Pilot Study Investigating Safety and Efficacy of Tadalafil as Treatment for Benign Prostatic Hyperplasia (BPH) in Asian Men: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot Study Investigating Safety and Efficacy of Tadalafil as Treatment for Benign Prostatic Hyperplasia (BPH) in Asian Men (NCT00540124), a randomized phase 2 study. The primary outcome is Change From Baseline to 12 Week Endpoint in International Prostate Symptom Score (IPSS) Total Score.

2. Clinical Question

3. Trial Design

This was a phase 2, randomized, double-blind, placebo-controlled, parallel-design pilot study. Its official title describes evaluation of efficacy and safety of once-a-day tadalafil and tamsulosin dosing for 12 weeks in Asian men with signs and symptoms of benign prostatic hyperplasia. The registry reports enrollment of 151 and a completed status. The sponsor was Eli Lilly and Company.

The registry gives a start date of 2007-10 and a primary completion date of 2008-06. These dates describe the recorded study timeline; the record does not provide more detail about recruitment or the timing of individual participant visits. The primary purpose in the brief summary is to evaluate change in IPSS total score from study beginning to study end among participants randomized to tadalafil 5mg once a day or placebo once a day.

Randomization indicates that assignment was intended to follow a random process, while double masking indicates that the study was designed to keep treatment assignment concealed from participants and relevant study personnel. The parallel design means participants were assigned to a study group rather than described as crossing between treatments. The registry does not report the allocation ratio, group sizes, randomization method, or who specifically was masked.

Although tamsulosin is listed among the interventions, arm descriptions are blank in the registry record. The details of its dosing, the precise role of each group, and any planned comparisons involving tamsulosin are therefore not reported in the registry record. The record also does not give a sample-size justification or a detailed protocol synopsis.

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: There were three periods to this study. Period 1 was a 4-week Screening/Washout Period. 196 subjects screened (45 failures). Period 2 was a 4-week Placebo Run-in Period. Period 3 was a 12-week Treatment Period (151 subjects randomized).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Primary analysis was performed on an intent-to-treat basis. Data from participants with baseline and at least one post-baseline data were used for the analysis. Last observation carried forward.

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 Change From Baseline to 12 Week Endpoint in International Prostate Symptom Score (IPSS) Total Score, measured over baseline, 12 weeks.

The primary endpoint is change from baseline to the 12-week endpoint in IPSS total score. The registry describes the score as the combined responses to 1 through 7 component questions. Each question is scored from 0-5, yielding an overall range of 0-35 points. Higher numerical scores represent greater symptom severity.

Change from baseline is used to describe how a participant’s measured score differs at follow-up from the starting measurement. Comparing changes between randomized groups can help distinguish the pattern during treatment from the starting symptom levels, provided that the analysis and missing-data handling are appropriate. This is a continuous outcome, and the registry identifies the measure of location as the mean and the measure of dispersion as the standard deviation.

As a general statistical point, a symptom score offers a structured way to quantify participants’ reported experience, while a change score focuses on movement over the study period. The registry record does not report the group means, standard deviations, between-group estimate, confidence interval, or p-value for the primary endpoint. The magnitude and precision of any treatment-group contrast therefore cannot be established from the registry entries.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary outcome analyzed as a mean, with standard deviation as its measure of dispersion. It also names the analysis population and a procedure for carrying observations forward when follow-up data are unavailable. Several important details of the statistical plan, including the model used to compare groups and any adjustment for baseline score, are not reported in the registry record.

What does a mean and standard deviation describe?

In general, the mean describes the average value in a group, while the standard deviation describes how spread out participant values are around that average. A standard deviation is not the same as the uncertainty in the mean or in a between-group effect. Those uncertainties are commonly described by a standard error or confidence interval. The registry identifies means and standard deviations for the primary endpoint but does not report their numerical values.

For a change endpoint, each participant’s follow-up score is considered in relation to that participant’s baseline score. A group mean change summarizes the average movement in that group. The treatment comparison would ordinarily focus on a contrast between groups, but the registry record does not report the contrast or specify the statistical model used to estimate it. It would therefore be inappropriate to infer a particular analysis method from the endpoint description alone.

What does intent-to-treat mean in this record?

In general, intent-to-treat analysis aims to preserve randomized group assignment when evaluating outcomes. The registry says the primary analysis was performed on an intent-to-treat basis, but defines the analyzed data as coming from participants with baseline and at least one post-baseline measurement. This means the stated analysis population is not described as including every randomized participant regardless of available follow-up. The record does not report how many participants were excluded from the endpoint analysis or how their absence affected the groups.

