This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Effect of Dihydrotestosterone (DHT) on Prostate Tissue [Short Title: DHT-3] (NCT00490022), a randomized phase 1, phase 2 study. The primary outcome is Prostate Tissue DHT and Testosterone Levels After 28 Days of Treatment With Dihydrotestosterone [DHT] Gel Versus Placebo Gel..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00490022 |
| Phase | Phase 1, Phase 2 |
| Condition | Healthy |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Double |
| Enrollment | 31 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of Washington |
| Results posted | Yes |
2. Clinical Question
Population
Healthy men, as described in the trial title and registry record. Enrollment was 31.
Intervention
DHT gel at 70 mg/day for one month.
Comparator
Placebo gel for one month.
Primary question
After 28 days of treatment, what were the prostate tissue concentrations of DHT and testosterone in the two groups?
The study concerns the effect of DHT administered as a skin-applied gel on hormone concentrations in prostate tissue. The primary outcome is described as prostate tissue DHT and testosterone levels measured after treatment. The registry says that participants underwent a prostate biopsy after four weeks of daily DHT or placebo gel and that concentrations were measured in ng/g.
The comparison is between a group receiving DHT gel and a group receiving placebo gel. The registry describes the study as randomized, double-masked, and parallel-group. These design features identify the intended comparison, but the registry record does not report the randomization procedure, the people masked, or how allocation was implemented.
The research description places the tissue measurements within a broader investigation of hormone levels in blood and prostate tissue, as well as cells and gene expression within the prostate. The posted primary outcome, however, is specifically about tissue DHT and testosterone levels after treatment. Prostate epithelial cell proliferation is listed as a secondary outcome.
The registry record does not report numerical primary-outcome results or a single comparison estimate. It also does not report the population details beyond the description of healthy men, such as eligibility characteristics or a detailed account of who contributed tissue measurements. Accordingly, the question can be stated from the planned comparison, but the magnitude and precision of the observed tissue-level contrast cannot be read from this record.
3. Trial Design
This completed study is listed as Phase 1 and Phase 2, with randomized allocation, double masking, and a parallel design. The registry reports enrollment of 31 and identifies healthy participants. It lists the University of Washington as sponsor. The recorded start was 2007-06, and primary completion was 2009-01.
One group received DHT gel at 70 mg/day for one month; the comparison group received placebo gel for one month. The intervention listing identifies DHT gel as 0.7%. The primary outcome description says participants underwent a prostate biopsy after four weeks of daily treatment. It describes measuring intraprostatic DHT and testosterone concentrations in ng/g. Prostate epithelial cell proliferation is listed as a secondary outcome.
The record's design labels indicate that participants were assigned to one of two parallel groups rather than crossing between treatments. Randomization is reported, but the sequence-generation method, allocation concealment, and details of who was masked are not reported in the registry record. The record also does not describe adherence assessment, treatment discontinuation, or the handling of participants who did not complete the biopsy or other measurements.
The posted safety summaries list 16 people at risk in the placebo DHT gel group and 15 in the DHT gel group. Those are the denominators in the safety section; the record does not separately give a flow diagram or explain the relationship between enrollment and each analysis population. Do not assume that the safety denominators establish the number included in every outcome analysis.
Although the study is marked completed, the status alone does not establish that every planned measurement has a posted numerical result. The primary-outcome entry names two tissue hormone measures and a 28-day timeframe, but a specific numerical group comparison is not reported in the registry record. Detailed protocol and statistical-plan information, including the sample-size justification and interim analyses, is not reported in the registry record.
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: Subjects must meet all study protocol inclusion criteria such as informed consent, normal lab values, normal physical examination and normal prostate ultrasound, and not have exclusion criteria such as a first degree relative with or personal history of prostate cancer, PSA \>2.0 or a history of a bleeding disorder or need for anticoagulation.
