This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Investigation of Metformin for the Prevention of Progression of Precursor Multiple Myeloma (NCT04850846), a randomized phase 2 study. The primary outcome is (M-)Protein Concentrations Change.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT04850846 |
| Phase | Phase 2 |
| Condition | Monoclonal Gammopathy of Undetermined Significance, Smoldering Multiple Myeloma |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 60 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Dana-Farber Cancer Institute |
| Results posted | Yes |
2. Clinical Question
Population
People with monoclonal gammopathy of undetermined significance (MGUS) or smoldering multiple myeloma (SMM), conditions named in the registry record.
Intervention
Metformin extended release (XR), given with stepped dose escalation toward a target daily dose of 1500mg.
Comparator
Placebo, with stepped dose escalation to 3 pills per day as described in the registry record.
Primary question
What change in serum M-protein concentration, measured by serum-protein electrophoresis, is observed from baseline to 6 months in each randomized group?
The study’s stated purpose is to investigate whether metformin could be used in the future to help prevent progression to multiple myeloma among people with MGUS or SMM. The primary outcome reported in the registry is a biomarker measure: percent change in M-protein concentration over the 6-month assessment period. It is not itself a posted count of participants progressing to multiple myeloma. The registry also lists secondary outcomes involving serum free light chains, hemoglobin, HbA1c, molecular changes in cell groups, plasma metabolites, global health, and willingness to continue metformin beyond the primary assessment period. Results for those outcomes are not included in the posted results; their values are not reported in the registry record.
The record describes a randomized, placebo-controlled comparison, but it does not report a formal statistical comparison for the primary outcome. The posted group summaries therefore describe the observed distributions; they do not establish whether any difference between groups is statistically distinguishable from chance or whether it reflects prevention of disease progression.
3. Trial Design
This is a phase 2, randomized, quadruple-masked, parallel-group study sponsored by Dana-Farber Cancer Institute. The registry lists an enrollment of 60 and identifies MGUS and SMM as the conditions under study. The study began on 2021-04-27, has a primary completion date of 2025-01-29 in the record, and is listed as active, not recruiting. These dates and the status are registry entries; the record does not establish whether all follow-up or other study activities have concluded.
Participants were assigned to metformin XR or placebo. The metformin description specifies stepped dose escalation toward a target daily dose of 1500mg, given as 3 pills of 500mg each. The placebo description specifies escalation to 3 pills per day but does not give a dose in milligrams. Both descriptions specify a 6-month intervention period. The metformin arm description also mentions an option for participants to be unblinded at the end of their 6-month period. Further details of an extension, including its procedures and duration, are not reported in the registry record.
Randomization is intended to create groups that are comparable on average, while masking is intended to limit the influence of treatment knowledge on participant experience, care, and outcome assessment. The registry identifies quadruple masking but does not specify which four roles were masked or how masking was maintained. The parallel model means the record describes two groups receiving their assigned intervention over the study period, rather than participants crossing between treatments.
The primary outcome is assessed from baseline to 6 months. The posted outcome summaries include 22 participants in the metformin arm and 24 in the placebo arm with analyzable M-protein data. The registry notes that 8 participants in the metformin arm and 6 in the control arm did not have analyzable M-protein data. The safety summaries use 30 participants at risk in each group. The record does not explain the relationship between these different denominators or provide a participant flow accounting for all enrolled participants.
The study’s original sample-size justification, planned interim analyses, and full statistical analysis plan are not reported in the registry record. Any planning illustration based on the observed effect is retrospective and should not be read as the trial’s original design justification or as observed power.
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
| Stage | Metformin | Placebo |
|---|---|---|
| STARTED | 30 | 30 |
| COMPLETED | 22 | 23 |
| NOT COMPLETED | 8 | 7 |
Reasons for not completing this period:
| Reason | Metformin | Placebo |
|---|---|---|
| Withdrawal by Subject | 1 | 2 |
| Adverse Event | 3 | 1 |
| Subject stopped taking medication | 2 | 4 |
| Other | 2 | 0 |
Analysis population for the primary outcome, as defined in the registry: 8 participants in the metformin arm and 6 participants in the control arm did not have analyzable m-protein data.
