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 A Pilot Study: Metformin Therapy in Heart Failure Patients With Early Diabetes or at High Risk of Developing Diabetes (Pre-Diabetes) (NCT01573949), a na na study. The primary outcome is Health-Related Quality of Life (HRQoL).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01573949 |
| Phase | NA |
| Condition | Diabetes, Heart Failure |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 7 |
| Arms in the primary outcome | n/a |
| Lead sponsor | University of California, Los Angeles |
| Results posted | Yes |
2. Clinical Question
Population
The study concerned people with heart failure who had pre-diabetes or early type II diabetes. The study summary says participants had to be 18 years old to participate. Other eligibility criteria and a more detailed description of the enrolled participants are not reported in the registry record.
Intervention
The intervention was metformin. The arm description says treatment would start at 500 mg PO BID and, depending on laboratory values, could be titrated to 1000 mg PO BID at 1 month. The summary describes treatment for approximately 3 months, with blood draws, echocardiograms and a questionnaire as part of study testing.
Comparator
This was a single-group study, with no control group or active comparator listed. Allocation is recorded as NA and masking as none. Consequently, the design does not provide a concurrent group against which changes during metformin treatment can be directly contrasted.
Primary question
The primary outcome was health-related quality of life, assessed with the Minnesota Living With Heart Failure Questionnaire at 3 months. The clinical question was whether quality-of-life scores would be assessed during the metformin study. The registry record does not report the observed scores or a numerical change, so the size and direction of any change cannot be described from this record.
3. Trial Design
This was a completed pilot study of metformin in heart failure patients with pre-diabetes or early type II diabetes. The registry record describes a single-group model, with no masking and allocation recorded as NA. It lists 7 participants enrolled and identifies the University of California, Los Angeles as the sponsor. The study began in 2011-12, with primary completion in 2012-12. Its phase is listed as NA.
The treatment arm was metformin. The arm description says treatment would begin at 500 mg PO BID, with possible titration to 1000 mg PO BID at 1 month depending on laboratory values. The study summary describes receiving metformin for approximately 3 months. It also describes comprehensive testing, including blood draws and echocardiograms, and completion of a questionnaire. The primary outcome was assessed at 3 months.
Because the study has a single group and no listed comparator, it is not a randomized treatment comparison. The record does not describe a control condition, a masking procedure, or allocation to different groups. It therefore does not support a direct between-group estimate of the effect of metformin. The record also does not report the detailed enrollment criteria, the number who completed follow-up, or how treatment exposure and adherence were summarized.
The title identifies the study as a pilot, but the registry record does not report a protocol-based sample-size justification or specify whether the study was intended to estimate a particular treatment effect with a prespecified level of precision. It does not report interim analyses or a detailed statistical analysis plan. The design and available outcome information should therefore be read as a description of a small, single-group study, rather than as evidence from a controlled comparison.
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 |
|---|---|
| STARTED | 7 |
| COMPLETED | 7 |
| NOT COMPLETED | 0 |
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 |
|---|---|---|
| Participants analysed | 7 | |
| Age, Continuous | years | 59 (SD 8) |
| Sex: Female, Male: Female | Participants | 1 |
| Sex: Female, Male: Male | Participants | 6 |
| Race and Ethnicity Not Collected | Participants | — |
| Region of Enrollment: United States | Participants | 7 |
6. Primary Endpoint
The registry lists the primary outcome as Health-Related Quality of Life (HRQoL), measured over 3 months.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Full Range |
| Unit | score on a scale |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint was health-related quality of life, or HRQoL, measured with the Minnesota Living With Heart Failure Questionnaire (MLHFQ) at 3 months. The registry describes the MLHFQ as a self-administered questionnaire for patients with heart failure. It contains 21 items rated on six-point Likert scales, with responses from 0 (none) to 5 (very much). The total score ranges from 0-105, and lower scores indicate better health-related quality of life.
A patient-reported quality-of-life measure can capture the perceived impact of heart failure on daily life, complementing physiological measures such as left ventricular ejection fraction or laboratory measures. In general, a questionnaire score is useful only when its scale direction and measurement timing are clear; the registry provides those details for this outcome. The record identifies the intended summary as a mean with a full range, but does not report the observed score, range, baseline value, or change over time. It also does not report how questionnaire responses were handled if an item was unanswered.
