Cancer: Rapid Diagnostics and Immune Assessment for SARS-CoV-2 (COVID-19): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cancer: Rapid Diagnostics and Immune Assessment for SARS-CoV-2 (COVID-19) (NCT04427280), a registered phase not stated study. The primary outcome is Percentage of Patients at Each Sample Timepoint With a Positive Detection of Immunoglobulin G (IgG) Specific Antibodies to SARS-CoV-2 (Spike-protein)..

2. Clinical Question

The broader study aim was to describe the clinical course of COVID-19 in people with cancer and assess the utility of antibody and antigen tests. The primary endpoint addresses antibody detection over scheduled blood collection timepoints, rather than a comparison of treatments or a direct measure of clinical benefit. Secondary outcomes also describe antibody detection, pseudovirus neutralisation and test performance against a neutralisation threshold, including analyses organized by vaccination history. The record does not report numerical results for these outcomes.

3. Trial Design

This was an observational study of people with cancer related to SARS-CoV-2 infection and testing. Its stated aims were to describe the clinical course of COVID-19 infection in people with cancer and evaluate antibody and antigen tests. The registry lists Royal Marsden NHS Foundation Trust as sponsor. Enrollment was 153, the study is marked completed, and the recorded start and primary completion dates are 2020-05-26 and 2021-06-29.

The record describes two groups. Arm A consisted of people with suspected acute COVID-19 infection. Arm B consisted of asymptomatic patients with no clinical suspicion of COVID-19. Allocation is not stated, and the arms should not be interpreted as randomized groups or as a like-for-like control comparison. The primary antibody analysis was restricted to Arm B because antibody test results were not available for the eligible Arm A patient.

Study procedures included throat/nose swabs, saliva collection and blood collection. The primary endpoint used serum collected at Day 0 (baseline), Day 28, Day 56 and Day 84. The registry describes the primary analysis population as patients with at least one blood test during the study, with inclusion at each timepoint conditional on having an assay result at that timepoint. This means the number of contributing observations could differ across timepoints; the record does not give those counts.

The registry lists 14 outcome measures and 0 analyses. It does not report a detailed statistical analysis plan, the allocation process, a sample-size justification, interim analyses, or numerical results for the primary or secondary outcomes. The study's completion status does not itself establish that all planned measurements were available or that results were posted.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: 163 patients were recruited in the trial: 11 in Arm A and 152 in Arm B. Of the 11 patients recruited to Arm A, only one patient tested positive for COVID-19 (Coronavirus Disease 2019) at baseline and so was eligible for analysis.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Patients who had at least one blood test taken during the study. Patients were included in the analysis at each timepoint if they had available assay results at that timepoint. The analysis was restricted to Arm B patients, as antibody test results were not available for the eligible Arm A patient.

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: 153 patients were eligible for analysis in the trial: 1 in Arm A and 152 in Arm B.

6. Primary Endpoint

The registry lists the primary outcome as Percentage of Patients at Each Sample Timepoint With a Positive Detection of Immunoglobulin G (IgG) Specific Antibodies to SARS-CoV-2 (Spike-protein)., measured over Blood collection timepoints: Day 0 (baseline), Day 28, Day 56, Day 84.

The primary endpoint is the percentage of patients with a positive detection of IgG specific to the SARS-CoV-2 spike protein at each of four blood collection timepoints: Day 0 (baseline), Day 28, Day 56 and Day 84. The assay was the COV2T assay on an Atellica analyser (Siemens). The registry states that index values of at least 1.0 were considered positive according to the manufacturer's protocol.

This is a binary measurement at the patient level: at a given timepoint, the assay result is classified as positive or not positive, and the endpoint expresses the proportion positive as a percentage. Describing the percentage at multiple timepoints can characterize how frequently detectable spike-specific IgG was present across scheduled sampling occasions. It does not, by itself, establish when an individual first developed antibodies, explain why a result changed, or show a clinical consequence.

