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 Clinical and Cost Effectiveness of ACE Inhibitor, Ramipril, in Intermittent Claudicants (NCT01037530), a randomized phase 4 study. The primary outcome is Maximum Walking Distance (MWD)..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01037530 |
| Phase | Phase 4 |
| Condition | Intermittent Claudicants |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 33 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Hull University Teaching Hospitals NHS Trust |
| Results posted | Yes |
2. Clinical Question
Population
People with intermittent claudication were the intended study population. The registry record reports an enrollment of 33 participants. The brief summary describes a recruitment aim of 78 participants, with 39 assigned to each group. Further eligibility criteria and participant characteristics are not reported in the registry record.
Intervention
The intervention was ramipril, described in the brief summary as an anti-hypertensive medication. The registry record does not report the dose, schedule, duration of treatment, or any dose adjustments.
Comparator
The comparison group received placebo. The study is described as randomized, double blind, placebo controlled, and quadruple masked. The registry record does not specify the identities of all parties included in the quadruple masking description.
Primary question
The trial aimed to investigate the clinical and cost effectiveness of ramipril in intermittent claudication. The stated primary outcome was maximum walking distance on a treadmill. The brief summary also describes aims concerning arterial function, cardiovascular prognosis, quality of life, and cost effectiveness. The posted primary summaries are measured at baseline, and a between-group treatment comparison is not reported in the registry record.
3. Trial Design
This was a randomized, parallel-group, placebo-controlled trial listed as phase 4. The registry record describes quadruple masking and reports Hull University Teaching Hospitals NHS Trust as sponsor. The trial status is completed, with a start date of 2010-12 and a primary completion date of 2012-12. These record dates describe the registered study; they do not by themselves establish when each participant was assessed or how long participants received treatment.
The two groups were ramipril and placebo. The registry record reports 14 participants in the ramipril group and 19 in the placebo group, for an enrollment of 33. The brief summary states an aim to recruit 78 participants, divided into groups of 39. The record does not explain the difference between that recruitment aim and the enrollment reported with the results. The randomization procedure, allocation concealment method, treatment dose, treatment duration, and details of follow-up are not reported in the registry record.
The stated primary endpoint was maximum walking distance, measured in metres using a treadmill exercise test. Six secondary outcomes are listed, covering lower-limb ischaemia indicators, quality of life, cardiovascular prognosis, endothelial function and ischaemia-reperfusion markers, arterial effects, and health economics. Listing an outcome does not establish that a result for it was posted. The record contains no analysis results for a two-arm comparison and does not report the planned statistical analysis in sufficient detail to describe its implementation.
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 | Ramipril | Placebo |
|---|---|---|
| STARTED | 14 | 19 |
| COMPLETED | 12 | 17 |
| NOT COMPLETED | 2 | 2 |
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 | Ramipril | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 14 | 19 | 33 | |
| Age, Continuous | Years | 64.4 (SD 8.2) | 64.7 (SD 7.7) | 64.55 (SD 7.82) |
| Sex: Female, Male: Female | Participants | 3 | 5 | 8 |
| Sex: Female, Male: Male | Participants | 11 | 14 | 25 |
6. Primary Endpoint
The registry lists the primary outcome as Maximum Walking Distance (MWD)., measured over Baseline.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Inter-Quartile Range |
| Unit | Metres |
| Endpoint classification | not reduced to a single comparison |
Maximum walking distance (MWD) is the distance a participant can walk on a treadmill before reaching the protocol-defined stopping point. It is used as a functional measure relevant to intermittent claudication: it records walking performance under a specified exercise test rather than relying only on a participant’s description of walking ability. The registry describes the test speed as 2.5 km/h. Its primary-outcome description ends after the words “with a 10”; the meaning of that incomplete detail is not reported in the registry record.
The registered unit is metres, and the reported summary type is median with inter-quartile range. A median describes the middle of the observed values, while the inter-quartile range describes the interval containing the middle half of those values. These summaries characterize the distributions in each group; they do not, on their own, estimate a treatment effect or establish whether group outcomes differ beyond chance.
