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 Cyclooxygenase-2 (COX-2) Inhibitor Reduces Serum Prostatic Specific Antigen (PSA) Levels (NCT01678313), a randomized phase 2 study. The primary outcome is Change From Baseline in the Serum Prostate Specific Antigen (PSA) Level.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01678313 |
| Phase | Phase 2 |
| Condition | Benign Prostatic Hyperplasia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | None (open label) |
| Enrollment | 140 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Buddhist Tzu Chi General Hospital |
| Results posted | Yes |
2. Clinical Question
Population
Men with lower urinary tract symptoms associated with benign prostatic hyperplasia (LUTS/BPH) and an elevated serum prostate-specific antigen (PSA) level were the intended study population. The registry record does not report further eligibility details or a description of the population included in the primary-outcome analysis.
Intervention
The study group was assigned doxazosin 4 mg daily plus celecoxib 200 mg every day. The planned treatment period was 3 months.
Comparator
The control group was assigned doxazosin 4 mg every day, also for 3 months. This comparison evaluates the addition of celecoxib to doxazosin, rather than celecoxib as a replacement for doxazosin.
Primary question
The primary endpoint was change from baseline in serum PSA, with change defined as the month 3 value minus the baseline value. The clinical question is whether PSA change differs between the assigned treatment groups. A numerical between-group result, including its uncertainty, is not reported in the registry record.
The trial also listed changes in void volume, maximum flow rate, and symptom questionnaire scores as secondary outcomes. These measures address urinary flow and reported symptoms, while the primary endpoint is a blood measurement. The registry title raises the possibility that a fall in PSA could predict a lower risk of prostate cancer, but a PSA change alone does not establish that prediction. The registry record does not report a cancer outcome or a follow-up analysis validating PSA change as a predictor. Consequently, the posted information frames a treatment comparison in men with elevated PSA; it does not establish what a PSA change means for an individual participant or what the longer-term cancer risk is.
3. Trial Design
This was a randomized, parallel-group phase 2 trial recorded as completed. The registry lists an enrollment of 140. The brief summary describes random assignment in a 2:1 ratio to treatment for 3 months: doxazosin 4 mg daily plus celecoxib 200 mg every day, or doxazosin 4 mg every day. The registered allocation is randomized, the model is parallel, and masking is listed as none. The sponsor is Buddhist Tzu Chi General Hospital.
The study began in 2012-08, and primary completion is recorded as 2013-08. These dates describe the registry record; they do not provide the dates on which individual participants were enrolled, treated, or assessed. The registry identifies benign prostatic hyperplasia as the condition. More detailed eligibility criteria, recruitment procedures, treatment-adherence information, and the number of participants assigned to each arm are not reported in the registry record.
The primary endpoint is continuous: change from baseline in serum PSA, measured in ng/mL at baseline and 3 months after initial treatment. The description defines change as Month 3 minus Baseline. Thus, a negative change represents a lower month 3 PSA value than the participant’s baseline value, while a positive change represents a higher value. This sign convention describes the endpoint; it does not tell whether the groups differed.
The registry also names five secondary outcomes: change in void volume, maximum flow rate, IPSS voiding subscore, IPSS storage subscore, and total International Prostate Symptom Score. Although six outcome measures are recorded, the registry lists no analysis entries. The record does not report whether all listed outcomes were assessed, how participants were handled after treatment discontinuation, or which analysis populations were used. Those omissions limit how fully the design and results can be evaluated from the registry record alone.
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.
