The Oxford Optimisation of PCI Study (OXOPT-PCI Study): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Oxford Optimisation of PCI Study (OXOPT-PCI Study) (NCT03111940), a non-randomized na study. The primary outcome is Final Fractional Flow Reserve (FFR) After Intracoronary Stenting.

2. Clinical Question

The study addresses whether a standardised optimisation procedure informed by FFR and OCT can be evaluated using coronary blood-flow indices, intravascular imaging findings, and clinical follow-up. The stated clinical follow-up was contact with patients 12 months after stenting. The registry record does not report the primary endpoint values, the results of that follow-up, or estimates comparing the groups. Therefore, the posted record does not establish how much the groups differed on final FFR or on any other outcome.

The arm definitions are based on post-PCI FFR thresholds, and the allocation is recorded as non-randomized. The groups should not be interpreted as if participants had been assigned at random to comparable treatment strategies. Their grouping criteria and the procedure being assessed are important when considering any observed difference. The registry record does not report enough outcome data to determine whether the optimisation algorithm changed final FFR or clinical outcomes.

3. Trial Design

OXOPT-PCI is recorded as a completed, parallel, non-randomized study with no masking. Its listed condition is coronary artery disease, and the intervention is a procedure: optimisation of intracoronary stenting according to a specific algorithm. The registry record lists an enrollment of 35. Oxford University Hospitals NHS Trust is the sponsor. The recorded study start is 2016-08 and primary completion is 2017-07.

The intervention description says the algorithm was intended to standardise optimisation based on assessment with FFR and OCT. The arm descriptions classify “PCI Optimisation” as post-PCI FFR below 0.9 and “No PCI Optimisation” as post-PCI FFR 0.9 or higher. Because allocation is non-randomized, these are not randomized treatment groups. In particular, the recorded post-PCI FFR criteria mean that group membership is tied to a measured clinical value. The registry record does not report a randomized assignment process or a like-for-like control comparison.

The primary outcome is final FFR after intracoronary stenting, measured as a ratio and summarized as a mean with standard deviation. Its timeframe is immediately post-stenting for Group 1A and 1B, and after FFR/OCT-guided optimisation for Group 1A. The outcome description specifies measurement after intracoronary nitrates, under maximal hyperaemia using intravenous adenosine, as the ratio of distal coronary pressure to aortic pressure. OCT-guided PCI optimisation was only performed in Group 1A.

Secondary outcomes listed in the registry concern OCT-assessed stent-edge dissection, reference-lumen narrowing or geographical miss, stent malapposition, plaque or thrombus protrusion, and stent under-expansion. The record does not report results for these outcomes. It also does not report the protocol, a sample-size justification, or details of the statistical 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.

Before assignment: 35 pts recruited

Overall Study

Analysis population for the primary outcome, as defined in the registry: OCT-guided PCI optimisation was only performed in Group 1A

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 Final Fractional Flow Reserve (FFR) After Intracoronary Stenting, measured over Immediately post-stenting for Group 1A and 1B, and post FFR/OCT-guided optimisation for Group 1A.

The primary endpoint is final fractional flow reserve (FFR) after intracoronary stenting. FFR is recorded as a ratio of distal coronary pressure (Pd) to aortic pressure (Pa), measured after intracoronary nitrates and under maximal hyperaemia induced with intravenous adenosine. The registry describes the endpoint as a continuous measure, summarized using a mean and standard deviation.

FFR is used in this study as an index of coronary blood flow. The registry’s rationale is that conventional methods may make it challenging to assess the result of stenting at the end of the procedure. Measuring FFR alongside intravascular imaging is part of the study’s approach to evaluating the procedural result. The endpoint timing differs by group: it is measured immediately after stenting for Group 1A and 1B, and after FFR/OCT-guided optimisation for Group 1A. This timing matters when interpreting any comparison, because a measurement taken after an additional optimisation procedure is not the same measurement occasion as one taken immediately after stenting.

The registry record does not report the mean FFR, standard deviation, group-specific denominators, or a statistical comparison for the primary endpoint. It therefore does not show the magnitude or precision of any between-group difference. The endpoint is a physiological measurement; by itself, it is not a report of the listed OCT findings or of clinical outcomes at 12 months.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Continuous outcomes and comparisons

FFR is a continuous measure, and the registry specifies a mean and standard deviation as its summary statistics. A mean describes the center of a set of measurements; a standard deviation describes how dispersed measurements are around that mean. These summaries are useful for describing a continuous endpoint, but they do not by themselves establish whether groups differ or how precisely a difference has been estimated. The registry record does not report the FFR means, standard deviations, or a comparison test.

A confidence interval, in general, expresses the uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision, while a wider interval indicates less precision. The record does not report a confidence interval for the primary endpoint, so the precision of any estimated group difference is not available. A p-value, in general, describes how compatible the observed data are with a specified null model; it is not a measure of clinical importance and does not give the probability that a hypothesis is true. No primary-endpoint p-value or analysis is reported in the registry record.

Why does the non-randomized design matter?