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.
| Characteristic | Unit | Metformin | Placebo | Total |
|---|---|---|---|---|
| Participants analysed | 30 | 30 | 60 | |
| Age, Continuous | years | 65 (38 to 80) | 65 (34 to 89) | 65 (34 to 89) |
| Sex: Female, Male: Female | Participants | 16 | 14 | 30 |
| Sex: Female, Male: Male | Participants | 14 | 16 | 30 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 0 | 1 | 1 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 29 | 29 | 58 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 1 | 0 | 1 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Asian | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Black or African American | Participants | 2 | 2 | 4 |
| Race (NIH/OMB): White | Participants | 26 | 25 | 51 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 2 | 3 | 5 |
| Region of Enrollment: United States | participants | 30 | 30 | 60 |
| Diagnosis: MGUS | Participants | 11 | 12 | 23 |
| Diagnosis: SMM | Participants | 19 | 18 | 37 |
6. Primary Endpoint
The registry lists the primary outcome as (M-)Protein Concentrations Change, measured over Baseline to 6-months.
| Element | Registry entry |
|---|---|
| Result type | Median |
| Measure of spread | Full Range |
| Unit | percent change |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint is percent change in M-protein concentration between baseline and 6 months, assessed using serum-protein electrophoresis. The registry reports the median and full range for each group. M-protein is the quantity named by the endpoint; the outcome therefore summarizes a change in a measured concentration rather than directly counting cases of progression to multiple myeloma.
Percent change expresses a follow-up measurement relative to a participant’s baseline measurement. Reporting a median describes the middle observation in the ordered set of participant-level changes. The full range gives the smallest and largest reported values, showing the span of observed changes but not how values are distributed between those extremes. These are descriptive summaries, not estimates of a treatment effect with a reported measure of statistical uncertainty.
The endpoint can be used to describe whether measured M-protein concentrations shifted over the assessment period in each group. The registry’s stated study purpose concerns prevention of progression, while this primary measure is a biomarker change at 6 months. A biomarker result can inform a study question without being identical to a clinical progression outcome. The registry record does not report a primary endpoint based on time to progression or the number of participants who progressed.
The record notes that 8 participants in the metformin arm and 6 in the control arm did not have analyzable M-protein data. Consequently, the reported medians and ranges are based on the participants with analyzable measurements, not all enrolled participants. Reasons for unavailable data and the method, if any, for handling missing measurements are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The posted primary outcome is a median percent change of -3.2 in the metformin group, with a full range from -33.0 to 20.4. In the placebo group, the median percent change is 7.7, with a full range from -15.4 to 29.7. These summaries describe observed M-protein changes among participants with analyzable data from baseline to 6 months. They do not, on their own, quantify the uncertainty around a between-group effect.
The ranges overlap, and both include values on either side of zero. This indicates that participants’ observed changes varied within each group and that the direction of change was not uniform across the reported range. A median gives a central location but does not show every participant’s result, the shape of the distribution, or how concentrated observations are near the median. The range is sensitive to extreme observations and cannot substitute for a confidence interval.
The registry does not report a formal statistical comparison for this outcome: the number of posted analyses is zero. No confidence interval, p-value, adjusted effect estimate, or model-based comparison is reported in the registry record. As a result, the descriptive difference between the group medians should not be treated as a tested treatment effect. No new contrast or inferential statistic can be recovered from the medians and ranges alone, particularly because they do not contain the participant-level data or the analysis details needed for such a comparison.
The outcome summaries also do not establish whether metformin prevents progression to multiple myeloma. The primary measure is M-protein change over 6 months, not a reported progression event. The study’s stated purpose provides the context for why this population and intervention were studied, but the posted endpoint results do not answer every aspect of that purpose.
Missing outcome data are relevant to interpretation. The registry reports 8 participants in the metformin arm and 6 in the control arm without analyzable M-protein data. The group summaries therefore do not include those participants’ primary outcome values. The reasons for missingness and the analysis approach are not reported in the registry record. If missingness is related to participant characteristics or outcomes, a summary of observed measurements alone may not represent the full randomized groups; whether that concern applies cannot be determined from the record.
The safety information is also descriptive. One participant in each group is listed as affected by a serious adverse event, while other adverse events are reported for 26 participants in the metformin group and 18 in the placebo group. Deaths are listed as 0 in the metformin group and 1 in the placebo group. Without additional detail about event definitions, follow-up, attribution, and statistical comparisons, these counts should not be interpreted as estimates of a causal difference in safety.
9. Statistical Methods Explained
Several statistical ideas help distinguish what the posted summaries show from what they do not establish. The primary outcome is summarized with a median and full range, while the record does not provide a formal inferential analysis for that endpoint.
What does a median describe?
A median is a measure of the center of a set of observations: after ordering the observations, it identifies the middle position, or the middle pair when the count is even. Unlike a mean, it is less affected by the magnitude of a small number of extreme observations. That can make it useful for describing participant-level changes when values are unevenly distributed. A median does not reveal the whole distribution, however. Two groups can have similar medians but different patterns of spread, or different medians while still having substantial overlap among individual observations.