How does last observation carried forward work?

In general, last observation carried forward fills a missing later measurement with the participant’s most recent available measurement. It creates a complete analysis value for some participants, but relies on an assumption about how the outcome would have behaved after the last recorded visit. The method does not itself establish that the carried-forward value accurately represents the unobserved endpoint. The registry specifies this procedure but does not report the amount or pattern of missing data, the number of values carried forward, or sensitivity analyses using alternative assumptions.

Missingness can matter when participants with unavailable outcomes differ from those with observed outcomes, or when missingness is related to treatment or symptom change. As a general point, a single imputation procedure can understate uncertainty if it treats imputed values as though they were observed. Whether that issue affected this study cannot be assessed from the registry record because the necessary missing-data details and comparative analyses are not reported.

What can be inferred from the study design?

Random allocation and double masking are design features intended to reduce bias in group comparisons. A parallel design evaluates assigned groups over the same study period. These design labels do not, on their own, establish that the groups were balanced, that masking was maintained, or that the analysis was free from bias. The registry does not report the randomization sequence method, concealment details, or an assessment of masking.

The study is described as a pilot, and the registry gives total enrollment as 151. A detailed sample-size justification, target enrollment, and assumptions behind the study’s original design are not reported in the registry record. Any sample-size planning illustration based on an observed effect is a retrospective planning exercise under stated assumptions, not an account of the trial’s original design and not observed power. Such an illustration cannot replace the actual effect estimate and its uncertainty.

How should multiplicity and over-dispersion be considered?

In general, multiplicity arises when many outcomes, time points, or analyses are considered. Repeated testing can increase the chance of at least one apparently notable result under a no-effect scenario. The registry lists 13 outcome measures and 48 analyses, but does not report whether a multiplicity adjustment was planned or how the analyses were prioritized. The number of listed analyses alone does not establish which results were confirmatory.

Over-dispersion is a general concern when observed variability is greater than assumed by a statistical model; ignoring it can make uncertainty appear too small. The primary outcome is continuous and summarized by a mean and standard deviation, but the registry does not report a model or evidence of over-dispersion. This concept should not be interpreted as a claim that over-dispersion occurred in this study.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 13 outcome measures and 48 analyses. Secondary outcomes include IPSS total score at earlier follow-up endpoints, IPSS irritative, obstructive, and nocturia subscores, BPH-II, patient and clinician global impression categories, and voiding-diary measures. Considering several outcomes or analysis choices can make selective emphasis a concern. As a general statistical principle, multiplicity procedures can control the chance of false-positive findings across a defined family of tests, but the registry record does not report whether any such procedure was used.

The registry record does not report a hierarchy of outcomes, a testing sequence, a multiplicity adjustment, or which analyses were designated confirmatory. The stated primary endpoint is change in IPSS total score at 12 weeks, but the available information does not explain how its interpretation was protected from the wider set of outcomes and analyses. The number of analyses alone cannot establish that a multiplicity problem occurred; it does make the missing analysis-plan details relevant to interpretation.

For the primary analysis, the record says an intent-to-treat approach was used and specifies that participants had to have baseline and at least one post-baseline measurement. It also states that last observation carried forward was used. The number of participants with missing outcomes, reasons for missingness, timing of the last observed data, and any sensitivity analyses are not reported in the registry record.

In general, missing-data methods rely on assumptions about the relationship between observed and unobserved values. Carrying forward the last observation can be transparent as a procedure, but it does not show that the missing endpoint would have stayed unchanged. Without missingness summaries or alternative analyses, the robustness of the primary result to those assumptions cannot be assessed. The registry record also does not report a detailed analysis population flow or group-specific numbers included in the endpoint analysis.

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

The registry record establishes that the trial was designed to compare change in IPSS total score over 12 weeks in participants assigned to tadalafil or placebo. It also records tamsulosin as an intervention and describes several additional symptom, global-impression, and voiding-diary outcomes. However, numerical results for the primary endpoint are not reported in the registry record. The available information therefore does not establish the size, direction, or precision of the primary group contrast.

A statistically significant result, if reported, would address compatibility with a statistical null hypothesis under the specified analysis; it would not by itself describe the size or practical importance of a difference. Conversely, a result that is not statistically significant would not establish that the groups were equivalent. In general, interpretation requires the estimated effect and its uncertainty, along with an understanding of the outcome scale and study design. Those primary numerical results are unavailable in the registry record.

The score ranges from 0-35 points, and higher numerical scores represent greater symptom severity. This describes how to read the scale, not the trial’s observed change. The registry’s analysis description also indicates use of last observation carried forward, but does not provide enough information to assess how missing data might have influenced the outcome.