The primary outcome timeframe in the posted results is baseline. The registry record reports a median of 137.0 metres for ramipril, with quartile values of 110.0 and 213.0, and a median of 143.0 metres for placebo, with quartile values of 72.0 and 213.0. Because these are baseline summaries, they are not a reported comparison of change during treatment. Follow-up MWD values and an analysis comparing the groups are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary-outcome summaries describe baseline maximum walking distance in the two randomized groups. For ramipril, the median is 137.0 metres, with an inter-quartile range from 110.0 to 213.0 metres. For placebo, the median is 143.0 metres, with an inter-quartile range from 72.0 to 213.0 metres. The group summaries show the distributions recorded at baseline, not an estimate of how ramipril affected walking distance.
No follow-up primary-outcome summaries, between-group estimate, confidence interval, or p-value are reported in the registry record. Therefore the posted data do not support a statistical conclusion about a treatment difference in MWD. The baseline medians cannot substitute for an analysis of outcomes after treatment or a comparison of change from baseline. Nor does overlap between inter-quartile ranges provide a formal test of a treatment effect: it is a descriptive feature of the distributions, not a measure of statistical significance.
The record reports 14 participants in the ramipril group and 19 in the placebo group. The brief summary describes a recruitment aim of 78 participants, while the result record lists enrollment of 33. Reasons for the difference, participant flow, and the numbers contributing to each outcome analysis are not reported in the registry record. The displayed group sizes do not establish that every enrolled participant contributed a usable primary-outcome result.
Other aims included assessment of walking indicators, quality of life, cardiovascular prognosis, biological markers, arterial effects, and health economics. Their presence in the registered outcome list documents planned areas of assessment, but does not establish that results were available or analyzed. The record lists six secondary outcomes, yet values and comparative analyses for them are not reported in the registry record. In particular, there is no posted result from which to interpret the trial’s cost-effectiveness aim.
Statistical interpretation should therefore remain narrow: the record provides baseline descriptive MWD summaries and adverse-event counts. It does not provide an inferential result for the trial’s primary treatment question. A missing comparative result is not evidence that the groups were equivalent, and it is not evidence of a particular benefit or harm. The amount of uncertainty around a treatment effect cannot be evaluated without a reported estimate and its precision.
9. Statistical Methods Explained
The design is described as randomized, parallel-group, placebo controlled, and quadruple masked. In a randomized trial, assignment is intended to create groups whose differences at the start are not systematically determined by participant or clinician choice. Randomization does not guarantee identical groups, especially in a small study. Baseline summaries can describe observed values, but they cannot establish that all prognostic characteristics were balanced. The method used to generate the allocation sequence and the way allocation was concealed are not reported in the registry record.
What does the median and inter-quartile range describe?
The median is the central value after observations are ordered. It is often useful when an outcome has a skewed distribution or unusually high or low observations, because it is less sensitive to extreme values than the mean. The inter-quartile range gives the lower and upper quartile limits and indicates the spread of the middle half of the observations. It does not show every value, and it is not a confidence interval for the median. The posted MWD values are summarized with this approach, consistent with the outcome’s registered median and inter-quartile range format.
Each group’s baseline summary answers a descriptive question: what walking-distance values were observed in that group at baseline? A treatment-effect analysis would answer a different question, comparing outcomes after treatment or comparing change over time between groups. Such an analysis would need a defined estimand and an appropriate statistical method. Those details and a comparative MWD result are not reported in the registry record.
How should uncertainty be assessed?
A confidence interval, in general, expresses the precision of an estimated quantity under the assumptions of the statistical method used. A narrow interval indicates greater precision than a wide interval, while an interval that includes values compatible with both benefit and harm may leave the direction and size uncertain. No confidence interval for a treatment comparison is reported in the registry record. The inter-quartile ranges given for the groups describe variation among observed baseline values; they should not be read as confidence intervals or as evidence for or against a between-group effect.
A p-value, in general, measures how incompatible the observed data are with a specified statistical null model, under the assumptions of the analysis. It is not the probability that the null hypothesis is true, and it does not measure the clinical importance of an effect. No p-value or test for the primary between-group comparison is reported in the registry record. Accordingly, a significance claim cannot be drawn from the baseline summaries.
What do sample-size calculations mean?
In general, a sample-size calculation is a planning exercise based on a target effect, variability assumptions, significance level, allocation, and desired power. It estimates how many participants would be needed under those assumptions; it does not describe the number actually analyzed, and it is not observed power. The brief summary gives a recruitment aim of 78 participants, divided equally between the two groups. A protocol sample-size justification, its assumptions, and the reason the reported enrollment was 33 are not reported in the registry record.
