Calcium: Magnesium Balance, Microbiota, and Necroptosis and Inflammation: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Calcium: Magnesium Balance, Microbiota, and Necroptosis and Inflammation (NCT04229992), a randomized na study. The primary outcome is Comparisons of the Changes of Genera Prevotella by Mg Treatment vs. Placebo in Rectal Mucosa, Swab and Stool Samples.

2. Clinical Question

The biological motivation described in the registry record concerns TRPM7, magnesium regulation, calcium-to-magnesium intake and gut microbiota. The study summary notes prior observations relating TRPM7 genotype and diets with a high calcium-to-magnesium ratio to colorectal polyps, while also stating that the molecular mechanism remains unclear. The trial therefore focuses on whether changing magnesium intake is accompanied by a change in a microbial measure, rather than reporting a clinical cancer outcome.

The trial is described as part of the Personalized Prevention of Colorectal Cancer Trial, NCT01105169. Its primary outcome title refers to comparisons in three sample types and to changes in Prevotella. The registry record does not report a single pooled effect estimate, a prespecified hierarchy among sample types, or a result separated by genotype. Consequently, the clinical question is clear at a broad level, but the available record does not establish how the separate comparisons were intended to support a single conclusion.

3. Trial Design

The registry record lists a randomized trial with a factorial model and triple masking. It lists the phase as not applicable. The brief study summary, however, describes a double-blind 2x2 factorial randomized trial. These masking descriptions do not match, and the registry record does not explain the difference. The allocation method beyond being randomized, the specific parties masked, and the procedures used to maintain masking are not reported in the registry record.

The intervention groups are magnesium glycinate and placebo. The arm descriptions cross these assignments with two TRPM7 genotype categories: GG and GA/AA. This creates four named groups: GG with magnesium, GG with placebo, GA/AA with magnesium, and GA/AA with placebo. The record lists enrollment as 250, and the study status is completed. The study start is listed as 2017-05-05 and primary completion as 2024-02-28.

The study summary describes the objective as investigating whether optimizing the calcium-to-magnesium intake ratio to 2.3 alters the abundance of microbes at the genus level in at least one of stool, swab or tissue samples. The primary outcome entry narrows the named measure to changes in Prevotella in rectal mucosa, rectal swab and stool. It defines change as the value at 12 weeks minus the baseline value. The intervention listing names magnesium glycinate and placebo, but the supplement dose, treatment adherence procedures and details of dietary management are not reported in the registry record.

Although a factorial structure can be used to examine intervention effects across genotype groups and potentially to assess whether effects differ by genotype, the specific statistical contrasts are not reported in the registry record. It is therefore not possible to determine whether the main planned comparison was an overall magnesium-versus-placebo contrast, genotype-specific contrasts, an interaction, or some combination. The record also does not report the randomization ratio, any stratification or blocking, or whether the analysis preserved the randomized assignments.

The enrollment, status and dates describe the trial record, but they do not establish how many participants contributed to each outcome analysis. The endpoint population is stated as participants with rectal mucosa, rectal swab and stool samples. The registry record does not report the number with complete samples, the number analyzed in each group, or reasons for missing samples.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Among participants with with rectal mucosa and rectal swab and stool samples.

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 Comparisons of the Changes of Genera Prevotella by Mg Treatment vs. Placebo in Rectal Mucosa, Swab and Stool Samples, measured over 12 weeks.

The primary endpoint is the change in the abundance of the genus Prevotella from baseline to 12 weeks. The change is defined as the 12-week value minus the baseline value, and the unit is percentage of sample. The outcome is described as a mean of a continuous measure, with standard error as the dispersion measure. Separate sample types named in the endpoint are rectal mucosa, rectal swab and stool.

A change score represents movement between two measurements for the same outcome over time. A positive change, under the stated subtraction order, corresponds to a higher measured abundance at 12 weeks than at baseline; a negative change corresponds to a lower measured abundance. This interpretation concerns the direction of the measure only. It does not establish whether a change is important biologically or clinically.

The endpoint is used to address the study’s microbiota question: whether magnesium treatment is associated with a different change in Prevotella abundance than placebo. Measuring several sample types can characterize the outcome in different biological materials, but the registry record does not report how results across those types are combined or prioritized. The entry also does not report the laboratory method, how abundance was quantified, or whether values underwent transformation before analysis.