Without the numerical endpoint results, it is not possible to characterize the level of HRQoL at follow-up or the precision of an estimated change. Nor does the registry record report a comparison group that could help distinguish treatment-associated change from changes over time for other reasons.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies HRQoL at 3 months as the primary outcome, but does not report a numerical mean, full range, change from baseline, confidence interval, or statistical test for that endpoint. As a result, the primary outcome cannot be quantitatively interpreted from the record. Although the endpoint metadata specify a mean and full range, those descriptors do not substitute for the underlying results.
The study enrolled 7 participants and used a single-group design. There is no listed control group, and no allocation to a comparator is described. Even if paired scores before and after treatment had been reported, a change within one group would not by itself isolate the effect of metformin. In general, changes over time can also reflect the natural course of illness, concurrent care, expectations, measurement variability, or other influences. The record does not report numerical before-and-after results that could be assessed in any case.
The registry lists glycated hemoglobin (HbA1c), left ventricular ejection fraction (LVEF), and creatinine level as secondary outcomes. Numerical results for these outcomes are not reported in the registry record. It reports four outcome measures overall, but does not provide a numerical result for the additional measure in the information available for this analysis. No conclusions about changes in glucose-related measures, cardiac function, or renal function can be drawn from the outcome names alone.
The adverse-event record lists 7 participants at risk for serious events and 0 serious events; it also lists 7 at risk for other events and 0 other events. These are registry counts, not a controlled safety comparison. The death count is not reported in the registry record. The absence of a listed event count is not evidence that all possible harms were ruled out, and the record does not give the collection window or detailed event definitions.
A planning illustration is described as using an observed effect, a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. Such a calculation is not an observed result and does not change the single-group design of this study. The observed effect value and the resulting planning numbers are not reported in the registry record. No recalculated treatment comparison or statistical significance claim is available from the stated information.
Overall, the registry record documents the question, intervention, design, and selected outcomes, but does not provide the outcome estimates needed to assess the magnitude or precision of any change. The small enrollment and absence of a comparator further limit what the design could establish about treatment effects, even if descriptive outcome values were available.
9. Statistical Methods Explained
The study’s single-group structure determines what kinds of statistical conclusions are possible. There is no listed control arm, so there is no between-group contrast in the registry record. A single-group study can describe measurements collected from participants, but a treatment effect is ordinarily estimated by comparing outcomes under different treatment conditions. Without a concurrent comparator, changes observed during follow-up cannot be cleanly separated from other changes that may occur over time. This is a general design limitation, not a finding about the participants’ actual outcomes.
What would a within-person comparison describe?
If the same participants have an outcome measured at baseline and follow-up, an analysis can describe within-person change. Such an analysis depends on having both measurements and on defining how the difference is calculated. The registry record identifies HRQoL at 3 months, but does not report baseline scores, follow-up scores, or a change estimate. It also does not state whether the primary analysis was planned as a comparison with baseline, a follow-up-only summary, or another approach. Those analysis details are not reported in the registry record.
For a paired analysis, the unit of information is the change within each participant. The variability of those changes matters; the spread of baseline scores alone would not determine the precision of a mean change. If follow-up responses are missing, the number of participants contributing paired data can differ from the number enrolled. The record does not report missing outcome counts or a method for handling missing measurements, so neither the analysis set nor the precision of a possible change can be reconstructed.
How should a mean and full range be read?
The outcome metadata specify a mean and full range. In general, a mean is an arithmetic average that summarizes the center of a set of measurements. A full range describes the lowest and highest observed values. The range can help convey how widely values varied, but it does not reveal how values were distributed between its endpoints. It can also be sensitive to extreme observations. For a small study, individual measurements may have substantial influence on the mean and range. The registry record does not provide either statistic for HRQoL, so there is no observed distribution to interpret.
A confidence interval, in general, expresses uncertainty around an estimate under the assumptions of the statistical method used. Its width depends on the variability in the data and the amount of information available. A confidence interval is not reported for the primary outcome in the registry record. Nor are a p-value, test statistic, or other inferential result reported. Without an estimate and its uncertainty, it is not possible to assess how precisely the primary outcome was measured or whether the data are compatible with a broad range of possible changes.
What does the planning illustration represent?
The planning note describes an illustration based on the observed effect, using a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a stated fraction of the observed effect. These are planning assumptions for a hypothetical two-arm calculation; they are not a description of the actual single-group design. The registry record does not report the observed effect value or the resulting planning numbers in the information available for this analysis.
