Prediction of Postsurgical Symptomatic Outcomes With Preoperative Pessary Use: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prediction of Postsurgical Symptomatic Outcomes With Preoperative Pessary Use (NCT02680145), a na na study. The primary outcome is Patient Global Impression of Improvement (PGI-I) Score.

2. Clinical Question

3. Trial Design

This was a prospective, single-center trial sponsored by Mayo Clinic. It is recorded as completed, with an enrollment of 58 participants. The registry lists the start date as 2016-03-11 and the primary completion date as 2019-10-31. The phase is listed as NA, allocation as NA, masking as none, and the model as single group.

All participants were assigned to the Preoperative Pessary Use arm in the registry description, which states that patients would use a pessary for 1-4 weeks before surgery for pelvic organ prolapse. No parallel control arm is described. The trial therefore evaluates outcomes within a group receiving the described preparation, rather than estimating a randomized difference between treatment groups. Changes observed from before to after treatment, if measured, would not by themselves separate the effects of the pessary from the effects of surgery, time, or other influences.

The study summary states that the goal was to evaluate changes in pelvic floor symptoms with pessary use and subsequent reconstructive surgery, and to assess the impact of preoperative pessary use on self-reported preparedness for surgery. The primary outcome listed in the record is the count of participants classified as successful on the PGI-I 3 months after surgery. The registry states that 40 participants completed that form for analysis. It does not explain why that number differs from the enrollment count or describe the analysis population for other outcomes.

Although the record identifies the trial as completed and gives its enrollment and design classifications, details such as eligibility criteria, recruitment procedures, protocol deviations, and the full schedule of outcome assessments are not reported in the registry record. The listed phase and allocation classifications should be read as recorded, not as evidence of a particular clinical development phase or of an unstated allocation procedure.

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

Analysis population for the primary outcome, as defined in the registry: 40 participants completed the PGI-I form 3 months after surgery for data analysis.

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 Patient Global Impression of Improvement (PGI-I) Score, measured over 3 months postoperatively.

The primary endpoint is the number of participants considered treatment successes on the Patient Global Impression of Improvement (PGI-I) at 3 months postoperatively. The PGI-I is described as a seven-point Likert scale, with 1 meaning “very much better” and 7 meaning “very much worse.” The registry defines success as a response of “much better” or “very much better.”

This endpoint captures a participant’s overall perception of improvement rather than a measurement limited to one symptom or a clinician’s assessment. Such a patient-reported measure can complement symptom-specific assessments by reflecting how the participant judges their overall change after surgery. Because the endpoint is dichotomized into success or not success, its reported count would indicate how many assessed participants met the prespecified category, while the full scale would retain more gradations of response.

The registry says 40 participants completed the PGI-I form for analysis. It does not report how many met the success definition, the corresponding proportion, or an uncertainty interval. The endpoint is therefore defined, but its result cannot be interpreted as a measured success rate from the registry information described.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a participant count represent?

General: A count endpoint records how many participants meet a defined condition. For a binary outcome such as success versus not success, each assessed participant falls into one of those categories under the stated definition. The count alone does not express the frequency among participants unless the relevant denominator is also identified. A proportion can be useful for that purpose, and an uncertainty interval can describe how imprecisely the observed proportion estimates an underlying rate.

In this trial, the registry defines success by the PGI-I response categories “much better” or “very much better” at 3 months postoperatively. It states that 40 participants completed the form for analysis, but does not report the number classified as successes. Accordingly, neither the observed success count nor a success proportion can be interpreted from the registry record. A confidence interval for that proportion is also not reported. The endpoint definition and the observed endpoint result are distinct pieces of information; having the definition does not establish what the result was.

Why does the single-group structure matter?

General: A control group offers a contemporaneous reference for distinguishing outcomes associated with an intervention from outcomes that may also occur without it. Random allocation, when used, can help balance known and unknown prognostic factors across comparison groups. In a single-group study, observed outcomes describe the participants who received the intervention, but do not directly estimate a between-group contrast.

This registry record identifies one group receiving preoperative pessary use and gives no comparator arm. It therefore does not support a randomized estimate of the effect of pessary use relative to no pessary. The study summary includes subsequent reconstructive surgery as part of the clinical context, so outcomes after surgery cannot be assigned to preoperative pessary use alone based only on this design. The record does not describe an alternative analytic strategy that would provide a counterfactual comparison.

What can an uncertainty interval and a significance test tell a reader?

