Safety and Efficacy of Low Intensity Shockwave for the Treatment of Erectile Dysfunction: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Safety and Efficacy of Low Intensity Shockwave for the Treatment of Erectile Dysfunction (NCT03067987), a randomized na study. The primary outcome is International Index of Erectile Function (IIEF-EF) Questionnaire.

2. Clinical Question

In statistical terms, the study was intended to compare outcomes under two active schedules, not to establish how either schedule compares with no treatment or a sham procedure. Its hypothesis text describes within-group improvement thresholds for mild and moderate erectile dysfunction, as well as a null hypothesis of no baseline-to-after-treatment difference. The registry does not clarify how those statements relate to the randomized comparison between schedules. No results are reported for the primary score, so the registered question cannot be answered from the outcome information in the record.

3. Trial Design

The registry describes a randomized, unmasked, parallel-group trial. Participants were assigned to one of two low-intensity linear shockwave schedules. Randomization can help make groups comparable on average, while a parallel design means that each participant receives one assigned schedule rather than crossing between schedules. The record does not report the randomization method, allocation concealment, or procedures used to protect against selection bias.

The two groups differed in session pattern and the number of shocks per session. The 720 shockwave therapy schedule consisted of 5 daily sessions within a week, with 720 shocks applied to each treated region in each session. The 600 shockwave therapy schedule consisted of three sessions per week for 2 consecutive weeks, with 600 shocks in each session at each treated region. The device was directed to the left and right corpora cavernosa and the crura. The description for the 600 schedule ends mid-sentence after a statement about what happens following the last session; any further detail about that schedule is not reported in the registry record.

The registry lists enrollment as 103, identifies the study as completed, and gives the phase as NA. The start date is 2017-02-22, and the primary completion date is 2019-05-22. These record details describe the study's conduct and status; they do not supply evidence about the magnitude or precision of treatment effects.

The primary efficacy objective concerned change in the International Index of Erectile Function score from baseline to follow-ups. Secondary objectives concerned sexual activity and included the Sexual Encounter Profile, Global Assessment Questionnaire and Erection Hardness Score. The registry lists four outcome measures and two analyses, but does not report enough detail to identify the analysis methods, analysis populations, or how the two analyses relate to the outcome measures.

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 International Index of Erectile Function (IIEF-EF) Questionnaire, measured over 7 months.

The primary endpoint is the International Index of Erectile Function (IIEF-EF) questionnaire score. The registry describes the questionnaire as a 15-item self-administered instrument for assessing erectile dysfunction and treatment outcomes. Its stated objective is to measure change from baseline, with follow-up assessments at 1, 3 and 6 months after treatment. The endpoint description locates these visits at 2, 4 and 7 months, respectively, in relation to its stated baseline timing.

A repeated score can describe change in reported erectile function over time. Comparing change between randomized groups can address whether the observed trajectories differ between the assigned schedules, subject to the analysis method and the completeness of follow-up. The registry record does not report the scores at baseline or follow-up, nor does it report a treatment contrast, confidence interval or test result. Therefore, the measurement plan is described, but the endpoint's observed results and precision are not available in the registry record.

The endpoint description says the total IIEF score ranges from 5 to 25 and lists categories from severe erectile dysfunction through no erectile dysfunction. It does not clarify whether the stated range and categories apply to the IIEF-EF endpoint as named or to a broader total score. That distinction matters when interpreting score changes, so the exact score definition used in the analysis is not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical methods available in the registry record are limited. It describes random assignment to parallel treatment groups and specifies the primary outcome and assessment schedule. It does not report the statistical model, the exact contrast used, covariate adjustment, missing-data approach, or a complete statistical analysis plan. The concepts below are general explanations of how those choices affect interpretation; they are not claims about methods used in this trial.

What does randomization contribute?

In general, randomization assigns participants to groups using a chance-based process. When implemented as intended, it reduces systematic differences between groups at the point of assignment, on average. It does not guarantee that every characteristic is balanced in a particular trial, and it does not correct problems that occur after assignment, such as unequal loss to follow-up or inconsistent outcome measurement. The record says the study was randomized, but the method of sequence generation and allocation concealment is not reported in the registry record.

The trial was unmasked. In general, lack of masking can affect expectations, behavior, treatment delivery, and assessment, especially when outcomes rely on participant-reported questionnaires. The registry does not describe additional procedures to limit those influences. This design feature is relevant when interpreting a self-administered score, but it does not by itself establish the direction or size of any bias.

What would a between-group estimate describe?

For a randomized comparison, an analysis could estimate the difference between groups in score change, or compare follow-up scores while accounting for baseline scores. These approaches answer related but not identical questions and rely on different modeling choices. The registry record does not state which approach was used. It also does not report an estimated effect, so no conclusion about the size or direction of the schedule difference can be drawn from the listed outcome plan alone.