Overall Study
| Stage | Placebo DHT Gel | DHT Gel |
|---|---|---|
| STARTED | 16 | 15 |
| COMPLETED | 15 | 12 |
| NOT COMPLETED | 1 | 3 |
Reasons for not completing this period:
| Reason | Placebo DHT Gel | DHT Gel |
|---|---|---|
| Adverse Event | 0 | 2 |
| Withdrawal by Subject | 1 | 0 |
| Subject failed to disclose concommitant | 0 | 1 |
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.
| Characteristic | Unit | Placebo DHT Gel | DHT Gel | Total |
|---|---|---|---|---|
| Participants analysed | 16 | 15 | 31 | |
| Age, Categorical: <=18 years | Participants | 0 | 0 | 0 |
| Age, Categorical: Between 18 and 65 years | Participants | 16 | 15 | 31 |
| Age, Categorical: >=65 years | Participants | 0 | 0 | 0 |
| Age Continuous | years | 44.4 (SD 6.7) | 42.7 (SD 1.6) | 43.6 (SD 4.2) |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 16 | 15 | 31 |
| Region of Enrollment: United States | participants | 16 | 15 | 31 |
6. Primary Endpoint
The registry lists the primary outcome as Prostate Tissue DHT and Testosterone Levels After 28 Days of Treatment With Dihydrotestosterone [DHT] Gel Versus Placebo Gel., measured over 28-days.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ng/g |
| Endpoint classification | Continuous Endpoint |
The primary endpoint concerns concentrations of DHT and testosterone in prostate tissue after treatment. The registry describes collection by prostate biopsy after four weeks of daily DHT gel or placebo gel, with hormone concentrations expressed in ng/g. It labels the measure as a mean with standard deviation as the dispersion measure and gives the timeframe as 28 days.
These tissue measurements address the study's stated interest in whether administered DHT is associated with different hormone concentrations within the prostate. A tissue measurement is distinct from a blood hormone measurement: it describes the sampled prostate tissue rather than circulating concentrations. The registry's broader summary also mentions blood hormones, cells, and gene expression, but those are not the stated primary endpoint.
In general, a continuous endpoint such as a concentration can be summarized by a group mean, with a standard deviation describing variation among individual measurements. A comparison of group means can summarize the average difference between treatment groups, while an interval estimate can convey uncertainty around that comparison. Those concepts do not supply a result for this trial: numerical group means, standard deviations, an effect estimate, and its confidence interval are not reported in the registry record.
The primary outcome title refers to both DHT and testosterone, and the record indicates more than one outcome measure. It also notes that the primary outcome has several categories or time points and was not reduced to one comparison in the posted presentation. The record therefore does not support a single numerical summary of the primary endpoint on this page. The listed endpoint helps identify what was measured and when, but it does not by itself show the size, direction, or precision of a treatment-group difference.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question and design, but it does not provide numerical primary-outcome results. It describes a randomized, double-masked, parallel comparison of DHT gel and placebo gel in healthy men, with prostate tissue DHT and testosterone concentrations measured after 28 days. Without group-level outcome values or a reported comparison, the direction and magnitude of any difference cannot be characterized from this record.
The primary endpoint is a continuous measurement reported in ng/g and described using means and standard deviations. For such an endpoint, a group mean would summarize the average concentration in that group, and the standard deviation would describe the spread of individual measurements around that average. A treatment contrast would then quantify the difference between group summaries. None of those numerical outcome summaries or a corresponding interval estimate is reported in the registry record. There is therefore no basis for judging the precision of the primary comparison.
The record lists 31 enrolled participants and safety denominators of 16 for placebo gel and 15 for DHT gel. These counts describe enrollment and safety reporting, respectively; they do not establish how many participants contributed to each tissue measurement. The number included in each primary-outcome analysis, and how missing measurements were handled, are not reported in the registry record. This matters because a biopsy-based endpoint may be available only for participants with an observed specimen and a usable assay result.
The posted results section identifies two outcome measures and zero analyses in the record information. It also indicates that the primary outcome has several categories or time points and is not reduced to one comparison. These details do not provide a substitute for estimates or tests. In particular, they do not establish that there was no difference, nor do they establish that there was a difference. The primary numerical results are not reported in the registry record.
In general, statistical interpretation of a treatment comparison considers both the estimated effect and its uncertainty. A confidence interval gives a range of values compatible with the data under the stated model and procedure; it is not a guarantee that the true value lies inside that particular interval. A p-value, when reported, describes the compatibility of data with a specified null model, not the probability that a treatment is effective or ineffective. No primary-outcome confidence interval or p-value is reported in the registry record.
The sample-size section on the page is a planning illustration based on an observed effect, not a report of the trial's original design or observed power. The listed assumptions are a two-sided significance level of 0.05, equal allocation, a normal approximation, and effects expressed as stated fractions of the observed effect. Since the numerical observed effect and planning values are not included in this record information, no particular planning count can be interpreted. Even where displayed, such planning counts should be read as hypothetical requirements for a future design under stated assumptions, not as evidence about the results of this study.
