Head to Head Pilot Trial of Mailed Cologuard to Mailed FIT: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Head to Head Pilot Trial of Mailed Cologuard to Mailed FIT (NCT06173375), a randomized na study. The primary outcome is Number of Participants Completing Colorectal Cancer Screening.

2. Clinical Question

3. Trial Design

This is a randomized, parallel-group pilot trial comparing two mailed colorectal cancer screening outreach approaches. The registry lists the allocation as randomized and masking as none. The study is marked completed, and its phase is listed as NA. The sponsor is the University of California, San Diego. The record gives a total enrollment of 12 and lists 6 participants in each arm. Those enrollment figures describe the study record; they do not establish how many participants contributed usable data to every outcome.

One group received mailed Cologuard outreach, and the other received mailed fecal immunochemical test outreach. Both descriptions ask participants to complete and return the mailed screening test. The descriptions also state that participants with a negative test are advised to repeat screening after an interval specific to the test offered, while those with a positive test are advised to schedule colonoscopy for further testing. The primary outcome, however, counts completion of any of a set of recommended screening tests, not just completion of the mailed test.

The primary outcome timeframe is within 3 months of randomization. The registry lists the study start as 2024-05-15 and primary completion as 2024-12-31. These registry dates do not provide the dates on which individual participants were randomized or assessed. The registry record does not report further details about the randomization procedure, concealment, recruitment, participant flow, protocol deviations, or the statistical analysis plan. The study's pilot designation and enrollment context are relevant when interpreting the descriptive results: the record does not establish that the trial was designed to provide a definitive comparative-effectiveness estimate.

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: A total of 200 individuals were identified as potentially eligible via EHR queries and invited to participate. Of these, 12 individuals provided informed consent and were randomized to study arms (6 to mailed Cologuard outreach and 6 to mailed FIT outreach). Only participants who consented and were randomized are included in the Participant Flow module.

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 Participants Completing Colorectal Cancer Screening, measured over Within 3 months of randomization.

The primary endpoint is the number of participants who complete any colorectal cancer screening test recommended by the US Preventive Services Task Force within 3 months of randomization. The listed tests are colonoscopy, FIT, Cologuard, sigmoidoscopy, and CT colonography. This definition measures screening completion over a specified follow-up period rather than simply whether the test mailed by the assigned outreach group was returned.

Counting any recommended test makes the endpoint relevant to the broad objective of screening completion. A participant could meet the endpoint through a test other than the one mailed, according to the registry's definition. The outcome therefore reflects completion of screening within the stated period, not necessarily acceptance of the assigned test, a particular test's diagnostic yield, or completion of follow-up after an abnormal result. Those are distinct questions.

The registry reports 5 participants completing screening in the mailed Cologuard group and 3 in the mailed FIT group; each arm lists 6 participants. These are counts, not a reported effect estimate with a confidence interval or hypothesis test. The registry record does not report endpoint-specific missing-data details or explain how completion was verified. Consequently, the displayed counts describe the recorded outcome but do not by themselves quantify the precision of a comparative effect.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Statistical methods can be understood in relation to what the record reports and what it leaves unspecified. The registry identifies a randomized, parallel-group design and posts counts for the primary endpoint, but lists 0 analyses. It does not report a statistical analysis plan, an effect estimate comparing the groups, a confidence interval, or a hypothesis test. The methods are general explanations, not a claim that any particular inferential method was used for this trial.

What does random allocation contribute?

In general, random allocation assigns participants to study groups using a chance-based process. Its purpose is to reduce systematic differences between groups at assignment, including differences that investigators may not have measured. In a randomized comparison, the assigned group is the basis for evaluating the intervention strategies, provided that follow-up and analysis are handled appropriately. Randomization does not guarantee that groups will look alike in every characteristic, particularly in a small pilot, and it does not prevent missing outcome data or errors in outcome measurement.

