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 Efficacy of Ambrisentan in Limited Scleroderma Patients in Improving Blood Flow to Hands or Feet (NCT01072669), a randomized na study. The primary outcome is Digital Micro-vascular Flow.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01072669 |
| Phase | NA |
| Condition | Ischemia |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 20 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Soumya Chatterjee |
| Results posted | Yes |
2. Clinical Question
Population
People with limited systemic sclerosis, Raynaud’s phenomenon, and digital ischemia are the population described for the primary outcome. The registry’s brief summary also frames the study around scleroderma patients and Raynaud’s flares. The record does not report detailed eligibility criteria, baseline characteristics, or how many participants met each clinical feature.
Intervention
Ambrisentan was the drug intervention. The registry describes its use in limited scleroderma patients with Raynaud’s to evaluate digital microvascular flow. The record does not report the dose, schedule, treatment duration beyond the outcome timeframe, or adherence.
Comparator
The comparator was a sugar pill. The arm description says it was used to assess whether active drug improved digital microvascular flow. The record does not give further details about the pill or how closely it matched the active treatment.
Primary question
The central question was whether ambrisentan changed digital microvascular flow, measured by laser Doppler perfusion imaging, in people with systemic sclerosis and Raynaud’s phenomenon with digital ischemia. The registry lists baseline and 12 weeks as the primary timeframe, while the outcome description also mentions measurement at 1 week. It does not report the observed change in either group, a between-group estimate, or an uncertainty interval. Therefore, the clinical question is recorded, but the treatment comparison cannot be evaluated from the posted outcome results.
3. Trial Design
The registry describes a randomized, parallel-group study with quadruple masking. The two arms were ambrisentan and sugar pill. Random allocation is intended to make treatment groups comparable on average, while masking is intended to limit the influence of treatment knowledge on participants’ experiences, care, or outcome assessment. Those are general features of these design methods; the record does not describe how randomization or masking was implemented or maintained.
The registry lists enrollment as 20 and the study status as completed. The start is recorded as 2010-02 and primary completion as 2010-12. These dates and the enrollment entry do not establish how many participants were randomized, completed follow-up, or contributed to the primary analysis. The registry does not report those analysis-population counts. The phase is listed as NA.
The active intervention was ambrisentan, and the comparator was a sugar pill. The sponsor is listed as Soumya Chatterjee. The condition is listed as ischemia. The brief summary describes an investigation of possible benefit for relieving or preventing Raynaud’s flares in people with scleroderma, while the official title focuses on digital microvascular flow measured with laser Doppler perfusion imaging.
The primary outcome is titled “Digital Micro-vascular Flow,” with perfusion units and a mean as the stated measure. Its timeframe is listed as baseline and 12 weeks. Its description also refers to measurement at 1 week and 12 weeks. The registry does not explain whether the 1-week measurement was a secondary time point, how multiple time points were handled, or which visit posted the primary comparison. Detailed protocol information about the treatment regimen, eligibility criteria, allocation procedures, and analysis populations 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.
Overall Study
| Stage | Ambrisentan | Sugar Pill |
|---|---|---|
| STARTED | 15 | 5 |
| COMPLETED | 15 | 5 |
| NOT COMPLETED | 0 | 0 |
Analysis population for the primary outcome, as defined in the registry: Assuming a standard deviation of 0.40, and use of a two-sample t-test with significance level of 0.05, there will be 80% power to detect differences in the change from baseline of at least 0.65 units if moderate correlation (r=0.50) exists, and 0.45 units if strong correlation (r=0.75) exists between treated
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 | Ambrisentan | Sugar Pill | Total |
|---|---|---|---|---|
| Participants analysed | 15 | 5 | 20 | |
| Age Continuous | years | 50.6 (SD 12.8) | 46.8 (SD 10.5) | 49.7 (SD 12.1) |
| Sex: Female, Male: Female | Participants | 13 | 3 | 16 |
| Sex: Female, Male: Male | Participants | 2 | 2 | 4 |
| Region of Enrollment: United States | participants | 15 | 5 | 20 |
6. Primary Endpoint
The registry lists the primary outcome as Digital Micro-vascular Flow, measured over Baseline and 12 weeks.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | 95% Confidence Interval |
| Unit | perfusion unit |
| Endpoint classification | Continuous Endpoint |
The primary endpoint concerns digital microvascular flow, a continuous measure reported in perfusion units. The registry says flow was measured by laser Doppler perfusion imaging in patients with Raynaud’s phenomenon and digital ischemia secondary to systemic sclerosis. It describes change from baseline and identifies the mean as the summary measure.