Any planning illustrations based on an observed effect must be interpreted as hypothetical design calculations, not as proof that a trial had adequate or inadequate power. When no comparative treatment estimate is posted, an observed-effect planning illustration cannot replace the missing primary analysis. The registry record’s detailed statistical plan and any interim-analysis plan are not reported.
Why can count outcomes need special methods?
General statistical methods for event counts must account for how counts vary across participants. If the variability is greater than a simple count model expects, over-dispersion can make standard errors too small and confidence intervals too narrow unless the analysis allows for it. The registry record does not report a count-based treatment analysis for the listed secondary outcomes, nor does it specify a model or an over-dispersion assessment. This general point does not imply that such an analysis was used in this trial.
The registry lists multiple outcome domains, but does not describe a hierarchy of secondary analyses or the statistical procedures used. Without those details, the interpretation of any isolated finding across many outcomes would require caution. In this record, comparative results for those outcomes are not reported, so no multiplicity-adjusted or unadjusted secondary finding can be described.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists a primary walking-distance outcome and six secondary outcomes spanning clinical indicators, quality of life, cardiovascular prognosis, biological markers, arterial measures, and health economics. When a study assesses multiple outcomes or performs multiple statistical tests, the chance of at least one apparently unusual result can increase. General approaches to multiplicity include specifying a primary outcome hierarchy or adjusting inference across a defined family of tests. Which outcomes were treated as confirmatory, whether any adjustment was planned, and how the multiple outcomes were handled are not reported in the registry record.
Missing-data methods are also not reported in the registry record. The enrollment count and group counts do not say how many measurements were available at each visit, whether participants withdrew, or why outcome observations might be absent. There is no reported approach to imputation, sensitivity analysis, or handling of incomplete follow-up. Those omissions make it impossible to assess whether missing observations could affect a treatment comparison.
The analysis population is not described. The record does not state whether an intention-to-treat, per-protocol, or other population was used, nor does it report how participants were handled if they did not follow their assigned treatment. A statistical interpretation of randomized groups depends in part on knowing which participants were included and how the analysis preserved the randomized comparison. Since no comparative primary analysis is posted, these analysis details cannot be checked against a reported estimate.
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 |
|---|---|---|---|
| Ramipril | 0 | 14 | 0.0% |
| Placebo | 0 | 19 | 0.0% |
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 |
|---|---|
| Ramipril | 6 of 14 |
| Placebo | 0 of 19 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Ramipril | Placebo |
|---|---|---|---|
| Cough | Cardiac disorders | 4 of 14 | 0 of 19 |
| Dizziness | General disorders | 1 of 14 | n/a of 19 |
| Hyperkalaemia | Endocrine disorders | 1 of 14 | n/a of 19 |
The adverse-event record lists zero serious adverse events among 14 participants at risk in the ramipril group and zero among 19 participants at risk in the placebo group. These are reported event counts for the listed groups. They do not establish that serious events were impossible, or that the groups had identical safety experience. With no comparative safety analysis or precision estimate reported, the counts should be read descriptively.
The record also lists other adverse events affecting 6 participants in the ramipril group and 0 in the placebo group. The categories, definitions, timing, severity, and relationship to treatment for these other events are not reported in the registry record. The counts alone do not establish causation or permit a complete comparison of the nature of the events.
Death counts are not reported in the registry record. No serious-event terms are listed. These omissions do not indicate that no deaths or event types occurred; they indicate that such details are unavailable in the posted record. The at-risk counts and event counts are not a substitute for individual event descriptions or a full safety analysis.
12. What the Result Does, and Does Not, Mean
The record establishes that a randomized, placebo-controlled study of ramipril in intermittent claudication was registered and completed, and that baseline MWD summaries were posted for the two groups. It also records group enrollment and selected adverse-event counts. These registry entries describe the trial and its available results, but they do not answer whether ramipril changed walking distance compared with placebo.
The central limitation for interpreting efficacy is the absence of a posted follow-up or between-group primary-outcome result. Baseline medians describe where the groups began on the treadmill measure; they are not treatment effects. Without an estimated difference, confidence interval, or p-value, the size, direction, and precision of a treatment contrast cannot be assessed from the registry record. A result that is not reported should not be interpreted as a null result or as evidence of equivalence.