Random allocation is one way to make treatment groups comparable on average with respect to measured and unmeasured characteristics. This study is recorded as non-randomized. Its arm descriptions also use post-PCI FFR thresholds to define the groups. As a result, the comparison cannot be interpreted as if the groups were formed by random assignment to optimisation or no optimisation. Differences may be associated with the group-defining FFR values as well as with other participant or procedural features. The registry record does not report an adjusted analysis or enough information to evaluate whether confounding was addressed.

In general, adjustment can account for measured characteristics included in a statistical model, but it cannot automatically remove bias from unmeasured factors. The record does not report model details, covariates, or estimates from an adjusted analysis. It is therefore not possible to determine from the registry record whether any adjustment was used or how it would affect interpretation.

How should the measurement timing be read?

The primary endpoint description gives different measurement occasions: immediately post-stenting for Group 1A and 1B, and after FFR/OCT-guided optimisation for Group 1A. Measurements made at different procedural stages do not represent the same point in the treatment sequence. In general, an endpoint measured after an additional procedure may reflect both the initial procedure and the subsequent optimisation. The record does not provide the numerical measurements needed to assess the contribution or size of any change.

The description of FFR specifies conditions for measurement: intracoronary nitrates are administered, maximal hyperaemia is induced with intravenous adenosine, and FFR is calculated as Pd divided by Pa. Standardized measurement conditions can support consistent measurement, but the registry entry alone does not provide information about measurement variability, quality control, or missing measurements.

What do the planning illustrations represent?

The sample-size illustrations are planning calculations based on the observed effect, not the study’s own design justification. Their stated assumptions include a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. In general, such calculations estimate the number of participants per arm that would be needed under specified assumptions. They are not observed power and do not describe the probability that this completed study detected an effect.

These illustrations depend on assumptions about the effect size and statistical model. If the underlying observed effect is uncertain, a planning calculation based on it is also uncertain. The registry record does not report a protocol-based sample-size rationale, and the planning calculations should not be treated as evidence that the original study was designed around those assumptions.

What can be assessed from the posted analysis information?

The registry record lists no statistical analyses. It does not report the analysis population, handling of missing data, model specification, confidence intervals, hypothesis tests, or adjusted estimates. These items matter because different analytic choices can affect both the estimate and its precision. Without them, readers cannot reproduce an analysis, assess its assumptions, or determine whether results were analyzed according to a prespecified plan.

In general, over-dispersion occurs when variability in the data is greater than a model assumes. It can make standard errors too small if the model does not account for that extra variability. This concept is relevant to some count-data analyses, but the primary endpoint is continuous and the registry record does not report an analysis model. No claim about over-dispersion in this study can be made from the posted information.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists the primary endpoint of final FFR and secondary OCT outcomes concerning stent-edge dissection, reference-lumen narrowing or geographical miss, stent malapposition, plaque or thrombus protrusion, and stent under-expansion. When several outcomes are assessed, the chance of at least one apparently unusual result can increase if many separate statistical tests are conducted. General approaches to multiplicity include prespecifying a primary comparison, adjusting testing thresholds, or interpreting secondary analyses as exploratory. The registry record does not report a multiplicity strategy or statistical analyses, so it is not possible to determine how multiple outcomes were handled.

The record does not report missing-data counts, reasons for missingness, or methods for handling missing observations. In general, missingness can affect an estimate when the observed participants differ systematically from those without measurements. The assumptions used to handle missing data can also influence the result. Since the record does not describe the amount or handling of missing data for FFR, OCT findings, or follow-up, the impact of missingness cannot be assessed.

The registry record does not identify analysis populations or say whether results were analyzed according to a prespecified population definition. It also does not report a statistical analysis plan, model specifications, or analysis code. Although the study is marked completed, that status does not provide those methodological details. No statistical analyses are listed in the registry record. Consequently, the available information does not establish whether the analyses were prespecified, whether all enrolled participants contributed to each outcome, or whether the methods differed across outcomes.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The adverse-event record lists 21 participants at risk in the PCI Optimisation group and 14 in the No PCI Optimisation group. It reports zero participants with a serious adverse event and zero with another adverse event in each group, and zero deaths in each group. These are the event counts recorded in the registry; they should be read as no events reported in these entries, not as proof that the underlying event risk was zero.

Counts of zero can occur when events are uncommon or when the period and methods of ascertainment capture no events. In general, the precision of safety estimates depends on the amount of observation and completeness of follow-up, as well as on the number of events. The registry record does not report detailed safety follow-up duration, event definitions beyond the serious and other adverse-event categories, or methods for collecting adverse events. It also does not provide a separate safety analysis or confidence intervals.

The non-randomized design means the group counts should not be treated as a randomized comparison of safety. The adverse-event entries do not establish whether the groups had comparable underlying risks. The record also does not describe whether the listed adverse-event reporting covers the entire study period or all participants in the same way.

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

This registry record describes a study of FFR/OCT-guided optimisation after intracoronary stenting, with final FFR as the primary endpoint. It identifies how FFR was measured and lists several OCT-assessed secondary outcomes. It also records a planned contact with patients 12 months after stenting. These details show what the study set out to assess, but the registry record does not report the numerical outcome results.

