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 Study To Investigate The Hemodynamic Effects Of Single Dose Vardenafil In Subjects Receiving Maraviroc (NCT00853840), a randomized phase 4 study. The primary outcome is Standing and Supine Systolic and Diastolic Blood Pressure (BP).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT00853840 |
| Phase | Phase 4 |
| Condition | AIDS |
| Allocation | Randomized |
| Design model | Crossover |
| Masking | Single |
| Enrollment | 18 |
| Arms in the primary outcome | n/a |
| Lead sponsor | ViiV Healthcare |
| Results posted | Yes |
2. Clinical Question
Population
The registry lists AIDS as the condition and records 18 enrolled participants. The primary vital-sign analysis population was defined as enrolled participants who received at least 1 dose of study medication and had at least 1 vital-sign parameter measured in at least 1 treatment period. Further participant characteristics are not reported in the registry record.
Intervention
The intervention of interest was a single dose of vardenafil while participants were receiving maraviroc dosed to steady state. The registry describes the combination as Maraviroc + Vardenafil, or Treatment A. The vardenafil dose and other dosing details are not reported in the registry record.
Comparator
The comparison was maraviroc with placebo, described as Treatment B. The study is identified as placebo-controlled and crossover, so the intended comparison concerns the vardenafil and placebo treatment conditions in the same study framework. The order of treatment periods and any washout details are not reported in the registry record.
Primary question
The primary question was how a single dose of vardenafil affected standing and supine systolic and diastolic blood pressure in participants receiving maraviroc. Measurements were scheduled at 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after vardenafil or placebo. The registry also describes an objective to assess the safety and tolerability of maraviroc in participants receiving a single dose of vardenafil.
3. Trial Design
This was a Phase 4, randomized, single-blinded, placebo-controlled, two-way crossover study. It enrolled 18 participants and is listed as completed. The recorded start was 2008-04, with primary completion in 2008-05. ViiV Healthcare is named as the sponsor.
The two treatment conditions were Maraviroc + Vardenafil and Maraviroc + Placebo. Maraviroc was dosed to steady state, and the study compared the effects of a single vardenafil dose with placebo. In a crossover design, participants receive more than one treatment condition in different periods; the within-participant comparison can account for stable differences between participants. That is a general description of the design, not a statement about the trial’s exact analysis model. The registry does not report treatment sequence, period length, washout procedures, or how the single blinding was implemented.
Randomization describes how treatment assignment or sequence is determined, while blinding is intended to limit the influence of treatment knowledge. The registry identifies the study as randomized and single-blinded but does not specify which parties were blinded or how randomization was conducted. The record lists AIDS as the condition and includes maraviroc, vardenafil, and placebo as interventions. Additional eligibility details and participant characteristics are not reported in the registry record.
The primary outcome concerned standing and supine systolic and diastolic blood pressure at several post-dose times. Secondary outcomes included standing and supine pulse rate, postural changes in systolic and diastolic blood pressure, postural changes in pulse rate, and the number of participants with postural hypotension. The registry lists 5 outcome measures and 48 analyses. Those counts describe the breadth of recorded outcomes and analyses; they do not, on their own, establish how many distinct hypothesis tests were performed or how those tests were handled.
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: All subjects received 3 to 4 days of maraviroc 300 mg twice daily (BID) before receiving single oral doses of either vardenafil 20 mg (Treatment A) or placebo (Treatment B).
Period 1
| Stage | Vardenafil + Maraviroc | Non-matching Placebo + Maraviroc |
|---|---|---|
| STARTED | 9 | 9 |
| Maraviroc (Days 1 - 4) | 9 | 9 |
| Vardenafil or Placebo (Day 4) | 9 | 9 |
| COMPLETED | 9 | 9 |
| NOT COMPLETED | 0 | 0 |
Period 2
| Stage | Vardenafil + Maraviroc | Non-matching Placebo + Maraviroc |
|---|---|---|
| STARTED | 9 | 9 |
| Maraviroc (Days 1 - 3) | 9 | 9 |
| Vardenafil or Placebo (Day 3) | 9 | 9 |
| COMPLETED | 9 | 9 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: The vital sign analysis population was defined as all enrolled subjects who received at least 1 dose of study medication and had at least 1 vital sign parameter in at least 1 treatment period.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
| Characteristic | Unit | All Subjects |
|---|---|---|
| Participants analysed | 18 | |
| Age Continuous | years | 34.6 (SD 9.1) |
| Sex: Female, Male: Female | Participants | 0 |
| Sex: Female, Male: Male | Participants | 18 |
6. Primary Endpoint
The registry lists the primary outcome as Standing and Supine Systolic and Diastolic Blood Pressure (BP), measured over 1.5, 2, 2.5, 3, 4, 6, 8, 12 hours post Vardenafil or Placebo dose.
| Element | Registry entry |
|---|---|
| Result type | Least Squares Mean |
| Measure of spread | Standard Error |
| Unit | mm Hg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint was standing and supine systolic and diastolic blood pressure, measured in mm Hg. These measures describe blood pressure in two body positions and allow assessment of values at rest and after a postural change. Blood pressure is relevant to the stated hemodynamic question because the study sought to estimate the effect of a single vardenafil dose while participants were receiving maraviroc.