For this endpoint, the median percent change is reported as -3.2 for metformin and 7.7 for placebo. Those are separate group summaries. The registry does not report a modeled or directly tested between-group contrast. It is therefore important not to treat a comparison of the two medians as equivalent to a prespecified statistical test or an adjusted effect estimate.
What does the full range show?
The full range identifies the lowest and highest observed values in a group. The reported metformin range is -33.0 to 20.4, and the placebo range is -15.4 to 29.7. A range gives information about the extremes but not about the density of observations between them. It is not a confidence interval: it describes observed values, whereas a confidence interval describes uncertainty in an estimated quantity under a statistical model and sampling assumptions. No confidence interval for the primary comparison is reported in the registry record.
Why is a formal comparison important?
Randomization supports a fair comparison by assigning participants to groups through a chance process, but randomization alone does not supply an estimate of the uncertainty in the observed results. A statistical analysis typically defines the contrast of interest, the population to analyze, the outcome model, and how uncertainty will be quantified. Those details matter because different methods can address different estimands and make different assumptions. The record identifies randomized allocation and posts group-level descriptive summaries, but it does not report the statistical model, the planned contrast, or a formal test for the primary outcome. The registry lists zero analyses.
A confidence interval, when reported, would give a range of values compatible with the data under the chosen method and assumptions. Its width conveys precision: narrower intervals generally indicate more precise estimation than wider ones. It would not by itself establish clinical importance or eliminate bias from missing data or other design limitations. No confidence interval for the M-protein outcome is reported in the registry record.
How should the sample counts be read?
The primary outcome summaries use 22 participants in the metformin group and 24 in the placebo group. The registry explicitly notes that 8 participants in the metformin arm and 6 in the control arm did not have analyzable M-protein data. Analyzable counts describe the observations contributing to the posted summary; they do not explain why measurements were unavailable or how those participants were treated in any other analysis. The safety denominators are 30 participants at risk in each group, so the safety counts use a different stated denominator from the primary outcome summaries.
In general, missing outcomes can reduce precision and can also affect validity if the availability of a measurement is related to the outcome or to participant characteristics. The direction and size of any resulting bias cannot be inferred from counts alone. A complete-case summary describes those with observed analyzable data; it does not necessarily describe all randomized participants. The registry record does not specify a missing-data method or define an analysis population for the primary endpoint.
What does masking contribute?
Quadruple masking indicates that the registry classifies the study as masked at four levels, but it does not identify those roles. In general, masking can reduce the risk that knowledge of assignment changes behavior, co-interventions, assessment, or reporting. It cannot guarantee that groups remain comparable in all respects, and it does not replace transparent outcome definitions and analysis methods. The registry describes a randomized, placebo-controlled, parallel study but does not provide operational details of masking or its success.
What does the planning illustration mean?
The registry’s planning illustration is described as a calculation based on the observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. It is not the trial’s own design justification. A calculation that asks how many participants per arm would be needed to detect a selected fraction of an observed effect is a planning illustration, not observed power. Observed power is not a substitute for a confidence interval or a direct description of uncertainty in the trial’s result. The original sample-size justification is not reported in the registry record.
In general, statistical power is the chance that a planned test will detect an effect of a specified size when that effect is present, under the assumptions of the design and analysis. A retrospective calculation using an effect estimated from trial data does not show that the study had a particular probability of detecting a true effect. The registry’s illustration should therefore be kept separate from the interpretation of the posted endpoint summaries.
Finally, secondary outcomes and multiple comparisons require a prespecified approach if results are to be interpreted inferentially. Testing many outcomes can increase the chance of at least one apparently notable result under a null hypothesis. Methods such as adjustment or a hierarchy of tests can address multiplicity, but the appropriate approach depends on the study plan. Such a plan is not reported in the registry record, and no secondary outcome analyses are included in the posted results.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists 9 secondary outcomes, in addition to the primary M-protein outcome. These include changes in serum free light chains, hemoglobin, HbA1c, molecular features of cell groups, plasma metabolites, PROMIS Global Health Summary Score v1.2, and willingness to continue metformin beyond the 6-month primary assessment period. The registry lists 10 outcome measures in total, but no secondary outcome results are included in the posted results. Their values are not reported in the registry record.
When several outcomes are tested, the chance of at least one apparently unusual result can increase if every test is treated as a separate confirmatory test. In general, a prespecified hierarchy, family-wise error adjustment, or another multiplicity strategy can help control how results are interpreted. The planned approach to multiplicity, including whether any secondary outcomes were intended to be confirmatory, is not reported in the registry record. The registry lists zero analyses, so no multiplicity-adjusted inferential results are available.
