Vitamin D and Screening Colonoscopy or Polyp Surveillance: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Vitamin D and Screening Colonoscopy or Polyp Surveillance (NCT02269332), a registered phase not stated study. The primary outcome is Serum Vitamin D.

2. Clinical Question

The clinical question is whether serum 25-OH vitamin D status is associated with findings on screening colonoscopy or polyp surveillance. The registry describes an observational association question, not a comparison of assigned treatments. It does not report results that establish the direction, size, or precision of any association.

The clinical question is about a relationship between a measured blood level and colonoscopy findings. An association can be informative about how two measured characteristics vary together, but by itself it does not show that one caused the other. The registry does not report the categories or thresholds used to define vitamin D status or colonoscopy findings, so the precise comparison intended for analysis is not fully specified in the record.

3. Trial Design

NCT02269332 is listed as completed, with enrollment of 298. The study start is recorded as 2014-08 and primary completion as 2015-11. Mike O'Callaghan Military Hospital is the sponsor. The title identifies vitamin D status and colonoscopy findings as the subject; the official title describes an association of 25-OH vitamin D status with findings on screening colonoscopy.

The brief description concerns DoD beneficiaries 18 years or older who were referred for screening colonoscopy or polyp surveillance, or had undergone one in the last 2 weeks. It excludes people with a previous diagnosis of colorectal cancer. The stated plan was to obtain a 25-OH vitamin D level and examine its association with colonoscopy findings or previous findings when the procedure was a repeat. The primary measure description says vitamin D blood levels would be obtained at the time of the procedure.

The registry lists Screening Colonoscopy as the sole intervention entry and describes the group as people referred for screening or surveillance, or who had recently undergone it. The record does not describe random assignment, and allocation is not stated. It specifically cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Accordingly, the design should be read as an investigation of association rather than as a randomized trial of an assigned intervention against a control.

The record lists 2 outcome measures but records 0 analyses. It does not report a statistical analysis plan, a sample-size justification, or detailed definitions for the colonoscopy findings to be related to vitamin D. The listed completion status and dates describe the registry record; they do not establish that a particular association was found.

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 Serum Vitamin D, measured over 2 weeks.

The primary outcome is titled Serum Vitamin D. Its unit is participants, its parameter is a count of participants, and its timeframe is 2 weeks. The description states that vitamin D blood levels would be obtained at the time of the procedure. The study description frames the intended question as whether the measured 25-OH vitamin D level is associated with colonoscopy findings or previous findings in repeat surveillance.

A blood measurement can serve as an exposure or explanatory measure in an association analysis: researchers compare its distribution or status with an outcome such as a colonoscopy finding. In general, a clearly defined endpoint is important because it specifies what is counted or measured, when it is measured, and how findings are classified. A count of participants is not itself an estimate of association. To interpret an association, readers would need the actual measurement results and a description of how both vitamin D and colonoscopy findings were grouped or modeled.

The registry record does not report the measured vitamin D values, a threshold defining vitamin D status, the categories of colonoscopy findings, or an estimated relationship between them. It also does not make clear how the title “Serum Vitamin D” corresponds to the count-of-participants parameter. Consequently, the outcome description identifies the planned blood measurement and timeframe, but does not provide enough detail to reconstruct an analysis or interpret an endpoint result.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies an association question: whether serum 25-OH vitamin D status relates to colonoscopy findings. In general, an association analysis asks whether measurements vary together across participants. It does not, by itself, show that changing one measurement would change the other. That distinction matters in an observational study, particularly when the registry does not describe randomized allocation or a comparable control group.

What the outcome description tells readers

The primary outcome is called Serum Vitamin D, is expressed in participants, uses a count-of-participants parameter, and has a 2 weeks timeframe. Its description says that vitamin D blood levels would be obtained at the time of the procedure. These details identify a measurement and a timing window, but they do not specify the statistical contrast. The registry record does not state vitamin D categories, thresholds, summary measures, or the classification of colonoscopy findings. Without those definitions, readers cannot tell from the record exactly what result would answer the association question.

What an estimate and its uncertainty would mean

In general, an estimate summarizes the relationship observed in the study data. A confidence interval communicates uncertainty around that estimate under the statistical model and its assumptions. It helps readers judge whether the data are compatible with a range of association sizes. A p-value, when reported, addresses how unusual the data would be under a specified null model; it does not measure the size or clinical importance of an association. The registry record reports no association estimate, confidence interval, or p-value, so none of these interpretations can be applied to this study's association from the posted record.