The registry labels the allocation randomized, but the record does not report the sequence-generation or concealment procedures. Masking is listed as none. That means the registry does not describe masked study conduct; it does not, by itself, specify who knew each participant's assignment at every stage or how outcome assessment was conducted. Further detail is not reported in the registry record.

What does the primary count convey?

The primary outcome is a count of participants meeting a binary completion criterion: screening was completed within the stated timeframe or it was not. The posted counts are 5 participants in the Cologuard outreach arm and 3 in the FIT outreach arm, with 6 participants listed in each arm. A count is a direct description of recorded outcomes. By itself, it does not provide a measure of uncertainty or a formal comparison between outreach strategies.

General statistical principle: a comparative analysis for a binary outcome often expresses the contrast using a difference in proportions, a relative measure, or a model-based effect estimate. The choice affects interpretation and assumptions. No such comparative measure is reported in this registry record, and no new measure is calculated. A confidence interval, when reported, communicates uncertainty around an estimate under the analysis assumptions. A narrow interval generally indicates greater precision than a wide interval, while an interval compatible with a range of effects can make clear that the data do not distinguish those possibilities well. No confidence interval is reported for this result.

Why does the pilot context matter?

A pilot can provide preliminary information about implementing a study or intervention and can describe observed outcomes. General statistical principle: small samples tend to provide limited precision, and individual outcomes can have an appreciable influence on the apparent pattern. This is especially relevant when the outcome is recorded as participant counts. A pilot's observed effect should not automatically be treated as the effect expected in a later, larger study; it may be unstable and may reflect chance variation as well as any underlying difference.

The registry includes a planning-illustration framework based on the observed effect. It describes a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation, with planning for stated fractions of the observed effect. These are planning assumptions, not reported evidence that the trial had a particular level of power. General statistical principle: sample-size planning asks how much information a future study might need under chosen assumptions. It does not retrospectively establish that a completed study was adequately powered, and planning calculations based on an observed pilot effect can be sensitive to that effect's uncertainty. The registry record does not report that these planning assumptions were the trial's original design basis.

What can be inferred from the analysis status?

The record lists 0 analyses. Accordingly, no inferential result should be attributed to the trial from the posted counts. A p-value, if reported in a suitable analysis, would address how compatible the data are with a specified null model under its assumptions; it would not give the probability that the treatment approaches are equivalent or that a finding is true. A p-value also would not describe the size or practical importance of an effect. No p-value is reported, so the counts should remain descriptive rather than be characterized as statistically significant or non-significant.

General statistical principle: model choice should follow the design, outcome, and analysis objective. For binary outcomes, possible approaches can differ in how they represent the effect, account for covariates, and treat sparse data. The registry does not report a model or test, and there is not enough information to identify which approach would have been specified. It would be inappropriate to infer that a particular model, adjustment, or small-sample correction was used.

What is not established by the posted results?

The primary completion counts do not establish whether screening results were positive or negative, whether follow-up after a positive test occurred, or whether screening completion led to lesion detection. The registry lists secondary outcomes concerning opt-outs, adenomas, sessile serrated lesions, colorectal cancer detection, and undeliverable tests, but their results are not reported in the record. The record also does not provide missing-data methods, analysis-population definitions, or an account of outcome ascertainment. These omissions limit both reproducibility and interpretation. General statistical principle: a transparent analysis report should make the endpoint definition, comparison method, treatment of missing outcomes, and uncertainty estimates clear so readers can evaluate how conclusions follow from the observations.

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("Mailed Cologuard Outreach", "Mailed Fecal Immunochemical Test Outreach")
n      <- c(6, 6)
events <- c(5, 3)
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  Mailed Cologuard Outreach  6  5  83.3  35.9  99.6  43.6  97.0  42.1  96.3
ARM  Mailed Fecal Immunochemical Test Outreach  6  3  50.0  11.8  88.2  18.8  81.2  18.4  81.6

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 10 outcome measures and identifies 5 secondary outcomes: participants opting out of the pilot, adenomas detected, sessile serrated lesions detected, participants with colorectal cancer detected, and participants with undeliverable FIT or Cologuard tests. Their results are not reported in the record. The primary endpoint concerns screening completion within 3 months of randomization.

