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 Functional ComprEhensive AssessmenT by IVUS Reconstruction in Patients With Suspected IschEmic Heart Disease (FEATURE) (NCT05694065), a registered phase not stated study. The primary outcome is Diagnostic Accuracy of Onsite UFR.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT05694065 |
| Phase | Phase not stated |
| Condition | Ischemic Heart Disease |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 112 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Ruijin Hospital |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns patients with suspected ischemic heart disease. The registry lists ischemic heart disease as the condition and states that six participants were excluded according to predefined exclusion criteria. The characteristics of those excluded and the final analysis population are not reported in the registry record.
Intervention
The diagnostic approach under investigation is onsite Ultrasonic Flow Ratio (UFR). The registry describes UFR as a pressure ratio across a coronary stenosis and evaluates its ability to classify stenosis as hemodynamically significant or not.
Comparator
Angiography-derived fractional flow reserve (FFR) serves as the reference standard. The registry defines FFR at or below 0.80 as the reference for hemodynamically significant stenosis. This is a diagnostic reference, rather than a treatment comparator.
Primary question
How accurately does onsite UFR classify cases relative to the FFR reference standard? The primary endpoint is diagnostic accuracy, defined as the percentage of correctly classified cases, counting true positives and true negatives among the total population. The registry also describes receiver operating characteristic (ROC) curve analysis. The primary accuracy estimate and its 95% confidence interval are not reported in the registry record.
3. Trial Design
FEATURE is a diagnostic-accuracy investigation in patients with suspected ischemic heart disease. Its stated purpose is to assess onsite UFR for identifying hemodynamically significant coronary stenosis, with angiography-derived FFR serving as the reference standard. The registry describes UFR as a pressure ratio across a coronary stenosis and uses FFR at or below 0.80 to define the reference classification.
The registry lists enrollment as 112. It records a start date of 2023-02-17 and a primary completion date of 2024-11-22. Its status is active, not recruiting. Ruijin Hospital is listed as the sponsor. The record states that six participants were excluded under predefined exclusion criteria, but the number included in the primary analysis and the analyzed denominator are not reported in the registry record.
The record characterizes this as not a randomized comparison and says allocation is not stated. It therefore does not describe a randomized, like-for-like comparison of treatment arms. Its central comparison is diagnostic: onsite UFR classifications are assessed against the FFR reference. The record does not report details of how UFR classifications were assigned, whether the UFR and FFR assessments were interpreted independently, or how the timing of the assessments was managed.
The registry lists sensitivity and specificity of onsite UFR, and sensitivity and specificity of minimal lumen area (MLA), among the secondary outcomes. It does not report the secondary outcome estimates. The protocol details, statistical analysis plan, and rationale for the listed enrollment are not reported in the registry record. The stated status and dates describe the registry entry; they do not, on their own, establish that outcome results have been posted.
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 | Functional Assessment in Patients With Suspected Ischemic Heart Disease |
|---|---|
| STARTED | 112 |
| COMPLETED | 106 |
| NOT COMPLETED | 6 |
Reasons for not completing this period:
| Reason | Functional Assessment in Patients With Suspected Ischemic Heart Disease |
|---|---|
| Intravascular ultrasound (IVUS) pullback fails to cover the complete target lesion | 3 |
| Ineligible for diagnostic intervention (IVUS or FFR examination) | 2 |
| Target vessel with severe myocardial bridge | 1 |
Analysis population for the primary outcome, as defined in the registry: Six participants were excluded according to the predefined exclusion criteria.
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 | Functional Assessment in Patients With Suspected Ischemic Heart Disease |
|---|---|---|
| Participants analysed | 106 | |
| Age, Continuous | years | 68.5 (57.0 to 74.0) |
| Sex: Female, Male: Female | Participants | 30 |
| Sex: Female, Male: Male | Participants | 76 |
| Race and Ethnicity Not Collected | Participants | — |
| Body Mass Index (BMI) | Kg/m^2 | 24.6 (SD 3.2) |
6. Primary Endpoint
The registry lists the primary outcome as Diagnostic Accuracy of Onsite UFR, measured over baseline.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | 95% Confidence Interval |
| Unit | percentage of correctly classified cases |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is diagnostic accuracy of onsite UFR, expressed as the percentage of correctly classified cases. The registry defines a correct classification as a true positive or a true negative relative to the FFR reference standard. FFR at or below 0.80 defines hemodynamically significant stenosis for that reference. The endpoint is listed for baseline, and its stated dispersion measure is a 95% confidence interval.
