Coronary Atherosclerosis Evaluation by Arterial Wall Magnetic Resonance Imaging (MRI): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Coronary Atherosclerosis Evaluation by Arterial Wall Magnetic Resonance Imaging (MRI) (NCT00353795), a randomized na study. The primary outcome is Mean Coronary Wall Thickness.

2. Clinical Question

The primary outcome is a cross-sectional measure of mean coronary wall thickness, expressed in mm. The record describes this as the average thickness across the named coronary arteries. It does not provide an outcome value, a standard deviation, or results for associations with risk factors or other markers.

The stated overall aims are broader than the registered primary endpoint. They include examining links between wall thickness and known cardiovascular risk factors, comparing wall thickness with carotid wall thickness and coronary calcium scores, and assessing the feasibility of measuring progression in a subset. These aims describe questions the study intended to examine; the registry record does not report their findings. In particular, it does not identify a comparison treatment or a between-group treatment-effect question.

3. Trial Design

The registry record identifies the study as completed, with a start date of 2005-07 and a primary completion date of 2008-06. Enrollment is listed as 179. The phase is recorded as NA, and the intervention is MR imaging of the coronary arteries, classified as a procedure. These details describe a study using imaging to assess coronary artery wall thickness rather than a comparison of named therapies.

Two design entries do not align cleanly: allocation is listed as randomized, while the model is listed as single group. The record also indicates that the primary outcome has fewer than two arms, and it identifies no comparator group. The registry record does not explain this combination of entries, so it is not possible to infer what, if anything, was randomized or to reconstruct a group allocation scheme.

The primary outcome timeframe is described as “n/a (cross sectional analysis).” The primary measure is mean coronary wall thickness assessed by MRI. Separately, the study summary describes an aim to examine the feasibility of measuring progression over time in a subset of participants. The record does not report the subset size, the timing or number of repeat assessments, or results from a longitudinal analysis. A planned feasibility aim should therefore not be read as evidence that progression was measured successfully or that change was estimated.

The record lists one outcome measure and zero analyses. It does not report an analysis population, a statistical model, a prespecified hypothesis, or details of recruitment and eligibility beyond the total enrollment. A sample-size justification, interim analyses, and a detailed statistical plan are not reported in the registry record. Those omissions limit the ability to assess how the study was designed to answer its aims or how the posted outcome information relates to the original analysis plan.

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

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.

6. Primary Endpoint

The registry lists the primary outcome as Mean Coronary Wall Thickness, measured over n/a (cross sectional analysis).

The primary endpoint is mean coronary wall thickness in mm. The registry description defines it as the average thickness of the walls of the left anterior descending, right, and left main coronary arteries, measured using magnetic resonance imaging. The timeframe is identified as a cross-sectional analysis rather than a specified follow-up interval.

As a continuous measure, wall thickness can be summarized by a mean to describe the central value and by a standard deviation to describe variation among measured values. Those summaries would characterize the distribution of the MRI measurement in the analyzed participants. The registry record identifies the mean and standard deviation as the intended outcome parameter and dispersion measure, but it does not report their numerical values or the number of participants with usable measurements.

In general, imaging measures can be used to characterize a feature of anatomy and to examine whether it varies alongside other characteristics. That is relevant to the stated aims concerning cardiovascular risk factors, carotid wall thickness, and coronary calcium scores. However, the record does not establish that coronary wall thickness is a validated surrogate for a clinical outcome, nor does it report evidence about measurement reliability or clinical prediction.

The primary endpoint is also distinct from the study’s stated feasibility aim about assessing progression over time in a subset. A cross-sectional mean describes measurements at an assessment; it does not itself estimate change. The registry record does not provide longitudinal endpoint results.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is this?

The primary endpoint is continuous: it is a mean thickness measured in mm. In general, a continuous outcome can take values across a measurement scale rather than being limited to categories such as event or no event. A mean describes the center of observed measurements, while a standard deviation describes how dispersed individual measurements are around that mean. These summaries answer different questions. The mean is not a description of how similar every participant’s measurement was, and the standard deviation is not the uncertainty of the mean.

The registry record identifies the mean as the outcome parameter and the standard deviation as the dispersion measure. It does not post either statistic. It also does not report the number of participants with a usable MRI measure, whether the mean combines measurements in a particular way across the named arteries, or how images were processed. Those details matter when interpreting a continuous imaging endpoint, but they are not reported in the registry record.

How should uncertainty be considered?

General explanation: an estimate from a sample is subject to sampling variability. A confidence interval is a way to express uncertainty around an estimate under a specified analysis and its assumptions. Its width helps readers assess precision; a narrow interval indicates greater precision than a wide interval, while neither width alone nor the interval’s position establishes clinical importance. The registry record does not report a confidence interval for mean wall thickness or for any association.

A standard deviation and a confidence interval should not be confused. The standard deviation describes variability among individual measurements. A confidence interval describes uncertainty about an estimated quantity, such as a mean, under the selected method. Assessing either requires knowing what measurements were included and how the analysis handled them. Those analysis details are not reported in the registry record.