The registry record does not report numerical group means, treatment contrasts, confidence intervals or p-values for this endpoint. It therefore does not permit assessment of the estimated magnitude, direction or precision of the primary outcome. The endpoint is a microbial measure, not a direct measure of colorectal cancer incidence or polyp recurrence.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The statistical information in the registry record is limited. It identifies a randomized factorial design, a continuous primary measure, a mean as the summary parameter, standard error as the dispersion measure, and a change-from-baseline endpoint at 12 weeks. It does not report the analysis model, the treatment-effect estimates, confidence intervals, p-values, or a detailed statistical analysis plan. The explanations below distinguish what the record states from general statistical principles.

What does a factorial design mean?

As a general statistical point, a factorial design assigns participants across combinations of intervention factors so that the effects of more than one factor may be studied. The record describes a 2x2 factorial trial involving TRPM7 genotype categories and calcium-to-magnesium ratios in its summary, and its arm descriptions cross two genotype categories with magnesium glycinate or placebo. This arrangement allows questions about magnesium treatment, genotype, and whether treatment effects vary by genotype to be considered. The registry record does not report which of these effects were primary analysis targets or how they were modeled.

Randomization is intended, in general, to make treatment groups comparable in expectation with respect to measured and unmeasured characteristics. The record states that allocation was randomized, but does not specify the sequence-generation method, concealment procedures, or any stratification. Those details are not reported in the registry record. The record’s masking descriptions differ: its design fields say triple masking, while its summary says double-blind. The identity of masked parties and the reason for the difference are not reported.

What does a change score represent?

The endpoint defines change as the measurement at 12 weeks minus the baseline measurement. A change score summarizes within-participant movement over the measurement interval. Comparing average changes between groups can estimate how much the groups differed in their average movement, subject to the analysis assumptions. This is distinct from comparing only the follow-up values or from estimating a time trend using multiple follow-up measurements. The record names baseline and 12 weeks; additional measurement occasions are not reported in the registry record.

As a general statistical point, change scores can be sensitive to baseline measurement variability and to the relationship between baseline and follow-up values. An analysis of follow-up values adjusted for baseline is another possible approach, but no such method is reported in the registry record. It would be inappropriate to assume that the trial used a particular model just because the endpoint is defined as a change.

How should the mean and standard error be read?

The stated parameter is a mean, meaning an average of the continuous measure under the analysis definition. The standard error describes the sampling uncertainty of an estimated mean; it is not the same as the spread of individual participant values. In general, the standard deviation describes variation among observations, whereas the standard error concerns the precision of an estimated summary. The record does not include numerical means or standard errors for the primary endpoint.

Confidence intervals are commonly used to show uncertainty around an estimate. Their width depends on factors such as the amount of information in the analysis and variability in the data, as well as the method used. A narrow interval indicates greater precision than a wide interval under the same framework, but precision does not by itself establish clinical importance. No confidence intervals for the primary endpoint are reported in the registry record.

Why can over-dispersion matter?

As a general statistical point, over-dispersion occurs when observed variability is greater than a model assumes. It can make standard errors too small if the analysis does not accommodate the extra variability, which can in turn make confidence intervals too narrow and statistical tests too optimistic. The endpoint is recorded as a continuous percentage-of-sample measure, and the record does not describe its distribution or any assessment of over-dispersion. It also does not say whether a model requiring such an assessment was used. This is therefore a general consideration, not a finding about this trial.

What do the sample-size assumptions say?

The record describes planning illustrations based on the observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The effect to detect is defined as a stated fraction of the observed effect. In general, these are assumptions for exploring how a future study might be sized under selected conditions; they are not a measure of the probability that the completed trial found a real effect. The assumptions explicitly distinguish participants per arm for continuous outcomes from total events for time-to-event outcomes. The registry entries do not include the numerical planning illustrations, and the trial’s own sample-size justification is not reported in the registry record.

Such planning calculations depend on the chosen effect size, variability assumptions, allocation, significance level and target power. Changing the assumed effect changes the implied sample-size requirement. Illustrations based on an observed effect can also be optimistic if that effect is uncertain. They should be interpreted as planning scenarios, not as evidence that the completed trial had adequate precision for its outcome.