The record does not report the primary endpoint means, standard deviations, confidence intervals, p-values, or group-specific analysis results. It therefore cannot establish the magnitude or precision of a difference in final FFR. Nor does it report results for the listed OCT findings or the stated clinical follow-up. No conclusion about the observed clinical outcomes can be drawn from the posted information alone.

The study’s non-randomized allocation and arm definitions are also central to interpretation. The groups are described using post-PCI FFR thresholds, and Group 1A’s primary endpoint is measured after optimisation. Any group comparison would need to be understood in light of these criteria and measurement timings. The registry record does not report an analysis that addresses potential differences between groups or allows a causal interpretation.

More generally, a procedural physiological measure, an imaging finding, and a later clinical outcome describe different aspects of a study. A result for one type of outcome would not automatically establish a result for another. Here, the record describes all three areas of interest but does not post the corresponding outcome results. The adverse-event entries record zero events in the listed categories for each group, but that does not prove the absence of all harms or quantify underlying risk.

The appropriate reading is limited to the study’s design, measurement definitions, outcome list, and recorded safety counts. Claims about treatment benefit, lack of benefit, clinical effectiveness, or comparative safety are not supported by the registry information presented.

13. Why This Trial Matters Statistically

This study raises a useful statistical issue: the interpretation of a comparison depends not only on the measured endpoint but also on how groups were formed and when measurements were taken. OXOPT-PCI is recorded as non-randomized, and its arm descriptions use post-PCI FFR thresholds. Those design features affect what a group comparison can mean and make it important not to read the labels as randomized assignments.

The primary endpoint is physiological and continuous, while the listed secondary outcomes are OCT-assessed findings. The registry also describes 12-month patient contact. These outcomes address different parts of the procedural and clinical picture, and they require clear outcome definitions, timing, and analysis methods. The record gives some measurement details for FFR but does not report the numerical results or statistical analyses needed to evaluate the outcomes.

The record also illustrates why reporting uncertainty and analytic methods matters. Group means alone would not fully convey precision, and statistical significance alone would not indicate clinical importance. A reader would need effect estimates, uncertainty intervals, and a transparent account of the analysis population and missing data to evaluate results. Those items are not reported in the registry record.

Finally, sample-size planning illustrations based on an observed effect are not equivalent to an original design justification or to observed power. The registry’s non-randomized design, outcome timing, unreported analyses, and absent result estimates all limit the conclusions that can be drawn. The study’s statistical importance lies in the questions its design poses and the need to interpret procedural comparisons with appropriate caution, rather than in an outcome claim that the posted record does not establish.

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 principal limitation of the registry information is that it does not report the primary FFR results or the results for the listed OCT outcomes. There are no reported group means, standard deviations, confidence intervals, or tests for the primary endpoint. Without these, neither the estimated difference nor its precision can be assessed. The record also does not report the results of the stated 12-month patient contact.

Allocation is non-randomized, and group descriptions are based on post-PCI FFR thresholds. This creates an important interpretive limitation: the groups are not described as comparable groups formed by random assignment. The registry record does not report an adjusted comparison, covariates, or other methods that might address differences between groups. It also gives different primary endpoint timing for Group 1A and 1B versus Group 1A after optimisation, which complicates a direct comparison of measurements taken at different procedural stages.

Other relevant details are not reported in the registry record, including a protocol-based sample-size justification, analysis population, missing-data handling, statistical analysis plan, and multiplicity strategy. The registry record lists no statistical analyses. The absence of these details prevents assessment of prespecification, model assumptions, or the effects of missing measurements.

The safety entries report zero affected participants and deaths in each group, but the record does not describe detailed event ascertainment or safety follow-up. These entries should not be treated as proof of no risk. Taken together, the missing outcome results and analysis details sharply limit what can be concluded from the registry record, even though the study is marked completed.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Oxford Optimisation of PCI Study (OXOPT-PCI Study) — NCT03111940.
• Registry record last updated 2021-04-08; status last verified 2021-03.
• Results first posted 2021-04-08.
• 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.

18. Record Summary

The Oxford Optimisation of PCI Study is a completed, parallel, non-randomized study sponsored by Oxford University Hospitals NHS Trust. The registry lists an enrollment of 35, coronary artery disease, no masking, a start date of 2016-08, and primary completion in 2017-07.

The intervention is an algorithm-based optimisation procedure informed by FFR and OCT. The primary endpoint is final FFR after intracoronary stenting, recorded as a mean with standard deviation. The registry describes FFR measurement conditions and different measurement timing for Group 1A and 1B. Secondary outcomes concern OCT-assessed stent findings, and the brief summary describes patient contact 12 months after stenting.

The registry record does not report primary or secondary outcome results, clinical follow-up results, or statistical analyses. It lists zero serious adverse events, zero other adverse events, and zero deaths in each group. Those safety counts are registry entries and do not establish zero underlying risk.