What does a relationship analysis require?

The stated aims include examining relationships between wall thickness and cardiovascular risk factors, carotid wall thickness, and coronary calcium scores. General explanation: an association analysis estimates how variables vary together. The estimate depends on the variables measured, their distributions, the analysis model, and any adjustment for other characteristics. An association does not by itself establish that one characteristic caused another. The registry record does not report the estimates, models, adjustment variables, or uncertainty for these aims, so no specific association can be interpreted.

The summary’s progression aim is different. General explanation: assessing change over time requires measurements at multiple times and an analysis that accounts for the relationship between measurements from the same participant. A cross-sectional mean alone does not estimate change. The record labels the primary endpoint cross-sectional and does not report repeat-measurement results or methods for the subset mentioned in the summary.

What can be inferred from the design entries?

Allocation is recorded as randomized, but the model is listed as single group and the record identifies fewer than two arms for the primary outcome. No comparator is described. Randomization is generally used to allocate participants to groups so that comparisons can be made, but the registry entries do not clarify what was randomized in this study. A group comparison, treatment effect, or causal contrast cannot be reconstructed from the information recorded.

The record lists one outcome measure and zero analyses. It does not report a statistical model, a significance threshold, a method for handling missing measurements, a prespecified analysis population, or interim analyses. A statistical analysis plan and sample-size justification are not reported in the registry record. The absence of those details means readers cannot determine whether a particular model or testing strategy was planned or how the reported results would have been selected and interpreted.

How should planning illustrations be read?

General explanation: sample-size planning calculations describe how many participants might be needed under specified assumptions about an effect, variability, allocation, and error rates. They are planning illustrations, not observed evidence and not “observed power.” The registry record states that its planning illustration uses an observed effect and describes assumptions of a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. However, no observed effect or analysis result is reported in the registry record, and the primary outcome is listed with fewer than two arms. Those illustrations therefore should not be interpreted as a description of the study’s actual design or as evidence of its ability to detect a result.

General explanation: when count outcomes vary more than a simple model expects, over-dispersion can make standard errors too small if the extra variability is ignored. This study’s registered primary measure is continuous rather than a count outcome, and the record does not identify an over-dispersion analysis. This concept is not evidence that over-dispersion was present or relevant to the reported outcome.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Participants")
n   <- c(179)
m   <- c(2)
sp  <- c(0.3)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Participants  179  2.000  0.300  1.956  2.044

11. Multiplicity, Missing Data and Analysis Populations

The study summary gives several aims: examining risk-factor relationships, comparing coronary wall thickness with carotid wall thickness and coronary calcium scores, and assessing the feasibility of measuring progression in a subset. The registry lists one outcome measure and zero analyses. It does not identify a set of statistical tests or explain whether any adjustment for multiple comparisons was planned. Multiplicity methods and their rationale are not reported in the registry record.

General explanation: when several hypotheses are tested, the chance of at least one apparently noteworthy result can increase if each test is considered separately. A prespecified hierarchy, adjustment procedure, or clear distinction between primary and exploratory analyses can help readers understand how to interpret multiple findings. The record does not provide enough information to determine which, if any, approach was used. The stated aims should not be treated as reported significant findings.

Information about missing measurements is also absent. The registry record does not report how many participants had analyzable MRI measurements, whether any measurements were missing, why measurements might have been unavailable, or how missing data were handled. It does not identify an analysis population or state whether all enrolled participants were included in the primary analysis. Thus, the enrollment of 179 should not be assumed to equal the number contributing to the endpoint.

General explanation: missing-data handling can affect an estimate if the participants with observed measurements differ from those without them. An analysis that uses only available measurements may describe the measured subset rather than all enrolled participants. Determining the implications requires the amount and pattern of missingness and the analysis methods, none of which are reported in the registry record.

The randomized-allocation entry, single-group model, and lack of a two-arm primary outcome create further uncertainty about the planned analysis structure. The registry record does not explain whether multiple groups or repeated assessments were part of any analysis. A multiplicity strategy, missing-data method, and analysis-population definition therefore cannot be reconstructed from the record.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry record lists 179 participants at risk for serious adverse events and 0 affected. It also lists 179 at risk for other adverse events and 0 affected. No serious adverse-event terms are listed. Deaths are not reported in the registry record.

These entries describe what the registry record posts; they do not establish that every event was collected in the same way, that all participants had identical follow-up, or that no unrecorded event occurred. The record does not provide event definitions, the observation period for safety reporting, or a narrative explaining how events were assessed. It also does not state whether the zero counts reflect active surveillance, passive reporting, or another collection method.

Because the intervention is listed as an imaging procedure and no comparator group is identified, the posted safety counts do not support a comparative safety estimate. The counts should not be interpreted as demonstrating absence of risk. They are descriptive registry entries, and the missing details constrain how fully they can be interpreted.