Overall, the record supports explanation of the endpoint definition and broad design, but not reconstruction of the statistical analysis. The test, model, handling of repeated or correlated measurements, multiplicity approach, and confidence-interval method are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The primary outcome entry spans three sample types: rectal mucosa, rectal swab and stool. The registry record does not report a single comparison that combines these measurements, a hierarchy among them, or an adjustment for making multiple comparisons. It also does not report whether treatment effects were examined separately by genotype, whether a treatment-by-genotype interaction was tested, or how such analyses related to the primary question.

Multiplicity is a general statistical concern when several outcomes, groups, sample types or hypotheses are tested. As the number of tests grows, the chance of at least one apparently notable result can increase if each test is interpreted without accounting for the set of tests. Methods such as prespecifying a primary comparison, adjusting significance thresholds, or emphasizing estimates and confidence intervals can address different aspects of this issue. Which, if any, approach was used is not reported in the registry record.

The stated endpoint population includes participants with rectal mucosa, rectal swab and stool samples. The number analyzed for each sample type, the number lacking particular specimens, and the reasons for missing data are not reported in the registry record. The record also does not describe imputation, complete-case analysis, sensitivity analyses, or how any participants who discontinued treatment or follow-up were handled.

In general, missing measurements can affect precision and can also bias an estimate if their absence is related to participant characteristics or outcomes. The appropriate analysis depends on the pattern and reasons for missingness and on the assumptions used. No missing-data assumptions are reported for this trial, so their adequacy cannot be evaluated from the registry record.

The record does not define an intention-to-treat, per-protocol or other analysis population. It therefore does not establish whether all randomized participants were included in the primary analysis or how the stated sample requirement was applied. The randomized design and listed enrollment do not by themselves resolve these analysis-population questions.

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.

Most frequent non-serious adverse event terms

The registry record lists serious adverse events as affecting 0 participants in each of the four groups: GG genotype with magnesium treatment, GG genotype with placebo, GA/AA genotype with magnesium treatment, and GA/AA genotype with placebo. Deaths are listed as 0 in each group. The listed numbers at risk for serious adverse events are 77, 78, 47 and 48, respectively, in the same group order.

For other adverse events, the record lists 1 affected participant among 77 at risk in the GG magnesium group, 2 among 78 in the GG placebo group, 3 among 47 in the GA/AA magnesium group, and 1 among 48 in the GA/AA placebo group. These are the figures recorded for the groups; the record does not provide event descriptions in the available information.

As a general statistical point, event counts should be interpreted alongside the number at risk, the event definitions, follow-up duration and methods of collection. Small counts provide limited information about the range of possible event rates, and the absence of a recorded serious event does not establish that risk is absent. The registry record does not report detailed safety definitions, severity grading, exposure duration for safety analyses, or confidence intervals for these counts. The adverse-event figures are descriptive and do not establish a treatment effect on safety.

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

The record describes a randomized comparison of magnesium glycinate and placebo in groups defined by TRPM7 genotype, with changes in Prevotella abundance as the primary endpoint. That description identifies the scientific question and the planned measurement interval. It does not provide the numerical results required to determine what differences were observed between treatment groups.

The registry record does not report the primary-outcome means, treatment contrasts, confidence intervals or p-values. Consequently, it is not possible to characterize the observed direction or magnitude of the treatment comparison, or how precisely it was estimated. The completed status of the trial does not fill this gap. Nor does the enrollment listing establish the number of participants included in each endpoint analysis.

Even if a difference in microbial abundance were reported, interpretation would depend on its size, uncertainty, consistency across sample types and relevance to the research question. The record does not report those results or a method for combining the sample types. The endpoint concerns Prevotella abundance, not colorectal cancer incidence or polyp development. The record’s motivation discusses colorectal cancer prevention research and prior observations involving genotype and dietary calcium-to-magnesium balance, but the primary endpoint does not directly measure those clinical outcomes.

As a general statistical point, a statistically compatible or incompatible result under a hypothesis test is not by itself a measure of clinical importance. Estimates and uncertainty, along with the outcome’s meaning and the study’s limitations, are needed for a balanced interpretation. These elements cannot be assessed for the primary outcome from the information reported in the registry record.

