Safety and Efficacy of Autologous Platelet-Rich Plasma for Erectile Dysfunction.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Autologous Platelet-Rich Plasma for Erectile Dysfunction. (NCT04396795), a randomized phase 2 study. The primary outcome is Number of Participants Achieving MCID in IIEF-EF..

2. Clinical Question

3. Trial Design

This was a phase 2, randomized, parallel-group, placebo-controlled, multicenter clinical trial sponsored by the University of Miami. The registry labels the masking as quadruple. Its official title describes the trial as double-blind, while the registry’s masking field gives the more specific label; the identities of the masked parties are not reported in the registry record.

The planned comparison was autologous platelet-rich plasma injection versus placebo injection. The PRP group description specifies two penile injection sessions, each administered one month apart ± 7 days. The placebo group description specifies the same schedule. The registry lists saline solution as an intervention, but does not give further details about the placebo procedure.

Enrollment was 61. The study began on 2020-05-21, had a primary completion date of 2023-01-23, and is marked completed. These design and status details describe the trial’s organization and timeline; they do not establish how many participants completed each visit or were included in an outcome analysis.

The primary outcome was the number of participants achieving a minimal clinically important difference in IIEF-EF score. It was assessed at 1 month, 3 month, and 6 month. Secondary outcomes included change in IIEF-EF scores, change in Doppler ultrasound peak systolic velocity, adverse-event counts, and the number of participants with an end diastolic velocity value greater than 0 at baseline and month 6. The registry record does not report the allocation method beyond randomization, the randomization ratio, or the detailed statistical plan.

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.

Baseline

Month 1

Reasons for not completing this period:

Month 3

Reasons for not completing this period:

Month 6

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Not all subjects completed all visits due to lost to follow up or did not complete the IIEF questionnaire.

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 Participants Achieving MCID in IIEF-EF., measured over 1 month, 3 month, 6 month.

The primary endpoint counts participants who met a defined threshold for improvement in the International Index of Erectile Function–Erectile Function subdomain score, or IIEF-EF. The threshold is based on erectile dysfunction severity at baseline: an increase of 2 points for participants with mild erectile dysfunction and an increase of 5 points for participants with moderate erectile dysfunction. The outcome is reported as a participant count in each treatment group, with assessments listed at 1 month, 3 month, and 6 month.

The IIEF-EF is described as a five-item self-evaluation questionnaire about erectile function. Its total score ranges from 0-25, with higher scores indicating better erectile function. A minimal clinically important difference is used to identify a change that reaches a prespecified meaningful threshold rather than merely recording any score change. The registry states that these scores are used to determine treatment efficacy in the comparison, but the endpoint definition alone does not show how many participants reached the threshold.

Primary endpoint counts and a group comparison are not reported in the registry record. The registry notes that not all subjects completed all visits because of loss to follow-up or failure to complete the IIEF questionnaire. Consequently, the endpoint definition is available, but the observed results and their precision cannot be assessed from this record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute?

Randomization assigns participants to study groups by a chance-based process. As a general statistical principle, this is intended to reduce systematic differences between groups at the time of assignment, including differences that are measured and those that are not measured. It does not guarantee that the groups will be identical, particularly in a trial with limited enrollment. The registry identifies this study as randomized, but details of sequence generation, allocation concealment, and the allocation ratio are not reported in the registry record. The randomization label alone therefore does not allow those procedures to be assessed.

What does masking mean in this record?

The registry labels the study quadruple-masked, while the official title describes it as double-blind. Masking is generally intended to limit the influence of treatment knowledge on participant reports, clinical care, outcome assessment, or analysis. Which parties were masked and how masking was maintained are not reported in the registry record. The labels identify the intended design feature but do not establish whether masking was successful.

How should the primary endpoint be understood?

The endpoint counts participants who achieved a severity-specific minimal clinically important difference in IIEF-EF score. This converts a change in a questionnaire score into a yes-or-no outcome according to the stated threshold: an increase of 2 points for mild erectile dysfunction or 5 points for moderate erectile dysfunction at baseline. The IIEF-EF is a five-item self-evaluation questionnaire with a score range of 0-25; higher scores indicate better erectile function.

As a general statistical distinction, a threshold-based count answers how many participants crossed a defined cutoff. It does not retain all the information in each participant’s score change. A continuous score analysis can describe the amount of change, while a threshold-based analysis emphasizes whether a specified criterion was reached. Both can be informative, but they answer different questions. The registry lists change in IIEF-EF scores separately as a secondary outcome. No primary or secondary outcome values are reported in the registry record.