Completed the 3-month Therapy
| Stage | Study Group | Control Group |
|---|---|---|
| STARTED | 70 | 70 |
| COMPLETED | 64 | 58 |
| NOT COMPLETED | 6 | 12 |
Reasons for not completing this period:
| Reason | Study Group | Control Group |
|---|---|---|
| Lost to Follow-up | 3 | 8 |
| Physician Decision | 3 | 4 |
PSA >4 ng/dL at 3 Months
| Stage | Study Group | Control Group |
|---|---|---|
| STARTED | 64 | 58 |
| COMPLETED | 56 | 49 |
| NOT COMPLETED | 8 | 9 |
Reasons for not completing this period:
| Reason | Study Group | Control Group |
|---|---|---|
| PSA≦4 | 8 | 9 |
Prostate Biopsy at 3 Months
| Stage | Study Group | Control Group |
|---|---|---|
| STARTED | 56 | 49 |
| COMPLETED | 45 | 37 |
| NOT COMPLETED | 11 | 12 |
Reasons for not completing this period:
| Reason | Study Group | Control Group |
|---|---|---|
| Not received prostate biopsy | 11 | 12 |
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 | Study Group | Control Group | Total |
|---|---|---|---|---|
| Participants analysed | 64 | 58 | 122 | |
| Age, Continuous | years | 70.4 (SD 9.5) | 73.8 (SD 8.0) | 72.1 (SD 8.75) |
| Sex: Female, Male: Female | Participants | 0 | 0 | 0 |
| Sex: Female, Male: Male | Participants | 64 | 58 | 122 |
| Region of Enrollment: Taiwan | participants | 64 | 58 | 122 |
6. Primary Endpoint
The registry lists the primary outcome as Change From Baseline in the Serum Prostate Specific Antigen (PSA) Level, measured over Baseline and 3 months after initial treatment.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | ng/mL |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change from baseline in serum prostate-specific antigen (PSA) level, reported in ng/mL. PSA is a blood measurement; the trial record selected it to assess change during treatment in men with LUTS/BPH and an elevated PSA level. The stated assessment points are baseline and 3 months after initial treatment, and the endpoint is defined as the month 3 value minus the baseline value.
Using change rather than the final measurement alone can describe how the measurement moved relative to its starting point. A negative change indicates a lower measured PSA at month 3 than at baseline; a positive change indicates a higher value. The registry specifies that the outcome is a mean with standard deviation as its dispersion measure. These summaries can describe the average change and the spread of participant changes, but they do not by themselves establish a difference between assigned groups. A between-group estimate and its confidence interval would be needed to assess the size and precision of that contrast.
The title proposes that a reduction in PSA might predict a lower risk of prostate cancer. The registered primary endpoint, however, is PSA change, not a reported cancer diagnosis or validated prediction measure. Cancer outcomes, their ascertainment, and a predictive analysis are not reported in the registry record. Therefore, the endpoint can address measured PSA change over the stated treatment period, but the registry information does not establish a link between that change and subsequent cancer risk.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies a clear treatment contrast: adding celecoxib to doxazosin versus doxazosin alone in men with LUTS/BPH and elevated PSA. It also defines the primary outcome and when it was to be measured. However, the registry record does not report numerical primary-outcome values, a comparison between arms, or a confidence interval. No direction, magnitude, or precision of a treatment-group difference can therefore be described from the posted results.
The primary endpoint is mean change in PSA, with change defined as month 3 minus baseline. In general, a negative mean change describes a decrease from baseline, and a positive mean change describes an increase. Without the arm-specific means and a between-group estimate, those interpretations cannot be applied to this trial’s participants. The record also gives no p-value or other test result for the primary comparison. It would be inappropriate to infer a result from the study title, which states a proposed conclusion, rather than from numerical outcome data.
The registry lists six outcome measures and zero analysis entries. A measure being listed does not show that its results were analyzed or posted. The secondary outcomes include urinary flow measures and symptom scores, but their numerical results and between-group comparisons are not reported in the registry record. The planned study enrollment of 140 likewise does not establish how many participants contributed data to any particular endpoint or analysis.
The result section is marked as not reduced to one comparison because the primary outcome has several categories or time points. The endpoint description identifies baseline and 3-month assessments, but a single reported contrast is not available in the registry record. This means there is no reported numerical estimate on which to assess statistical uncertainty or practical importance. The registry also does not report a prespecified threshold for a clinically important PSA change, so no claim about the meaning of any hypothetical difference can be made.
