Impact Of Viagra On Sexual Satisfaction Of Men With Mild Erectile Dysfunction Who Are Sexually Dissatisfied: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Impact Of Viagra On Sexual Satisfaction Of Men With Mild Erectile Dysfunction Who Are Sexually Dissatisfied (NCT00301262), a randomized phase 4 study. The primary outcome is Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) Index at the End of the DB Treatment (Week 8).

2. Clinical Question

3. Trial Design

The registry describes a Phase 4, multicenter, randomized, parallel-group trial with a double-blind, placebo-controlled phase followed by an open-label phase. The official title also describes flexible dosing. Enrollment was 183, and the record lists the status as completed. The registry dates the study start to 2005-11 and primary completion to 2007-09.

The principal comparison was between DB Viagra and DB Placebo at Week 8. The primary endpoint was the EDITS Index, analyzed as an adjusted mean score. The record identifies the primary outcome population as participants in the Full Analysis Set with an observation. The numbers contributing to the posted primary outcome are 88 for DB Viagra and 73 for DB Placebo.

The open-label phase is distinct from the randomized, blinded comparison. The brief summary says all study subjects had the opportunity to receive active treatment for 6 weeks. Secondary results include measurements at Week 14, with groups identified by their double-blind assignment and open-label treatment. Because the later phase was open-label, its comparisons should not be read as retaining the same blinded placebo-controlled contrast as the Week 8 comparison.

The registry record does not report the original sample-size justification, detailed allocation procedures, dose schedule, or the full operational description of the open-label phase in the information summarized for this analysis. Those omissions limit reconstruction of the design rationale, but do not alter the fact that the primary posted comparison is a randomized double-blind comparison at Week 8.

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.

Before assignment: 183 subjects entered the study, and 176 subjects were treated in the Double Blind (DB) phase. One subject completed DB phase and continued into the open-label (OL) phase but had no events of sexual activity and therefore, did not take study drug and was excluded from the number of treated subjects, the safety analysis set, and PP population.

Double Blind Phase (DB)

Reasons for not completing this period:

Open Label Phase (OL)

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: number of subjects in the Full Analysis Set (FAS) population with an observation

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 Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) Index at the End of the DB Treatment (Week 8), measured over Week 8.

The primary endpoint was the Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) Index at the end of double-blind treatment, Week 8. The registry describes it as an adjusted mean score on a scale from 0 to 100, where 0 represents extremely low treatment satisfaction and 100 represents extremely high treatment satisfaction. It is therefore a patient-reported measure of satisfaction with treatment, rather than a direct clinical event count.

Using a defined scale makes it possible to summarize participants’ responses as group means and compare those means between randomized groups. An adjusted mean can account for covariates included in the stated analysis; the registry identifies ANCOVA for the sponsor’s primary comparison, but the covariates used are not reported in the registry record. The endpoint is relevant to the trial’s stated focus on sexual satisfaction and quality of life, while remaining narrower than those broader concepts.

A score difference should be interpreted in the scale’s units. The registry does not report a threshold for a clinically important difference on the EDITS Index, so the posted statistical contrast alone does not establish how participants would experience the size of the difference. Nor does the endpoint establish effects on every other outcome measured in the trial.

7. Results Posted in the Registry

• DB Viagra: mean 80.27 versus 62.15 on control; difference 18.12 (95% CI 11.39 to 24.85), standardized effect d = 0.83; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) Index

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • DB Viagra Week 8: mean 79.21 versus 61.64 on control; difference 17.57 (95% CI 10.93 to 24.21), standardized effect d = 0.83; z-test p = <0.001.
  • DB Viagra/OL Viagra Week 14: mean 84.12 versus 61.64 on control; difference 22.48 (95% CI 16.04 to 28.92), standardized effect d = 1.12; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for DB Viagra Week 8 than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for DB Viagra/OL Viagra Week 14 than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline to End of Double-Blind Phase (Week 8) in Patient Reported Erectile Function Assessment (PREFA) Total Score

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • DB Viagra: mean 3.97 versus 2.21 on control; difference 1.76 (95% CI 0.33 to 3.19), standardized effect d = 0.38; z-test p = 0.016.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for DB Viagra than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Patient Reported Erectile Function Assessment (PREFA) Total Score

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • DB Viagra Week 8: mean 28.54 versus 26.79 on control; difference 1.75 (95% CI 0.63 to 2.87), standardized effect d = 0.49; z-test p = 0.002.
  • DB Viagra /OL Viagra Week 14: mean 29.58 versus 26.79 on control; difference 2.79 (95% CI 1.71 to 3.87), standardized effect d = 0.83; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for DB Viagra Week 8 than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically higher for DB Viagra /OL Viagra Week 14 than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The secondary outcome pattern is broadly aligned with the primary satisfaction result: the posted Week 8 summaries for EDITS and PREFA give higher group means for DB Viagra than DB Placebo, and the sponsor-reported analyses identify differences for both outcomes. This directional consistency adds context across treatment satisfaction and patient-reported erectile function, but it does not make the secondary outcomes equivalent to the primary endpoint.