Multiplicity refers, in general, to the interpretive issue that arises when several outcomes or statistical comparisons are examined. When many tests are conducted, the chance of at least one apparently unusual result can increase, depending on the testing strategy. Methods for addressing multiplicity can include prespecifying a primary outcome, adjusting tests, or interpreting secondary outcomes as exploratory. The registry record does not report whether any multiplicity strategy was planned or used, nor does it report a statistical analysis plan. Since the record lists 0 analyses, there are no posted inferential tests to assess for multiplicity.

The record does not report endpoint-specific missing-data counts, reasons for missing outcomes, imputation, or sensitivity analyses. It also does not define the analysis population for the posted primary counts or state whether all randomized participants were analyzed according to assignment. The arm descriptions and randomized design do not resolve those questions. Missing outcomes can affect a binary completion endpoint if participants without recorded follow-up are classified differently or excluded; general statistical principle: interpretation depends on both the amount and pattern of missingness and the analysis assumptions used to address it. Those details are not reported in the registry record, so their possible influence cannot be assessed from the posted counts.

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 5% reporting threshold.

The registry's adverse-event record lists 6 participants at risk in each arm. It reports 0 serious adverse events, 0 other adverse events, and 0 deaths in each group. These are recorded counts for the groups and safety categories specified in the registry; they should not be treated as evidence that no adverse events could occur or that the approaches have been shown to be equally safe.

General statistical principle: when event counts are zero, uncertainty about the underlying event rate can remain, especially when the amount of observed information is limited. A zero count means no event in that category was recorded for the listed at-risk group in the registry entry; it does not mean that the true event risk is known to be zero. The record does not report the safety observation window, event-collection procedures, or further details on definitions and ascertainment. It also does not provide event-level descriptions. These omissions limit what can be concluded from the zero counts.

Safety counts are separate from the primary screening-completion endpoint. They do not indicate how many participants completed screening or whether screening tests led to additional procedures. The appropriate reading is descriptive: the registry reports no serious or other adverse events and no deaths in either listed group, while the extent and precision of safety surveillance are not reported in the registry record.

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

The registry records screening completion in 5 participants assigned to mailed Cologuard outreach and 3 assigned to mailed FIT outreach, with 6 participants listed in each group. The endpoint counts completion of any recommended colorectal cancer screening test within 3 months of randomization. These figures describe what was recorded in this completed pilot; they do not provide a reported comparative effect estimate or an inferential test.

The result does not establish that either outreach strategy leads to more screening completion in a broader population. The registry reports 0 analyses and provides no confidence interval or p-value for the comparison. General statistical principle: observed differences in small studies can be imprecise, and inference requires an analysis that accounts for the outcome definition, study design, and uncertainty. Without that analysis, the counts should not be presented as proof of a difference or proof of no difference.

The endpoint also has a specific scope. It includes multiple screening tests, not only the stool test mailed to the participant. Therefore, a recorded completion does not necessarily show that the assigned kit was returned. Conversely, the primary outcome alone does not describe test positivity, colonoscopy completion following a positive result, adenomas, sessile serrated lesions, or colorectal cancer detection. The registry lists some of these as secondary outcomes, but their results are not reported in the record.

The record does not report missing-outcome handling, participant flow, or details about outcome ascertainment and the comparative statistical plan. Those gaps make it difficult to assess how completely the posted counts represent outcomes under each assignment. The pilot designation is also important: the registry result is preliminary descriptive information, not a definitive estimate of comparative effectiveness. It can be interpreted as a record of screening-completion counts under the two outreach approaches, with substantial limits on what can be inferred about precision, generalizability, and downstream screening outcomes.