Measurements were scheduled at 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after the vardenafil or placebo dose. For supine measurements, participants rested supine for 5 minutes. They then sat for 2 minutes and stood for 2 minutes before standing blood pressure was taken. Duplicate supine and standing readings were collected, and their average was calculated before analysis.
The registry identifies the reported measure as a least-squares mean with standard error. A least-squares mean is an estimated mean from a statistical model; the specific model used is not reported in the registry record. A standard error describes the precision of an estimated mean, rather than the spread of individual measurements. Numerical endpoint estimates and their standard errors are not reported in the registry record, so the direction and magnitude of the blood-pressure findings cannot be described.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record defines a clinically focused comparison: standing and supine blood pressure after a single vardenafil dose versus placebo, with participants receiving maraviroc to steady state. It also gives the measurement schedule, posture procedure, and intended vital-sign analysis population. However, the numerical results for the primary blood-pressure endpoint are not reported in the registry record. Without those estimates, it is not possible to describe whether the posted results indicate higher or lower blood pressure under either treatment condition, or how large any difference was.
The outcome was assessed across systolic and diastolic blood pressure, two positions, and multiple post-dose times. This is a set of related measurements rather than one single contrast. The registry’s note that the primary outcome has several categories or time points and was not reduced to one comparison is important: a single summary estimate cannot be substituted for a collection of time-specific and posture-specific results. The record does not identify one time point as the sole basis for interpretation.
The registry lists 5 outcome measures and 48 analyses. Those counts indicate that the results were organized across multiple measures or analyses, but they do not establish the number of statistical tests, the tests’ prespecified status, or whether an adjustment for multiple comparisons was used. Those details are not reported in the registry record. When many estimates are considered, it is important to distinguish a prespecified primary comparison from exploratory comparisons and to consider how uncertainty and multiplicity were addressed. That is a general statistical consideration, not a claim about the trial’s analysis.
The study’s crossover structure is relevant to interpreting any eventual estimates. In general, crossover studies compare treatments within participants, which can reduce the influence of stable between-participant variation. Interpretation can also depend on period effects, treatment sequence, carryover, and completeness of observations across periods. The registry identifies a two-way crossover design but does not report the sequence, washout, model specification, or diagnostic checks. It is therefore not possible to assess from the registry record how those design issues were handled.
The listed vital-sign population required at least one dose and at least one vital-sign parameter in at least one treatment period. This definition describes who could contribute to that analysis, but the number of participants included in each endpoint analysis is not reported in the registry record. Nor are missing-measurement counts or methods for handling missing values reported. The enrollment count alone should not be treated as the number contributing to every outcome or time point.
For safety, the registry lists 0 participants with serious adverse events among 18 at risk in each of the maraviroc run-in, Maraviroc + Vardenafil, and Maraviroc + Placebo groups. This is a descriptive count, not evidence that the risk is zero. The registry record does not provide a precision estimate for these counts, and the deaths field is not reported. Other adverse-event counts are listed separately, but the corresponding at-risk denominators are not reported. These safety summaries do not supply the missing primary blood-pressure results.
Overall, the record establishes the study question, design, measurement procedures, and some safety counts, but does not report numerical estimates for the primary endpoint. No conclusion about the size, direction, or precision of a blood-pressure contrast can be drawn from those outcome definitions alone. General statistical interpretation requires estimates and measures of uncertainty, along with a clear account of which comparisons were planned and how the analysis treated the repeated measurements.
9. Statistical Methods Explained
The record describes a continuous primary outcome, standing and supine systolic and diastolic blood pressure in mm Hg. The reported statistic is identified as a least-squares mean, with standard error as the measure of dispersion. These labels tell readers the form of the intended summary, but the numerical estimates, standard errors, and statistical model are not reported in the registry record.
What does a least-squares mean represent?