For the primary endpoint, the record states that 8 participants in the metformin arm and 6 in the control arm did not have analyzable M-protein data. It does not report why those values were unavailable, whether missingness occurred before or after treatment, or whether any imputation or sensitivity analysis was used. These omissions matter because observed-data summaries may not represent the full randomized groups if outcome availability is related to the values that would have been observed.
The record does not define an intention-to-treat, per-protocol, or other analysis population for the primary outcome. Nor does it give a participant flow explanation that reconciles the enrolled count, primary outcome counts, and safety denominators. The posted medians and ranges should therefore be read as descriptive summaries for participants with analyzable outcome data, with the broader analysis-population and missing-data handling not reported in the registry record.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Metformin | 1 | 30 | 3.3% |
| Placebo | 1 | 30 | 3.3% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Metformin | 0 of 30 |
| Placebo | 1 of 30 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Metformin | 26 of 30 |
| Placebo | 18 of 30 |
Most frequent serious adverse event terms
| Event term | Organ system | Metformin | Placebo |
|---|---|---|---|
| Lower gastrointestinal hemorrhage | Gastrointestinal disorders | 0 of 30 | 1 of 30 |
| Bloating | Gastrointestinal disorders | 1 of 30 | 0 of 30 |
| Sepsis | Infections and infestations | 0 of 30 | 1 of 30 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Metformin | Placebo |
|---|---|---|---|
| Nausea | Gastrointestinal disorders | 14 of 30 | 9 of 30 |
| Diarrhea | Gastrointestinal disorders | 14 of 30 | 5 of 30 |
| Constipation | Gastrointestinal disorders | 8 of 30 | 3 of 30 |
| Headache | Nervous system disorders | 6 of 30 | 5 of 30 |
| Bloating | Gastrointestinal disorders | 8 of 30 | 2 of 30 |
| Flatulence | Gastrointestinal disorders | 4 of 30 | 4 of 30 |
| Anorexia | Metabolism and nutrition disorders | 6 of 30 | 1 of 30 |
| Dyspepsia | Gastrointestinal disorders | 3 of 30 | 3 of 30 |
| Abdominal pain | Gastrointestinal disorders | 2 of 30 | 3 of 30 |
| Fatigue | General disorders | 3 of 30 | 1 of 30 |
Serious events with the highest arm-level rate: lower gastrointestinal hemorrhage (3.3%), bloating (3.3%), sepsis (3.3%).
The safety record lists 30 participants at risk in each group. In the metformin group, 1 participant is listed as affected by a serious adverse event and 26 by other adverse events; deaths are listed as 0. In the placebo group, 1 participant is listed as affected by a serious adverse event and 18 by other adverse events; deaths are listed as 1. These are counts as posted, not estimates of comparative risk adjusted for follow-up or other factors.
The serious-event terms listed among the most frequent are lower gastrointestinal hemorrhage, bloating, and sepsis, each reported as 3.3%. The registry record does not provide additional detail in the information available about event timing, duration, severity criteria, attribution to study intervention, recurrence, or whether a participant could contribute more than one event term. The terms should not be used to infer causation or to compare the groups without fuller definitions and an analysis plan.
Serious adverse events and other adverse events are separate categories in the registry summary. A count of participants affected is not necessarily the same as a count of individual events, because one participant may experience multiple events. The posted figures are descriptive, and the record does not report a formal statistical comparison of safety outcomes. Differences in counts should not be read as evidence that either intervention caused or prevented an event.
12. What the Result Does, and Does Not, Mean
The posted primary results describe M-protein concentration changes over the 6-month assessment period among participants with analyzable data. The median percent change is -3.2 in the metformin group and 7.7 in the placebo group. The ranges span -33.0 to 20.4 and -15.4 to 29.7, respectively. These values summarize observed measurements; without a reported uncertainty interval or formal test, they do not establish whether the groups differ beyond what might arise from sampling variability.
The outcome is not a direct report of progression to multiple myeloma. Although the study’s stated purpose concerns preventing progression among people with MGUS or SMM, the primary outcome posted is a short-term biomarker change. A change in a biomarker can be relevant to a study question, but it is not interchangeable with a clinical event unless that relationship is established and described. Such evidence is not reported in the registry record.
The results do not establish that metformin works, fails, or changes the risk of progression. They also do not establish that the interventions are equivalent. Equivalence or non-inferiority requires a prespecified margin and an appropriate analysis; those are not reported in the registry record. A lack of a posted p-value or confidence interval is not evidence of no effect. It means that the registry record does not provide those inferential quantities for this endpoint.