In general, diagnostic accuracy gives an overall summary of agreement with the reference classification. It combines correct positive and correct negative classifications, so it does not, by itself, show how well a method identifies positive cases separately from negative cases. Sensitivity and specificity address those two aspects separately; both are also listed as secondary outcomes for onsite UFR. Accuracy can depend on how common each reference classification is in the analyzed population, so its interpretation benefits from knowing the population and classification threshold as well as the estimate itself.
The registry also states that diagnostic performance was assessed by ROC curve analysis. In general, an ROC curve describes how sensitivity and specificity change across possible classification thresholds. The record does not state the UFR threshold used to classify cases for the primary accuracy calculation, nor does it report the ROC result. The accuracy estimate and its 95% confidence interval are not reported in the registry record, so the endpoint's numerical result and precision cannot be assessed from this entry.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the diagnostic question and the intended reference standard, but it does not report a primary diagnostic-accuracy estimate. It also does not report the associated 95% confidence interval. Consequently, the posted registry information does not establish the observed level of agreement between onsite UFR and FFR classifications, or how precisely that agreement was estimated.
In general, a confidence interval describes uncertainty around an estimate under the assumptions of the analysis. A 95% confidence interval is not a guarantee that the true value lies within a particular interval, and it does not replace consideration of the study population, methods, or possible bias. Without the interval endpoints and the point estimate, readers cannot judge the statistical precision of the primary endpoint. Those values are not reported in the registry record.
The endpoint definition counts true positives and true negatives together. That overall accuracy measure does not convey the separate rates of correctly identified reference-positive and reference-negative cases. Sensitivity and specificity of onsite UFR are listed as secondary outcomes, but their estimates are not reported in the registry record. Sensitivity and specificity for MLA are also listed, with no estimates reported. Thus, the entry does not allow a numerical comparison of the diagnostic measures or an assessment of their relative performance.
Although the registry says ROC curve analysis was used to assess diagnostic performance, it does not give the ROC result or specify the UFR classification threshold for the primary accuracy calculation. In general, a threshold determines which test results are treated as positive or negative, and different thresholds can change the balance between sensitivity and specificity. Without the threshold and results, the classification procedure and its consequences cannot be evaluated from the registry entry.
The record reports that six participants were excluded according to predefined criteria. It does not state the final analysis denominator, give details of the exclusions, or describe how missing observations were handled. These omissions limit assessment of who contributed to the accuracy calculation and whether the analysis population differs from the enrolled population in ways relevant to interpretation. The registry also does not report the analysis plan or whether any analyses were adjusted.
The entry's status is active, not recruiting, and it lists a primary completion date of 2024-11-22. Neither the status nor the completion date is a diagnostic result. No conclusion about the performance of UFR should be drawn from those administrative details. The appropriate interpretation is that the registry states a diagnostic objective and endpoint definition, while the numerical evidence needed to quantify performance is not reported in the registry record.
9. Statistical Methods Explained
The stated endpoint is diagnostic accuracy, with ROC curve analysis described as the approach used to assess diagnostic performance. The registry gives the reference definition and the broad endpoint calculation, but it does not report enough detail to reconstruct the analysis or verify its numerical result.
What does diagnostic accuracy measure?
In general, diagnostic accuracy is the proportion of classifications that agree with a reference standard. In this study's description, true positives and true negatives count as correctly classified cases. A false positive is a case classified as positive by the test but negative by the reference; a false negative is classified as negative by the test but positive by the reference. The endpoint combines correct positive and correct negative classifications rather than presenting those components separately.
The reference classification is based on angiography-derived FFR, with FFR at or below 0.80 defining hemodynamically significant stenosis. Onsite UFR is described as a pressure ratio across a coronary stenosis. The record does not specify the UFR threshold that determines a positive classification. That detail matters because a threshold is needed to turn a measurement into a positive or negative result for calculating accuracy, sensitivity, and specificity.
Why are sensitivity and specificity also relevant?
In general, sensitivity is the proportion of reference-positive cases classified as positive by the diagnostic method. Specificity is the proportion of reference-negative cases classified as negative. These measures describe different error patterns and can provide information that an overall accuracy value does not. The registry lists sensitivity and specificity for onsite UFR, as well as sensitivity and specificity for MLA, but it does not report their estimates or confidence intervals.
In general, accuracy can vary with the mix of reference-positive and reference-negative cases in the population. A high overall accuracy value can be difficult to interpret without knowing that mix, particularly when the two classifications are not equally common. The registry does not report the numbers of FFR-positive and FFR-negative cases, so that context is not available in the entry.
What does ROC analysis add?
In general, an ROC curve represents sensitivity against the false-positive rate across possible test thresholds. It can describe how classification performance changes as the threshold changes, rather than focusing on only one threshold. The registry states that ROC curve analysis was used but does not report a curve, an area under the curve estimate, or details of the thresholds considered. It defines the primary endpoint as percentage correctly classified, so the ROC description should not be mistaken for a reported numerical result for that endpoint.