In general, a least-squares mean is a model-based estimate of an average. Unlike a simple arithmetic average, it may reflect adjustment for terms included in the statistical model. Its interpretation therefore depends on which model terms were used and how the estimate was calculated. The registry identifies the statistic as a least-squares mean but does not report the model, its covariates, or whether estimates were adjusted. It is not possible to reconstruct or interpret a model-based contrast without those details and the numerical results.
What does the standard error describe?
In general, a standard error describes how precisely a sample-based estimate is estimated. It is not the same as the standard deviation, which describes variation among individual observations. A smaller standard error generally corresponds to greater precision for an estimate, but a standard error alone does not state the range of plausible effects as a confidence interval would. No numerical standard errors or confidence intervals for the primary endpoint are reported in the registry record. Consequently, the precision of any blood-pressure estimate cannot be assessed from the record.
Why were duplicate readings averaged?
The protocol description says that duplicate supine and standing blood-pressure readings were obtained and averaged before analysis. In general, averaging repeated readings can produce a summary that is less dependent on a single measurement. The registry gives the measurement procedure but does not report the individual readings or their variability. The reported method does not, by itself, tell whether duplicate readings were consistent or how measurement variability affected the final estimates.
How should the time points and postures be understood?
Measurements were scheduled at 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after vardenafil or placebo. Systolic and diastolic blood pressure were assessed in both supine and standing positions. This creates a series of related outcomes across time and posture. In general, repeated measurements from the same participant are correlated; statistical methods often account for that dependence rather than treating every measurement as independent. The registry does not report the model or covariance structure used, so it is not possible to determine how repeated measurements were handled.
The posture procedure also matters to interpretation. Participants rested supine for 5 minutes, then sat for 2 minutes and stood for 2 minutes before standing blood pressure was taken. These details define how the recorded measurements were obtained. The secondary outcomes include postural changes in systolic and diastolic blood pressure and in pulse rate, as well as the number of participants with postural hypotension. The primary endpoint description itself covers standing and supine blood pressure; the registry does not report a single combined summary across these categories.
What does a crossover design imply statistically?
In general, a crossover design lets participants receive multiple treatment conditions, allowing comparisons that can use within-participant information. Because the same participant contributes under more than one condition, stable individual characteristics can be accounted for in a suitable analysis. The design also makes treatment period, sequence, and possible carryover relevant. A statistical model may need to distinguish treatment effects from changes associated with period or order. The record states that the study was randomized and two-way crossover, but treatment sequence, washout procedures, period details, and model terms are not reported in the registry record. No claim about their handling can be made.
What do the planning assumptions mean?
The planning illustration is described as using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It is based on the observed effect, with the effect to detect expressed as a fraction of that observed effect. These are planning assumptions, not observed trial findings, and any resulting sample-size illustration is not observed power. No numerical planning results are reported in the registry record. The record also does not report the trial’s own sample-size justification, so the illustration should not be treated as evidence of the basis for enrolling 18 participants.
In general, a significance level is a threshold used in a hypothesis-testing procedure; it does not describe the probability that a treatment effect is true. A sample-size calculation depends on assumptions about the effect to detect, variability, significance threshold, allocation, and analysis. If those assumptions differ from the realized data or intended analysis, the calculation may not describe the study’s actual ability to estimate an effect. Here, the stated assumptions describe an illustration only; the study’s original design rationale is not reported in the registry record.
What cannot be reconstructed?
Although the record lists 48 analyses, it does not report the analysis plan, model specification, hypothesis tests, confidence intervals, or numerical primary-outcome results. It also does not state whether the analyses were adjusted for multiple comparisons or whether any interim analyses occurred. General explanations of least-squares means, standard errors, repeated measurements, and crossover designs clarify what such methods are intended to address, but they cannot replace a trial-specific analysis description. Without estimates and uncertainty measures, effect size and precision remain unassessable.
10. Multiplicity, Missing Data and Analysis Populations
The primary outcome includes several categories and time points: systolic and diastolic blood pressure, supine and standing measurements, and measurements at 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after vardenafil or placebo. The registry record notes that the primary outcome has several categories or time points and was not reduced to one comparison. It also lists 5 outcome measures and 48 analyses. These features create multiple opportunities for estimates and tests, but the counts alone do not reveal the number of distinct hypotheses or which comparisons were designated primary.
In general, when multiple statistical tests are conducted, the chance of at least one apparently notable result can increase unless the analysis plan accounts for multiplicity. Possible approaches include defining a hierarchy of outcomes, adjusting thresholds, or interpreting secondary comparisons as exploratory. Which approach, if any, was used is not reported in the registry record. The registry also does not report an interim-analysis plan or stopping rules.