Safety entries include counts of serious and other adverse events, but group-specific denominators are not reported in the registry record. Counts alone do not give event rates or permit a reliable comparison of risk across groups. Death counts are not reported in the registry record. The listed serious-event terms include Acute myocardial infarction, Inguinal hernia, Lumbar spinal stenosis, Lung adenocarcinoma metastatic, and Pleural effusion, each accompanied by 2.0% in the record; further details needed to interpret those entries are not reported.

The appropriate reading is therefore limited: the record describes a randomized pilot study and its planned primary measure, but does not supply the numerical efficacy results needed to characterize the observed treatment comparison. This does not support a conclusion for or against either treatment.

12. Why This Trial Matters Statistically

This study is statistically informative as an example of how a registry record can describe design and endpoint definitions without furnishing the numerical outcome results needed for an effect interpretation. The randomized, double-blind, parallel design and the prespecified-looking focus on change in IPSS total score define the intended comparison, while the absence of an effect estimate, uncertainty interval, and p-value leaves the central statistical finding unknown.

The endpoint’s construction is explicit: it combines responses to 1 through 7 questions, uses a range of 0-35 points, and assigns greater severity to higher scores. Such detail helps readers understand what a reported change would represent. But a scale definition is not an outcome finding. Without group summaries and a between-group estimate, the direction and precision of the study’s primary comparison cannot be evaluated.

The record also identifies a notable analysis issue: the primary population is described as intent-to-treat, while the actual analysis data are restricted to participants with baseline and at least one post-baseline measurement, with last observation carried forward. This makes clear why analysis-population definitions and missing-data assumptions matter. The registry does not give the counts needed to judge the impact of these choices.

Finally, the listing of multiple outcomes and analyses highlights the value of a transparent statistical plan. The registry does not report multiplicity procedures or a hierarchy of tests. These omissions do not prove flawed analysis, but they constrain independent assessment of how results were selected and interpreted. Together, the record illustrates that design descriptors, score definitions, and safety counts are useful context, yet cannot replace a reported primary effect estimate and its uncertainty.

13. 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.

Key details needed to evaluate the trial’s execution and its primary analysis are not reported in the registry record. Although total enrollment is 151, group-specific enrollment and the number analyzed for the primary endpoint are not given. The allocation ratio, randomization method, allocation concealment, and identities of the people masked are also not reported. These omissions prevent assessment of group balance and the practical implementation of the stated design.

The registry does not report numerical results for the primary endpoint, including group means, standard deviations, an estimated between-group contrast, a confidence interval, or a p-value. It also does not report protocol sample-size justification or the statistical model used for the endpoint. The original rationale for the pilot enrollment and the precision intended by the investigators therefore cannot be assessed.

The primary analysis description names last observation carried forward but does not provide missing-data counts, reasons for missingness, or sensitivity analyses. The stated intent-to-treat label is qualified by the requirement for baseline and at least one post-baseline measurement; the number of randomized participants not meeting that requirement is not reported. The record does not explain whether other methods were considered.

Secondary outcomes and analysis counts are listed, but the registry does not report a statistical testing hierarchy or a multiplicity approach. Arm descriptions are blank, leaving treatment details beyond the brief primary comparison unclear, including further details for tamsulosin. For safety outcomes, the numbers at risk are not reported, and death counts are not reported in the registry record. These limitations restrict interpretation of both the efficacy and safety information available.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Pilot Study Investigating Safety and Efficacy of Tadalafil as Treatment for Benign Prostatic Hyperplasia (BPH) in Asian Men — NCT00540124.
• Registry record last updated 2010-11-25; status last verified 2010-11.
• Results first posted 2009-07-20.
• 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.

17. Record Summary

The registry record identifies NCT00540124 as a completed phase 2 randomized, double-blind, placebo-controlled, parallel-design pilot study sponsored by Eli Lilly and Company. It reports enrollment of 151, a start date of 2007-10, and a primary completion date of 2008-06. The study concerned Asian men with signs and symptoms of benign prostatic hyperplasia and listed tadalafil, placebo, and tamsulosin as interventions.

The primary endpoint was change from baseline to the 12-week endpoint in IPSS total score, described as a mean with standard deviation. The primary analysis description specifies an intent-to-treat basis, data from participants with baseline and at least one post-baseline measurement, and last observation carried forward. The record lists 13 outcome measures and 48 analyses. Numerical primary-outcome results, group-specific denominators, and several statistical-plan details are not reported in the registry record.