At most, the record supports a description of the question the trial was designed to investigate and the treatment groups planned. It does not support a conclusion about whether the added treatment changed PSA more than doxazosin alone, whether any change was clinically meaningful, or whether PSA change predicted prostate cancer risk. The absence of a reported numerical result is not evidence that the groups were the same; it leaves the treatment comparison unresolved in the registry record.
9. Statistical Methods Explained
The registry describes a randomized, parallel-group comparison. Randomization is a method for assigning participants to treatment groups by chance. In general, it is intended to reduce systematic differences between groups at the start of a study, although it does not guarantee that the groups will be identical. The record says allocation was randomized and that assignment was planned in a 2:1 ratio. It does not report the randomization sequence, how assignments were concealed, or the number assigned to each group.
What does a parallel-group comparison estimate?
In a parallel design, participants are assigned to a treatment group and a comparator group, and the groups are followed over the same study period. Here, the intended contrast is doxazosin plus celecoxib versus doxazosin alone. A direct group comparison is more informative about the addition of celecoxib than observing change in the combination group alone, because PSA can change over time for reasons not attributable to the added treatment. The registry record does not report a numerical group contrast.
How should change from baseline be read?
The recorded endpoint is a continuous measure summarized as a mean with standard deviation. Each participant’s change is defined as the month 3 PSA value minus the baseline value. In general, a mean summarizes the average observed change, while a standard deviation describes the spread of individual changes around that average. The standard deviation is not the same as a confidence interval: it describes variability among observations, whereas a confidence interval describes uncertainty around an estimate. No mean changes, standard deviations, or confidence intervals for the primary endpoint are reported in the registry record.
What does a confidence interval contribute?
In general, a confidence interval gives a range of values compatible with the data and the statistical method used, reflecting uncertainty in an estimate. Its width is affected by factors such as variability and the amount of usable information. A narrow interval indicates greater precision than a wide interval, but precision alone does not establish clinical importance. Because the registry record does not report a primary between-group estimate or confidence interval, neither the likely range of effects nor the precision of the comparison can be assessed.
What can a p-value tell a reader?
In general, a p-value describes how incompatible the observed data are with a specified statistical null model, under the assumptions of the analysis. It does not state the probability that the null hypothesis is true, and it does not quantify the size or clinical importance of a difference. A p-value needs to be read alongside an effect estimate, uncertainty interval, analysis plan, and the limitations of the data. The registry record does not report a primary p-value or analysis entry, so no significance test can be interpreted.
Why does the analysis population matter?
In general, an analysis population defines which participants contribute to an estimate. An analysis based on assigned treatment groups can preserve the rationale of randomization, while analyses restricted to participants who completed treatment may be affected by differences in who remained under observation. Other approaches may address adherence or missing measurements, but their interpretation depends on their definitions and assumptions. The registry record does not report the population used for the primary analysis, participant flow, adherence, or how departures from the assigned treatment were handled.
What is over-dispersion, and is it relevant?
In general, over-dispersion means that observed variability is greater than a statistical model assumes. It matters when a model’s uncertainty estimates rely on a variance assumption that is too small; standard errors and confidence intervals may then understate uncertainty. The registered primary endpoint is a continuous measure summarized by a mean and standard deviation, but the registry record does not describe a model, a variance assessment, or an adjustment for over-dispersion. There is no basis in the record to say whether it was assessed or whether it affected the reported analysis.
How should planning illustrations be understood?
In general, sample-size planning asks how many participants would be needed to detect a chosen effect under stated assumptions. Such calculations are planning illustrations, not results observed in the trial and not evidence that a study had a particular probability of finding an effect. The recorded planning assumptions describe a two-sided significance level of 0.05, equal allocation, a normal approximation, and an effect defined as a stated fraction of the observed effect. The description says that continuous-outcome planning values are participants per arm. The registry record does not report numerical planning values or the trial’s own sample-size justification. These assumptions therefore cannot be taken as the protocol’s design rationale or as proof that the study was adequately powered.
