Cangrelor Prasugrel Transition Study: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cangrelor Prasugrel Transition Study (NCT01852019), a randomized phase 2 study. The primary outcome is Extent of Preservation of Inhibitory Effect After Transition From Cangrelor to Prasugrel Compared With Effect Observed With Prasugrel Alone (Reference Timepoint).

2. Clinical Question

The study addresses a pharmacodynamic question: whether the measured platelet-aggregation response is preserved across transitions between the intravenous and oral medicines. The registry’s primary endpoint is expressed as percent aggregation in response to ADP, measured with light transmittance aggregometry. Lower or higher values should not be interpreted in isolation as a clinical outcome; the stated primary comparison is against a reference measurement attributed to prasugrel alone.

The registry lists a randomized allocation, no masking, and a single-group model. The dosing descriptions show different timing schedules, but the record does not make clear how those schedules relate to the model label or to the randomized allocation. The question is therefore best read as a study of measured platelet response around treatment transitions, not as a comparison of clinical events between conventional parallel treatment groups. The record does not report an estimate of the primary comparison or its uncertainty.

3. Trial Design

The Cangrelor Prasugrel Transition Study is listed as a phase 2 trial in patients with coronary artery disease. The registry reports randomized allocation, no masking, and a single-group model. Enrollment is listed as 12. The study is marked completed, with a start date of 2013-06 and a primary completion date of 2013-07. The sponsor is The Medicines Company.

The listed treatment descriptions cover several transition schedules. On Day 1, oral prasugrel 60mg is described as being administered at 1.0h or 1.5h after cangrelor infusion start, or within 5 minutes after cangrelor discontinuation. The Day 8 descriptions involve prasugrel 10mg dosing, followed by discontinuation before a cangrelor infusion. One description specifies discontinuation 48h before cangrelor initiation and identifies n=6; another specifies discontinuation 24h before initiation. The record describes a 2h cangrelor infusion in these Day 8 descriptions.

These schedule descriptions establish that timing around drug transition is central to the study. However, the registry labels the study model as single group while also reporting randomized allocation and multiple treatment descriptions. How the randomization was implemented, whether schedules were assigned in a particular sequence, and how observations from different schedules were combined are not reported in the registry record. The descriptions should therefore not be used to infer a crossover design or a particular allocation scheme beyond the labels explicitly recorded.

The primary endpoint is continuous: mean percent aggregation, with standard deviation as the stated dispersion measure. The registry lists five outcome measures and no analysis entries. The primary outcome is described across several categories or timepoints and is not reduced in the posted analysis information to a single comparison. A protocol-level sample-size justification, details of randomization, and a prespecified statistical analysis plan 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.

Day 1

Day 8

Analysis population for the primary outcome, as defined in the registry: Subjects treated with cangrelor and prasugrel were used for the analysis and presentation of data.

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.

Population: Intent-to-treat (ITT) population

6. Primary Endpoint

The registry lists the primary outcome as Extent of Preservation of Inhibitory Effect After Transition From Cangrelor to Prasugrel Compared With Effect Observed With Prasugrel Alone (Reference Timepoint), measured over Day 1 measures taken at timepoints after cangrelor infusion end to end of Day 1 measures..

The primary endpoint is the extent to which the inhibitory effect after transition from cangrelor to prasugrel is preserved, compared with the effect of prasugrel alone at a reference timepoint. It is measured as percent aggregation in response to 20 micromolar ADP at 300 seconds, using light transmittance aggregometry. The stated summary parameter is the mean, with standard deviation.

The registry designates the final Day 1 draw as the reference for prasugrel’s effect. It describes that draw as occurring 3.5 or 4.0 hours after cangrelor had been discontinued. Its timeframe field refers to Day 1 measurements at timepoints after cangrelor infusion end through the end of Day 1. The endpoint therefore focuses on the laboratory response during the transition period and at the selected reference measurement.