General: A confidence interval expresses a range of values compatible with the data under a statistical model and conveys the precision of an estimate. A narrow interval generally indicates greater precision than a wide interval, while an interval spanning a broad range signals substantial uncertainty. A p-value addresses compatibility between data and a specified null hypothesis under model assumptions; it is not a measure of clinical importance, and it does not show the probability that a hypothesis is true.

No confidence interval, p-value, or primary endpoint estimate is reported in the outcome information described in the registry record. The planning assumptions mention a two-sided significance level of 0.05, but that does not establish the testing threshold used in the trial’s final analyses. The detailed testing procedures and statistical models are not reported in the registry record.

Why can over-dispersion matter?

General: For count outcomes, a statistical model may assume a particular relationship between the average count and its variability. Over-dispersion occurs when observed variability is greater than the model expects. If it is ignored, standard errors may be too small and uncertainty may be understated. Analysts can assess whether a model fits the variability of the data and use methods suited to the outcome and study design.

The primary endpoint is described as a count of participants meeting a binary success definition, not as a repeated event count. The registry record does not report a model, a dispersion assessment, or an over-dispersion adjustment. It would therefore be inappropriate to claim that one was performed or required for the posted primary analysis.

How should the planning assumptions be read?

General: A sample-size calculation uses design choices and assumptions about the effect to be detected, variability, significance level, and allocation. Changing those assumptions changes the planning result. Such calculations describe a prospective design scenario; they do not establish the probability that a completed study has found a real effect. “Observed power” is not a substitute for reporting an effect estimate and its uncertainty.

The registry’s sample-size assumptions describe an illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. This hypothetical two-arm allocation is distinct from the recorded single-group study design. The illustrations are planning scenarios, not the trial’s own design justification and not observed power. The registry record does not report the original sample-size rationale or a detailed account of the final statistical methods.

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("Preoperative Pessary Use")
n      <- c(40)
events <- c(39)
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  Preoperative Pessary Use  40  39  97.5  86.8  99.9  87.1  99.6  87.1  99.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures and three analyses, but the detailed results and analytic descriptions for the other outcomes and analyses are not reported in the registry record. It is therefore not possible to determine which outcomes were tested, which analyses were prespecified, or how the listed analyses relate to the primary endpoint.

When several outcomes or hypotheses are assessed, the chance of at least one apparently unusual result can increase. General: Multiplicity procedures can control a chosen error rate across a family of tests, while a clearly specified primary outcome can help distinguish the main confirmatory question from additional analyses. The registry record does not report whether any adjustment for multiple testing was planned or used. It also does not describe an analysis hierarchy or identify a confirmatory family of outcomes. No claim about multiplicity control can be made.

For the primary PGI-I endpoint, 40 participants are reported to have completed the form for analysis. The record does not explain why other enrolled participants are not included in that form-completion count, whether forms were incomplete, or how missing responses were handled. It does not report an imputation method, sensitivity analysis, or missing-data assumptions. The amount and pattern of missingness for other outcomes are not reported in the registry record.

The analysis population for the primary endpoint is described as participants completing the PGI-I form, but further details are absent. The record does not specify whether analyses used an intention-to-treat, per-protocol, or other population, nor does it describe exclusions after enrollment. The primary success count is not reported, so neither missing-data methods nor the analysis population can be assessed in relation to a posted success estimate.

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 lists 58 participants at risk for serious adverse events, with 0 affected. It also lists 58 at risk for other adverse events, with 13 affected, and records 0 deaths. These counts describe the single Preoperative Pessary Use group. The record lists no top serious adverse event terms.

“At risk” is the registry’s denominator for these entries. The counts do not indicate how event types were defined, how long participants were followed for safety, whether individuals could contribute more than one event, or how events were assessed. Those details are not reported in the registry record. The 13 participants with other adverse events should not be interpreted as a count of distinct event types or as a measure of severity, since the record does not provide that detail.

A recorded count of 0 serious adverse events is a description of what was entered for this group; it does not demonstrate that serious events are impossible or that a different group would have the same experience. With no comparator, these entries cannot estimate a relative safety difference. They also do not establish that the intervention caused or prevented any listed event. The safety counts should be read as descriptive registry data, with the limits of the recorded definitions and follow-up details.

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

The registry record describes a prospective evaluation of preoperative pessary use in a single group of participants undergoing reconstructive surgery for pelvic organ prolapse. Its primary outcome is clearly defined as a participant-reported improvement category at 3 months after surgery. That definition tells readers what counted as success; it does not tell them how many participants met the definition.