The record also includes Week 14 results after the open-label phase, including group summaries and paired analyses. Those results address outcomes after participants initially assigned to placebo could receive open-label Viagra, so they do not preserve the original blinded placebo comparison. Changes within treatment histories can be informative descriptively, but they should not be interpreted as a direct continuation of the Week 8 randomized contrast.

The registry lists additional secondary outcomes for the IIEF domains of erectile function, orgasmic function, sexual desire, intercourse satisfaction, and overall satisfaction. Numerical results for those outcomes are not reported in the registry record information summarized for this analysis. The listed outcomes therefore cannot be used to extend the interpretation beyond the posted results.

Secondary results generally carry less confirmatory weight than a prespecified primary result, particularly when many outcomes or analyses are reported. General statistical explanation: testing multiple outcomes raises the chance that at least one result appears statistically notable by chance if no multiplicity adjustment or hierarchy is used. The registry record does not report a multiplicity strategy. The number of outcome measures is 49, and the number of analyses is 78; the existence of multiple results supports caution, but the record does not establish how the sponsor handled that issue.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Erectile Dysfunction Inventory of Treatment Satisfaction (EDITS) Index
• Change From Baseline to End of Double-Blind Phase (Week 8) in Patient Reported Erectile Function Assessment (PREFA) Total Score
• Patient Reported Erectile Function Assessment (PREFA) Total Score
• Change From Baseline to End of DB Phase (Week 8) in International Index of Erectile Function (IIEF) Domain Scores- Erectile Function
• Change From Baseline to End of DB Phase (Week 8) in International Index of Erectile Function (IIEF) Domain Scores- Orgasmic Function
• Change From Baseline to End of DB Phase (Week 8) in International Index of Erectile Function (IIEF) Domain Scores- Sexual Desire
• Change From Baseline to End of DB Phase (Week 8) in International Index of Erectile Function (IIEF) Domain Scores- Intercourse Satisfaction
• Change From Baseline to End of DB Phase (Week 8) in International Index of Erectile Function (IIEF) Domain Scores- Overall Satisfaction

9. Statistical Interpretation

10. Statistical Methods Explained

The registry reports an adjusted mean difference for the primary Week 8 comparison and identifies ANCOVA as the sponsor’s method. It also gives group adjusted means and standard errors. The recalculated figures use the posted summaries to make a simple, unadjusted comparison; they are useful as a check on scale and direction, but do not reproduce the sponsor’s adjusted model.

What does ANCOVA contribute?

General statistical explanation: analysis of covariance compares group outcomes while accounting for specified covariates. Adjustment can improve precision when the chosen covariates explain variation in the outcome, and it can account for baseline or other measured differences according to the model. The registry record does not report which covariates were included, how they were selected, or the model diagnostics. The sponsor’s estimated difference is therefore best interpreted as the reported ANCOVA result, without assuming details that are not in the record.

For the primary endpoint, the reported ANCOVA mean difference is 18.13, its 95% confidence interval is 11.40 to 24.86, and p < 0.001. The posted adjusted means are 80.27 in DB Viagra and 62.15 in DB Placebo. These summaries describe the primary comparison at Week 8. The record identifies an observation-based Full Analysis Set population, but does not give further detail about the handling of missing endpoint observations.

What is the recalculated comparison?

General statistical explanation: an unadjusted comparison based on group summaries contrasts the observed group means without covariate adjustment. The recalculated primary difference is 18.12, with a confidence interval from 11.39 to 24.85 and p < 0.001. Its standard deviation estimate is marked approximate because it is inferred from the posted standard errors. This approximation is not a substitute for participant-level data or for the sponsor’s model.