The analysis was restricted to Arm B. A patient was included at a timepoint only if an assay result was available at that timepoint, among patients who had at least one blood test during the study. The registry specifies a 95% confidence interval for the percentage, but does not report the observed percentages, interval limits, or timepoint-specific denominators. Consequently, the endpoint definition is available, while the magnitude and precision of the observed endpoint are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a percentage based on a binary assay classification. For each relevant timepoint, a patient with an assay result is classified according to whether the result meets the stated positive threshold. The percentage describes the share of included patients classified positive at that timepoint. This kind of summary is useful for communicating the frequency of a condition or test result in a defined analysis population. It does not preserve all information contained in the underlying assay value, because values are grouped into positive and not positive using the specified threshold.

The positivity rule in the registry is based on the manufacturer's protocol: index values of at least 1.0 count as positive. That rule makes the outcome definition explicit and reproducible in principle. However, the numerical assay results, the counts classified positive, and the denominators at each timepoint are not reported in the registry record. Without those values, the percentage and its uncertainty cannot be checked or interpreted quantitatively.

The endpoint is measured repeatedly at Day 0 (baseline), Day 28, Day 56 and Day 84. A sequence of timepoint-specific percentages can describe the pattern of positive results across scheduled collections. These percentages are not necessarily a within-person change measure: the registry says a patient was included at each timepoint if an assay result was available then. If the patients contributing differ across timepoints, a change between percentages can reflect both assay classifications and changes in who was measured. The record does not provide the timepoint-specific participant counts or a paired analysis, so the extent to which observations were compared within the same patients is not reported in the registry record.

A 95% confidence interval is named as the measure of dispersion. In general, a confidence interval conveys uncertainty around an estimate under the statistical method used; narrower intervals indicate greater precision, while wider intervals indicate less precision. It is not a range containing a known proportion of individual patient results, and it does not account automatically for biases from missing measurements or study design. The registry does not state the interval calculation method, and the interval limits themselves are not reported in the registry record.

The primary analysis population consists of patients who had at least one blood test during the study, with availability assessed separately at each timepoint. The analysis was restricted to Arm B because antibody results were not available for the eligible Arm A patient. This restriction is important: the primary endpoint does not represent a combined estimate across both arms, and the record gives no basis for interpreting it as an estimate for all enrolled participants with cancer. No additional eligibility details for the endpoint analysis are reported in the registry record.

Several secondary outcomes are also framed as percentages at sample timepoints. They include spike-specific IgG and nucleocapsid-specific IgG, with some outcomes distinguishing participants by vaccination status or timing. Other outcomes describe pseudovirus neutralisation and the sensitivity and specificity of the Siemens spike test against pseudovirus neutralisation results at the PV50 threshold. These are different statistical questions. Antibody positivity is a prevalence-like proportion for a measurement occasion; sensitivity and specificity compare a test classification with a reference classification under a stated threshold. The registry lists these outcomes but does not report their numerical estimates, denominators, confidence intervals, or analysis methods.

General statistical interpretation of sensitivity and specificity requires knowing how the reference classification and test classification were applied to the same eligible observations. Missing results or changes in the tested population can affect these measures. The registry identifies pseudovirus neutralisation at the PV50 threshold as the comparator for the stated secondary test-performance outcomes, but details such as handling of indeterminate or unavailable results are not reported in the registry record. No test-performance conclusion can be reconstructed from the outcome titles alone.

The record includes a planning illustration based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. This is a planning framework, not the trial's own design justification. The actual planning values and the observed effect are not reported in the registry record. Any such sample-size illustration is not observed power and should not be read as evidence that the study had a particular probability of detecting an effect. The record says time-to-event illustrations use total events and other illustrations use participants per arm; the primary endpoint itself is a percentage rather than a time-to-event outcome.