In general, a continuous endpoint can retain information about the size of a measured response rather than reducing observations to event/no-event categories. The standard deviation describes how dispersed individual measurements are around their mean; it is not a measure of uncertainty in the mean itself. The endpoint is used to assess pharmacodynamic preservation because the stated study question concerns platelet inhibition. It is not, by itself, a measure of bleeding, cardiovascular events, or other clinical outcomes.

Numerical means, standard deviations, and a reported estimate of the primary comparison are not reported in the registry record. The clinical meaning and precision of the primary endpoint therefore cannot be quantified from the registry information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a continuous primary outcome summarized as a mean and standard deviation. The measurement is percent aggregation following stimulation with ADP, assessed by light transmittance aggregometry. The principal contrast is framed as preservation of inhibitory effect after transition from cangrelor to prasugrel relative to a prasugrel-alone reference timepoint. The record identifies the endpoint but does not report a numerical analysis of it.

What does the mean describe?

In general, the mean is the arithmetic center of a set of continuous measurements. It gives a compact summary of the observed response on the endpoint’s scale. For this study, the scale is percent aggregation. A mean is most informative when accompanied by its spread and by a clear account of the observations included in each condition or timepoint. The registry names standard deviation as the dispersion measure, but numerical means and standard deviations are not reported in the registry record.

What does the standard deviation describe?

In general, standard deviation summarizes how far individual observations tend to lie from the mean. A larger standard deviation indicates more variability among measured responses; a smaller value indicates measurements are more tightly clustered around the mean. It describes variability in observations, not the precision of the estimated mean. Precision would also depend on how many observations contributed and how the analysis handled the study’s measurements. The registry does not report numerical standard deviations or a detailed account of the primary analysis population beyond saying that subjects treated with cangrelor and prasugrel were used for analysis and presentation.

Why does the reference timepoint matter?

A reference timepoint defines the measurement against which the transition response is assessed. Here, the registry identifies the final Day 1 draw, described as 3.5 or 4.0 hours after cangrelor discontinuation, as the reference for the effect of prasugrel. Comparisons are meaningful only when the measurement timing and treatment context are understood. The record also lists different Day 1 timings for prasugrel administration relative to cangrelor infusion. It does not provide the analysis details needed to determine how those timing categories contributed to a reported estimate.

How should uncertainty be assessed?

In general, a confidence interval gives a range of values compatible with the data and a specified statistical procedure. Its width communicates precision: a narrower interval indicates greater precision than a wider interval, under the method’s assumptions. A confidence interval also helps readers assess whether the data are compatible with effects of different sizes. No confidence interval for the primary comparison is reported in the registry record. A p-value, which measures compatibility of data with a specified null model under stated assumptions, is also not reported for the primary endpoint.

The registry labels allocation as randomized and masking as none. Randomization can help balance measured and unmeasured factors across assigned conditions in expectation, while lack of masking can leave measurement or conduct susceptible to knowledge of treatment. These are general methodological considerations, not a claim that bias occurred in this study. Details of sequence generation, concealment, and implementation are not reported in the registry record. The single-group model label, alongside randomized allocation and multiple schedule descriptions, leaves the exact structure of comparisons unclear.

What do the planning assumptions mean?

The record describes sample-size illustrations using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says the effect to detect is a stated fraction of the observed effect. In general, a planning calculation asks how much information a future study might need under selected assumptions about the effect, variability, allocation, and error rate. It does not tell readers how much power the completed study actually had. The illustrations are explicitly planning calculations, not observed power and not necessarily the design rationale used for this trial.

The assumptions do not replace information about the actual primary analysis. The registry’s sample-size justification, assumed endpoint variability, handling of repeated measurements, and model for the primary comparison are not reported in the registry record. The posted results do not contain a primary-outcome estimate from which to evaluate the planning assumptions. The registry also says that the primary outcome has several categories or timepoints and is not reduced to one comparison. Consequently, a single effect estimate should not be inferred from the endpoint title or the planning description.

