Management of Platelet Transfusion Therapy in Patients With Blood Cancer or Treatment-Induced Thrombocytopenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Management of Platelet Transfusion Therapy in Patients With Blood Cancer or Treatment-Induced Thrombocytopenia (NCT03195010), a randomized phase 2 study. The primary outcome is Number of Patients Successfully Following Protocol.

2. Clinical Question

The study addresses a practical question about managing platelet transfusions while participants receive anticoagulant medication for blood clots. Its brief summary frames the comparison around the safety of different transfusion thresholds: the lower-threshold approach entails transfusing at a lower morning platelet count than the higher-threshold approach. The registry describes the intended context as blood cancer or treatment-induced thrombocytopenia requiring anticoagulation.

The primary outcome is not a direct measure of bleeding, clot progression, or transfusion burden. It is a count of participants who were successfully following the assigned protocol at the end of the study period. The registry also lists outcomes covering hemorrhagic events, major bleeds, platelet transfusion use and related complications, and arterial or venous thromboembolism. Those outcomes describe other aspects relevant to the comparison, but their results and analyses are not reported in the registry record.

This was a pilot study with four participants enrolled. Its registry record therefore describes a small-scale comparison and reports the primary outcome counts, but does not establish a precise estimate of differences between transfusion strategies. The clinical question and the available endpoint data should be kept distinct: the study intended to compare thresholds in a population receiving anticoagulation, while the posted primary result records protocol adherence rather than the occurrence of a clinical benefit or harm.

3. Trial Design

The study is listed as Phase 2, randomized, unmasked, and parallel. It compared two platelet transfusion groups. Group I used the lower threshold, transfusing when the morning platelet count was below 30 x 10^9/L. Group II used the higher threshold, transfusing when the morning platelet count was below 50 x 10^9/L. In each group, transfusions were specified for up to 30 days or until the platelet count spontaneously recovered to > 50 x 10^9 for 3 consecutive days in the absence of transfusions.

The registry record gives enrollment as 4. The posted primary outcome lists 2 participants in Group I and 2 in Group II, with a successful-protocol count of 2 for each. These counts are descriptive; the registry record does not report a statistical analysis comparing the groups. The study status is terminated. The recorded start date is 2017-06-09, and the primary completion date is 2018-12-21.

The study is described as a pilot focused on management of venous thromboembolic events in people with hematologic disorders and treatment-induced thrombocytopenia. Its brief summary describes participants as requiring anticoagulant medication for blood clots. The registry lists Fred Hutchinson Cancer Center as the sponsor. The arm descriptions define the transfusion thresholds and stopping condition, but further operational details about treatment delivery are not reported in the registry record.

Randomization indicates that treatment assignment was intended to use a chance-based process, but the method of sequence generation and allocation concealment is not reported in the registry record. The study is listed as having no masking. Accordingly, the registry design information does not describe blinded assignment or assessment. Details such as the randomization procedure, how adherence was monitored, and how departures from the assigned protocol were handled 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

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 Number of Patients Successfully Following Protocol, measured over Up to 1 year.

The primary endpoint is the number of participants successfully following protocol. The registry defines success as receiving transfusions on protocol at the end of the study period. The outcome is recorded as a participant count, with a timeframe of up to 1 year. The posted count is 2 for Group I and 2 for Group II; each group has 2 participants reported.

This endpoint is used to describe whether participants were receiving transfusions according to the assigned approach at the endpoint assessment. For a pilot comparing transfusion thresholds, protocol adherence can indicate whether the assigned regimens were followed sufficiently to be evaluated. It is not itself a measure of bleeding, clot progression, survival, or the number of transfusions. A participant can be classified as following protocol without that classification showing whether a clinical event occurred.

The count is especially important to interpret in light of the small enrollment. The registry reports the same success count in both groups, but it does not report an inferential analysis or a measure of uncertainty for this endpoint. The endpoint description also does not specify the precise assessment process beyond the definition of success and the end-of-study timing. Further details about outcome adjudication, missing observations, and how protocol adherence was determined are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a randomized, unmasked, parallel-group study. In a randomized trial, assignment is intended to create groups whose differences are not determined solely by clinician or participant choice. Randomization can reduce systematic differences at assignment, but it does not guarantee that small groups will be balanced on relevant characteristics. With enrollment of 4 and 2 participants listed in each group, baseline balance and the details of assignment cannot be assessed from the primary result alone. The method used to generate the assignment sequence and conceal it before enrollment is not reported in the registry record.