Over-dispersion is a general concern when binary outcomes vary more across groups or observations than a simple model assumes. If present, a model that underestimates this variability may produce confidence intervals that are too narrow and tests that are too optimistic. The registry does not describe a model for the primary endpoint, a dispersion assessment, or an adjustment for repeated measurements. It is therefore not possible to say whether over-dispersion was assessed or how dependence among repeated measurements was handled.

In general, an observational study describes measurements under the conditions in which participants were observed. Statistical adjustment can address measured differences only when appropriate information and methods are available; it cannot turn an unrandomized comparison into a randomized one. Here, allocation is not stated, and the registry explicitly cautions that the arms are not a like-for-like control comparison. No adjustment methods or covariates are reported in the registry record. These design and reporting limits matter independently of the endpoint's calculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 14 outcome measures, including the primary antibody percentage and secondary outcomes covering antibody detection, pseudovirus neutralisation, vaccination timing, and test performance. Considering multiple outcomes and multiple sample timepoints creates multiple opportunities to observe apparently notable patterns. In general, multiplicity procedures can control the chance of false-positive conclusions across a family of statistical tests, but the appropriate approach depends on the prespecified questions and analysis plan.

Any multiplicity strategy, including whether outcomes were grouped into families or adjusted for multiple comparisons, is not reported in the registry record. The record lists 0 analyses, so it does not provide inferential results from which to assess how multiple outcomes were interpreted. The primary endpoint specifies a 95% confidence interval, but that alone does not establish whether or how multiplicity was addressed across timepoints or outcomes.

Missingness is relevant because a patient was included at each primary endpoint timepoint only when an assay result was available at that timepoint. The number of available results at each timepoint, reasons for missing measurements, and methods for handling missing data are not reported in the registry record. No imputation or sensitivity analysis is described. Consequently, the degree to which the observed percentages, if posted, would represent all eligible Arm B patients cannot be assessed from this record.

The primary analysis population was restricted to Arm B, and the registry states that antibody results were unavailable for the eligible Arm A patient. The record does not explain further how missing information in other outcomes or analysis populations was handled. It also does not report a detailed analysis plan defining populations for each secondary outcome. Those omissions make it difficult to assess selection effects or compare outcome populations.

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

The registry record establishes what the primary antibody endpoint was intended to measure: the percentage of eligible Arm B patients with a positive spike-specific IgG result at each of four scheduled blood collection timepoints. It also supplies the assay description, positivity threshold and nominal confidence level. These details clarify the measurement and its intended summary.

The record does not give the observed percentages, confidence interval limits, timepoint-specific denominators, or numerical secondary outcome results. It therefore does not show the frequency of antibody positivity, whether that frequency changed across sampling occasions, or how precisely any estimate was measured. The outcome definitions cannot substitute for the results themselves.

A positive antibody test is an assay classification, not proof of a particular clinical outcome. The endpoint does not directly measure protection from infection, severity of disease, or response to a treatment. The study is observational and describes people with cancer; it does not assign an intervention. The arm descriptions also differ by clinical status, allocation is not stated, and the registry cautions against treating the arms as a like-for-like control comparison. The available record therefore cannot establish a causal effect from a comparison between arms.

The secondary outcomes indicate that the study planned to examine vaccine-related antibody patterns, pseudovirus neutralisation and diagnostic test performance. Those questions require their own result estimates, denominators and methodological details. None of those numerical results is reported in the registry record. The record's completed status means the study is marked completed, but does not supply evidence about the magnitude, direction, or clinical relevance of its measurements.

In general, statistical estimates describe the data collected under a study's design and analysis methods. Their interpretation depends on the population observed, the completeness of measurements, the outcome definition and the uncertainty around estimates. Because several of those result details are absent, the available registry information supports a description of the study's aims and endpoint, not a quantitative conclusion about its findings.

