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 The Drift-Reduction for Improved FFR Using Fiberoptic Technology (DRIFT) Study (NCT03848650), a na na study. The primary outcome is Percentage of Recordings of Significant Drift in Pre and Post-PCI.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03848650 |
| Phase | NA |
| Condition | Left Anterior Descending Coronary Artery Stenosis |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 60 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Columbia University |
| Results posted | Yes |
2. Clinical Question
Population
The study concerns people with angiographically intermediate proximal left anterior descending coronary artery stenoses who had, or were expected to have, FFR measured using the OpSens Medical OptoWire Deux system. The registry record does not report further eligibility details or a more specific description of the population analyzed.
Intervention
The device of interest is the OpSens Medical OptoWire Deux pressure wire system, used during fractional flow reserve measurement. FFR is described as a ratio of pressure measured distal to a stenosis to pressure measured proximally, using specialized pressure-measuring guidewires during maximal hyperemia.
Comparator
This is a single-group study, not a randomized comparison. The registry record does not identify a separate control group or a comparator device. The arm description refers to subjects who will have or recently had FFR with the OpSens system, so the available record does not support a between-group treatment comparison.
Primary question
The primary question is how often recordings meet the registry's definition of significant drift in the pre- and post-PCI setting. The definition uses FFR lower than 0.97 or higher than 1.03 for the pre-PCI recording. The observed percentage and the analysis result are not reported in the registry record.
3. Trial Design
DRIFT is listed as a completed, single-group study sponsored by Columbia University. The registry record lists an enrollment of 60. Allocation is recorded as NA, and masking is listed as none. These design details describe an observational, non-randomized assessment rather than a randomized comparison between device groups. The phase is listed as NA.
The study's stated objective is to assess the accuracy, efficacy, and durability of the OpSens Medical OptoWire Deux pressure wire in clinical practice for angiographically intermediate proximal LAD stenoses. The intervention listings include the OpSens Medical OptoWire device and the FFR procedure. The arm description says that subjects will have or recently had FFR using the OpSens Medical OptoWire Deux FFR system. The registry record does not provide further detail about how those subjects were selected, whether all recordings were collected prospectively, or how repeated recordings were handled.
The recorded study start date is 2018-06-19, and the primary completion date is 2019-05-13. The status is completed. One outcome measure is listed, with significant drift in pre- and post-PCI recordings named as the primary endpoint. No analysis is listed in the registry record. That absence means the record does not include an analysis result; it does not establish what analyses may have been performed outside the registry.
Because there is no listed control group, the design can describe the recorded frequency of the endpoint in the studied group, but does not by itself estimate a difference between the OpSens system and another device or strategy. Protocol details such as the recruitment approach, planned analysis methods, and sample-size justification are 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 | Opsens Medical OptoWire |
|---|---|
| STARTED | 60 |
| COMPLETED | 60 |
| NOT COMPLETED | 0 |
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 | Opsens Medical OptoWire |
|---|---|---|
| Participants analysed | 60 | |
| Age, Continuous | years | 65 (SD 8.7) |
| Sex: Female, Male: Female | Participants | 18 |
| Sex: Female, Male: Male | Participants | 42 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | participants | 60 |
| Hypertension | Participants | 45 |
6. Primary Endpoint
The registry lists the primary outcome as Percentage of Recordings of Significant Drift in Pre and Post-PCI, measured over During procedure, approximately less than an hour.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | Percentage |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is titled Percentage of Recordings of Significant Drift in Pre and Post-PCI. It is intended to quantify how often pressure-wire FFR recordings fall into a range the registry classifies as significant drift. The description defines significant drift as an FFR lower than 0.97 or higher than 1.03 in the pre-PCI FFR recording. It also explains FFR as the ratio between pressure distal to a stenosis and pressure proximal to it, measured with specialized guidewires during maximal hyperemia.
A percentage is useful for expressing the frequency of an event relative to the recordings evaluated. Its interpretation depends on the numerator—the recordings meeting the drift definition—and the denominator—the recordings included in the assessment. Neither the observed percentage nor those component counts is reported in the registry record. The record also does not specify whether each participant contributed one recording or multiple recordings.