The safety section reports one serious adverse event in the DHT gel group and none in the placebo DHT gel group. It also reports other adverse events in the same counts and denominators. These descriptive figures do not establish that the event was caused by treatment, and the record does not provide enough detail to assess comparative safety statistically. Overall, the registry information supports a description of the planned comparison and recorded safety counts, but not a conclusion about the primary tissue hormone result.
9. Statistical Methods Explained
The registry labels this study randomized, double-masked, and parallel-group. These are design descriptions, not a complete statistical analysis plan. The record does not report the randomization method, the masking roles, the planned model, or detailed procedures for the primary comparison. The interpretation below distinguishes the general meaning of common statistical ideas from what can actually be assessed using this record.
What does randomization contribute?
In general, randomization assigns participants to groups using a chance-based process. Its purpose is to reduce systematic differences between groups at assignment, including differences that are known and unknown to investigators. Randomization does not guarantee that two groups will be identical, particularly in a small study. It also does not prevent bias arising after assignment, for example through differential missing measurements or changes in treatment. Here, the registry reports randomization, but the sequence-generation and allocation-concealment methods are not reported in the registry record.
What does masking mean?
In general, masking is intended to limit the influence of knowledge about group assignment on care, measurement, or reporting. The study is described as double-masked, but the registry record does not state which participants or study personnel were masked, how masking was maintained, or whether it was assessed. The use of DHT gel and placebo gel is described; the record does not give further details that would establish how similar the gels appeared or were handled.
How should a continuous endpoint be summarized?
The primary measure is continuous: tissue concentrations of DHT and testosterone in ng/g. The registry labels the summary parameter as a mean and the dispersion as a standard deviation. In general, the mean describes the arithmetic average, while the standard deviation describes how spread out individual observations are around that average. Neither quantity alone provides a treatment comparison. A comparison also requires group results and a specified contrast, with uncertainty expressed using a suitable interval or test.
The record does not include the group means, standard deviations, sample sizes for the outcome analysis, or a reported contrast. It therefore cannot support a recalculation from summary statistics. No recalculated result is presented. A mean-based comparison is also most interpretable when the measurement distribution and analysis assumptions are appropriate; distributional checks and model details are not reported in the registry record.
Why does uncertainty matter?
In general, an estimate is more informative when paired with an uncertainty interval. A confidence interval communicates the range of effect values that are reasonably compatible with the observed data and the assumptions of the method. Wider intervals indicate less precision than narrower intervals, although precision alone does not determine clinical or scientific importance. A p-value answers a different, more limited question about compatibility with a null hypothesis under a statistical model. Neither an interval nor a p-value replaces the effect estimate itself.
No confidence interval, p-value, or numerical primary-outcome contrast is reported in the registry record. The study's enrollment count cannot be used to infer precision without outcome variability and the actual analysis population. It also cannot be used to infer whether the study was adequately powered for a particular effect, since the sample-size justification and target effect are not reported in the registry record.
What does the planning illustration show?
In general, a planning calculation asks how many participants a future study might require under specified assumptions about the effect to detect, variability, significance level, allocation, and statistical method. The sample-size section describes an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation. It describes planning for stated fractions of the observed effect. The calculated values are planning illustrations, not the trial's original sample-size justification and not observed power.
Observed power is not a useful substitute for presenting an effect estimate and its uncertainty. In general, power is a design property defined for a particular assumed effect and analysis; after a study, a post hoc calculation based on the observed effect does not add independent evidence about the result. The registry record does not report the trial's original sample-size justification, so the illustrative planning section should not be read as describing why enrollment was set at 31.
How should multiple outcomes be considered?
The record lists two primary outcome measures and a secondary outcome of prostate epithelial cell proliferation. The primary outcome entry also states that it has several categories or time points and was not reduced to one comparison. In general, examining multiple outcomes, time points, or contrasts can raise a multiplicity issue: the chance of at least one apparently unusual result can increase as more tests are conducted. Analysts may address this through a prespecified hierarchy or adjustment, or may clearly identify analyses as exploratory. Which approach was planned or used is not reported in the registry record.