Finally, the registry lists no analysis entries. That absence limits reproducibility from this record: readers cannot check which observations were included, how measurements across timepoints were handled, what estimate was targeted, or how missing values were treated. It does not establish that no statistical work was conducted. Those analysis details are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome with several categories or timepoints and states that it is not reduced to one comparison in the posted analysis information. It also lists secondary outcomes concerning preservation of inhibition after transitions in both directions and bleeding events in accordance with the GUSTO scale. With multiple outcomes, timepoints, or treatment schedules, the number and selection of comparisons can affect how findings should be interpreted. In general, multiplicity procedures address the increased chance of false-positive findings that can arise when many statistical hypotheses are tested. Whether any such procedure was prespecified or used is not reported in the registry record.

The registry lists five outcome measures and no analysis entries. It does not report a complete hypothesis-testing plan, a hierarchy among secondary outcomes, or which timepoint or schedule was intended to drive a primary conclusion. The absence of these details means that the posted record does not allow readers to determine how selective reporting or multiple testing was addressed. It is not evidence that a particular problem occurred.

Information about missing data is also not reported in the registry record. The posted information does not describe missing-measurement counts for the primary endpoint, reasons for missingness, or a statistical approach to incomplete observations. In general, missingness matters because conclusions can depend on whether unobserved measurements differ systematically from those recorded. The record does not provide enough information to assess that possibility.

The endpoint population is described as subjects treated with cangrelor and prasugrel, but detailed analysis-population definitions are not reported in the registry record. There is no posted account of exclusions, adherence requirements, or whether all randomized participants were included in each analysis. These omissions limit assessment of how the analysis population relates to the randomized allocation. They also prevent a check of whether the primary and safety summaries use the same set of participants.

11. 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.

Most frequent non-serious adverse event terms

The registry reports serious and other adverse-event counts separately for each listed group. Serious adverse events are recorded as zero in all five groups. For other adverse events, the Day 1 prasugrel 60mg at 1.5 hours group has a count of two; the other listed groups have counts of zero. The reported groups include Day 1 timing schedules and the two Day 8 prasugrel dosing schedules.

These figures are raw counts, not rates or comparative estimates. The registry also gives the number at risk for each serious and other adverse-event summary. Because the record does not provide event-level descriptions for the other events, their nature and clinical importance cannot be determined from these counts. The serious-event term list is empty. Death counts are not reported in the registry record.

In general, a zero count means no events were recorded in that group for the specified category; it does not prove that the underlying event risk is zero. Small studies can provide limited information about uncommon harms, and the listed counts alone do not support a reliable comparison across schedules. The registry lists bleeding events in accordance with the GUSTO scale as a secondary outcome, but these adverse-event counts should not be assumed to be a complete account of that endpoint. Numerical bleeding results are not reported in the registry record.

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

The study’s central contribution in the registry is its description of a measurable laboratory question: how platelet aggregation changes around transitions between intravenous cangrelor and oral prasugrel. It identifies the assay, response stimulus, endpoint scale, and reference-timepoint approach. This makes the intended pharmacodynamic comparison understandable even though numerical results are absent.

The registry information does not show the magnitude or direction of the primary endpoint result. It therefore cannot establish whether the measured inhibitory effect was preserved to a particular degree, nor whether any observed difference was estimated precisely. Neither the endpoint title nor the study objective is a substitute for a reported estimate. The record also does not report a confidence interval or primary-outcome p-value.

Even if numerical platelet-aggregation results were available, a laboratory endpoint would remain distinct from patient-important clinical outcomes. The endpoint measures aggregation in a laboratory assay; it does not directly establish effects on bleeding or cardiovascular events. The registry lists bleeding events as a secondary outcome, but numerical results for that outcome are not reported in the registry record. The listed adverse-event counts also do not provide enough detail for broad safety conclusions.

The enrollment and phase describe the scale and stage of the registered study, but do not by themselves establish the study’s precision or adequacy for any particular inference. The registry’s planning assumptions are not observed power and do not substitute for the trial’s own design justification, which is not reported in the registry record. Details of the statistical model, missing-data handling, and analysis population are also not reported.