In general, a measure of blood flow can serve as a physiological outcome when a study aims to assess circulation in a specific body area. A continuous outcome preserves the scale of the measurement, rather than reducing it to a yes-or-no event. Comparing changes from baseline can account for where participants began, but the interpretation depends on the analysis method and the timing of measurements.
The record identifies baseline and 12 weeks as the timeframe, and the outcome description additionally names 1 week. It does not report observed means, changes, group differences, confidence intervals, or participant counts for this endpoint. Nor does it clarify which time point was designated as the primary analysis. Consequently, the endpoint’s intended measurement is identifiable, but its observed results and precision are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry establishes that the study was designed to compare ambrisentan with a sugar pill for digital microvascular flow in people described as having systemic sclerosis, Raynaud’s phenomenon, and digital ischemia. It also identifies a mean change from baseline as the outcome concept and laser Doppler perfusion imaging as the measurement approach. These details describe the research question; they are not evidence of the outcome of the comparison.
No primary outcome analysis is reported. The registry gives no observed flow values, change estimates, treatment-group contrast, confidence interval, or p-value. It is therefore not possible to determine from the posted results which group had a higher measured flow, how large any difference was, or how precisely a difference was estimated. The absence of a reported estimate should not be interpreted as an estimate of zero or as evidence that the groups were equivalent.
The registry lists enrollment as 20, but does not report the number randomized or analyzed for the primary endpoint. The safety entries use different at-risk counts for the two arms, but those entries do not supply the missing outcome-analysis denominators. Without outcome results and their analysis population, the relationship between the listed enrollment and any endpoint comparison is unclear.
The outcome timing is also not fully specified. The timeframe gives baseline and 12 weeks, whereas the outcome description names measurements at 1 week and 12 weeks. The record does not identify the primary visit for the treatment contrast or explain how measurements from multiple visits were incorporated. This matters because estimates at different visits address different time-specific questions, and selecting among multiple outcomes or time points can affect interpretation.
The record includes planning assumptions about detecting changes under specified standard-deviation and correlation assumptions. Those assumptions are not observed treatment effects, and they do not substitute for trial results. The planning text does not report the eventual treatment contrast or show whether the assumptions matched observed data. No inferential conclusion about the intervention can be drawn from those design statements alone.
In statistical terms, the posted record supports a description of the design and intended outcome, but not an assessment of the estimated effect or its uncertainty. It also does not report whether a prespecified statistical analysis was followed, whether any analysis was adjusted, or how missing outcome measurements were handled. These omissions limit both statistical and clinical interpretation.
9. Statistical Methods Explained
The registry identifies a randomized, parallel-group comparison with quadruple masking. In general, randomization assigns participants to treatment groups by chance and can reduce systematic differences between groups at the start of a study. It does not guarantee that every characteristic will be balanced, particularly in a small study. Parallel-group design means participants are assigned to one treatment group rather than receiving both treatments in sequence. Masking is intended to reduce the influence of knowledge about assignment. The registry does not report the procedures used to generate or conceal assignments, or which people were included in the quadruple masking.
What was the planned outcome?
The primary outcome is a continuous measure of digital microvascular flow in perfusion units, summarized as a mean. The description says change from baseline was measured using laser Doppler perfusion imaging. In general, a change score represents the difference between a participant’s measurement at a later visit and the baseline measurement. A comparison of mean changes between randomized groups can estimate the average difference in change, provided the analysis and the underlying data support that interpretation. No such observed comparison is reported in the registry record.
The timeframe names baseline and 12 weeks, but the outcome description also mentions 1 week and 12 weeks. The registry does not clarify whether the 1-week assessment was part of the primary analysis or an additional measurement. In general, when outcomes are measured at several visits, an analysis plan should specify which visit or overall trajectory answers the primary question. The plan and the actual analysis are not reported.
What do the planning assumptions mean?
The registry’s planning text states an assumed standard deviation of 0.40 and describes a two-sample t-test with significance level 0.05. It says there would be 80% power to detect differences in change from baseline of at least 0.65 units if moderate correlation (r=0.50) existed, and 0.45 units if strong correlation (r=0.75) existed. The text ends with an incomplete phrase, so the full wording is not available in the record.