Why do the assessment times matter?

The primary endpoint is listed at 1 month, 3 month, and 6 month. A comparison at each time point would describe the groups at that particular assessment; results at one time point cannot be substituted for results at another. Repeated assessments also raise statistical planning questions, including whether one time point is primary, how multiple comparisons are handled, and whether repeated measures are analyzed jointly or separately. The registry record does not report the method used to address these questions or designate a single assessment time as the sole primary comparison.

What would a statistical comparison normally add?

In general, a group comparison should include an effect estimate and an indication of its uncertainty. A confidence interval describes a range of values reasonably compatible with the data and the statistical model; a narrower interval indicates greater precision than a wider one. A p-value, when reported, describes how unusual the observed data would be under a specified null hypothesis and model. Neither a confidence interval nor a p-value establishes clinical importance by itself. Here, the registry record does not report a primary endpoint estimate, confidence interval, or p-value, so the effect size and precision cannot be described.

For a participant-count endpoint, statistical methods can compare the chance of meeting the threshold between groups. The method should account for the endpoint definition, the available observations, and the analysis population. The record does not specify which method was used, whether estimates were adjusted, or how participants with missing questionnaire data were handled. No inferential method should be attributed to the trial from the endpoint description alone.

How should the safety counts be read?

Adverse-event counts are descriptive unless accompanied by a defined analysis. The registry reports serious adverse-event counts, other adverse-event counts, and deaths for the groups, with the number at risk for each category. General interpretation should consider the number of participants observed, the event definitions, follow-up duration, and whether events were collected consistently. The registry’s counts do not provide detailed event terms or timing, and no formal between-group safety analysis is listed.

What can planning calculations establish?

As a general principle, a sample-size calculation uses assumptions about the effect to detect, variability or event frequency, significance level, power, and allocation. It is a planning exercise, not a measure of what a completed study observed. The registry record does not report the trial’s own sample-size justification. Planning illustrations based on an observed effect would not constitute the original design justification or observed power. Since the primary outcome result is not reported, such an observed effect cannot be interpreted from this record. The specified assumptions for any illustration do not replace a documented protocol-based plan.

10. Multiplicity, Missing Data and Analysis Populations

The primary endpoint is listed at 1 month, 3 month, and 6 month, and the registry also lists secondary outcomes. Multiple time points and outcomes create a multiplicity question: when several comparisons are examined, the chance of at least one apparently notable result can increase. General approaches include designating a primary comparison in advance, adjusting for multiple testing, or treating additional comparisons as exploratory. The registry record does not report a multiplicity strategy, a hierarchy among outcome measures, or a prespecified primary time point.

Missing outcome data are a specific concern because the registry states that not all subjects completed all visits due to loss to follow-up or failure to complete the IIEF questionnaire. The number of missing questionnaires, the number assessed at each visit, reasons by group, and the method used to handle missing data are not reported in the registry record. Without those details, it is not possible to assess whether the participants contributing outcome data differed from those without data or how missingness may have affected the comparison.

The analysis populations are also not described. The registry record does not report whether the primary outcome analysis included all randomized participants, only participants with available questionnaire data, or another defined group. It lists no analysis entries. Therefore, the group counts and statistical procedures used for the primary endpoint cannot be reconstructed or evaluated from the record.

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.

Most frequent non-serious adverse event terms

The registry reports 0 serious adverse events among 28 participants at risk in the PRP group and 0 among 33 participants at risk in the placebo group. For other adverse events, it reports 1 among 28 participants at risk in the PRP group and 1 among 33 participants at risk in the placebo group. Deaths are listed as 0 in both groups. The registry does not list serious adverse-event terms.

These are counts, not a complete description of safety. The record does not give event descriptions for the other adverse events, their timing, duration, severity, or whether any event was judged related to an intervention. It also does not report a statistical comparison of safety between groups. The numbers at risk identify the denominators used in the registry’s safety listing; they should not be assumed to be the denominators for the primary IIEF-EF outcome at each visit.

In general, zero recorded serious events does not establish that no serious events could occur, and a small number of reported events does not by itself establish a difference between groups. The counts describe what the registry lists for this trial, within the record’s limited event detail and follow-up information.

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

The trial record describes a randomized comparison of autologous platelet-rich plasma injections with placebo injections in participants with erectile dysfunction. It defines a primary outcome based on whether participants reached a severity-specific improvement threshold on the IIEF-EF questionnaire, with assessments at 1 month, 3 month, and 6 month. It also reports limited adverse-event counts. These registry entries clarify what the study was designed to examine, but do not reveal the primary outcome findings.