The registry names a 95% confidence interval as the dispersion measure for primary accuracy. In general, a confidence interval communicates sampling uncertainty around an estimate. Its width depends in part on the amount and distribution of information in the analyzed sample, as well as the method used to calculate it. The estimate and interval are not reported in the registry record, and the method for calculating the interval is not described there. It is therefore not possible to assess its precision or reproduce it from the registry entry.
What can be inferred from the analysis description?
The entry specifies an FFR reference threshold and states that six participants were excluded according to predefined exclusion criteria. It does not report the analyzed denominator, a participant flow description, details of the exclusion criteria, or whether missing UFR or FFR measurements occurred. It also does not state whether the primary analysis was based on all eligible cases or on cases with complete paired measurements. These details are important in general because diagnostic-accuracy estimates depend on which cases contribute to the comparison.
The registry indicates two analyses, but their methods and results are not reported in the registry record. The statistical analysis plan, including any adjustment, subgroup analysis, or interim analysis, is not reported. No such procedures should be inferred from the endpoint description alone.
How should planning calculations be read?
In general, a sample-size calculation is a planning exercise based on assumptions about the effect to detect, variability, allocation, and statistical method. The record's planning assumptions specify a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the effect to detect as a stated fraction of the observed effect. No specific fraction or numerical planning result is reported in the registry record.
Any sample-size figures generated under those assumptions are planning illustrations, not observed power and not results from the diagnostic-accuracy analysis. The record also notes that such illustrations use participants per arm for non-time-to-event outcomes, while time-to-event illustrations use a total event count. The primary diagnostic endpoint is not presented as a time-to-event outcome. A planning calculation cannot substitute for the actual accuracy estimate, its confidence interval, or a clear account of the analyzed population.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists the primary diagnostic-accuracy endpoint and secondary outcomes for sensitivity and specificity of onsite UFR and sensitivity and specificity of MLA. It does not report estimates for these outcomes. The entry does not state how testing across the primary and secondary outcomes was handled, whether a hierarchy was specified, or whether any adjustment for multiple comparisons was planned or used. Those multiplicity methods are not reported in the registry record.
The record states that six participants were excluded under predefined exclusion criteria. It does not provide the criteria themselves, describe whether all exclusions occurred before analysis, or report the final denominator for the primary endpoint. Missing-data handling is not reported in the registry record. In particular, the entry does not say how incomplete UFR or FFR measurements were treated, whether any imputation was performed, or whether the accuracy calculation used only paired measurements.
The analysis populations are not defined beyond the statement about exclusions. The record does not explain whether the primary analysis included all enrolled participants, only those meeting eligibility criteria, or another specified population. Nor does it provide a flow of participants from enrollment through the diagnostic assessment and analysis. The statistical analysis plan is not reported, so the handling of exclusions, missing observations, thresholds, and secondary outcomes cannot be checked against a prespecified plan.
The registry indicates two analyses but does not describe their purpose, methods, or results. Interim analyses and stopping rules are not reported in the registry record. The absence of these details does not establish that a particular method was or was not used; it means the entry does not permit that assessment.
11. What the Result Does, and Does Not, Mean
The record describes a diagnostic study question: whether onsite UFR can classify coronary stenosis consistently with an FFR reference definition. It defines primary accuracy as the percentage of true positives and true negatives among the total population, and it names a 95% confidence interval as the measure of dispersion. However, the accuracy estimate and interval are not reported in the registry record. The entry therefore does not quantify the observed diagnostic performance or its precision.
In general, diagnostic accuracy is not equivalent to a treatment effect or to evidence about patient outcomes. A classification measure describes agreement with a reference standard under the study's definitions. By itself, it does not establish that using the diagnostic method changes care or outcomes. The registry describes a diagnostic objective and does not report a treatment comparison or a clinical outcome result.
The FFR threshold in the record defines the reference classification; it does not supply a UFR cutoff. The UFR threshold used for the primary classification is not reported. Without that threshold and the numerical results, readers cannot assess how the method's positive and negative classifications were determined or how sensitivity and specificity relate to the overall accuracy endpoint.
The registry's enrollment figure and exclusion statement do not establish the final analysis size. Six participants are stated to have been excluded according to predefined criteria, but the analysis denominator and participant flow are not reported. The scope of inference is consequently difficult to judge from the registry record alone. The record also does not give the characteristics of the analyzed population or the distribution of FFR classifications.
