Cognitive Problems in Veterans With Heart Failure: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Cognitive Problems in Veterans With Heart Failure (NCT01049308), a registered phase not stated study. The primary outcome is SLUMS Scores.

2. Clinical Question

3. Trial Design

The registry record describes a completed study titled “Cognitive Problems in Veterans With Heart Failure.” Its official title frames cognitive impairment as a possible risk in the admission-readmission cycle and refers to medication adherence. The sponsor is the US Department of Veterans Affairs. The record lists an enrollment of 300, a start of 2010-02, and a primary completion of 2011-04.

The described group is a veteran population with documented heart failure. The record does not describe a randomized allocation, and it states that allocation is not stated and the arms are not a like-for-like control comparison. No intervention assignment or comparator is described. These features matter because an outcome measured in a single described group, or in groups that are not comparable, does not by itself estimate an intervention effect.

The primary measure is SLUMS at baseline collection. Medication adherence is listed as a secondary outcome. The record identifies two outcome measures and one analysis, but the detailed analysis method, analysis population, and results are not reported in the registry record. The record also does not explain how the enrollment figure relates to the number contributing data to each measure. It therefore supports a description of the study's stated aims and outcome definitions, but not a reconstruction of participant flow or a full account of how the analyses were conducted.

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.

Evaluation of Cognitive Impairment

Pill Counts

Reasons for not completing this period:

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 SLUMS Scores, measured over baseline collection.

The primary outcome is the mean score on the Saint Louis University Mental Status exam, abbreviated SLUMS, collected at baseline. The record describes SLUMS as a validated screening test for cognitive impairment and a 30-point interview scale. A screening score provides a standardized way to describe cognitive performance in the population being assessed; the registry record does not report the observed mean or standard deviation.

The record specifies different thresholds according to education. For a person with a high school diploma, a score <27 is considered positive for mild cognitive impairment; for a person who did not complete high school, the threshold is <25. For severe impairment consistent with dementia, the corresponding thresholds are <21 for persons with a high school diploma and <20 for persons who did not complete high school. These are screening definitions in the record, not reported findings about participants.

A mean conveys the central value of a set of scores, while the standard deviation describes their spread. A group mean alone cannot show how many individuals fall below a screening threshold or describe the full score distribution. The registry record does not report education-specific results, the number of participants below any threshold, or the numerical mean and standard deviation. Its stated use of SLUMS is therefore clear, but the prevalence of screening-positive results cannot be determined from the reported information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry classifies the primary measure as continuous and describes its summary as a mean with standard deviation. A continuous measure can take values across a scale rather than being limited to a set of categories. A mean summarizes the central location of the scores, and a standard deviation describes how dispersed scores are around that mean. These summaries are useful for describing a group, but they do not reveal the shape of the score distribution or the proportion of individuals meeting a screening threshold. The record does not report the mean or standard deviation.

What does the mean describe?

For SLUMS, the mean would summarize baseline scores for the participants included in the analysis. It is not itself a count of people with cognitive impairment. The registry supplies screening thresholds that vary with education, but does not report the distribution of scores across those thresholds or the education-specific results. General statistical interpretation therefore distinguishes a group average from a threshold-based prevalence: they answer different questions.

The standard deviation is a measure of spread, not a measure of uncertainty in the mean. A confidence interval, when reported, addresses uncertainty in an estimate under a specified statistical method. Those quantities are not interchangeable. No confidence interval, standard error, or numerical standard deviation for the primary outcome is reported in the registry record, so the precision of the mean cannot be evaluated from this record.

What can be inferred from the analysis listing?

The registry lists two outcome measures and one analysis. That count does not identify the statistical model, the variables included, or whether the analysis adjusted for participant characteristics. It also does not establish that every listed outcome was analyzed in the same way. The analysis method and its assumptions are not reported in the registry record. It would therefore be inappropriate to infer a regression model, a test of association, or an adjustment strategy from the outcome descriptions alone.

Medication adherence is named as a secondary outcome, and the study summary says the relationship between adherence and cognitive or memory problems was evaluated. Yet the definition and scale of adherence, the specific statistical comparison, and its numerical estimate are not reported. General statistical practice would require clarity about how each measure is represented and what association is being estimated before interpreting a result. That information is unavailable in the registry record.

How should the planning illustrations be understood?

The sample-size planning assumptions describe an illustration based on the observed effect, rather than the trial's own design. The assumptions specify a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. They also describe detecting a stated fraction of the observed effect. These are planning assumptions, not evidence that the study randomized participants equally or used that analysis in its own design.