The information does not include the analysis model, assumptions, handling of repeated measurements, missing-data method, or analysis populations. It also does not describe interim analyses. Those omissions mean that a reader cannot reconstruct or independently verify the inferential procedure from the registry record alone. They do not, by themselves, show that the analyses were inappropriate; they show that these methodological details are not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists two primary outcome measures, prostate tissue DHT and testosterone levels, and identifies prostate epithelial cell proliferation as a secondary outcome. It also states that the primary outcome has several categories or time points and was not reduced to one comparison. This creates an important interpretive distinction: the record identifies what was measured, but does not specify which contrast or time point should be treated as the single primary statistical test.
In general, multiplicity arises when several outcomes, time points, subgroups, or statistical contrasts are tested. Looking at many comparisons can make at least one result appear notable by chance, even when no underlying effect exists. Study plans may control this through a prespecified primary contrast, an ordered testing strategy, or an adjustment to the inference. The registry record does not report a multiplicity strategy or clarify how the several categories or time points were handled. No adjustment or unadjusted analysis should be presumed.
The registry information reports zero analyses, and numerical primary-outcome results are not reported in the registry record. The analysis population for each outcome is not specified. Although enrollment was 31 and safety denominators are given, those figures do not establish the number of participants with analyzable tissue measurements. Reasons for missing specimens or measurements, methods for handling missing data, and whether analyses followed assigned treatment are not reported in the registry record.
In general, missing-data methods rely on assumptions about why observations are missing. The amount and pattern of missingness, and the method used, can affect interpretation. Without participant flow, outcome-specific denominators, and a stated method, readers cannot assess those issues. Interim analyses and stopping rules are also not reported in the registry record. These gaps limit reproducibility and interpretation, but they do not establish that missing data or multiplicity affected the study's findings.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Placebo DHT Gel | 0 | 16 | 0.0% |
| DHT Gel | 1 | 15 | 6.7% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Placebo DHT Gel | 0 of 16 |
| DHT Gel | 1 of 15 |
Most frequent serious adverse event terms
| Event term | Organ system | Placebo DHT Gel | DHT Gel |
|---|---|---|---|
| Rectal Bleed | Gastrointestinal disorders | 0 of 16 | 1 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Placebo DHT Gel | DHT Gel |
|---|---|---|---|
| Urinary Frequency | Renal and urinary disorders | 0 of 15 | 1 of 15 |
Serious events with the highest arm-level rate: rectal bleed (6.7%).
The safety summary lists 16 people at risk in the placebo DHT gel group and 15 in the DHT gel group. It records zero participants with a serious adverse event in the placebo group and one in the DHT gel group. The other-adverse-event counts are also zero and one, respectively. These are descriptive counts, not an adjusted comparison or a causal assessment.
In general, an at-risk denominator indicates the group size used for a reported safety summary. Event counts should be read together with that denominator and with the definitions and observation period used. The registry record does not provide a detailed account of the event definitions, the method of ascertainment, or the timing of events. It does not report a statistical comparison of these safety counts.
The record lists Rectal Bleed among the top serious adverse-event terms, with 6.7%. It does not establish in this information whether that term corresponds to the one serious event in the DHT gel group or provide an event-level account. The cause of the event is not reported. Death counts are not reported in the registry record.
These small descriptive totals should not be interpreted as proof that a treatment caused or did not cause an event, nor do they quantify comparative risk with precision. The registry figures are a limited summary of reported adverse events, not a complete safety evaluation.
12. What the Result Does, and Does Not, Mean
This trial asks a focused biological question: whether one month of DHT gel, compared with placebo gel, is associated with different DHT and testosterone concentrations in prostate tissue. The registry identifies a randomized, double-masked, parallel-group design and describes biopsy-based measurement after 28 days. It also lists prostate epithelial cell proliferation as a secondary outcome.
The record does not report numerical primary-outcome values or an inferential comparison. Consequently, this page cannot say whether tissue concentrations were higher or lower in either group, how large any difference was, or how precisely it was estimated. The absence of a numerical result in the registry record is not evidence of no effect. It is a limitation on what can be concluded from the available record.
Even if a group difference were available, a difference in tissue hormone concentration would be a biological measurement, not by itself evidence about a clinical outcome. The research summary describes possible future relevance to male hormonal contraception, low male hormone levels, and prostate diseases, but the trial information does not establish effects on pregnancy prevention, symptoms, disease development, or long-term health. The study duration described for treatment is one month.
In general, interpreting a treatment study requires attention to the population, intervention, comparator, outcome, follow-up, and uncertainty. The registry identifies healthy men and the gels, but does not provide detailed participant characteristics, outcome-analysis denominators, or estimates with confidence intervals. Generalizability beyond the described study population therefore cannot be assessed from these details alone.