The vital-sign analysis population included enrolled participants who received at least 1 dose of study medication and had at least 1 vital-sign parameter in at least 1 treatment period. This is an explicit population definition, but it does not state how many participants contributed data at each time point or to each treatment comparison. The handling of missing measurements, withdrawals, and incomplete treatment periods is not reported in the registry record. Nor is an imputation method or sensitivity analysis described.
In general, missingness can affect interpretation if participants with unavailable measurements differ systematically from those with observed measurements. A crossover analysis may also depend on which treatment periods are complete. The registry’s population definition identifies a minimum contribution to the analysis, but does not establish that every participant contributed a complete set of readings. Without participant flow and outcome-specific missing-data information, the scope of the analyzed data cannot be assessed fully.
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 |
|---|---|---|---|
| Maraviroc Run-In | 0 | 18 | 0.0% |
| Maraviroc + Vardenafil (Treatment A) | 0 | 18 | 0.0% |
| Maraviroc + Placebo (Treatment B) | 0 | 18 | 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 |
|---|---|
| Maraviroc Run-In | 4 of n/a |
| Maraviroc + Vardenafil (Treatment A) | 16 of n/a |
| Maraviroc + Placebo (Treatment B) | 5 of n/a |
Most frequent non-serious adverse event terms
| Event term | Organ system | Maraviroc Run-In | Maraviroc + Vardenafil (Treatment A) | Maraviroc + Placebo (Treatment B) |
|---|---|---|---|---|
| Headache | Nervous system disorders | 1 of 18 | 8 of 18 | 1 of 18 |
| Nasal congestion | Respiratory, thoracic and mediastinal disorders | 0 of 18 | 8 of 18 | 0 of 18 |
| Hot flush | Vascular disorders | 0 of 18 | 8 of 18 | 0 of 18 |
| Dizziness | Nervous system disorders | 0 of 18 | 2 of 18 | 2 of 18 |
| Erection increased | Reproductive system and breast disorders | 0 of 18 | 3 of 18 | 0 of 18 |
| Sensation of heaviness | Musculoskeletal and connective tissue disorders | 0 of 18 | 2 of 18 | 1 of 18 |
| Tooth fracture | Injury, poisoning and procedural complications | 1 of 18 | 1 of 18 | 1 of 18 |
| Back pain | Musculoskeletal and connective tissue disorders | 1 of 18 | 1 of 18 | 1 of 18 |
| Fatigue | General disorders | 0 of 18 | 2 of 18 | 0 of 18 |
| Abdominal discomfort | Gastrointestinal disorders | 1 of 18 | 1 of 18 | 0 of 18 |
The registry lists serious adverse events for three groups: Maraviroc Run-In, Maraviroc + Vardenafil (Treatment A), and Maraviroc + Placebo (Treatment B). Each group had 18 participants at risk, and the serious-adverse-event count was 0 in each group. These are the posted descriptive counts for the recorded groups. They do not establish that serious events are impossible or that the underlying risk is zero.
The deaths field is not reported in the registry record, so it should not be interpreted as a count of zero deaths. The record lists other adverse events affecting 4 participants during maraviroc run-in, 16 during Maraviroc + Vardenafil, and 5 during Maraviroc + Placebo. The corresponding at-risk counts for these other events are not reported in the registry record. These counts should therefore be read as recorded affected-participant counts, without inferring rates or making a denominator-based comparison.
The registry lists no top serious adverse-event terms. The group counts are safety summaries and do not provide the primary blood-pressure estimates, their uncertainty, or a complete account of event severity and timing. In general, zero observed events in a group is a finite-sample observation; the precision of an underlying risk estimate depends on the amount and structure of the safety data. The record does not report a precision interval for these counts.
12. What the Result Does, and Does Not, Mean
The study was designed to estimate the hemodynamic effects of a single vardenafil dose in participants receiving maraviroc to steady state. Its primary endpoint was standing and supine systolic and diastolic blood pressure, measured at several post-dose times. The record also describes secondary pulse-rate and postural outcomes and lists safety summaries for the run-in and two treatment conditions.
The registry does not report numerical results for the primary blood-pressure endpoint. That absence means the direction and magnitude of the blood-pressure findings, and their precision, cannot be characterized from the registry record. The outcome definition and measurement schedule establish what the study intended to measure; they are not themselves evidence of a treatment effect. No statement that vardenafil changed, did not change, increased, or decreased blood pressure can be supported by the numerical outcome information recorded.
The serious-adverse-event counts are 0 among 18 at risk in each of the three listed groups. These counts describe what was recorded, not certainty about the underlying frequency of serious events. The deaths field is not reported, and denominators for other adverse-event counts are not reported. Safety counts should not be treated as a substitute for the missing primary outcome estimates or as a complete assessment of all potential effects.