A confidence interval communicates uncertainty around an estimated effect. In general, it helps distinguish a result estimated precisely from one with substantial uncertainty. A p-value addresses compatibility between data and a specified null model under statistical assumptions; it does not give the probability that the null hypothesis is true, and it does not describe clinical importance. No primary-outcome confidence interval or p-value is reported in the registry record.

Why do repeated follow-ups matter?

The endpoint plan includes baseline and follow-up assessments at 1, 3 and 6 months after treatment; the endpoint description also expresses these as 2, 4 and 7 months in relation to its baseline timing. Repeated observations can show whether scores change over time and whether the groups' trajectories differ. They also create analysis choices: investigators may compare a particular visit, model scores across visits, or define a summary of change. The choice affects both the question answered and the uncertainty estimate. The registry does not report which approach was used or how the differing descriptions of follow-up timing were resolved.

Repeated measurements on the same participant are generally correlated rather than independent. General methods for repeated measures account for this dependence; treating each measurement as unrelated can misstate uncertainty. The registry record does not identify whether a repeated-measures model or another method was used.

How should planning calculations be understood?

In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, significance level, allocation and analysis. The record's planning description specifies a two-sided significance level of 0.05, equal allocation, a normal approximation, and effect sizes expressed as fractions of the observed effect. It states that the planning illustration is computed from the observed effect, rather than from the trial's own design. Such planning values are not observed power and do not establish that the trial was adequately powered. The registry does not report the trial's own sample-size justification or design assumptions.

A planning calculation based on an observed effect is especially dependent on that effect estimate and its uncertainty. It should not be read as a guarantee that a future study would reproduce the same effect. The record does not provide a primary outcome estimate alongside the planning description, so the numerical basis for any such illustration is not reported in the registry record.

What role do distributional assumptions play?

General statistical models make assumptions about how outcomes vary and how observations relate to one another. For a score, analysts may consider whether a mean-based summary and its uncertainty are suitable, whether distributions are strongly skewed, and whether model residuals behave as expected. The registry reports the endpoint as a mean with full-range dispersion, but does not provide observed score distributions or diagnostic information. There is therefore no basis in the record for assessing those assumptions.

Over-dispersion is a general concern when observed variability exceeds what a model assumes. In count outcomes it can make standard errors too small if ignored; for a questionnaire score, the relevant model and diagnostics would depend on how the score was analysed. The registry does not state that over-dispersion was assessed, and no such claim should be inferred.

The statistical plan, including the primary contrast, handling of repeated measurements, missing-data methods, model diagnostics, and any sensitivity analyses, is not reported in the registry record. These omissions limit independent assessment of how robust a reported treatment estimate would be, but no estimate is available in the record to assess.

10. Multiplicity, Missing Data and Analysis Populations

The study includes a primary score with several assessment times and three named secondary measures: Erection Hardness Score, Sexual Encounter Profile and Global Assessment Questionnaire. Multiple outcomes, time points and comparisons create a multiplicity issue. In general, testing many hypotheses can increase the chance of at least one apparently notable result by chance. Researchers may prespecify a primary time point, use a hierarchy of outcomes, adjust for multiple testing, or describe secondary analyses as exploratory. The registry does not report a multiplicity strategy, and it does not identify which follow-up was the primary inferential comparison.

The record indicates that the primary outcome was not reduced to one comparison because it has several categories or time points. This leaves the intended single summary contrast unclear. The endpoint description and objective use different month references for follow-up timing, and the record does not explain the relationship between those descriptions.

Missing-data handling is not reported in the registry record. The record does not give the number of participants with observed primary scores at each assessment, reasons for missing observations, or whether analyses used imputation, likelihood-based methods, or another approach. It also does not report whether the analysis followed randomized assignment or used a different analysis population. These details matter because loss to follow-up can affect both estimated effects and their uncertainty, particularly if missingness differs between groups or relates to participants' outcomes.

The registry lists two analyses, but their relationship to the endpoint schedule and analysis populations is not reported in the registry record. Without an analysis plan and results, it is not possible to judge whether the reported comparisons, if any, followed prespecified methods or how multiplicity and missingness were addressed.

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 the following safety counts for 720 Shockwave Therapy: 0 serious adverse events among 50 at risk, 0 other adverse events among 50 at risk, and 0 deaths. For 600 Shockwave Therapy, it lists 0 serious adverse events among 53 at risk, 0 other adverse events among 53 at risk, and 0 deaths. These are the counts recorded in the registry for the categories shown.

A zero count in a registry listing means that no events were entered for that category in that group; it does not prove that no event occurred. The record does not provide event definitions, detail on how events were solicited or verified, or a description of the duration and completeness of safety follow-up. The groups listed as at risk also do not, on their own, explain the safety analysis population or whether all participants contributed safety information.