Why design and analysis details matter

The registry does not describe random assignment, and allocation is not stated. It also cautions that the listed arms are not a like-for-like control comparison. In general, comparisons in an observational setting may be influenced by differences among participants. Statistical adjustment can sometimes address measured differences, but it cannot guarantee removal of bias, especially when relevant factors are unmeasured or poorly recorded. The record does not report whether adjustment was planned or used, which variables were considered, or what model was applied.

The eligibility description combines people referred for a procedure with people who had one in the last 2 weeks. It also includes screening and polyp surveillance. In general, differences in measurement timing or clinical context can affect how observations should be grouped and interpreted. The registry does not report whether these groups were analyzed separately, how previous findings were handled, or whether the vitamin D measurement preceded the colonoscopy finding under study.

Planning assumptions are not study results

The registry's planning description refers to a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It says that the target effect is a stated fraction of the observed effect. For time-to-event calculations, the planning description uses total events with the Schoenfeld approach; for other calculations, it describes participants per arm. These are planning assumptions, not evidence of an observed association, and the record does not report numerical planning outputs or a trial-specific sample-size justification.

In general, sample-size planning depends on the effect targeted, outcome variability, allocation, and statistical assumptions. A planning calculation does not show that a study had a particular probability of detecting its actual effect after the data are collected. It should not be interpreted as observed power. Here, the absence of reported analysis results also means there is no posted effect estimate on which to base a reader's assessment of precision.

What can be concluded from the statistical record

The record lists 2 outcome measures and 0 analyses. It therefore documents that outcomes were registered but does not supply analyzed results. It does not report model diagnostics, assumptions checks, missing-data methods, or an analysis population. General statistical guidance cannot fill those gaps: the relevant method depends on the actual outcome definitions, data structure, and analysis objective. The appropriate interpretation is limited to the stated measurement plan and design description, without inferring a result or reconstructing an unreported analysis.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 2 outcome measures and 0 analyses. The primary outcome is titled Serum Vitamin D; the record does not provide the other outcome's name or detailed definition in the information reported. It does not report which outcomes were designated primary or secondary beyond the primary measure field, nor whether multiple comparisons were planned or adjusted for.

In general, testing several outcomes or several versions of an association can increase the chance that at least one result appears noteworthy by chance. Prespecified outcome definitions and a stated multiplicity strategy help readers understand how results should be interpreted. Neither a multiplicity plan nor a correction method is reported in the registry record. Since no analysis results are recorded, there is also no basis for evaluating how multiplicity may have affected any reported findings.

The record does not describe the amount or pattern of missing data, whether all enrolled participants contributed to each outcome, or how missing measurements were handled. It does not report an analysis population, exclusions after enrollment, or whether participants with unavailable vitamin D or colonoscopy information were included in any analysis. These details matter in general because analyses based on different subsets of participants can produce different estimates, and missingness may affect interpretation.

The registry record does not report a statistical analysis plan, model specification, or sensitivity analyses. Those omissions do not prove that such procedures were absent from the study; they mean they are not reported in the registry record. With no analysis results or missing-data description, readers cannot assess robustness, outcome selection, or the role of incomplete observations.

11. Safety Results

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

Deaths

Other (non-serious) adverse events

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

The adverse-event record lists 298 participants at risk for serious adverse events and 0 serious adverse events. It also lists 298 at risk for other adverse events and 0 other adverse events, with 0 deaths. These are the registry's recorded counts for the Screening Colonoscopy group.

In general, a count of zero recorded events means that no events of that category were entered in the reported record for the stated group; it does not establish that an event could not occur or that every possible event was captured. The registry record does not give detailed event definitions, collection procedures, or a narrative explaining how safety information was monitored. The figures should therefore be read as recorded counts, not as a comprehensive assessment of risk.

These counts do not answer the vitamin D association question. They also do not constitute a comparison of safety between randomized groups, because the record does not describe a like-for-like control comparison. No treatment effect or causal safety conclusion follows from these event counts. They describe what the registry records for the listed group and categories.

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

The record establishes that the study was designed to examine whether 25-OH vitamin D status was associated with colonoscopy findings among eligible DoD beneficiaries. It documents enrollment of 298, a completed status, the study dates, and a plan to obtain vitamin D blood levels at the procedure or in the setting described. These registry entries explain the study question and its context.