13. What the Result Does, and Does Not, Mean

The record describes a study intended to use MRI to measure coronary artery wall thickness and examine its relationship with cardiovascular risk factors and other markers of subclinical coronary atherosclerosis. It also describes an aim to assess the feasibility of measuring progression in a subset. The primary endpoint is defined as the mean thickness of the left anterior descending, right, and left main coronary artery walls, measured in mm in a cross-sectional analysis.

What the record does not provide is the numerical value of that mean, its standard deviation, a confidence interval, or results of the stated relationship analyses. It does not report whether progression was assessed or what the feasibility findings were. As a result, the record cannot establish the observed level or variability of coronary wall thickness in the analyzed participants, the size or direction of any association, or the precision of those estimates.

The record also does not establish a treatment comparison. Although allocation is listed as randomized, the model is recorded as single group and no comparator or two-arm primary outcome is identified. The registry does not explain that inconsistency. It is therefore not possible to interpret the posted information as a randomized test of one intervention against another.

General explanation: a measurement can be useful for describing anatomy or investigating relationships without, by itself, demonstrating that the measure predicts a clinical outcome or that changing it changes health outcomes. The registry record does not report validation of wall thickness as a surrogate endpoint or clinical-outcome results. Such conclusions should not be inferred from the stated aims.

The safety entries list zero serious and zero other adverse events among 179 participants at risk in each category, but the record lacks details about ascertainment and follow-up. These counts should be read as recorded counts, not as proof that no risk existed. Overall, the registry record documents study intent and a defined imaging endpoint, while leaving the primary results and their statistical uncertainty unreported.

14. Why This Trial Matters Statistically

This study is statistically notable because its central question concerns an imaging-based measure rather than a clinical event or a treatment comparison. The registry defines a continuous endpoint, mean coronary wall thickness, and situates it within broader aims about risk factors, other imaging markers, and possible measurement of progression. That framing makes clarity about the measurement and analysis essential: a mean summarizes measured values, but it does not alone establish how reproducible the measure is or what it implies about clinical outcomes.

The record also illustrates why design fields need to be interpreted together. Randomized allocation appears alongside a single-group model and a primary outcome with fewer than two arms. Without an explanation or comparator, readers cannot identify a randomized contrast or assess a between-group estimate. The study’s stated aims and its registered outcome structure are not interchangeable.

Another statistical issue is the distinction between a cross-sectional endpoint and a longitudinal aim. A cross-sectional mean describes the endpoint as defined in the record; progression requires repeated measurements and an appropriate analysis of within-participant change. The registry summary mentions feasibility work in a subset, but does not provide the data or methods needed to assess it.

Finally, the record contains no primary outcome results or analyses. That absence matters because statistical interpretation depends on estimates and their uncertainty, not only on enrollment, planned aims, or an endpoint definition. The record can identify what investigators intended to measure, but cannot show the magnitude, variability, precision, or relationships of the observed measurements. Transparent reporting of those elements would be necessary to evaluate the study’s empirical findings.

15. 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 interpretation is that the registry record contains no numerical primary-outcome result and lists zero analyses. The mean and standard deviation for coronary wall thickness are not reported in the registry record. Nor are confidence intervals, association estimates, or findings from the stated feasibility aim. This prevents assessment of the magnitude and precision of any result.

The design description is internally difficult to interpret: allocation is listed as randomized, the model is single group, and the record identifies no two-arm primary outcome or comparator. The registry record does not explain these entries. Consequently, the allocation process and any planned contrast cannot be reconstructed.

The record does not describe participant eligibility, recruitment, imaging acquisition or processing, measurement reliability, or the number of participants with usable endpoint data. It does not identify an analysis population or describe missing data. Although total enrollment is listed as 179, the number contributing to the primary outcome is not reported in the registry record.

The primary endpoint is identified as cross-sectional, while the summary also describes assessing progression in a subset. The record does not report the subset size, timing of repeat measurements, or longitudinal analysis. It therefore does not establish whether change over time was measured or how it would have been evaluated.

Statistical methods, multiplicity handling, interim analyses, and a sample-size justification are not reported in the registry record. Safety entries list zero events but do not include ascertainment or follow-up details. These limitations concern what can be learned from the registry record; they do not establish that the study lacked methods or that no results exist outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Coronary Atherosclerosis Evaluation by Arterial Wall Magnetic Resonance Imaging (MRI) — NCT00353795.
• Registry record last updated 2010-06-22; status last verified 2009-09.
• Results first posted 2010-06-22.
• 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.

19. Record Summary

The registry record describes a completed study of MRI measurement of coronary artery wall thickness, with enrollment of 179 and a primary endpoint defined as the mean thickness of the left anterior descending, right, and left main coronary artery walls in mm. The endpoint is identified as cross-sectional. The study summary also describes aims involving cardiovascular risk factors, carotid wall thickness, coronary calcium scores, and feasibility of measuring progression in a subset.

The record lists randomized allocation and a single-group model, but does not identify a comparator or explain the design entries. It lists one outcome measure and zero analyses. Numerical primary-outcome results, analysis methods, missing-data procedures, and the sample-size justification are not reported in the registry record. Safety entries list zero serious and zero other adverse events among 179 at risk in each category; deaths are not reported in the registry record.