The close alignment between the recalculated and sponsor-reported primary contrasts is a useful consistency check. It does not mean that the analyses are interchangeable: one is an unadjusted calculation from summaries, while the sponsor reports ANCOVA. Since the record does not flag a discrepancy, there is no stated conflict between their conclusions. The sponsor’s analysis remains the principal reported result.

How should the reported p-values be read?

General statistical explanation: a p-value describes how compatible the observed data are with a specified null model, under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. The primary sponsor-reported p-value is p < 0.001. A small p-value does not address the impact of missing data, bias, model misspecification, or multiplicity.

The confidence interval and point estimate are more informative about the scale and precision of the contrast than a p-value alone. In this trial, the interval is expressed in EDITS score units. It gives a range of values compatible with the data under the analysis, rather than a prediction interval for individual participants. The registry does not provide a clinical-importance threshold for interpreting that range.

Why do the phases matter?

The randomized double-blind placebo comparison is the basis for the primary Week 8 contrast. The later Week 14 outcomes include groups that received Viagra during the open-label phase. General statistical explanation: once treatment is open-label, participants and investigators know the treatment assignment, so later changes may reflect expectations, time, or other changes as well as treatment. A within-group change across visits is not equivalent to a randomized comparison between treatment groups.

The registry reports paired t-tests for the Week 14 EDITS and PREFA changes within the double-blind assignment groups. General statistical explanation: a paired t-test evaluates the average within-person change among participants with paired observations, accounting for the relationship between each person’s measurements. It does not, by itself, provide a randomized comparison of the open-label treatment against a concurrent placebo group. The record does not report the exact paired-observation counts or additional details of these analyses.

What do the planning calculations represent?

General statistical explanation: power planning calculations describe the sample size a hypothetical study might need under stated assumptions to detect a chosen effect with a target probability, if those assumptions hold. The posted planning illustrations use the observed effect as their anchor and include smaller fractions of that effect. They are not evidence about the original trial’s design rationale and are not observed power. The trial’s original sample-size justification is not reported in the registry record.

The planning method assumes two-sided significance level 0.05, equal allocation between two arms, and a normal approximation. These calculations are illustrative, rather than a full design analysis. They do not account for details not listed in those assumptions, such as attrition or covariate adjustment. Interpret them as conditional examples, not as a reconstruction of the decisions made when this trial was designed.

11. Confidence Intervals and Precision

The primary sponsor-reported estimate is a mean difference of 18.13 EDITS score points, with a 95% confidence interval from 11.40 to 24.86. The interval is entirely above zero, which is consistent with a higher mean satisfaction score in DB Viagra than in DB Placebo under the reported analysis. Its width expresses uncertainty in the estimated group contrast, rather than variation among individual participant scores.

General statistical explanation: a confidence interval is constructed by a method that, over repeated studies under its assumptions, would capture the target parameter at the stated confidence level at the corresponding rate. For a single trial, it is best read as a range of effect values reasonably compatible with the data and model. It is not a guarantee that the true effect falls within the particular interval, and it does not include uncertainties that the model does not address.

The unadjusted recalculation gives a 95% interval from 11.39 to 24.85. Its close proximity to the sponsor’s interval is reassuring as a summary-level cross-check, but the sponsor’s ANCOVA result is the reported primary analysis. The registry’s description of the primary endpoint includes standard errors for the adjusted means; it does not post separate confidence limits for each arm in the outcome summary.

Precision does not determine clinical importance. The score scale is anchored from 0 to 100, but the registry record does not report a threshold for a clinically meaningful difference. Nor does a confidence interval describe how responses vary among participants. The posted summary does not provide the outcome distribution or a responder analysis for the primary result, so those aspects of precision and heterogeneity cannot be assessed from these summaries.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The planning figures are expressed as participants per arm for the continuous outcomes in this analysis; they are not total event counts. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is set as the stated fraction of the observed effect. These assumptions describe the planning illustration, not the trial’s original design assumptions, which are not reported in the registry record.

The 80% power column gives the illustrative participants per arm for a hypothetical study to have an 80% chance of detecting the selected effect under those assumptions. The 90% power column gives the corresponding figure for a 90% chance. Power is conditional on the assumed effect, variability, analysis, and significance level; it is not a measure of how likely the trial’s observed result is to be true.

Rows representing 100% of the observed effect use the observed estimate as the planning target. Rows representing 75% or 50% of the observed effect plan for smaller effects. Smaller effects need more participants to be detected with the same target power under the stated assumptions. For the primary comparison, the illustration lists 23 participants per arm for 80% power and 31 for 90% power when planning for 100% of the observed effect; for 75%, it lists 41 and 54; for 50%, it lists 91 and 121.