Administrative status and dates should be kept separate from outcome evidence. The record lists status active, not recruiting and a primary completion date of 2024-11-22, but these details do not provide a result. The sound interpretation is limited: the registry defines what the investigators intended to evaluate, while the posted entry does not give the estimates needed to state how well onsite UFR performed.
12. Why This Trial Matters Statistically
Diagnostic studies rely on a clear distinction between the method being evaluated and the reference standard used to classify cases. FEATURE's registry description makes that distinction explicit: onsite UFR is the diagnostic method under investigation, while angiography-derived FFR supplies the reference classification, with FFR at or below 0.80 defining hemodynamically significant stenosis. This setup gives readers a framework for understanding the intended comparison without treating it as a randomized treatment comparison.
The statistical distinction between overall accuracy, sensitivity, and specificity is important. Accuracy combines correct positive and correct negative classifications. Sensitivity and specificity separate performance among reference-positive and reference-negative cases. Reporting all of these can make a diagnostic profile more interpretable than an overall accuracy percentage alone. The record lists these secondary measures but does not report their estimates, so the intended range of evaluation is clearer than the results available to assess.
ROC analysis is also relevant because diagnostic performance can depend on the threshold used to classify measurements. In general, examining performance across thresholds helps describe that trade-off. The registry mentions ROC analysis, but it does not give the UFR threshold, curve, or ROC result. This illustrates why naming an analysis method is not a substitute for reporting its numerical output and key decision rules.
Precision and population definition matter as much as the choice of measure. A point estimate without an interval can obscure uncertainty, while an interval without a clear analysis denominator is difficult to contextualize. Here, the registry names a 95% confidence interval and reports exclusions, but does not give the estimate, interval, analyzed denominator, or missing-data method. Those details are necessary for a reader to judge the evidence rather than only the study's stated aim.
The entry also illustrates the difference between diagnostic performance and clinical benefit. Agreement with a reference standard is a statistical property of a test under specified conditions; it does not by itself demonstrate effects on treatment decisions or patient outcomes. Keeping these questions distinct prevents a diagnostic endpoint from being interpreted as an outcome claim.
13. 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.
Several trial-specific details needed to evaluate the diagnostic results are not reported in the registry record. The primary accuracy estimate and its 95% confidence interval are absent, as are the reported results for the listed sensitivity and specificity outcomes. Without these values, the magnitude and precision of diagnostic performance cannot be assessed.
The UFR classification threshold is not stated. The reference standard threshold is specified as FFR at or below 0.80, but the corresponding rule for converting UFR measurements into positive or negative classifications is not described. The record also mentions ROC analysis without reporting its result or the thresholds examined. This leaves key aspects of the classification procedure unclear.
The registry reports six exclusions under predefined criteria but does not list those criteria, describe the characteristics of excluded participants, or give the analyzed denominator. The method for handling missing measurements is not reported. The entry therefore does not show how exclusions and missingness may have affected the cases included in the diagnostic comparison.
Other design and analysis details are also unavailable: the record does not state whether assessments were interpreted independently, whether readers were blinded to the other test, or how any discordant measurements were handled. These procedures are not reported in the registry record, so their use should not be assumed. The statistical analysis plan, multiplicity approach, and details of the two listed analyses are also not reported.
Finally, the record characterizes the study as not a randomized comparison and says allocation is not stated. Its diagnostic comparison should not be read as a controlled treatment comparison. The registry information does not provide enough detail to assess how representative the analyzed population is of other settings or patient groups.
14. Related Tutorials
15. Related Statistical Calculators
16. Sources
- ClinicalTrials.gov: Functional ComprEhensive AssessmenT by IVUS Reconstruction in Patients With Suspected IschEmic Heart Disease (FEATURE) — NCT05694065.
- Registry record last updated 2026-07-24; status last verified 2025-08.
- Results first posted 2025-11-24.
- 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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17. Record Summary
FEATURE investigates onsite Ultrasonic Flow Ratio (UFR) for identifying hemodynamically significant coronary stenosis in patients with suspected ischemic heart disease. Angiography-derived FFR is the reference standard, with FFR at or below 0.80 defining significant stenosis. The primary endpoint is the percentage of cases correctly classified, with a 95% confidence interval specified.
The registry lists enrollment as 112, sponsor Ruijin Hospital, and status active, not recruiting. It records a start date of 2023-02-17 and a primary completion date of 2024-11-22. Six participants were excluded under predefined criteria. The record also lists sensitivity and specificity outcomes for onsite UFR and MLA.
The primary estimate, its confidence interval, secondary outcome results, analyzed denominator, UFR cutoff, and details of missing-data and multiplicity methods are not reported in the registry record. The entry therefore describes the diagnostic question and endpoint but does not provide the numerical results needed to assess performance.