The sample-size assumptions are described as planning illustrations based on an observed effect and selected statistical assumptions. They are not observed power, and they do not provide evidence about the trial’s actual result. The trial’s sample-size justification is not reported in the registry record. In short, the record supports a description of the study question and design, but not a conclusion about the result or its implications.

13. Why This Trial Matters Statistically

This trial is statistically informative as an example of a research question that links a randomized dietary-supplement comparison with a continuous microbiota outcome and a genotype-based factorial structure. The endpoint is defined as change from baseline to 12 weeks, which makes the direction of change explicit. The four arm descriptions also make clear that genotype and treatment assignments are both relevant to how the question is framed.

The factorial structure raises an important design and analysis distinction. A trial may be organized around multiple factors, but its interpretation depends on the contrasts that were prespecified and the model used to estimate them. An overall treatment comparison and a comparison of treatment effects across genotype groups answer different questions. The registry record does not identify the analysis strategy or explain how the sample types and genotype groups were to be handled together.

The three sample types create another statistical consideration: estimates may vary across biological materials, and multiple comparisons can complicate interpretation. Clear reporting of the primary contrast, the relationship among sample-specific analyses, uncertainty intervals and any multiplicity strategy would help readers assess the evidence. Those details are not reported in the registry record.

The record also illustrates why design information and outcome reporting must be read separately. Randomization, masking, enrollment and completion status describe features of the study, but they do not reveal the treatment-effect estimate. Here, the numerical primary-outcome results and analysis methods are not reported in the registry record, limiting interpretation despite a clear endpoint description.

Finally, the gap between a microbial endpoint and a clinical outcome matters. Prevotella abundance can address a microbiota-focused question, but it is not itself a measure of colorectal cancer or polyp outcomes. Statistical conclusions should remain aligned with the measured endpoint and the results actually reported.

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 for interpreting this trial record is that numerical primary-outcome results are not reported in the registry record. Without estimates, confidence intervals or p-values, readers cannot judge the direction, magnitude or precision of the magnesium-versus-placebo comparison. The record also does not report numerical results separately for rectal mucosa, rectal swab and stool.

The design description has an unresolved masking discrepancy: the design fields list triple masking, while the study summary describes a double-blind trial. The registry record does not explain which description applies or identify the masked parties. The planned statistical contrasts, analysis model and approach to the factorial structure are also not reported.

The endpoint population is described as participants with rectal mucosa, rectal swab and stool samples, but the number analyzed for each outcome and the completeness of specimen collection are not reported in the registry record. Reasons for missing samples, treatment discontinuation, and methods for handling missing outcomes are likewise not reported. These omissions prevent assessment of the analyzed populations and potential missing-data effects.

The record names a continuous percentage-of-sample measure but does not report laboratory procedures, data transformations, distributional checks or the handling of outlying values. It does not identify a multiplicity adjustment despite the endpoint spanning several sample types, nor does it report whether genotype-specific effects or interactions were analyzed. These details are important for evaluating the precision and robustness of any results, but cannot be assessed from the record.

Finally, the endpoint is a microbial measure rather than a clinical cancer outcome. The stated biological rationale does not make a change in Prevotella equivalent to a change in colorectal cancer risk. The registry record does not report clinical outcome findings that would bridge that distinction.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Calcium: Magnesium Balance, Microbiota, and Necroptosis and Inflammation — NCT04229992.
• Registry record last updated 2025-01-28; status last verified 2025-01.
• Results first posted 2025-01-28.
• 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 NCT04229992, titled “Calcium: Magnesium Balance, Microbiota, and Necroptosis and Inflammation.” It lists colorectal cancer as the condition, Vanderbilt University Medical Center as sponsor, randomized allocation, a factorial model and a completed status. The record lists enrollment as 250, a start date of 2017-05-05 and primary completion on 2024-02-28.

The intervention is magnesium glycinate, compared with placebo, with groups described by GG and GA/AA TRPM7 genotype. The primary endpoint is the mean change in Prevotella abundance from baseline to 12 weeks in rectal mucosa, rectal swab and stool samples, expressed as percentage of sample. The record lists standard error as the dispersion measure.

Numerical primary-outcome results, detailed statistical methods, the analysis population, missing-data procedures and multiplicity handling are not reported in the registry record. The masking description differs between the design fields and study summary. The listed safety figures include 0 serious adverse events and 0 deaths in each group.