The registry lists zero analysis entries. The prespecified statistical model, handling of baseline values, any covariate adjustment, and any interim analyses are not reported in the registry record. General statistical methods can clarify what information would be useful, but they cannot fill those gaps or recreate an unreported analysis.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists six outcome measures: the primary PSA change and secondary changes in void volume, maximum flow rate, IPSS voiding subscore, IPSS storage subscore, and total IPSS. When several outcomes or comparisons are analyzed, the chance of at least one apparently notable finding can increase. In general, multiplicity methods may control that risk, or the outcomes may be interpreted according to a prespecified hierarchy. The registry record does not report a multiplicity adjustment, a hierarchy among outcomes, or a statistical analysis plan. It is therefore not possible to determine how multiple outcomes were handled.
The primary endpoint is measured at baseline and 3 months after initial treatment. The registry notes that the primary outcome has several categories or time points and is not reduced to one comparison. It does not report which comparison was designated for inference, whether change scores or an adjusted model were used, or how repeated measurements were handled. These details are not reported in the registry record.
Missing-data information is also limited. The registry does not report the number of participants with primary endpoint measurements, reasons for missing measurements, or methods used to handle missing data. It also does not describe an analysis population or provide participant flow by treatment group. Without those details, it is not possible to assess whether the analyzed participants differ from those enrolled or how missingness may have affected the estimates.
The record lists an enrollment of 140, but does not report endpoint-specific analysis counts. Enrollment should not be treated as the number contributing to every outcome. In addition, no numerical primary result or analysis entry is reported, so the statistical treatment of missing data and multiple outcomes cannot be evaluated from results.
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 |
|---|---|---|---|
| Study Group | 0 | 64 | 0.0% |
| Control Group | 0 | 58 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Study Group | 0 of 64 |
| Control Group | 0 of 58 |
The registry’s safety figures list 64 participants at risk in the study group and 58 in the control group for serious adverse events. The number reported as affected is 0 in each group. For other adverse events, the record likewise lists 64 and 58 at risk, with 0 affected in each group. These are the posted registry counts, not a detailed account of event types, timing, severity, or possible relationship to treatment.
The deaths fields are null. A null entry is not the same as a reported count of zero; deaths are not reported in the registry record. The record also lists no top serious adverse-event terms. That absence does not establish that no other safety information was collected or that an event could not have occurred; it means a term-level account is not reported in the registry record.
Safety counts require context. The listed at-risk counts are not the planned enrollment figure, and the record does not explain the difference between them. It does not report follow-up completeness, the duration over which adverse events were collected, event definitions, or whether safety analyses followed assigned treatment. Therefore, the counts should be read as a limited registry summary, not as a comprehensive assessment of comparative safety.
12. What the Result Does, and Does Not, Mean
The trial record describes a randomized phase 2 comparison of doxazosin plus celecoxib against doxazosin alone in men with LUTS/BPH and elevated PSA. Its primary outcome was change in serum PSA from baseline to 3 months, calculated as the month 3 value minus baseline. Those details define the question and the outcome, but they do not provide the result of the comparison.
No numerical primary-outcome result, between-group estimate, confidence interval, or p-value is reported in the registry record. The statistical effect and its precision therefore cannot be judged. The missing result should not be interpreted as evidence that there was no difference, just as the registry title should not be treated as evidence that a difference was found. The title describes a proposed interpretation; the posted record lacks the numerical analysis needed to evaluate it.
Even if a PSA change were reported, a change in this measure would not on its own establish that the change predicts prostate cancer risk. The record does not report a cancer outcome, a predictive model, or an assessment of how well PSA change identifies later cancer outcomes. It therefore cannot establish the proposed predictive value from the information recorded.
The listed secondary measures concern void volume, maximum flow rate, and urinary symptom scores. Their results are also not reported in the registry record. The safety summary reports zero affected for serious and other adverse events in the listed groups, but deaths are not reported, and the safety information is limited. Neither the missing efficacy results nor the abbreviated safety summary supports a broad conclusion about benefit or harm. The evidence available in the registry record is descriptive of the study design and its planned measurements, not a basis for determining the comparative outcome.