The serious adverse-event summary records one event in the DHT gel group and none in the placebo group, without enough detail to attribute cause or estimate a precise comparative safety difference. Overall, the record describes the research question, design, and a limited safety summary, but does not provide the primary numerical findings needed to characterize the tissue hormone comparison. No medical conclusion should be drawn from the missing result.
13. Why This Trial Matters Statistically
This study is statistically interesting because it connects a randomized treatment comparison with a tissue-based biological endpoint. The endpoint is not simply a blood concentration: the registry describes prostate biopsy and measurement of intraprostatic DHT and testosterone in ng/g. That distinction matters when defining what a result would represent. A measurement in sampled tissue answers a different question from a circulating hormone measurement.
The design labels also matter. Randomization is intended, in general, to support a fair comparison between groups, while masking can reduce the influence of treatment knowledge on measurement or reporting. Yet design labels do not replace operational detail. The randomization procedure and the people masked are not reported in the registry record, so readers cannot evaluate those implementation features from this information.
The record also illustrates why outcome reporting needs to align with the stated endpoint. Two tissue hormone measures are named, and the registry notes multiple categories or time points without reducing them to one comparison. Without a clearly identified contrast, outcome-specific denominators, estimates, and uncertainty intervals, readers cannot determine what the principal numerical result was or how robustly it was estimated.
The planning illustration has a separate role. In general, sample-size calculations can show how a future study's requirements depend on an assumed effect and analysis method. Here the illustration is described as based on the observed effect and specified assumptions, but it is not the trial's own design justification and is not observed power. Keeping those purposes separate prevents a planning table from being mistaken for evidence about the trial result.
Finally, the small safety counts demonstrate why event summaries require context. Counts and denominators are useful descriptive information, but do not establish causation or precise comparative safety. The value of this record for statistical education lies in separating the study question and design from information that would be needed for a full interpretation of effects.
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 central limitation for interpreting the primary endpoint is that numerical results are not reported in the registry record. Although the endpoint title and description specify DHT and testosterone concentrations in prostate tissue after 28 days, the record information does not include group means, standard deviations, a treatment contrast, or a confidence interval. The direction, magnitude, and precision of the comparison therefore cannot be assessed.
The registry notes several categories or time points and says the primary outcome was not reduced to one comparison. It does not identify a primary contrast among them or describe a multiplicity approach. The analysis model, distributional assumptions, and procedures for handling multiple measures are not reported in the registry record. This limits reproducibility and makes it difficult to relate the listed outcomes to a single inferential question.
Enrollment was 31, while safety denominators were 16 and 15. The record does not report outcome-specific denominators, participant flow, reasons for missing tissue measurements, or the analysis population. Because the endpoint relies on biopsy and assay measurement, the availability and usability of specimens are relevant; the extent of missingness cannot be assessed from this record.
The methods information is also limited. The randomization procedure, allocation concealment, identities of masked groups, original sample-size justification, interim analyses, and detailed statistical plan are not reported in the registry record. The sample-size illustration is described as planning based on the observed effect, so it should not be treated as the original design rationale or as observed power.
Finally, the safety summary contains few events and does not provide event-level details or a causal assessment. The registry describes healthy men, but detailed participant characteristics and longer-term outcomes are not available. These limitations define what can be concluded from the record; they do not establish that the study was conducted improperly.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effect of Dihydrotestosterone (DHT) on Prostate Tissue [Short Title: DHT-3] — NCT00490022.
- Registry record last updated 2011-06-27; status last verified 2011-06.
- Results first posted 2011-06-09.
- 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.
Continue through the Clinical Biostats statistical pathway
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18. Record Summary
This completed Phase 1 and Phase 2 study is listed as randomized, double-masked, and parallel-group, with enrollment of 31. The recorded start was 2007-06 and primary completion was 2009-01. The sponsor is the University of Washington.
The comparison was DHT gel at 70 mg/day for one month versus placebo gel for one month. The primary endpoint is prostate tissue DHT and testosterone concentrations after 28 days, measured in ng/g following prostate biopsy. Prostate epithelial cell proliferation is listed as a secondary outcome.
The registry record does not report numerical primary-outcome results, an effect estimate, or its uncertainty. It lists safety denominators of 16 for placebo and 15 for DHT, with zero and one serious adverse event, respectively. Statistical-plan details, outcome-specific analysis populations, and missing-data methods are not reported in the registry record.