions include psychological skills intended to increase positive emotions during physical activity, but the remaining description is truncated. The record identifies single masking without saying who was masked. It does not provide detailed eligibility criteria, participant characteristics, the randomization procedure, the number of sites, or follow-up completion details. These omissions limit assessment of who the findings might apply to and how the study was conducted.

The record does not describe how intervention adherence beyond the primary session count was measured, how acceptability was assessed, or how physical activity measures were collected. It does not report missing-data methods, analysis populations, a statistical plan, or handling of multiple outcomes. These omissions make it impossible to evaluate whether the intended analyses were prespecified or how incomplete observations influenced results.

The safety entries are also limited: event timing, attribution, and the relationship between event terms and groups are not described. The available counts do not support causal interpretation. Finally, although the trial is listed as completed, completion status does not fill the gaps in outcome reporting. These limitations are specific to interpreting this registry record and should not be mistaken for evidence about what the investigators may have reported elsewhere.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Gaining Optimism After Weight Loss Surgery (GOALS) II — NCT04868032.
• Registry record last updated 2026-03-27; status last verified 2026-03.
• Results first posted 2026-03-27.
• 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

GOALS II is listed as a completed randomized, parallel-group trial with single masking and enrollment of 58. It compared PP-MI with a physical activity education control among people who had recently undergone bariatric surgery. The intervention was planned as 10 weekly 30-minute phone sessions with a written manual; the control received a Fitbit and mailed educational materials at 4 time points.

The primary endpoint was the mean number of intervention sessions completed over 10 weeks, with a stated feasibility criterion of an average of at least 7/10. Secondary outcomes included changes in physical activity and psychological measures. The registry record lists 26 outcome measures and no analyses; it reports no primary or secondary outcome estimates. Safety entries list serious events, other events, and deaths by group, but do not establish causation. The record does not report the statistical plan, missing-data methods, or analysis populations.