13. Why This Trial Matters Statistically
This trial is statistically interesting because its main endpoint is a continuous change measure, while the proposed interpretation in the title reaches beyond that measure to possible cancer-risk prediction. Keeping the estimand and the interpretation distinct is essential: a randomized comparison of PSA change addresses whether that measurement differs between assigned treatment groups, whereas prediction of cancer risk requires relevant cancer outcomes and an analysis connecting PSA change to those outcomes. The registry record describes the former endpoint but does not report the latter evidence.
The allocation is recorded as randomized, with a planned 2:1 assignment, and the study is described as parallel and unmasked. These design features matter when interpreting comparisons: randomization supports a causal comparison under appropriate conduct and analysis, while lack of masking can matter for outcomes influenced by assessment or reporting. PSA is a laboratory measure, but the registry does not provide details about measurement procedures or analysis. The record also does not report how allocation was generated or concealed, so those elements cannot be assessed.
The trial’s planned enrollment and the listed safety counts are not substitutes for outcome-specific analysis counts. Nor can planning assumptions be read as observed evidence. The registry lists zero analysis entries and does not provide numerical results, which means uncertainty, effect size, multiplicity handling, and missing-data impact cannot be evaluated. This illustrates why a trial’s question and design can be clear even when the strength and meaning of its evidence remain indeterminate from the registry record.
For clinical researchers, the key statistical lesson is to distinguish a measured endpoint from the broader claim attached to it, and a study’s planned design from its reported analysis. Without an estimate and its uncertainty, the relative outcomes of the groups cannot be assessed. Without a predictive analysis and cancer outcomes, a PSA change cannot be interpreted as validated evidence about subsequent cancer risk.
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 of the registry record is the absence of numerical primary-outcome results. Although it identifies the PSA endpoint and its measurement period, it does not report arm-specific changes or a between-group estimate. This prevents assessment of effect size, direction, and precision. The record also lists zero analysis entries, so there is no reported statistical test or model to evaluate.
The design description is incomplete for a detailed risk-of-bias assessment. Randomized allocation and no masking are recorded, but the method of sequence generation, allocation concealment, participant flow, adherence, and treatment discontinuation are not reported in the registry record. The number enrolled is listed, but the number analyzed for the primary endpoint is not. Reasons for missing measurements and the method for handling them are also not reported.
The endpoint description specifies change in PSA at baseline and 3 months, but the record does not provide a single reported comparison or explain the analysis approach. The statistical analysis plan, any covariate adjustments, multiplicity procedures, and interim analyses are not reported in the registry record. These gaps leave uncertainty about how the intended comparison was implemented.
The title suggests a possible relationship between PSA reduction and prostate cancer risk, but the recorded primary outcome is PSA change. Cancer outcomes, follow-up for those outcomes, and validation of a predictive relationship are not reported in the registry record. Therefore, the registry information cannot support the proposed prediction claim. Safety reporting is also limited: affected counts are listed, but event detail and follow-up context are absent, and deaths are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Cyclooxygenase-2 (COX-2) Inhibitor Reduces Serum Prostatic Specific Antigen (PSA) Levels — NCT01678313.
- Registry record last updated 2014-07-15; status last verified 2014-07.
- Results first posted 2014-06-30.
- 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
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
The registry record describes NCT01678313, a completed randomized phase 2 parallel-group trial sponsored by Buddhist Tzu Chi General Hospital. Enrollment is listed as 140; the study began in 2012-08, with primary completion in 2013-08. Masking is listed as none. The brief summary describes planned randomization in a 2:1 ratio for 3 months.
The study group received doxazosin 4 mg daily plus celecoxib 200 mg every day, while the control group received doxazosin 4 mg every day. The primary endpoint was change from baseline in serum PSA, measured in ng/mL at baseline and 3 months after initial treatment, defined as Month 3 minus Baseline. Secondary outcomes covered void volume, maximum flow rate, and IPSS symptom scores.
The registry lists zero analysis entries and does not report a numerical primary-outcome comparison. Safety figures list 0 affected for serious and other adverse events in both groups; deaths are not reported in the registry record. Numerical efficacy, analysis methods, missing-data handling, and the proposed relationship between PSA change and cancer risk remain unreported.