Such illustrations ask how many participants per arm would be needed under stated assumptions to detect a target effect with a selected power. The resulting values are planning quantities, not observed participant counts and not a retrospective demonstration that the study had a particular probability of detecting its result. They depend on the effect used as the starting point and on the chosen assumptions. The numerical effect and the numerical planning results are not reported in the registry record, so no specific planning value can be interpreted. In particular, planning based on an observed effect should not be described as observed power.

The assumptions mention equal allocation between two arms, but the trial record explicitly says this is not a randomized comparison and that the arms are not a like-for-like control comparison. The hypothetical setup used for planning should not be confused with the study's documented design. Nor should the planning calculation be taken as a sample-size justification: the registry record does not report the trial's own sample-size rationale.

What uncertainty remains about the statistical plan?

The registry record does not report the model specification, inferential test, handling of missing observations, or analysis population. It does not state whether analyses were adjusted, whether assumptions were checked, or whether any interim analyses were conducted. These omissions prevent a detailed audit of the statistical plan. They do not imply that a particular method was or was not used; they mean that the method is not reported in the registry record.

In general, the interpretation of a continuous outcome depends on the scale, the distribution of observations, the analytic model, and the population included. If a model relies on assumptions about residual variation or distributional form, those assumptions need to be suitable for the data. The registry's description of SLUMS as a continuous outcome and of mean and standard deviation summaries does not disclose which inferential assumptions, if any, were applied. No model diagnostics or sensitivity analyses are reported.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Heart Failure")
n   <- c(251)
m   <- c(24.39)
sp  <- c(4)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Heart Failure  251  24.390  4.000  23.893  24.887

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists two outcome measures and one analysis. It identifies SLUMS scores as the primary outcome and medication adherence as a secondary outcome, but does not report a detailed analysis plan or explain how the outcomes were prioritized for inference. The record does not state whether multiple statistical tests were performed or whether any adjustment for multiplicity was planned or used. The number of listed measures alone is not enough to determine the multiplicity of the actual analyses.

Multiplicity matters in general when several hypotheses are examined: the chance of at least one apparently noteworthy finding can increase as the number of tests grows. Methods for addressing it depend on the analysis plan and the inferential goals. Since those details are not reported in the registry record, it is not possible to determine whether multiplicity affected the interpretation of the posted results.

Missing-data methods are also not reported. The record does not describe how missing SLUMS or adherence measurements were handled, whether any values were imputed, or whether analyses included all enrolled participants or only those with available measurements. It does not report a participant flow or explain how the enrollment of 300 relates to the participants contributing to each outcome. No assumptions about missingness or analysis populations can be made from the available record.

These gaps matter because estimates can depend on which observations are included and how missingness is handled. In general, complete-case analyses and imputation approaches can rely on different assumptions. Without a reported method, neither approach should be attributed to this study. The registry record also does not report a prespecified statistical analysis plan, so whether the posted analyses followed a plan cannot be assessed.

12. Safety Results

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

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 Group 1 with 251 at risk and zero affected by serious adverse events. It also lists 251 at risk and zero affected for other events. The death count is not reported in the registry record. These figures describe the event fields as posted; they do not provide a detailed account of event definitions, collection procedures, timing, or completeness of reporting.

A zero in an affected field means that zero is recorded for that field in the registry listing. It should not be expanded into a claim that no event could have occurred, that surveillance was complete, or that a treatment is safe. The record does not describe a treatment comparison, and the at-risk count is not explained in relation to the enrollment figure of 300. The figures therefore support only a narrow description of the posted event counts and denominators.

The registry record does not list serious-event terms. It also does not report a death count, so the absence of a numeric death value should not be interpreted as a reported zero. Safety interpretation is limited by the sparse event detail and the lack of a stated comparator.

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

The record documents an investigation of cognitive or memory problems and medication compliance among veteran patients with heart failure. It specifies a baseline SLUMS mean as the primary outcome and medication adherence as a secondary outcome. It also describes SLUMS as a validated screening test and provides education-specific thresholds for screening classifications. These details clarify what the study set out to measure.

The registry record does not report the numerical primary outcome, its standard deviation, the prevalence of scores below screening thresholds, or the numerical adherence findings. It likewise does not report an estimate of the relationship between cognition and adherence. The central empirical question therefore remains unanswered by the information in the record: neither the magnitude nor the precision of the reported association can be described.