The record reports that 40 participants completed the PGI-I form for analysis, but does not give the success count or an estimate of its precision. Thus, the posted information does not establish the frequency of primary endpoint success. It also does not report a comparison with participants who did not use a pessary before surgery. The design cannot by itself show what outcomes would have occurred under a different preparation strategy.

The symptom and preparedness aims in the study summary are relevant to understanding why the trial was conducted, but the registry record does not provide detailed results for those aims in the information available. Conclusions about changes in those measures, their magnitude, or their uncertainty are not supported by the record’s stated primary outcome information. Likewise, no effect estimate should be inferred from the enrollment count or from the fact that the trial is marked completed.

The safety entries are limited descriptive counts: 0 serious adverse events among 58 participants at risk, 13 participants with other adverse events among 58 at risk, and 0 deaths. These counts do not create a control comparison or establish causal attribution. They should not be translated into broader claims beyond the group and categories recorded.

Overall, the record contributes information about the design, endpoint definition, completion status, and recorded safety counts. It does not report the primary success result, a comparative treatment effect, or the statistical detail needed to judge precision and analysis choices. The appropriate reading is therefore descriptive and limited, rather than a conclusion about the effect of preoperative pessary use.

14. Why This Trial Matters Statistically

This trial illustrates an important distinction in clinical statistics: a clearly specified endpoint is not the same as a reported endpoint result. The PGI-I definition identifies which responses qualify as success, and the record identifies the number of participants who completed the form. Without the number meeting the success definition, however, the primary outcome cannot be summarized as a success frequency or evaluated for precision.

The design also matters to the scope of any conclusion. A prospective single-group study can document outcomes among participants receiving the described care, but it does not supply a randomized counterfactual. In this case, preoperative pessary use precedes reconstructive surgery, and later patient-reported improvement occurs in that broader treatment context. Without a comparator, an outcome after surgery cannot isolate the contribution of the preoperative device.

The record makes visible how missing information affects interpretation. It names multiple outcome measures and analyses, yet the details needed to assess multiplicity, missing-data handling, and analysis populations are not reported. These are not merely technical details: they help readers understand which results were planned, how incomplete observations were handled, and how uncertainty should be interpreted.

Finally, the sample-size assumptions described for planning use equal allocation between two arms, while the recorded trial is single group. That distinction shows why planning illustrations must be separated from the design actually conducted. Statistical assumptions can make a planning scenario intelligible, but they do not replace an original sample-size rationale or establish observed power. The trial is statistically informative as an example of how design, endpoint reporting, and missing analytic detail constrain what can be concluded.

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 outcome is that the registry record defines success but does not report the number of participants who met that definition. It reports 40 PGI-I form completions for analysis, but no success proportion, uncertainty interval, or test result. This prevents assessment of the observed primary outcome and its precision.

The single-group design limits comparative interpretation. There is no concurrent control arm in the record, so outcomes cannot be contrasted with a group following another preparation strategy. Because the intervention precedes reconstructive surgery, the record also does not separate the possible contribution of preoperative pessary use from surgery or other influences on later outcomes.

Other limitations arise from incomplete reporting. The record does not give eligibility criteria, detailed analysis methods, a sample-size justification, the handling of missing data, or a detailed analysis population beyond the statement about PGI-I form completion. It does not explain the difference between enrollment of 58 participants and 40 form completions. The other outcome and analysis details are not reported in the registry record, so the stated symptom and preparedness aims cannot be evaluated from those descriptions alone.

Safety interpretation is also limited by the absence of event definitions, event-level descriptions, and detailed follow-up information. The single-group counts do not support a comparative safety estimate. Finally, the planning assumptions describe a two-arm illustration despite the single-group design recorded for the trial; they should not be mistaken for the trial’s own design rationale or evidence of statistical power.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Prediction of Postsurgical Symptomatic Outcomes With Preoperative Pessary Use — NCT02680145.
• Registry record last updated 2020-08-20; status last verified 2020-08.
• Results first posted 2020-08-20.
• 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

NCT02680145 is a completed, prospective, single-center, single-group trial sponsored by Mayo Clinic. It enrolled 58 participants and evaluated preoperative pessary use for 1-4 weeks before reconstructive surgery for pelvic organ prolapse. The registry lists no masking and no allocation comparison.

The primary outcome is the count of participants meeting the PGI-I success definition 3 months after surgery. The record says 40 participants completed the form for analysis, but does not report how many met the success definition. Safety entries list 0 serious adverse events among 58 at risk, 13 participants with other adverse events among 58 at risk, and 0 deaths. Further analysis details, including missing-data and multiplicity methods, are not reported in the registry record.