An unmasked design means the registry does not describe masking of participants or study personnel. Knowledge of assignment can affect care decisions, adherence, reporting, or assessment, depending on the endpoint. The primary endpoint concerns whether participants were receiving transfusions on protocol at the end of the study period, so its interpretation depends on how protocol adherence was determined. The registry record does not report a blinded adjudication process or additional details about the assessment.

The primary endpoint is a binary participant-level outcome represented by a count: participants either meet the registry definition of successful protocol adherence or they do not. The posted values are counts, not continuous measurements. For a binary endpoint, an analysis might ordinarily compare event counts or event proportions, but the registry record does not report such an analysis. The result data are identified as missing or not estimable for a two-arm comparison. No inferential method, effect estimate, standard error, confidence interval, or p-value is reported for the primary comparison.

A confidence interval, as a general statistical concept, gives a range of values compatible with an estimate under a specified method and assumptions. Its width conveys precision: a wider interval indicates greater uncertainty about the magnitude of an effect. A p-value, in general, measures how incompatible the observed data are with a specified null hypothesis under the analysis assumptions; it does not measure the probability that a treatment works or that the null hypothesis is true. Neither kind of inferential result is reported for the primary comparison in this record. The counts alone cannot replace them.

Clinical trial analysis also depends on defining the population to be analyzed. An intention-to-treat approach generally analyzes participants according to their randomized assignment, while a per-protocol approach generally focuses on participants who sufficiently followed the protocol. These are general statistical concepts, not a description of the analysis performed in this study. The registry record does not report an analysis population or state whether the primary endpoint was analyzed according to assignment, protocol adherence, or another rule. The endpoint definition itself concerns successful protocol following, but that does not reveal the analysis population used for other outcomes.

Missing data can affect both the count of observed outcomes and the interpretation of comparisons. If an outcome is unavailable, the analysis needs a rule for deciding whether to exclude the observation, classify it, or use a model or imputation method. Such choices can change estimates, particularly when missingness is related to the outcome or to treatment assignment. The registry record does not report missing-data counts, reasons for missingness, or a handling strategy for the primary or secondary outcomes. The absence of reported analyses means the impact of missing data cannot be assessed from the record.

Multiplicity arises when a study evaluates several outcomes or makes several statistical comparisons. Repeated testing can increase the chance of finding an apparently noteworthy result by chance if no adjustment or prespecified hierarchy is used. The registry lists a primary outcome and seven secondary outcomes, and reports 13 outcome measures overall. It does not report an analysis plan specifying how these endpoints were prioritized or whether any adjustment for multiple comparisons was intended. It is therefore not possible to determine whether multiplicity was addressed in the planned or conducted analyses.

The record includes a general planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It specifies that the effect to detect is a stated fraction of the observed effect. In general, such calculations describe the number of participants that might be needed under stated assumptions; they are not evidence of the study's actual power or a report of what was observed. A planning illustration based on an observed effect is especially dependent on that effect estimate and the assumptions used. The registry does not report its own sample-size justification, and the illustrations should not be read as observed power. The exact planning values and the assumptions behind the trial's original design are not reported in the registry record.

Over-dispersion is a general issue when count data vary more than a statistical model expects. If it is ignored, estimated uncertainty can be too small, making results appear more precise than they are. The primary outcome is reported as a participant count, but the registry record does not describe a count model, an over-dispersion assessment, or any model-based analysis. No such modeling approach should be inferred from the endpoint format.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Group I (Lower Dose Platelet Transfusion)", "Group II (Higher Dose Platelet Transfusion)")
n      <- c(2, 2)
events <- c(2, 2)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Group I (Lower Dose Platelet Transfusion)  2  2  100.0  15.8  100.0  34.2  100.0  29.2  99.2
ARM  Group II (Higher Dose Platelet Transfusion)  2  2  100.0  15.8  100.0  34.2  100.0  29.2  99.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary outcome of successful protocol following and seven secondary outcomes. The secondary outcomes cover hemorrhagic events, major bleeds, platelet transfusion counts and days, transfusion-related complications, and progressive or new arterial or venous thromboembolism. The record lists 13 outcome measures in total, but reports 0 analyses. The individual secondary outcome results and statistical comparisons are not reported in the registry record.