Accordingly, the most defensible reading is limited: the record documents a study designed to examine platelet response across drug transitions, but does not report the primary numerical results needed to assess the observed effect. The missing result information should not be interpreted as evidence for either a favorable or an unfavorable treatment effect.

13. Why This Trial Matters Statistically

This trial is statistically interesting because its question depends on timing and measurement context. The primary comparison is not simply a comparison of drug names: it concerns platelet aggregation after a transition and against a defined prasugrel-alone reference measurement. The registry describes different timing schedules for oral prasugrel in relation to the cangrelor infusion, making clear why endpoint timing and treatment sequence matter to interpretation.

The study also illustrates the distinction between a stated objective and an estimable result. The registry states an aim involving preservation of platelet inhibition, and identifies a continuous assay-based endpoint. However, the posted information does not give the endpoint’s numerical estimates or uncertainty. Without these, statistical readers cannot assess effect size, precision, or compatibility with different possible effects. A carefully described endpoint is not itself evidence that the intended comparison was demonstrated.

There is also a design-reporting issue. Randomized allocation and a single-group model are both recorded, while the intervention descriptions contain multiple schedules. Such labels and descriptions need to be reconciled in a detailed analysis report so readers can understand which comparisons are between conditions, within participants, or across timepoints. The registry does not report enough about allocation and analysis to resolve that structure.

Finally, this record illustrates why safety counts, planning assumptions, and outcome analyses answer different questions. Adverse-event counts describe recorded events in listed groups. Planning illustrations describe hypothetical sample-size requirements under assumptions. Neither supplies the missing estimate of the primary endpoint, and planning calculations should not be presented as observed power. The statistical value of the study for readers therefore lies in clarifying the measurement question and highlighting the need for transparent result-level reporting.

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 primary limitation of the posted information is that it does not report numerical results for the primary endpoint. Means, standard deviations, a contrast between transition and reference measurements, and uncertainty estimates are not reported in the registry record. The primary outcome spans several categories or timepoints and is not reduced to one comparison in the posted analysis information, further limiting any single-result interpretation.

The design structure is not fully clear from the registry labels. Randomized allocation and a single-group model are both stated, while several dosing schedules are described. Details of sequence generation, allocation implementation, and how the schedule descriptions map to the analysis are not reported in the registry record. It is therefore not possible to infer the exact comparison structure.

Analysis details are also limited. The registry lists no analysis entries and does not report a statistical model, a detailed definition of the analysis population, handling of repeated measures, or missing-data methods. The sample-size justification is not reported in the registry record. The planning assumptions described in the record should not be mistaken for the trial’s own design rationale or for observed power.

The safety information consists of group-level counts without descriptions of the other events. Serious-event terms are not listed, and death counts are not reported in the registry record. The listed counts do not establish comparative safety, particularly without numerical clinical-outcome results and fuller event descriptions. The absence of reported information does not establish that outcomes were not assessed; it limits what can be concluded from the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Cangrelor Prasugrel Transition Study — NCT01852019.
• Registry record last updated 2015-06-24; status last verified 2015-05.
• Results first posted 2015-05-28.
• 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 registry record describes a completed phase 2 study of cangrelor and prasugrel transitions in patients with coronary artery disease. It lists randomized allocation, no masking, a single-group model, and enrollment of 12. The recorded study dates are 2013-06 to 2013-07.

The primary outcome is mean percent aggregation measured with light transmittance aggregometry in response to ADP. The comparison concerns preservation of inhibitory effect after transition from cangrelor to prasugrel relative to a prasugrel-alone reference timepoint. The registry lists five outcome measures and no analysis entries.

Numerical primary-outcome results, uncertainty estimates, and detailed analysis methods are not reported in the registry record. Serious adverse events are recorded as zero across the listed groups; other adverse-event counts include two in the Day 1 1.5-hour group and zero in the other listed groups. These counts do not provide a comparative safety estimate.