In general, an estimate should be read together with a measure of uncertainty, such as a confidence interval, and with the design and analysis methods that produced it. The registry identifies the primary outcome summary as a least-squares mean with standard error, but does not report numerical values for either. It is therefore not possible to assess precision, compare the estimated magnitude with any benchmark, or determine how strongly the results distinguish among possible effects. The record supports a description of the study’s question and methods, but not a conclusion about the size or direction of the primary outcome result.
13. Why This Trial Matters Statistically
This trial is statistically notable for its crossover design and repeated hemodynamic measurements. In general, a crossover comparison can use each participant as a source of information under both treatment conditions, reducing the influence of stable differences between participants when the analysis is appropriate. At the same time, the design requires attention to treatment order, period effects, and possible carryover. The registry identifies a randomized, two-way crossover study but does not report the period structure or the methods used to address those issues.
The endpoint also illustrates how clinical measurements can form a family of related outcomes rather than one number. Blood pressure was assessed for systolic and diastolic values, in supine and standing positions, and at multiple times after dosing. The registry lists 5 outcome measures and 48 analyses. Such breadth makes clear reporting of the analysis plan and multiplicity handling especially relevant. Those details are not reported in the registry record.
The outcome procedure is described in operational detail: rest in the supine position, a change in posture, and duplicate measurements that were averaged before analysis. This helps define what the endpoint represents and how measurements were prepared. Yet method detail cannot replace the numerical estimates and uncertainty needed to judge what the observed data indicate. In this record, the primary blood-pressure results are not reported.
The record also illustrates the distinction between a study’s own design rationale and a planning illustration based on an observed effect. The stated illustration assumptions include a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such a calculation is a planning exercise, not observed power, and does not establish why the study enrolled 18 participants. The trial’s own sample-size justification is not reported in the registry record.
14. Limitations
- The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
- Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.
The main limitation for interpreting the primary question is that numerical blood-pressure results are not reported in the registry record. There are no posted estimates, standard errors, confidence intervals, or test results for the standing and supine systolic and diastolic measures. The result’s direction, magnitude, and precision therefore cannot be assessed.
The outcome spans several measurement categories and post-dose times. Although the record lists 48 analyses and 5 outcome measures, the analysis hierarchy, prespecified contrasts, and multiplicity approach are not reported. The statistical model is also not reported, including the treatment of repeated measurements and any adjustment terms. The record does not state whether interim analyses were planned or conducted.
Several design details needed to assess a crossover analysis are not reported in the registry record. These include treatment sequence, period details, washout procedures, and how potential period or carryover effects were handled. The description of single blinding does not identify who was blinded or how blinding was maintained. Dosing details beyond a single vardenafil dose and maraviroc dosed to steady state are not reported.
The enrollment count is 18, but the number contributing to each outcome, time point, or treatment-period comparison is not reported. The registry defines the vital-sign analysis population by receipt of at least 1 dose and at least 1 vital-sign parameter in at least 1 treatment period, but does not provide missing-data counts or the method used to handle missing measurements. Participant characteristics and additional eligibility details are also not reported, limiting assessment of the population represented.
Finally, the record does not report the trial’s own sample-size justification. The described planning assumptions are an illustration based on the observed effect, not evidence of observed power or the original design rationale. Safety information is also incomplete for some readings: deaths and at-risk denominators for other adverse events are not reported in the registry record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study To Investigate The Hemodynamic Effects Of Single Dose Vardenafil In Subjects Receiving Maraviroc — NCT00853840.
- Registry record last updated 2013-01-25; status last verified 2013-01.
- Results first posted 2009-06-23.
- 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.
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18. Record Summary
NCT00853840 is a completed, randomized, single-blinded, placebo-controlled, two-way crossover Phase 4 study sponsored by ViiV Healthcare. It enrolled 18 participants; the recorded start was 2008-04 and primary completion was 2008-05. The registry lists AIDS as the condition.
The study compared Maraviroc + Vardenafil with Maraviroc + Placebo. Its primary outcome was standing and supine systolic and diastolic blood pressure, measured at 1.5, 2, 2.5, 3, 4, 6, 8, and 12 hours after dosing. The vital-sign analysis population required at least 1 study-medication dose and at least 1 vital-sign parameter in at least 1 treatment period.
The record lists 5 outcome measures and 48 analyses. Serious adverse-event counts were 0 among 18 at risk in each of the run-in and two treatment groups. Numerical primary blood-pressure results, the analysis model, and the trial’s sample-size justification are not reported in the registry record.