These are planning illustrations, not observed power. The original design justification, assumptions about attrition, and any other planning adjustments are not reported in the registry record. The figures should not be used as evidence that the completed trial was designed around the observed effect.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 18.120; pooled standard deviation σ = 21.720.
2. n = 2 × (1.96 + 0.842)² × 21.720² / 18.120² = 22.6, rounded up to 23 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 18.12                      # observed difference in means
sigma <- 21.7203114158154                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(301262)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 23 (80% power), 31 (90% power)
 75% of observed effect: n per arm = 41 (80% power), 54 (90% power)
 50% of observed effect: n per arm = 91 (80% power), 121 (90% power)
power.t.test: 23.6 
Simulated power at n = 23 per arm: 0.789 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Analyses Reported by the Sponsor

The sponsor’s primary analysis is an ANCOVA comparison of DB Viagra and DB Placebo at Week 8. It reports a mean difference of 18.13, a 95% confidence interval from 11.40 to 24.86, and p < 0.001. This is the trial’s reported primary inferential result and takes precedence over the simple unadjusted recalculation.

The recalculation from posted summary statistics gives a difference of 18.12, a 95% confidence interval from 11.39 to 24.85, and p < 0.001. It uses group-level summaries and is not ANCOVA. The close agreement supports the consistency of the numerical direction and approximate magnitude, while the small differences are compatible with the fact that the analyses are not identical.

The recalculation is not a correction to the sponsor’s result and does not add participant-level adjustment. No discrepancy is flagged in the registry record. For interpretation of the trial’s primary analysis, the sponsor’s ANCOVA estimate and its reported interval and p-value should remain the reference. The summary-level recalculation is best treated as a transparent unadjusted check, not as an alternative official analysis.

15. Multiplicity, Missing Data and Analysis Populations

The registry record reports 49 outcome measures and 78 analyses. It does not report whether the trial used a prespecified hierarchy for secondary outcomes, an adjustment for multiple comparisons, or another strategy to control the chance of false-positive findings across analyses. In the absence of that information, the primary result should be distinguished from the collection of secondary findings, and unadjusted secondary p-values should be treated as exploratory or supportive rather than as a set of independent confirmations.

General statistical explanation: when several hypotheses are tested, the chance of seeing at least one apparently unusual result can increase even if each individual test uses the same significance threshold. Adjustments or a planned testing hierarchy can address this, but their presence and implementation cannot be assumed. The record’s reported p-values should be read as stated for their individual analyses; no multiplicity-adjusted interpretation is available from the registry entries summarized for this analysis.

The primary outcome population is described as participants in the Full Analysis Set with an observation. Outcome counts are 88 for DB Viagra and 73 for DB Placebo. The registry does not provide enough information to assess why some enrolled participants are not represented in these primary outcome counts, how missing values were handled, or whether missingness differed by group. Further analysis-population definitions and imputation procedures are not reported in the registry record.

General statistical explanation: missing outcome data can affect a treatment comparison if the observed participants differ from those without measurements in ways related to treatment or outcome. The consequences depend on the missingness pattern and the assumptions used for analysis. Without details on reasons for missingness, sensitivity analyses, and handling methods, the direction and size of any impact cannot be determined from the posted summaries.

The record identifies ANCOVA for the primary sponsor analysis and paired t-tests for the reported Week 14 changes. It does not report model diagnostics, covariate specifications, or sensitivity analyses in the summarized information. These gaps limit independent assessment of modeling assumptions and robustness; they do not justify assuming that a particular analysis was or was not performed.

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

The posted primary result indicates a higher mean Week 8 EDITS Index score in the DB Viagra group than in the DB Placebo group. The sponsor’s adjusted comparison estimates the group difference as 18.13 points, with a 95% confidence interval from 11.40 to 24.86 and p < 0.001. The scale’s direction is clear: higher scores correspond to greater treatment satisfaction. This describes the average reported score contrast in the analysis population, not an outcome experienced by every participant.

The result does not by itself establish the practical importance of the score difference. The registry record does not report a clinically important difference threshold for EDITS. Statistical evidence that a difference is inconsistent with zero under the model does not answer whether the difference is meaningful to individual participants, nor does it establish the effects of treatment on all dimensions of sexual health or quality of life.