The 6-month period and missing analyzable M-protein data also limit what can be concluded from the posted summaries. The registry reports 8 participants in the metformin arm and 6 in the control arm without analyzable data, but it does not report the reasons or how missing values were handled. The results therefore describe the available measurements rather than a documented analysis of every enrolled participant.
The adverse-event counts should be read in the same descriptive way. They report affected participants and deaths by group, but do not establish whether events were caused by an intervention or whether observed group differences are statistically reliable. The record does not give the detailed safety analysis needed to make such a comparison. Overall, the registry offers selected outcome and safety summaries but does not report the complete statistical analysis needed for a definitive inference about treatment effects or prevention of progression.
13. Why This Trial Matters Statistically
This study raises a statistical question common to trials of interventions intended to alter disease progression: the trial’s purpose and its primary measure are related but not identical. The stated purpose concerns prevention of progression in MGUS and SMM, while the posted primary outcome is change in M-protein concentration from baseline to 6 months. Keeping the biomarker endpoint distinct from a direct progression outcome helps prevent an overstatement of what the results can establish.
The record also illustrates why the summary measure matters. Medians and ranges convey a useful description of observed change, especially where participant values vary, but they do not provide the precision of a treatment-effect estimate. An inferential comparison requires a specified contrast and an account of uncertainty. The registry posts neither a formal analysis nor a confidence interval or p-value for the primary endpoint. Readers can describe the group summaries, but cannot use them alone to determine how precise a between-group effect would be.
Missing outcome data are another central issue. The record identifies participants without analyzable M-protein measurements, but does not explain why data are missing or how missingness was handled. These details help determine whether the available-case summaries are likely to represent the randomized groups and how sensitive conclusions may be to assumptions about unobserved outcomes.
Finally, the trial lists multiple secondary outcomes, but the registry record does not report secondary results or a multiplicity strategy. This matters because a collection of outcomes can support different exploratory questions, while confirmatory claims require clarity about which tests were planned and how their error rates were addressed. The posted record supplies a useful outline of the study and descriptive primary results, but the absent analysis details limit the strength and scope of statistical conclusions that can be drawn.
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 endpoint is reported as a median and full range, without a confidence interval or formal comparison between groups. This leaves the precision of any between-group difference unquantified. The registry lists zero analyses, so no model-based estimate or inferential test for the primary outcome is posted.
The primary outcome is M-protein change from baseline to 6 months, rather than a direct progression outcome. The registry does not post a result for progression to multiple myeloma, and the relationship between the biomarker change and progression is not reported. The endpoint therefore addresses a narrower measurement question than the study’s broad stated prevention purpose.
The M-protein summaries exclude participants without analyzable data: 8 in the metformin arm and 6 in the control arm. The reasons for missing data, timing of missingness, and any handling method or sensitivity analysis are not reported in the registry record. The record also does not define the primary analysis population or explain how the outcome denominators relate to the enrolled count and the safety denominators.
The registry lists 9 secondary outcomes but does not post their results or report a multiplicity plan. It also does not report the original sample-size justification, interim analyses, detailed statistical plan, or a formal comparison of adverse events. The registry’s planning illustration is described as based on the observed effect and should not be mistaken for the trial’s original design calculation or observed power.
Finally, the record lists a primary completion date and an active, not recruiting status, but does not provide enough information to determine the status of all follow-up or study activities. These reporting limitations restrict interpretation of the available summaries and should be kept separate from claims about the intervention or disease progression.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Investigation of Metformin for the Prevention of Progression of Precursor Multiple Myeloma — NCT04850846.
- Registry record last updated 2026-02-09; status last verified 2026-01.
- Results first posted 2026-02-09.
- 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.
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18. Record Summary
NCT04850846 is a randomized, placebo-controlled, quadruple-masked, parallel phase 2 study sponsored by Dana-Farber Cancer Institute. It investigates metformin XR in people with MGUS or SMM and is listed as active, not recruiting. The record gives an enrollment of 60 and a primary completion date of 2025-01-29.
The primary outcome is median percent change in M-protein concentration from baseline to 6 months, measured by serum-protein electrophoresis. The posted medians are -3.2 for metformin and 7.7 for placebo; their full ranges are -33.0 to 20.4 and -15.4 to 29.7. The registry notes that 8 metformin-arm and 6 control-arm participants did not have analyzable M-protein data.
No formal primary comparison, confidence interval, p-value, secondary outcome results, or detailed missing-data method is reported in the registry record. Safety summaries list one participant with a serious adverse event in each group, other adverse events in 26 metformin participants and 18 placebo participants, and deaths of 0 and 1, respectively. These figures are descriptive and do not establish causation or comparative effects.