When a study evaluates several endpoints, multiplicity matters because examining many outcomes can increase the chance of an apparently notable result occurring by chance. Statistical plans may address this through a prespecified hierarchy, adjusted testing, or a clearly exploratory interpretation. Which approach was intended or used is not reported in the registry record. There is no basis in the posted results to infer a multiplicity adjustment or to identify a hierarchy among the secondary outcomes.

The record does not report the number of missing observations for the primary or secondary outcomes, reasons for missingness, or rules for handling incomplete data. It also does not report the analysis population or describe whether participants were analyzed according to randomized assignment. These details matter because excluding participants, assigning missing outcomes, or analyzing only those who followed protocol can change the interpretation of a randomized comparison.

Because analyses are not reported, the posted outcome counts cannot be read as a complete prespecified statistical analysis. The registry record does not report a statistical analysis plan, interim analyses, or a sample-size justification. These omissions limit assessment of endpoint selection, missing-data handling, and the relationship between the planned and reported analyses.

12. 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.

Most frequent non-serious adverse event terms

The registry's adverse-event summary reports serious adverse events for 0 of 2 participants in Group I and 0 of 2 participants in Group II. For other adverse events, it reports 1 of 2 participants in Group I and 2 of 2 participants in Group II. Deaths are reported as 0 in each group. These are participant counts, not rates adjusted for follow-up time, and the small group sizes make them descriptive rather than reliable comparative estimates.

The adverse-event summary does not provide serious adverse-event terms; the list of top serious terms is empty. The record therefore does not describe the nature, timing, duration, or attribution of serious events beyond the reported counts. The other adverse-event counts likewise do not identify the events or indicate their severity. A participant-level count also does not necessarily equal the number of distinct events, since an individual may experience more than one event; event totals are not reported in the registry record.

These safety figures should be kept separate from the primary endpoint. Successful protocol following does not mean that no adverse event occurred, and the adverse-event counts do not establish whether one transfusion threshold is safer than the other. The registry does not report a statistical comparison of adverse events, and the small enrolled group does not support a precise estimate of comparative safety.

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

The registry record documents a randomized pilot comparing platelet transfusion thresholds in people with blood cancer or treatment-induced thrombocytopenia who required anticoagulant medication for blood clots. It reports four enrolled participants, with 2 participants in each group. The primary outcome count was 2 successful protocol-following participants in each group. The most direct interpretation is that the record reports matching counts for this adherence endpoint among the participants listed in the two groups.

That observation does not establish that the strategies are equivalent. An equivalence conclusion requires a statistical framework designed to assess whether any difference is small enough to meet a prespecified criterion. The registry record does not report such a criterion or analysis. Matching observed counts in a small pilot are not evidence that clinically relevant differences are absent, and no confidence interval is reported to show the range of differences compatible with the data.

The primary endpoint also does not answer whether the thresholds differ in bleeding, clot progression, transfusion burden, or transfusion-related complications. Although the registry lists these as secondary outcomes, their results are not reported in the registry record. Safety counts are available for serious and other adverse events, but they are sparse, do not provide event descriptions, and are not accompanied by a comparative analysis. Those counts cannot resolve the broader safety question by themselves.

The record does not report why the study was terminated, whether enrollment reached its intended target, or whether the termination altered the analysis. It also does not report the original sample-size rationale, analysis populations, missing-data handling, or statistical plan. These unknowns constrain any interpretation beyond the descriptive result. The posted data are best understood as a limited record of the pilot's primary adherence counts and adverse-event counts, not as a definitive comparison of transfusion strategies or a basis for treatment decisions.