In general, a sample-size calculation estimates the information needed for a future study under chosen assumptions about the effect, variability, significance level, power, and allocation. A calculation based on an observed effect can be especially uncertain when the original study is small, because an estimate from limited data may not represent the effect that a later study would observe. A planning illustration is not observed power and does not demonstrate that the pilot had a particular ability to detect an effect. The record does not report a protocol justification showing that the actual enrollment was selected using these assumptions.
Over-dispersion is a general concern when outcome variability is greater than a model assumes. If a statistical model understates variability, standard errors can be too small and confidence intervals too narrow. The record does not identify a model for the primary outcome or provide data with which to assess over-dispersion; this is a general consideration rather than a reported feature of this study. Likewise, no adjustment for baseline characteristics or other covariates is described.
For the listed secondary outcomes, analysis methods and numerical estimates are not reported in the registry record. The outcome labels indicate what was intended for assessment, not what values were observed or how any changes were analyzed. No independent re-calculation is possible without posted summary statistics. Where an analysis is not reported, it is not appropriate to infer a test, model, adjustment, or treatment effect.
10. Multiplicity, Missing Data and Analysis Populations
The registry record identifies HRQoL as the primary outcome and lists HbA1c, LVEF, and creatinine level as secondary outcomes. It reports four outcome measures overall. The additional measure’s description is not reported in the registry record. The record does not specify a hierarchy among the secondary outcomes or explain whether any were considered exploratory.
When several outcomes are assessed, general statistical practice recognizes that testing each one can increase the chance of at least one apparently unusual result by chance alone. A multiplicity strategy may define a primary endpoint, adjust tests, or treat secondary findings as exploratory. The registry record does not report a multiplicity procedure, a testing hierarchy beyond the primary-outcome label, or a statistical analysis plan. Since no outcome test results are reported, the effects of any multiplicity approach cannot be evaluated.
Missing-data methods are also not reported in the registry record. The record does not state how many participants posted the primary questionnaire at follow-up, whether any questionnaire items were incomplete, or how missing measurements were handled. It does not report imputation, a complete-case approach, or sensitivity analyses. Without those details, the analysis population and the potential influence of missing outcomes cannot be assessed.
The registry record does not define an intention-to-treat, per-protocol, or other analysis population. It lists 7 participants enrolled and 7 at risk in each adverse-event category, but those counts do not establish how many contributed data to each efficacy analysis. The number included in any outcome analysis is not reported in the registry record. Thus, outcome availability, analysis populations, and the handling of incomplete follow-up remain uncertain.
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 | 0 | 7 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 0% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Metformin | 0 of 7 |
The registry record lists the metformin group as having 7 participants at risk for serious adverse events, with 0 serious events reported. It also lists 7 at risk for other adverse events, with 0 other events reported. These counts describe what the record reports for this study; they do not establish that no adverse experiences occurred outside the recorded categories or reporting window.
The death count is not reported in the registry record. The record also does not report the adverse-event collection period, event definitions, severity grading approach, relatedness assessments, or details of monitoring. No serious-event terms are listed. A zero count in this small single-group study should not be read as proof that metformin caused no harms or as a comparative safety estimate. Without a comparator, the record cannot estimate whether event frequency differed from another treatment or from no study treatment.
In general, adverse-event counts are most informative when the number observed, the number at risk, the observation period, and the methods for collecting and classifying events are considered together. Here, the counts at risk and event counts are reported, but important context is not. The figures are therefore a limited description of registry reporting, not a complete characterization of safety.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed pilot study examined metformin in people with heart failure and pre-diabetes or early type II diabetes. It identifies a single-group treatment approach and HRQoL measured with the MLHFQ at 3 months as the primary outcome. It also names HbA1c, LVEF, and creatinine level as secondary outcomes. These details describe the study question and planned assessments; they do not establish what happened to the measured outcomes.
The numerical primary and secondary outcome results are not reported in the registry record. Therefore, the record does not show the size or direction of a change in HRQoL, glucose-related measures, cardiac function, or creatinine. It also does not provide confidence intervals or other estimates of precision. No conclusion about the presence, absence, or magnitude of a treatment-associated effect can be drawn from outcome names alone.
Even with numerical before-and-after scores, a single-group design would not separate treatment-associated change from other changes over time. In general, a concurrent comparator helps address that problem by showing what happened under a different condition during the same period. This study does not list such a group. Consequently, it cannot provide a randomized, between-group estimate of the effect of metformin.
The adverse-event record reports zero serious events and zero other events among the listed participants at risk, but this should be read as a limited registry count rather than proof of absence of harm. The death count and key details about adverse-event ascertainment are not reported in the registry record. The enrollment of 7 also means that the study offers limited information for characterizing uncommon outcomes, as a general statistical matter.