In general, a two-sample t-test compares group means under assumptions about the outcome distribution and the study design. A significance level is a decision threshold used in a testing procedure; it is not the probability that a particular result is true. Power is a design quantity describing the chance that a planned test will detect an effect of a specified size under stated assumptions. It is not a description of the observed trial result. The stated correlation assumptions concern the relationship between measurements; stronger correlation between repeated measurements can improve the precision of change estimates under appropriate conditions. These are general statistical explanations, not confirmation that the planned test was conducted.
The planning text is not a report of the observed standard deviation, correlation, or treatment effect. It also does not establish that the assumptions were met. The record does not report a completed primary analysis, so there is no basis for comparing an observed result with the planned detectable differences.
How should uncertainty be understood?
A confidence interval is a range of values generated by a statistical procedure to represent uncertainty around an estimate. In general, a narrower interval indicates greater precision, while a wider interval indicates less precision. The primary outcome lists a 95% confidence interval as its dispersion measure, but no interval or estimate is posted. The confidence level alone does not indicate the direction or size of an effect, and cannot be used to infer a result when the interval itself is absent.
The registry lists the mean as the parameter for the endpoint, but does not report the group means or their variability. It also does not give a standard error, a between-group estimate, or a test statistic. Therefore, neither statistical significance nor the practical scale of a possible difference can be assessed. A missing result is not equivalent to a null result.
What analysis details remain unknown?
The registry does not report whether the comparison used the stated two-sample t-test, whether the change scores were analyzed directly, or whether a model adjusted for baseline measurements. It does not describe assumptions checks, transformations, handling of outliers, or an alternative method if the test assumptions were not suitable. These are not claims that any particular method was used; they are analysis details not reported in the registry record.
General statistical practice distinguishes the planned analysis from analyses conducted after data collection. A complete interpretation ordinarily depends on the estimate, its uncertainty, the analysis population, and transparent reporting of deviations or missing data. None of those primary-outcome analysis details is posted. The design statements explain the study’s intended comparison and some planning assumptions, but they cannot establish what analysis was ultimately performed or what it found.
10. Multiplicity, Missing Data and Analysis Populations
The outcome description mentions measurements at 1 week and 12 weeks, while the listed timeframe says baseline and 12 weeks. The record does not clarify the status of the 1-week measurement or specify a primary time point for the comparison. When several visits or outcomes are assessed, multiplicity refers generally to the increased chance of a chance-positive finding from conducting multiple statistical tests. A prespecified approach can define which comparison is primary and whether adjustments are needed. No multiplicity strategy or analysis plan is reported in the registry record.
The record lists one outcome measure and zero analyses. It does not provide an analysis population definition, such as whether all randomized participants or only participants with available measurements were included. It also does not report how many people had endpoint data at each visit, whether any measurements were missing, reasons for missingness, or how missing values were handled. Those details are important because analysis of only observed measurements can be affected if data availability is related to treatment or outcome.
The registry does not report whether the primary outcome was analyzed according to assigned group, whether protocol deviations affected inclusion, or whether sensitivity analyses were performed. It is therefore not possible to assess the handling of missing data, the use of an intention-to-treat principle, or the robustness of any treatment estimate. These are unreported methods, not evidence that a particular approach was or was not used.
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 |
|---|---|---|---|
| Ambrisentan | 0 | 15 | 0.0% |
| Sugar Pill | 0 | 5 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Ambrisentan | 0 of 15 |
| Sugar Pill | 0 of 5 |
The registry lists serious adverse events and other adverse events separately for the two arms. For ambrisentan, 15 participants are listed as at risk, with 0 affected for serious events and 0 affected for other events. For sugar pill, 5 participants are listed as at risk, with 0 affected in each of those categories. These entries describe the counts posted in the registry and do not provide event rates or a comparative safety analysis.
The at-risk counts differ between arms, and the registry enrollment entry is 20. The record does not explain the relationship between those figures, including whether the at-risk counts reflect participants exposed, assessed, or otherwise included in safety reporting. It does not give event-level detail or follow-up time for these entries. The serious-event terms list is empty.
Deaths are recorded as null for both groups. A null entry means the death count is not reported in the registry record; it should not be read as a reported zero. The posted zero counts for affected participants do not establish that no events occurred outside the recorded categories or reporting period. The registry does not provide further detail needed to evaluate safety comprehensively.