The figures should therefore be read as reported safety counts, rather than as a comprehensive characterization of risk. The registry record does not provide event narratives or a breakdown of events by type beyond the categories shown.

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

The trial addresses a focused statistical question: whether two schedules of the same low-intensity linear shockwave device are associated with different changes in erectile-function questionnaire scores. Randomization and a parallel-group design are relevant strengths for comparing assigned schedules. However, the registry record does not report the primary endpoint results, so it is not possible to describe an observed difference, its direction, or its precision.

The study hypothesis text refers to improvement from baseline, with thresholds for mild and moderate erectile dysfunction. Such within-group changes are not the same as evidence that one treatment schedule performs differently from the other. To support a comparative conclusion, the between-group contrast and its uncertainty would need to be reported. Neither is available in the registry record.

The information also does not establish how the schedules compare with a sham procedure or no treatment: the listed groups both received active shockwave treatment. It does not show whether any change over time resulted from the device, the treatment schedule, expectations, other influences, or some combination. The absence of outcome results means these possibilities cannot be separated using the registry record.

The listed zero adverse-event counts are limited to the registry's reported categories and denominators. They do not constitute proof of no risk, and the record does not describe the completeness of event collection. Similarly, a completed study status does not indicate that the treatment schedules were beneficial, equivalent, or safe in all respects.

In short, the registry record explains what the investigators intended to measure and how the treatment schedules differed. It does not provide the outcome estimates needed to judge comparative effectiveness, statistical significance, clinical importance or precision. Any such conclusion would go beyond the results reported in the record.

13. Why This Trial Matters Statistically

This study is statistically interesting because it compares two active schedules rather than comparing treatment with a sham or no-treatment group. That design focuses the question on schedule differences, while making clear that an observed comparison would not by itself establish an effect relative to no treatment. The schedules vary in both timing and the number of shocks per session, so any between-group contrast would reflect the assigned schedule as a whole rather than isolating one schedule component.

The primary objective uses a repeated questionnaire outcome, with assessments planned across follow-up. This raises important analysis questions about which visit or trajectory is the central comparison, how baseline scores are handled, and how repeated observations are modelled. The registry record does not report these choices. The endpoint description also gives follow-up timing both as months after treatment and as months from its stated baseline timing, without explaining the relationship.

The study further illustrates the distinction between a stated hypothesis and a reported result. The hypothesis describes baseline improvement thresholds, while the trial is randomized between two schedules. A within-group change and a between-group difference answer different questions; the registry does not clarify how both aims were incorporated into analysis.

Finally, statistical interpretation depends on transparent reporting of effect estimates, uncertainty, analysis populations, missing outcomes and multiplicity. These details are not reported in the registry record. With no primary outcome values or comparative estimate, the record offers a useful view of the design but not a quantitative basis for judging the schedules' relative results.

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 outcome values or a between-group estimate. As a result, neither the direction nor magnitude of the observed score changes can be described, and no assessment of precision is possible. Results for the named secondary measures are also not reported in the registry record.

The endpoint description names IIEF-EF but describes the questionnaire as a 15-item instrument and gives a total IIEF score range of 5 to 25 with severity categories. It does not clarify whether those details apply to the specific IIEF-EF score analysed. This ambiguity limits interpretation of the score definition and any change in it.

The outcome plan identifies follow-ups at 1, 3 and 6 months after treatment, while also locating them at 2, 4 and 7 months. The relationship between these time references is not explained. The registry also does not report which assessment was used for the main comparison or how repeated observations were analysed.

Details of eligibility criteria, participant characteristics, randomization procedures, analysis populations and missing-data handling are not reported in the registry record. The 600 schedule description is incomplete, ending after a statement about the period following the final session. The registry lists zero adverse events in the reported categories, but does not describe ascertainment or follow-up completeness. Together, these omissions restrict assessment of the analysis, the generalizability of any result, and the completeness of the safety information.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Safety and Efficacy of Low Intensity Shockwave for the Treatment of Erectile Dysfunction — NCT03067987.
• Registry record last updated 2020-06-11; status last verified 2020-05.
• Results first posted 2020-06-11.
• 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

The registry record describes NCT03067987, a completed randomized, unmasked, parallel-group trial sponsored by the University of Miami. It compares two active low-intensity linear shockwave schedules for vasculogenic erectile dysfunction. Enrollment is listed as 103, the phase as NA, the start date as 2017-02-22, and the primary completion date as 2019-05-22.

The primary outcome is the International Index of Erectile Function questionnaire score, with follow-up assessments planned after treatment. Secondary outcomes include Erection Hardness Score, Sexual Encounter Profile and Global Assessment Questionnaire. The registry does not report primary or secondary outcome results, the statistical analysis plan, or missing-data methods. Safety listings record 0 serious events, 0 other events and 0 deaths in each group. The record supports description of the trial design and planned outcomes, but not a conclusion about comparative outcome effects.