The record likewise does not provide comparative results for the listed secondary aims, including quality of life, cardiovascular prognosis, arterial effects, and cost effectiveness. Their inclusion among the outcomes cannot be taken as evidence that a favorable or unfavorable result was found. In general, conclusions about health-economic value also require reported costs, outcomes, and an analysis framework; those results are not reported in the registry record.
The safety counts are also limited. They show the recorded serious-event counts and other-event counts in the groups, but do not provide event descriptions, a causal assessment, or a statistical comparison. Taken together, the posted information supports a description of baseline walking performance and recorded event counts, not a conclusion that ramipril does or does not work, or that it is or is not safe. The clinical question remains unresolved by the results reported in the registry record.
13. Why This Trial Matters Statistically
This trial illustrates an important distinction between a randomized design and a reported comparative result. Random allocation is a design feature intended to support fair comparisons. It does not itself supply an estimate of the treatment effect. Readers need the outcome values or an appropriate between-group estimate, together with information about uncertainty and the analysis population, to judge what the randomized comparison shows.
The primary outcome is a functional measure with a clear unit and a distributional summary: median MWD in metres with inter-quartile range. Those details help readers understand what was measured and how the baseline data were described. At the same time, the listed timeframe is baseline. Recognizing the timing prevents a descriptive starting-point summary from being mistaken for evidence about an effect during treatment.
The contrast between the recruitment aim of 78 and the reported enrollment of 33 also matters for transparency. The registry record does not explain that difference, nor does it provide participant flow or analysis counts by outcome. Such information helps readers understand which data support an estimate and whether the analysis reflects the randomized groups. Without it, even a reported result would be harder to evaluate fully.
Finally, the record demonstrates why completeness matters across outcomes and safety. Multiple clinical and economic aims are listed, but comparative findings and analysis methods are not reported. The absence of those details limits reproducibility and prevents a reader from distinguishing an unreported analysis from a result that was tested and found inconclusive. Statistically, clear reporting of estimates, uncertainty, missing-data handling, multiplicity, and analysis populations is central to interpreting a trial, not an optional supplement to its design description.
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 registry record reports baseline MWD summaries but does not report a follow-up primary outcome or a treatment comparison. The primary-outcome description is incomplete, ending after “with a 10,” so the meaning of that treadmill-test detail is not reported in the registry record. Dose, treatment duration, outcome visit schedule, and other protocol specifics are also not reported in the registry record.
Enrollment is reported as 33, while the brief summary describes a recruitment aim of 78. The record does not explain the difference, give participant flow, or state how many participants contributed to each outcome. Eligibility criteria and baseline characteristics beyond the primary outcome summaries are not reported in the registry record, limiting assessment of who was enrolled and the comparability of the groups.
The registry record does not report the randomization sequence method, allocation concealment, the planned statistical analysis, an analysis population, or how missing observations were handled. No comparative estimates, confidence intervals, or p-values are reported for the primary outcome. Results for the listed secondary outcomes and the health-economic aim are also not reported. The absence of these results prevents assessment of multiplicity, selective outcome reporting, and the precision of any clinical or economic effect.
Safety reporting is limited to group counts. Descriptions of other adverse events, their severity and timing, attribution, and death counts are not reported in the registry record. These record-specific gaps constrain interpretation; they do not establish what was or was not measured elsewhere in the trial.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Clinical and Cost Effectiveness of ACE Inhibitor, Ramipril, in Intermittent Claudicants — NCT01037530.
- Registry record last updated 2025-12-18; status last verified 2022-04.
- Results first posted 2025-12-18.
- 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
NCT01037530 is a completed, randomized, parallel-group, placebo-controlled phase 4 trial sponsored by Hull University Teaching Hospitals NHS Trust. It studied ramipril in intermittent claudication and is listed as quadruple masked. The registry dates are 2010-12 for trial start and 2012-12 for primary completion.
The registry reports enrollment of 33, with 14 participants in the ramipril group and 19 in the placebo group. The brief summary states a recruitment aim of 78. The primary outcome is maximum walking distance in metres, summarized by median and inter-quartile range at baseline. The record reports group baseline summaries but no comparative treatment result. Six secondary outcomes are listed; their comparative results are not reported in the registry record.
Serious adverse events are reported as 0 in each group. Other adverse events are reported for 6 participants in the ramipril group and 0 in the placebo group. Event descriptions and death counts are not reported in the registry record. Overall, the posted results are descriptive and do not provide an inferential estimate of the primary treatment effect.