12. What the Result Does, and Does Not, Mean
The record documents a randomized, quadruple-masked comparison of ambrisentan and sugar pill, with digital microvascular flow identified as the primary outcome. It provides a measurement description, a mean-based endpoint, a general timeframe, and planning assumptions. Those details show what the study set out to evaluate and how the outcome was intended to be measured.
The record does not report the outcome analysis. There is no observed change from baseline, group contrast, confidence interval, or p-value. As a result, the magnitude, direction, and precision of any difference cannot be described. The lack of a posted analysis does not establish that the treatments had the same effect, that there was no change, or that an effect was present.
The planning statements are not results. Their detectable differences depend on assumptions about variability and correlation, and the record does not report whether those assumptions were supported by the collected data. A design calculation cannot stand in for an observed estimate. Similarly, the enrollment entry does not by itself show how many participants contributed usable outcome data or how complete follow-up was.
The safety counts report no affected participants in the listed serious and other adverse-event categories among the stated at-risk groups. The death entries are not reported. These registry entries are limited and do not constitute a full safety evaluation or a comparison adjusted for differing denominators.
In general, evidence about a treatment comparison requires the estimated effect, uncertainty, analysis population, and enough methodological detail to assess how the result was obtained. Because those outcome-analysis elements are not reported, the posted record supports interpretation of the study question and design, but not a conclusion about the measured treatment effect.
13. Why This Trial Matters Statistically
This study is statistically notable because it combines a randomized parallel-group design with a continuous physiological outcome. Randomization is a design feature intended to support a fair group comparison, and a continuous measure can retain information about changes across its measurement scale. The record identifies both the intervention contrast and the measurement approach, allowing the intended question to be stated clearly.
The planning text also makes explicit that the anticipated ability to detect a difference depended on assumptions about variability and the correlation between measurements. In general, such assumptions matter because they influence precision and the sample size required for a study design. They are not evidence that the assumptions held in the completed study, and they do not reveal the actual treatment effect.
The record illustrates why outcome reporting is essential to statistical interpretation. Although the study status is completed and a primary endpoint is named, there is no primary analysis reported. Without an estimate and confidence interval, readers cannot assess either the direction of the observed comparison or its precision. The record also leaves the relationship between its stated time points unresolved.
The safety entries provide limited counts, but the unequal at-risk denominators and unreported death counts constrain interpretation. Taken together, the statistical value of the record is principally descriptive: it identifies a study design, a clinical measurement question, and some planning assumptions, while leaving the central efficacy comparison unreported.
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 most important limitation for interpreting this study is that the registry reports no analysis of the primary outcome. No observed means, changes, treatment contrast, confidence interval, or p-value is available. The number randomized and the number contributing primary outcome data are not reported, despite the registry listing enrollment as 20.
The outcome timing is not fully clear. The primary timeframe lists baseline and 12 weeks, while the description also refers to assessments at 1 week and 12 weeks. The record does not identify the primary comparison time point or explain the role of each visit. It also does not report whether any additional outcomes or analyses were conducted.
Key methods are not described, including the randomization procedure, details of masking, intervention dose and schedule, eligibility criteria, analysis populations, and missing-data handling. The planning statement gives a standard-deviation assumption and correlation-dependent detectable differences, but its text is incomplete and does not report whether those assumptions were borne out. It does not substitute for observed results.
The safety entries list different at-risk counts for the arms, without explaining how those denominators were defined. Serious and other adverse-event counts are listed as zero, while deaths are not reported. The record does not provide event-level descriptions or enough follow-up information to interpret those counts comprehensively.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Efficacy of Ambrisentan in Limited Scleroderma Patients in Improving Blood Flow to Hands or Feet — NCT01072669.
- Registry record last updated 2013-05-03; status last verified 2013-03.
- Results first posted 2013-05-03.
- 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
The registry describes a completed randomized, quadruple-masked, parallel-group study of ambrisentan versus sugar pill in limited systemic sclerosis patients with Raynaud’s phenomenon. Enrollment is listed as 20. The primary outcome is mean digital microvascular flow in perfusion units, measured by laser Doppler perfusion imaging; the timeframe lists baseline and 12 weeks, while the description also mentions 1 week.
The registry reports no primary outcome analysis. It gives planning assumptions for a two-sample t-test but no observed treatment effect or confidence interval. Safety entries list 0 serious and 0 other affected participants among 15 at risk for ambrisentan and 5 for sugar pill; deaths are not reported. Analysis populations, missing-data handling, and detailed analysis methods are not reported in the registry record.