There is a wording distinction between the endpoint title, which refers to pre- and post-PCI recordings, and the definition, which refers to the pre-PCI recording. The record does not explain how the paired pre- and post-PCI measurements contribute to the endpoint or how a recording is classified when the measurements differ. This limits the precision with which the endpoint's operational definition can be reconstructed. The outcome timeframe is during the procedure, approximately less than an hour.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry identifies the intended outcome and its threshold definition, but it does not report the outcome value. There is therefore no posted percentage of recordings classified as significant drift to interpret, and no event count or analyzed denominator from which to assess the observed frequency. The study's completed status and enrollment of 60 do not substitute for an endpoint result: enrollment describes the study population recorded in the registry, not necessarily the number of evaluable recordings for this outcome.
The primary endpoint is a frequency measure. If reported, its meaning would depend on the number of recordings that met the threshold and the number assessed. A percentage without its denominator can be difficult to assess because the amount of information supporting the estimate depends on how many observations contributed. In this record, neither the percentage nor its underlying counts are reported. A confidence interval, which would describe statistical uncertainty around an estimated frequency, is also not reported.
The outcome definition centers on values lower than 0.97 or higher than 1.03. Those cutoffs define the recorded classification; they do not, on their own, reveal the study's observed frequency, measurement precision, or clinical significance. The registry describes the intended objective as evaluating accuracy, efficacy, and durability, but no results are posted that allow those aspects to be assessed. The endpoint description's reference to pre- and post-PCI recordings is not fully reconciled with its definition, which specifies the pre-PCI recording. Accordingly, it is not possible to determine from the record exactly how the two measurement times were combined or compared.
The single-group design also determines what can be concluded. An observed frequency, if available, would describe the recorded experience in this group under the study's measurement conditions. Without a separate comparator, the design does not estimate a relative difference against another wire or strategy. It also cannot isolate the contribution of the device from other features of measurement and clinical practice. No causal effect or comparative advantage can be inferred from the posted record.
The registry lists 60 participants enrolled and a procedure-time endpoint, but it does not report how many participants or recordings contributed to the endpoint analysis, whether any observations were excluded, or how incomplete measurements were handled. The number of analyses listed is zero. That record status leaves the statistical findings unavailable, rather than establishing that the endpoint was zero or that no statistical work occurred. The appropriate reading is therefore limited: the registry describes a planned measurement question and its threshold, while the result and its precision are not reported in the registry record.
9. Statistical Methods Explained
A statistical interpretation begins by matching the analysis to the study question. DRIFT is listed as a single-group study, and its primary outcome is a percentage of recordings classified by a threshold. For such an outcome, the estimate would ordinarily be a count of recordings meeting the definition relative to the recordings assessed. The registry does not report either count, the resulting percentage, or a statistical analysis. Consequently, no observed endpoint estimate can be interpreted from the posted record.
What does a percentage estimate?
In general, a percentage describes the observed share of eligible observations in a defined category. It needs a clear numerator, a clear denominator, and a rule for deciding which observations qualify. Here, the rule is stated as FFR lower than 0.97 or higher than 1.03 for the pre-PCI recording, while the endpoint title refers to both pre- and post-PCI recordings. The registry does not clarify the relationship between that title and definition. It also does not say whether the unit of analysis is a participant, a procedure, or an individual recording. Those choices matter: repeated recordings from the same participant are not automatically independent observations, and the denominator should reflect the specified analysis unit.
How should precision be assessed?
In general, a confidence interval expresses the uncertainty around an estimated quantity. For a frequency, a narrow interval would indicate greater statistical precision than a wide interval, given the method and assumptions used. The registry record does not report a confidence interval or describe the method used to calculate one. Without the observed event count and denominator, the precision of the primary endpoint cannot be reconstructed from the record. The enrollment of 60 alone does not establish the denominator for the outcome, since the record does not state how many recordings were evaluable or whether participants contributed multiple recordings.
General methods for binary outcomes can use different interval procedures, particularly when event counts are small or observations are clustered. Which approach is appropriate depends on the actual analysis unit, the event frequency, the sampling structure, and the prespecified statistical plan. Those details are not reported in the registry record, so a particular method cannot be attributed to this study. Recalculations from summary data would also not be possible without the summary counts and the sponsor's analysis result.
What can a single-group study estimate?
In general, a single-group frequency estimate describes what was observed in that group under its study conditions. It does not provide a randomized between-group contrast. The listed allocation is NA, masking is none, and the model is single group. Therefore, methods that estimate a treatment difference between randomized arms do not describe the study's recorded design. A single-group estimate can still be informative as a description of recorded measurements, but causal attribution or a comparison with another device requires evidence beyond a frequency in one group.