12. Why This Trial Matters Statistically

This study raises statistical questions that are common in clinical measurement research: how to summarize repeated binary test results, how to interpret changing denominators over time, and how to distinguish antibody detection from clinical outcomes. The registry's explicit assay threshold and timepoint definitions make the intended primary measure understandable. Its restriction to Arm B also makes clear that the primary endpoint is not an estimate pooled across all participants.

The design illustrates why group labels do not automatically define a valid comparison. Arm A comprised people with suspected acute COVID-19, while Arm B comprised asymptomatic patients with no clinical suspicion. The allocation process is not stated, and the record cautions that the arms are not a like-for-like control comparison. Statistical interpretation must account for that design rather than treating the groups as interchangeable.

It also highlights the role of outcome completeness and analysis reporting. A timepoint-specific percentage depends on who had an assay result at that timepoint. Without denominators and missing-data details, readers cannot determine whether the populations behind successive percentages are comparable. Confidence intervals can communicate sampling uncertainty, but they cannot by themselves resolve selection or missing-data concerns.

Finally, multiple antibody and diagnostic outcomes raise questions about prespecification and multiplicity. The registry lists 14 outcomes but no analyses, and does not report a detailed analysis plan or numerical results. This is a useful reminder that a clear endpoint definition is only one part of statistical transparency: readers also need estimates, uncertainty, populations, and analysis methods to evaluate evidence. The record supports discussion of these design issues, while not supporting conclusions about the study's numerical findings.

13. Limitations

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

The most immediate limitation for interpretation is that numerical results are not reported in the registry record. The primary percentages, confidence interval limits and timepoint-specific denominators are unavailable, as are numerical findings for the listed secondary outcomes. The record therefore does not permit assessment of the observed antibody pattern or its precision.

The primary antibody analysis was restricted to Arm B. The registry states antibody results were not available for the eligible Arm A patient, but does not provide further detail about the analysis population or missing measurements. Inclusion depended on having an available assay result at each timepoint, and the numbers contributing at each occasion and the reasons for missingness are not reported in the registry record.

The study is observational, with allocation not stated. Arm A and Arm B are defined by different clinical circumstances, and the record explicitly notes that they are not a like-for-like control comparison. This limits interpretation of any between-arm contrast and does not support a causal treatment-effect interpretation.

The record lists 14 outcome measures but 0 analyses. A detailed statistical analysis plan, multiplicity handling, confidence interval calculation method, interim analyses and sample-size justification are not reported in the registry record. The sample-size description is a planning illustration based on an observed effect, not evidence of observed power; the numerical planning values are not reported in the registry record.

The adverse-event entries list zero values for the recorded at-risk and affected counts and deaths in both arms. The at-risk counts are also recorded as zero, so these entries should not be interpreted as demonstrating that no adverse events occurred among the enrolled participants. Further adverse-event detail is not reported in the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Cancer: Rapid Diagnostics and Immune Assessment for SARS-CoV-2 (COVID-19) — NCT04427280.
• Registry record last updated 2025-09-04; status last verified 2025-08.
• Results first posted 2025-09-04.
• 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.

17. Record Summary

The registry record describes NCT04427280, “Cancer: Rapid Diagnostics and Immune Assessment for SARS-CoV-2 (COVID-19),” sponsored by Royal Marsden NHS Foundation Trust. It is an observational study marked completed, with enrollment of 153 and recorded dates of 2020-05-26 for study start and 2021-06-29 for primary completion.

The study aimed to describe COVID-19 infection in people with cancer and evaluate antibody and antigen tests. Procedures included throat/nose swabs, saliva collection and blood collection. The primary endpoint was the percentage of Arm B patients with positive spike-specific IgG at Day 0 (baseline), Day 28, Day 56 and Day 84, using the Siemens COV2T assay on an Atellica analyser and a positivity threshold of at least 1.0.

The registry lists 14 outcome measures and 0 analyses. Numerical primary and secondary results, timepoint-specific denominators, and a detailed statistical analysis plan are not reported in the registry record. The two arms are not a like-for-like control comparison, and allocation is not stated.