The study is not presented as a randomized comparison. Allocation is not stated, and the registry warns that the arms are not a like-for-like control comparison. The study description consequently does not support a causal claim about an intervention. Even if an association had been numerically reported, an association alone would not establish that cognitive impairment caused a change in medication adherence or that changing one would change the other.

The screening thresholds are classification rules in the registry description, not evidence that participants crossed them. The mean score, if reported, would not substitute for counts or proportions at those thresholds. Likewise, the adverse-event listing of zero affected does not establish the absence of all safety concerns, and the unreported death count cannot be treated as zero.

In general, a study's meaning depends on its estimates, uncertainty, design, measurement definitions, and analysis population. Here, the record provides important outcome definitions and design limitations but not the numerical results or enough statistical detail to assess their reliability. The appropriate interpretation is therefore descriptive: the registry documents the research question and measurement framework, while the result-level conclusions are not reported in the registry record.

14. Why This Trial Matters Statistically

The trial is statistically notable because its stated topic connects a screening measure of cognition with medication adherence in a population described as veterans with documented heart failure. That question involves more than reporting an average score: prevalence at screening thresholds and the relationship between scores and adherence require outcome definitions and analyses that correspond to those specific questions.

The registry identifies a continuous primary outcome and specifies a mean with standard deviation. This makes clear what kind of summary was intended, while also highlighting what cannot be learned from a mean alone. A group average does not show how scores are distributed across education-specific thresholds. The absence of numerical outcome results means neither the central score nor its spread can be assessed.

The design information is equally important. The record says this was not a randomized comparison, allocation is not stated, and the arms are not a like-for-like control comparison. Recognizing those limits helps prevent descriptive observations from being mistaken for causal evidence. The record also separates the primary outcome from the secondary adherence outcome, but does not provide the analysis details needed to evaluate their relationship.

Finally, the planning assumptions illustrate how sample-size calculations depend on explicit choices about an effect, allocation, significance level, and statistical approximation. They are not a description of the actual design or evidence of observed power. This distinction is useful when reading planning values alongside an observational or otherwise non-comparative study. The record's statistical importance lies in the questions it raises about measurement, comparability, and reporting, not in a numerical result that is absent.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpretation is that the registry record does not report the numerical results for the primary SLUMS outcome or the secondary medication-adherence outcome. It also does not report an association estimate, confidence interval, or other measure of precision. The direction and magnitude of the findings therefore cannot be assessed.

The record describes the primary outcome as a baseline mean score but does not report the mean, standard deviation, score distribution, or number of participants meeting the education-specific screening thresholds. Although it gives the thresholds and describes the screening instrument, it does not provide the results needed to estimate the prevalence of positive screens.

Design details are limited. The record says this is not a randomized comparison, allocation is not stated, and the arms are not a like-for-like control comparison. It does not describe participant eligibility in detail, a comparator, or an intervention. The methods used to assess adherence and the statistical method for relating adherence to cognition are also not reported in the registry record.

The record lists enrollment of 300, while the adverse-event listing gives an at-risk count of 251. It does not explain the relationship between these figures or provide participant flow by outcome. Missing-data handling and analysis populations are not reported. The record also does not provide the trial's own sample-size justification or enough detail to assess multiplicity, adjustment, or interim analyses.

Safety information is limited to posted event counts and an unreported death count. Event definitions and collection details are not reported. Together, these omissions restrict both the assessment of statistical precision and the scope of conclusions that can be drawn from the registry record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Cognitive Problems in Veterans With Heart Failure — NCT01049308.
• Registry record last updated 2015-04-28; status last verified 2014-08.
• Results first posted 2014-11-24.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

This completed registry record concerns cognitive or memory problems and medication compliance in veteran patients with heart failure. The sponsor is the US Department of Veterans Affairs; the listed enrollment is 300, with a start of 2010-02 and primary completion of 2011-04. The primary outcome is mean baseline SLUMS score, described as a continuous measure summarized with a standard deviation. Medication adherence is listed as a secondary outcome.

The record states that the study is not a randomized comparison, allocation is not stated, and the arms are not a like-for-like control comparison. It lists two outcome measures and one analysis, but does not report numerical outcome results, an association estimate, or key details of the analysis and missing-data methods. The adverse-event listing records zero affected for serious events and other events among 251 at risk; a death count is not reported in the registry record. The stated research question and measurement definitions are available, but the numerical findings and their precision cannot be evaluated from this record.