The registry lists a sample-size planning framework based on 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 an observed effect. These are planning assumptions, not evidence that the study used a two-arm design: the registered study is single group. Any sample-size values associated with such assumptions are planning illustrations, not observed power and not a description of the enrolled cohort's realized power. The magnitude of the effect used in the illustration and numerical planning outputs are not reported in the registry record. A study's enrollment should not be treated as proof that it had a specified probability of detecting an effect.
General power calculations depend on the assumed effect, variability or event rate, significance threshold, allocation, and analysis method. Changing those assumptions can change the planned sample size. A planning calculation does not show that the assumed effect occurred, and it does not replace reporting an estimate with its uncertainty. Because the registry does not post the primary endpoint result or analysis method, the planning framework cannot be linked to an observed statistical result in this record.
How do multiplicity and analysis choices matter?
In general, testing multiple outcomes or making multiple comparisons can increase the chance of at least one apparently notable result unless the analysis plan accounts for multiplicity. The registry lists one outcome measure and zero analyses, but does not report a multiplicity strategy or a detailed statistical analysis plan. The listed count of outcomes does not establish whether other exploratory analyses were planned or performed, and no correction method can be inferred.
Likewise, a complete analysis description would clarify the population included, handling of missing or unevaluable recordings, treatment of repeated measurements, and any adjustments. None of those methods is reported in the registry record. These omissions do not show that a particular method was or was not used; they mean that the posted record does not permit a reproducible statistical interpretation of the primary endpoint. The available information supports describing the question and design, but not estimating the endpoint, its precision, or a comparative effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry identifies one primary outcome measure, the percentage of recordings meeting the significant-drift definition, and lists zero analyses. It does not report a statistical analysis plan or a method for handling multiple outcomes, multiple comparisons, or repeated looks at the data. The single listed outcome does not establish that no additional exploratory analyses were conducted; the record does not describe them. No multiplicity adjustment can therefore be attributed to the study.
Missing-data handling is not reported in the registry record. The record does not state whether recordings could be unevaluable, how missing pre- or post-PCI measurements were treated, or whether participants with incomplete recordings were included in any analysis. It also does not report the number of participants or recordings included in the endpoint denominator. Enrollment of 60 should not be interpreted as the endpoint analysis population without that information.
The analysis population is likewise not specified. The registry does not describe an intention-to-treat, per-protocol, or other defined analysis set. It does not explain how the study handled repeated recordings from a participant or whether participant-level and recording-level results differed. These details affect both the interpretation of a percentage and the uncertainty around it. Their absence does not prove that no rules were used; it means the analysis population and handling procedures are not reported in the registry record.
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 |
|---|---|---|---|
| Opsens Medical OptoWire | 0 | 60 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Opsens Medical OptoWire | 0 of 60 |
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 |
|---|---|
| Opsens Medical OptoWire | 0 of 60 |
The registry's safety listing reports 60 participants at risk in the OpSens Medical OptoWire group for both serious and other adverse events. It records zero participants affected by serious adverse events, zero affected by other adverse events, and zero deaths. No serious adverse-event terms are listed.
These figures describe the safety entries in the registry record. They are not a substitute for the primary drift endpoint, and they do not provide an estimate of device performance. Zero reported events in these categories means that the record lists none among the stated participants at risk; it does not establish that no event could occur or resolve how completely events were collected. The registry does not report the adverse-event observation period, event-collection procedures, or additional detail about severity and attribution beyond the categories shown.
The risk group counts should be read as separate reported safety categories, not added together. The record does not clarify whether participants could appear in more than one category or how event-level counts relate to participant-level counts. These safety figures are descriptive registry entries, not a comparative safety analysis, because the study has no listed control group.
12. What the Result Does, and Does Not, Mean
The registry record establishes that DRIFT was a completed, single-group study with enrollment of 60 and a primary endpoint concerned with the percentage of recordings classified as significant drift. It defines the threshold using FFR lower than 0.97 or higher than 1.03 in the pre-PCI recording and describes the intended measurement context. These details identify the study question, but they do not disclose the observed endpoint value.
Without a reported percentage, numerator, denominator, or uncertainty interval, the posted information cannot show how frequently significant drift was recorded or how precisely that frequency was estimated. The completion status and enrollment do not answer those statistical questions. The registry record also does not list an analysis, so no reported hypothesis test, confidence interval, or adjusted result is available to interpret.