The primary outcome group counts and treatment comparison are not reported in the registry record. Consequently, it is not possible to determine from this record how many participants reached the threshold, whether the groups differed, how large any difference was, or how precise an estimate might be. No primary outcome p-value, confidence interval, or analysis method is listed. The trial’s completed status should not be mistaken for a posted result.

The safety counts show no recorded serious adverse events or deaths in either group in the registry listing, and one other adverse event in each group. These observations are limited by the absence of event descriptions, timing, and a comparative safety analysis. They should not be generalized beyond the participants and follow-up represented in the record.

The record also notes that some participants did not complete all visits because of loss to follow-up or incomplete IIEF questionnaires. It does not give enough information to assess how that missingness affected the outcome analysis. In general, missing observations can affect both the estimated group results and their uncertainty, depending on their amount and pattern.

Accordingly, the registry information supports a description of the design, endpoint, and listed safety counts, but not a conclusion about comparative efficacy or a comprehensive safety profile. A more complete interpretation would require outcome values, analysis details, denominators at each assessment, and information about missing data.

13. Why This Trial Matters Statistically

This trial is statistically notable for the distinction between a clearly specified endpoint and absent posted outcome results. The registry defines a threshold-based IIEF-EF outcome and identifies several assessment times, allowing readers to understand the intended measurement. However, without the group counts or an analysis, the central comparative question remains unanswered in the registry record. Clear endpoint definitions are necessary for interpretation, but they are not a substitute for the observed data.

The endpoint also illustrates a common design choice: converting score change into a count of participants who meet a threshold. This can make the result easier to express as the number reaching a specified criterion, while discarding information about the size of changes above or below that criterion. Because the threshold depends on baseline severity, interpretation also depends on knowing how participants were classified and how many had outcome data at each visit. Those group-specific details are not reported in the registry record.

Several follow-up times and secondary outcomes make transparent statistical planning important. Prespecification of a primary time point, multiplicity handling, and missing-data procedures helps readers distinguish confirmatory analyses from exploratory ones. The record does not report those details or any analysis entries, so the statistical plan cannot be assessed.

The safety listing provides useful descriptive counts but also shows why denominators and event detail matter. Counts alone do not characterize timing, severity, or comparative uncertainty. Overall, the record demonstrates how design information can be available while the inferential evidence needed to assess a trial’s primary question remains unavailable.

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.

The main limitation for interpretation is that the registry record does not report primary endpoint results. It gives no group counts for participants achieving the IIEF-EF minimal clinically important difference at 1 month, 3 month, or 6 month, and no effect estimate or uncertainty measure. A comparative interpretation of the primary outcome is therefore not possible.

The record notes incomplete visits due to loss to follow-up or failure to complete the IIEF questionnaire, but does not report the amount of missing data by group or visit. It also does not describe the analysis population or missing-data handling. These gaps prevent assessment of how complete-case selection or other handling choices may have influenced the endpoint results.

Further limitations are the absence of listed statistical analyses, a reported multiplicity plan, and details of the trial’s sample-size justification. The registry record does not specify the randomization procedure, allocation ratio, identities of the masked parties, or the method used for outcome comparisons. These details matter when judging risk of bias and statistical precision.

Safety information is restricted to counts of serious and other adverse events and deaths. Descriptions and timing for the other events, and a formal group comparison, are not reported in the registry record. The safety counts therefore cannot serve as a full characterization of adverse events. These limitations concern the available registry information; they do not establish what may or may not be contained in other study documents.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of Autologous Platelet-Rich Plasma for Erectile Dysfunction. — NCT04396795.
• Registry record last updated 2024-01-09; status last verified 2023-12.
• Results first posted 2024-01-09.
• 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

NCT04396795 is a completed phase 2 randomized, parallel-group, placebo-controlled, multicenter trial sponsored by the University of Miami. Enrollment was 61. The trial evaluated autologous platelet-rich plasma injections against placebo injections in participants with erectile dysfunction. Its primary outcome was the number of participants achieving a severity-specific minimal clinically important difference in IIEF-EF score at 1 month, 3 month, and 6 month.

The registry record does not report primary outcome counts or statistical analyses. It notes that some participants did not complete all visits because of loss to follow-up or incomplete IIEF questionnaires. Safety listings show 0 serious adverse events and 0 deaths in each group, with 1 other adverse event in each group. The record does not include further detail about those other events.