14. Why This Trial Matters Statistically

This trial raises a useful statistical question about how to evaluate outreach strategies: what should count as successful screening? The primary endpoint counts any recommended colorectal cancer screening test completed within 3 months, rather than restricting success to return of the mailed test. That definition captures a broader screening outcome, but it also means the result is not a direct measure of whether participants used the kit assigned to them. Keeping the endpoint definition in view is essential when interpreting the arm counts.

The randomized, parallel design offers a framework for comparing the outreach approaches, while the pilot context and enrollment place limits on precision. The posted primary counts provide a concrete description of recorded screening completion, but the registry lists 0 analyses. No inferential comparison or uncertainty estimate is reported. This distinction is statistically important: descriptive data can inform understanding of what happened in the trial, but they do not on their own establish how much of an apparent difference reflects a consistent effect rather than uncertainty in a small study.

The registry also lists secondary outcomes related to screening participation, mail delivery, and detection. Their inclusion indicates that the trial's questions extend beyond the primary completion count, but their results are not reported in the record. A complete interpretation would need to distinguish these outcomes, their measurement, and any planned approach to multiplicity. The record does not report that analysis detail.

As a pilot, the trial may be informative as an initial comparison of mailed Cologuard and FIT outreach in the stated care setting and age range. Its statistical value lies in the design question and the descriptive data that are reported, alongside the limits of what can be inferred. The evidence should not be expanded beyond the registry's endpoint, population, and reported results.

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.

Several limitations are specific to the information reported for this trial. The registry describes a pilot with a total enrollment of 12 and lists 6 participants in each arm. The primary outcome counts are 5 for mailed Cologuard outreach and 3 for mailed FIT outreach. Such a small study provides limited information for precise estimation, and the registry does not report a confidence interval or comparative analysis that would quantify uncertainty.

The primary endpoint allows completion through any listed recommended screening test, including tests other than the mailed test. That broad definition addresses screening completion but does not isolate return or use of the assigned kit. The record does not report results for kit return separately, nor does it report how screening completion was verified. It also does not post results for the listed secondary outcomes on opt-outs, detected lesions or cancer, and undeliverable tests.

The record does not report participant characteristics beyond the stated eligibility context, participant flow, missing-outcome counts, or reasons for missing data. The randomization method and allocation concealment are not described. Masking is listed as none, and the record does not explain whether outcome assessment was masked. The statistical analysis plan, model, analysis populations, multiplicity approach, and sensitivity analyses are not reported in the registry record.

The outcome timeframe is within 3 months of randomization, but the record does not provide individual follow-up or ascertainment details. The posted safety figures also lack information about the observation window and collection procedures. These reporting limits mean that the registry counts are best read descriptively. They do not support a precise or definitive conclusion about comparative effectiveness or safety.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Head to Head Pilot Trial of Mailed Cologuard to Mailed FIT — NCT06173375.
• Registry record last updated 2026-05-12; status last verified 2026-04.
• Results first posted 2026-05-12.
• 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

NCT06173375 is a completed, randomized, parallel-group pilot comparing mailed Cologuard outreach with mailed FIT outreach for colorectal cancer screening among eligible adults ages 45-49 receiving care at the University of California San Diego Health system. The registry lists masking as none, phase as NA, enrollment of 12, study start as 2024-05-15, and primary completion as 2024-12-31.

The primary endpoint counts participants completing any recommended colorectal cancer screening test within 3 months of randomization. The registry reports 5 participants completing screening in the Cologuard arm and 3 in the FIT arm, with 6 participants listed in each arm. It reports 0 analyses and no inferential comparison in the record. The registry lists 5 secondary outcomes, but their results are not reported. Adverse-event entries show 0 serious events, 0 other events, and 0 deaths in each arm. Missing-data methods, analysis populations, and further statistical-plan details are not reported in the registry record.