The trial’s primary comparison was randomized and double-blind, but the posted group summaries do not show the distribution of individual scores, the extent of variation in response, or outcomes for participants without observations. The registry information does not report the missing-data methods or a multiplicity strategy. Those limits matter when considering how far the numerical conclusion can be generalized beyond the specific endpoint and analysis.

The Week 14 results belong to a subsequent open-label phase and have a different interpretive status from the Week 8 placebo-controlled comparison. They can describe reported scores after open-label treatment, but they do not isolate a blinded randomized effect for that phase. The posted results should therefore be read as statistical evidence about defined group summaries and time points, not as medical advice or a universal prediction about treatment response.

17. Why This Trial Matters Statistically

This trial illustrates how a patient-reported treatment satisfaction scale can serve as a primary endpoint when a study’s stated focus is sexual satisfaction. The EDITS Index provides a defined range and direction, allowing the mean difference to be interpreted in scale units. At the same time, a scale-based result does not automatically reveal how many participants experienced a meaningful change or how responses varied, questions that require additional reported analyses.

The record also makes an important statistical distinction visible: the sponsor’s reported ANCOVA result is adjusted, while the recalculated contrast is a simple unadjusted estimate from group summaries. The close agreement is a useful check, but the methods answer slightly different statistical questions. This distinction matters when readers compare registry analyses with calculations based only on posted summary data.

The trial’s two phases also show why timing and masking need to remain part of interpretation. The Week 8 outcome belongs to the double-blind placebo-controlled comparison; the Week 14 outcomes follow an open-label phase. Combining those findings without distinguishing phase and assignment could obscure what the randomized contrast can support.

Finally, the number of outcomes and analyses makes multiplicity and missing-data reporting important to the strength of secondary conclusions. The registry does not report a multiplicity strategy or full missing-data methods in the information summarized for this analysis. Recognizing those limitations helps keep the primary finding, supporting outcomes, and unresolved questions in their appropriate roles.

18. 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 registry record does not report the original sample-size justification, so the planning illustrations cannot explain how the study’s enrollment target was chosen. It also does not report the covariates included in the primary ANCOVA or model diagnostics. Those details would help readers evaluate the adjustment and assumptions behind the sponsor’s estimate.

The primary endpoint is described for the Full Analysis Set population with an observation, but the record does not report the reasons participants lack endpoint observations, the missing-data method, or sensitivity analyses. The number contributing to the primary endpoint differs between the posted treatment groups; the available information does not establish why. This prevents an assessment of whether missingness could have affected the comparison.

The registry record does not report a clinically important difference threshold for the EDITS Index. The statistical contrast and confidence interval therefore do not, on their own, define practical importance. The posted group summaries also do not describe the distribution of individual outcomes or the proportion of participants whose scores changed by a specified amount.

Multiplicity handling is not reported despite the record listing numerous outcome measures and analyses. The secondary p-values should consequently be interpreted cautiously. The Week 14 outcomes follow open-label treatment and are not the same kind of blinded randomized comparison as the primary Week 8 endpoint. Detailed information about the open-label phase and the analysis assumptions for the paired tests is not reported in the registry record.

Finally, the primary result concerns men described as having mild erectile dysfunction who were sexually dissatisfied. The information summarized for this analysis does not support extending the result to other populations, endpoints, or treatment settings.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Impact Of Viagra On Sexual Satisfaction Of Men With Mild Erectile Dysfunction Who Are Sexually Dissatisfied — NCT00301262.
• Registry record last updated 2021-02-01; status last verified 2021-01.
• Results first posted 2008-12-09.
• 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.

22. Record Summary

The registry record describes NCT00301262 as a completed Phase 4, multicenter, randomized, double-blind, parallel-group trial of Viagra versus placebo, followed by an open-label phase. Enrollment was 183. The study start is recorded as 2005-11 and primary completion as 2007-09.

The primary endpoint was the Week 8 EDITS Index score. The sponsor-reported ANCOVA comparison was a mean difference of 18.13, with a 95% confidence interval from 11.40 to 24.86 and p < 0.001. The registry also includes secondary measures of satisfaction and patient-reported erectile function, alongside listed IIEF domains.

The record names the sponsor as Pfizer's Upjohn has merged with Mylan to form Viatris Inc. It does not report the original sample-size rationale, multiplicity strategy, or full missing-data methods in the information summarized for this analysis. The primary statistical result is clear as a group-average score comparison; interpretation of clinical importance and secondary findings remains limited by those reporting gaps.