The design further limits the interpretation. A single group can describe measurements in the group studied, but it does not provide a randomized comparison with another device or strategy. The record cannot establish a relative difference or a causal effect. Although the stated objective includes accuracy, efficacy, and durability, the endpoint result and analysis needed to assess those aims are not reported in the registry record. The endpoint title refers to pre- and post-PCI recordings, while the description's threshold rule specifies a pre-PCI recording; the record does not explain that distinction.
The safety listing records zero affected participants in the reported serious and other adverse-event categories and zero deaths among the participants listed at risk. Those entries should be read as the registry's reported counts, not as proof that risk is absent. Taken together, the record supports a description of the design, endpoint definition, and posted safety counts. It does not support a conclusion about the observed frequency of drift, comparative performance, endpoint precision, or the study's broader stated objectives.
13. Why This Trial Matters Statistically
DRIFT is statistically notable as a measurement-focused, single-group study whose primary endpoint is a percentage of recordings classified by prespecified FFR thresholds. That kind of endpoint depends on more than the threshold itself: interpretation also needs a clearly defined unit of analysis, an evaluable denominator, and a reported count of recordings meeting the rule. The registry gives the threshold but does not report those outcome components.
The record also illustrates why design and question must be kept aligned. The study is listed as single group, with no randomized comparator, while the planning framework describes equal allocation between two arms. Such planning assumptions can be useful as hypothetical illustrations, but they do not describe this registered design or establish the precision of its endpoint estimate. Planning calculations and observed analyses answer different questions: one concerns what a design might require under assumptions, while the other reports what the study measured and how uncertain that estimate is.
Another statistical issue is the relationship between measurement times and analysis units. The endpoint title refers to pre- and post-PCI recordings, whereas the definition specifically describes a pre-PCI FFR recording. The registry does not explain how these records were paired or classified. This matters because a percentage based on recordings can differ in meaning from a percentage based on participants, especially if observations are repeated within a participant.
Finally, a completed study is not statistically interpretable from its status alone. The absence of a posted primary result, analysis method, and uncertainty estimate prevents readers from assessing the observed frequency or its precision. The record is useful for identifying the intended measurement question and design constraints, while also demonstrating why outcome reporting and a transparent analysis description are essential to interpreting a clinical study.
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.
Several limitations specific to this study follow from the details reported in the registry. First, the primary endpoint is named as a percentage of recordings in pre- and post-PCI settings, but its definition gives the significant-drift thresholds for the pre-PCI FFR recording. The record does not explain how the post-PCI measurement enters the endpoint, how recordings were paired, or how discordant measurements were classified. That ambiguity limits reconstruction of the precise outcome rule.
Second, the registry does not report the endpoint result, event count, denominator, confidence interval, or analysis method. It lists enrollment of 60, but does not state how many participants or recordings contributed to the endpoint. The number of analyses listed is zero. Consequently, the primary statistical finding and its precision cannot be assessed from the record.
Third, the single-group design has no listed control group. It can describe observations in the enrolled group if results are reported, but does not estimate a randomized comparison with another device or approach. Allocation is listed as NA and masking as none. The record does not provide further information about recruitment, measurement procedures, assessor roles, or possible sources of missing recordings.
Finally, the registry does not report the statistical analysis plan, analysis population, missing-data approach, or handling of repeated recordings. Nor does it provide a sample-size justification for the registered single-group design. These limitations concern what is documented in the registry; they do not establish that the study team lacked procedures or analyses outside the record.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: The Drift-Reduction for Improved FFR Using Fiberoptic Technology (DRIFT) Study — NCT03848650.
- Registry record last updated 2024-06-11; status last verified 2024-06.
- Results first posted 2024-06-11.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
18. Record Summary
DRIFT is a completed, single-group study sponsored by Columbia University, with enrollment of 60. The listed device is the OpSens Medical OptoWire, used for FFR assessment in angiographically intermediate proximal LAD stenoses. Allocation is NA, and masking is none. The recorded start date is 2018-06-19, and the primary completion date is 2019-05-13.
The primary endpoint concerns the percentage of recordings of significant drift in pre- and post-PCI settings. The definition classifies FFR lower than 0.97 or higher than 1.03 as significant drift in the pre-PCI recording. The registry record does not report the observed endpoint percentage, analysis result, or analysis method. It lists one outcome measure and zero analyses.
The safety entries list 60 at risk for serious and other adverse events, zero affected in either category, and zero deaths. No serious adverse-event terms are listed. The record does not describe the analysis population, missing-data procedures, or multiplicity plan.