The most defensible reading is therefore descriptive: the registry record documents a small, completed, single-group pilot and its outcome framework, but does not report numerical efficacy results or enough safety detail for broad conclusions. It does not demonstrate that metformin improved or failed to improve any outcome. The design and reporting gaps leave the size, precision, and causal interpretation of any possible changes unknown.
13. Why This Trial Matters Statistically
This study is statistically informative as an example of how design and reporting shape what a clinical record can establish. Its single-group structure is central: without a comparator, an outcome change cannot be separated from the other influences that may operate over time. This limitation remains even if a study measures an outcome carefully. Statistical methods cannot create a controlled contrast that the design did not include.
The pilot context also matters. The record lists 7 participants enrolled, so estimates from the study would be based on a limited amount of information. In general, limited information can lead to imprecise estimates and leave substantial uncertainty about the range of effects compatible with the data. In this record, numerical endpoint results and confidence intervals are not reported, so their precision cannot be assessed at all.
The primary measure is patient-reported HRQoL, using a questionnaire with an explicitly described score direction. This highlights the importance of stating what an outcome measures and how to interpret its scale. At the same time, an outcome definition does not replace reporting the observed results, the analysis population, missing responses, and uncertainty around estimates.
The planning note illustrates another statistical distinction: a sample-size calculation is a planning exercise, not a finding about the completed study and not observed power. Its assumptions refer to a hypothetical two-arm calculation, whereas the registered design is single-group. Keeping those roles separate prevents planning assumptions from being mistaken for evidence from the trial itself.
More broadly, this record shows why transparent reporting of outcome values, analysis methods, missingness, and adverse-event ascertainment is necessary for interpretation. When those elements are not reported, readers should distinguish what the design intended to measure from what the available results can actually establish.
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 limitations specific to this study begin with its single-group design. Allocation is recorded as NA, masking as none, and no comparator is listed. The record therefore does not support a controlled estimate of treatment effect. Any within-group change, if observed, could not by itself identify metformin as its cause. Numerical before-and-after results are not reported in the registry record, so even descriptive change cannot be evaluated.
Enrollment was 7. The registry record does not report a sample-size justification tied to a target precision or a prespecified treatment effect. It also does not provide the primary outcome mean, full range, baseline score, follow-up score, or confidence interval. Without these values, the magnitude and uncertainty of the primary outcome are unavailable. The record lists four outcome measures overall, but provides numerical results for none of them in the information available for this analysis.
Participant characteristics and eligibility details beyond heart failure, pre-diabetes or early type II diabetes, and the stated age requirement are not reported in the registry record. The number who completed follow-up and the number contributing to each outcome analysis are also not reported. These omissions limit assessment of representativeness, attrition, and the analysis population.
The record does not specify how missing questionnaire items or missing follow-up measurements were handled. It does not report a statistical analysis plan, outcome-specific models, adjustment for covariates, a multiplicity procedure, or interim analyses. These methods cannot be inferred from the listed outcome names or the planned summary descriptors.
Safety interpretation is constrained by the absence of detailed adverse-event definitions, collection timing, severity and relatedness information, and a reported death count. The reported zero event counts should therefore be treated as registry entries, not as complete evidence that no harms occurred. The treatment summary describes possible dose titration according to laboratory values, but the record does not report actual dose exposure or adherence.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Pilot Study: Metformin Therapy in Heart Failure Patients With Early Diabetes or at High Risk of Developing Diabetes (Pre-Diabetes) — NCT01573949.
- Registry record last updated 2020-09-04; status last verified 2020-08.
- Results first posted 2020-09-04.
- Data retrieved from ClinicalTrials.gov on 2026-11-09.
- Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.
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18. Record Summary
NCT01573949 is a completed pilot study sponsored by the University of California, Los Angeles. The record lists a single-group, unmasked design and 7 participants enrolled. The study began in 2011-12, with primary completion in 2012-12. It examined metformin in people with heart failure and pre-diabetes or early type II diabetes.
The primary outcome was HRQoL measured with the Minnesota Living With Heart Failure Questionnaire at 3 months. HbA1c, LVEF, and creatinine level are listed as secondary outcomes. The record describes the metformin starting dose and possible titration, but numerical efficacy results and the analysis methods are not reported in the registry record. It lists zero serious and zero other adverse events among the participants at risk; the death count is not reported. Without a comparator or numerical outcome estimates, the record does not establish a treatment effect.