14. Why This Trial Matters Statistically

This trial is statistically instructive because the clinical question and the primary endpoint are related but not interchangeable. The study compared two platelet thresholds in a population receiving anticoagulation, while its primary outcome counted successful protocol following. Adherence can show whether an assigned approach was followed, but it does not directly measure bleeding or thrombosis. Keeping the endpoint's meaning distinct from the broader clinical question prevents an adherence count from being overstated as a safety result.

The record also illustrates the limits of interpreting small pilot data. Enrollment was 4, and the posted primary counts were 2 in each group. Those values communicate what was recorded, but cannot by themselves provide a precise estimate of a between-group difference. Without an inferential analysis and a measure of uncertainty, equal counts should not be taken as proof of equivalence or absence of a clinically meaningful difference.

Another important lesson is that registration of outcomes does not guarantee that their results or analyses will be available in the registry record. Seven secondary outcomes are listed, but their results are not reported there. The registry reports 0 analyses, leaving readers unable to assess the planned comparison, multiplicity handling, analysis populations, or missing-data strategy. Transparent reporting of these elements is important for distinguishing prespecified analyses from exploratory interpretation and for understanding how much confidence to place in results.

Finally, the planning illustration should be distinguished from evidence about the completed pilot. Sample-size calculations describe what might be needed under stated assumptions; they are not observed power and cannot compensate for unreported analyses or missing outcome results. Reading the study statistically means considering the design, endpoint, enrollment, analysis reporting, and uncertainty together rather than treating a matching pair of counts as a conclusive result.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The most direct limitation is the small enrollment: 4 participants, with 2 listed in each group. The primary outcome is reported only as a count, without an effect estimate, confidence interval, or statistical test. The record explicitly has no reported analyses, and a two-arm comparison for this binary endpoint is identified as not estimable from the available values. The resulting evidence is descriptive and does not quantify uncertainty about a group difference.

The registry record does not explain why the study was terminated or whether the termination affected enrollment, follow-up, or analysis. It does not report whether the intended sample size was reached. The trial's own sample-size justification is not reported in the registry record; any planning illustration based on the observed effect is not a substitute for that rationale or for observed power.

Important design and analysis details are also absent. The randomization method, allocation concealment, adherence assessment procedures, analysis population, missing-data counts and handling, and statistical analysis plan are not reported in the registry record. The record does not describe interim analyses or multiplicity handling. These omissions make it difficult to evaluate potential bias or determine whether the reported outcome counts correspond to a prespecified analysis.

Although seven secondary outcomes are listed, their results are not reported in the registry record. The adverse-event summary gives participant counts but does not identify the events or provide timing, duration, attribution, or a comparative analysis. Consequently, the record cannot support a detailed evaluation of bleeding, thrombosis, transfusion burden, or the nature of harms. The limitations are especially relevant when interpreting the study as a comparison of safety: the available primary result is protocol adherence, not a reported analysis of those clinical outcomes.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Management of Platelet Transfusion Therapy in Patients With Blood Cancer or Treatment-Induced Thrombocytopenia — NCT03195010.
• Registry record last updated 2019-10-21; status last verified 2019-10.
• Results first posted 2019-10-21.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

NCT03195010 is a Phase 2 randomized, unmasked, parallel pilot sponsored by Fred Hutchinson Cancer Center. It compared platelet transfusion thresholds of 30 x 10^9/L and 50 x 10^9/L for participants with blood cancer or treatment-induced thrombocytopenia requiring anticoagulant medication for blood clots. Enrollment was 4, and the study status is terminated.

The primary endpoint was the number of participants successfully following protocol at the end of the study period, with a timeframe of up to 1 year. The registry reports a count of 2 in each group, with 2 participants in each group. It reports 0 analyses and no inferential comparison for this endpoint. Seven secondary outcomes are listed, but their results are not reported in the registry record. The adverse-event summary reports serious adverse events for 0 participants in each group, other adverse events for 1 participant in Group I and 2 participants in Group II, and 0 deaths in each group.

The study start date is 2017-06-09, and the primary completion date is 2018-12-21. The reason for termination, the original sample-size justification, and the statistical analysis plan are not reported in the registry record.