The record does not provide analyzed results for the association. It gives no estimate, uncertainty interval, p-value, or detailed outcome counts that would show the relationship between vitamin D status and colonoscopy findings. Thus, it does not show that an association was present, that one was absent, or how large or precise an association might have been. Missing results should not be interpreted as a null finding.

The record describes no randomized allocation and explicitly cautions that the arms are not a like-for-like control comparison. Even if an association estimate were available, an observational association would not alone demonstrate causation. In general, differences in participant characteristics, measurement timing, and outcome definitions can affect observed relationships. The registry does not report enough analysis detail to assess those issues for this study.

The primary outcome label and description identify vitamin D measurement, but the record does not define vitamin D status categories or the colonoscopy finding categories used in the intended association. It also does not report how findings from a recent prior procedure were linked to the blood measurement. These limitations restrict what can be inferred from the stated plan.

The proper reading is therefore narrow: the registry documents a completed study and an association question, but not the results needed to answer it. It does not support a conclusion about clinical benefit, harm, or a causal effect. The adverse-event counts are separately recorded as zero for serious events, other events, and deaths in the listed group; they do not resolve the primary association question.

13. Why This Trial Matters Statistically

This study is statistically interesting because it asks an association question using a measured blood level and findings from a clinical procedure. Such questions require clear definitions for both variables, an explicit account of when each was measured, and a description of how observations were compared. The registry provides the broad question and timing description, but leaves those analysis details unreported.

The design distinction is important. The record does not describe random allocation and cautions that the arms are not a like-for-like control comparison. In general, randomized and observational comparisons support different kinds of interpretation. An association in observational data can be shaped by participant differences and measurement choices, so readers need analysis details to judge how far an estimate can be interpreted.

The registry also illustrates why study status and enrollment alone are not statistical results. Although the study is marked completed and enrollment is 298, the record lists 0 analyses and does not report an association estimate or its precision. Without those results, neither statistical uncertainty nor practical importance can be evaluated.

Finally, the outcome description shows why registration detail matters. The primary measure is labeled Serum Vitamin D and described as a participant count, while the study question concerns an association with colonoscopy findings. Definitions of the exposure, findings, timing, and analysis would help readers connect the registered measure to the intended question. In their absence, interpretation must remain limited to the study aim and measurement plan.

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.

A central limitation of the registry record is that it does not report analyzed results for the association of interest. No estimate or measure of precision is available, so the direction, size, and uncertainty of the relationship cannot be assessed. The completed status and enrollment count do not substitute for those results.

The design description also limits interpretation. Allocation is not stated, the record does not describe randomization, and it cautions that the arms are not a like-for-like control comparison. The registry does not report a comparator suitable for a randomized treatment-effect interpretation. It also does not state whether or how potential differences among participants were addressed analytically.

The population description combines screening colonoscopy and polyp surveillance and includes people who had a procedure in the last 2 weeks. The record does not state whether those contexts were analyzed separately or how earlier findings were matched to vitamin D measurements. Although it says the blood level would be obtained at the time of the procedure, the timing relationship for people with a recent prior procedure is not explained.

The primary outcome is titled Serum Vitamin D, but the record does not provide thresholds or categories for vitamin D status, detail the colonoscopy finding definitions, or specify the statistical contrast. It lists 2 outcome measures but provides no analysis results. The statistical plan, missing-data handling, analysis population, and multiplicity approach are not reported in the registry record. These are limitations of what can be learned from the registry, not proof that the study investigators did not address them elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Vitamin D and Screening Colonoscopy or Polyp Surveillance — NCT02269332.
• Registry record last updated 2024-01-22; status last verified 2024-01.
• Results first posted 2024-01-22.
• 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

NCT02269332, “Vitamin D and Screening Colonoscopy or Polyp Surveillance,” is listed as completed with enrollment of 298. The sponsor is Mike O'Callaghan Military Hospital. The recorded study start is 2014-08 and primary completion is 2015-11.

The study description concerns DoD beneficiaries 18 years or older referred for screening colonoscopy or polyp surveillance, or who had a procedure in the last 2 weeks, excluding people with a previous colorectal cancer diagnosis. Its stated aim is to examine whether 25-OH vitamin D levels are associated with colonoscopy findings or prior findings in repeat surveillance. The primary measure is titled Serum Vitamin D, and the description says blood levels would be obtained at the time of the procedure.

The record lists 2 outcome measures and 0 analyses. It does not report an association estimate or its uncertainty. The recorded adverse-event counts are 0 serious adverse events, 0 other adverse events, and 0 deaths among the listed group.