The Role of Apathy in Glycemic Control: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Role of Apathy in Glycemic Control (NCT00844090), a randomized na study. The primary outcome is Change in HbA1c Over Baseline.

2. Clinical Question

The study rationale is that apathy—a lack of motivation and persistence—may make it harder for people to carry out diabetes self-care activities. The summary mentions taking medication regularly, diet, and exercise as examples. The clinical question therefore links an intervention intended to address apathy with a measure of longer-term glycemic control.

The posted primary endpoint is HbA1c change, not a direct measure of apathy, medication-taking, diet, or exercise. The registry record does not report a result for an apathy measure or for those self-care behaviors. It also does not report a formal comparison estimate or inferential test for the primary endpoint. The observed arm summaries can describe the posted HbA1c changes, but alone they do not establish whether an arm difference is compatible with chance variation or how precisely it estimates an underlying treatment effect.

3. Trial Design

The registry describes a randomized, parallel-group trial with quadruple masking. Participants were assigned to methylphenidate tablets or placebo tablets. The record does not report the randomization procedure, allocation concealment details, or which people were included in the quadruple-masking designation. Those details should not be inferred from the design labels.

The study is listed as completed. Its enrollment was 106; the posted primary endpoint uses a per-protocol population of 46 participants in each arm. These figures refer to different counts, and the registry record does not explain how the enrolled population relates to the posted per-protocol groups. The record identifies the sponsor as the US Department of Veterans Affairs and lists the study start as 2009-07 and primary completion as 2012-08.

The treatment period described in the summary is 6 months. HbA1c measurements are noted at baseline, 6 weeks, and 6 months, while the primary endpoint timeframe is 6 months from baseline. The primary outcome is titled “Change in HbA1c Over Baseline.” Its reported parameter is the median, with standard deviation as the dispersion measure, in the per-protocol population.

The record labels the phase as NA. It lists one outcome measure and no posted secondary outcomes. The registry record does not report the planned sample-size justification, a detailed analysis plan, procedures for handling protocol deviations, or how the per-protocol population was defined. Randomization and masking are useful design features, but their labels alone do not resolve questions about the conduct or analysis of the trial.

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.

Before assignment: All participants underwent a stress echo after consent. If stress echo was positive patient was not assigned to randomized arms

Overall Study

Analysis population for the primary outcome, as defined in the registry: per protocol

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.

Population: The number of participants for analysis was 92 in total since only 92 participants completed the study.

6. Primary Endpoint

The registry lists the primary outcome as Change in HbA1c Over Baseline, measured over 6 months from baseline.

HbA1c is described in the registry as a measure of longer-term glycemic control. The primary endpoint is the change in HbA1c from baseline at 6 months. The registry also notes measurements at baseline and 6 weeks, but the primary timeframe is 6 months from baseline.

A change-from-baseline endpoint expresses follow-up values relative to participants’ starting measurements. In general, using a change can account for differences in baseline levels when describing follow-up outcomes, although the interpretation depends on how the outcome is analyzed and on the trial’s analysis plan. The registry record does not report a baseline-adjusted model or other adjustment method.

The posted values are medians: -1.0 for methylphenidate and -0.1 for placebo. The reported group sizes are 46 in each arm. A negative change represents a lower HbA1c value at follow-up relative to baseline as described by the endpoint. The registry reports standard deviations of 1.02 and 1.04, respectively, as dispersion measures alongside the medians.

These summaries describe the per-protocol participants with posted outcome data. They are not an inferential comparison: no confidence interval, p-value, or sponsor-reported test is included. The registry record does not explain why the median was selected, how missing measurements were handled, or how the listed standard deviations were used in the analysis.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary parameter as a median and its dispersion as a standard deviation. It posts arm-specific summaries rather than a formal comparison estimate. No analysis is listed in the results record, and no confidence interval or p-value is reported for the primary endpoint.

What does a median describe?

In general, the median is the middle of an ordered set of observations. It is less influenced by unusually high or low values than the mean and can be useful when a distribution is skewed. It describes a typical position in the observed distribution, but it does not quantify uncertainty about a treatment contrast. To estimate a contrast between randomized groups, an analysis would need to specify a comparison measure and an appropriate method for uncertainty.

How should the standard deviations be read?

The registry pairs the median summaries with standard deviations. In general, a standard deviation describes the spread of observations around their mean. It is commonly paired with a mean, whereas other dispersion summaries are often used with medians. The presence of a standard deviation does not make the median a mean, and it does not reveal whether the endpoint distribution is symmetric. The registry record does not explain this pairing or say whether the standard deviations were used in a comparative analysis.

Why are confidence intervals useful?

In general, a confidence interval gives an estimate together with a range reflecting sampling uncertainty under the stated method. For a treatment comparison, the interval helps readers judge both the possible size of the difference and its precision. A narrow interval indicates greater precision under the model; a wide interval indicates greater uncertainty. The posted primary results include no confidence interval, so the precision of an arm contrast cannot be read from the reported medians alone.

A p-value, when reported, addresses compatibility between the observed data and a specified null model under the assumptions of a test. It does not measure the probability that a treatment works, and it does not convey the size or precision of an effect by itself. No primary p-value or test is reported in the registry record. Therefore, the descriptive difference between arm medians should not be translated into a claim about statistical significance.

What does randomization contribute?

In general, random assignment is intended to make treatment groups comparable on average at the start of a trial, including for factors that were not measured. It does not guarantee that the realized groups are identical, and it does not remove uncertainty from a finite sample. The record identifies the trial as randomized, but does not describe the allocation sequence or report baseline characteristics in the results posted for this endpoint. The randomized design is relevant context, but it cannot substitute for a reported comparative analysis.

How should planning calculations be interpreted?

The planning illustrations associated with the results are based on the observed effect, use a two-sided significance level of 0.05, assume equal allocation between two arms, and use a normal approximation. The target effect is expressed as a stated fraction of the observed effect. Such calculations are planning illustrations: they describe sample sizes for a hypothetical future study under those assumptions. They are not observed power for this completed trial, and they do not provide an additional test of the posted result.

In general, planning calculations based on an effect estimated in a small or uncertain dataset inherit uncertainty in that estimate. Choosing a fraction of the observed effect can explore different planning targets, but does not show which effect is clinically meaningful. The registry record does not report the trial’s own sample-size justification, assumptions used before enrollment, or whether any planning calculation informed the design. The planning assumptions do not fill in those missing protocol details.

Normal-approximation methods rely on conditions that make the approximation suitable for the statistic and design. For counts or rates with variability greater than a basic model expects, over-dispersion can make standard errors too small and intervals too narrow if it is ignored. That is a general statistical consideration; the registry does not report an over-dispersion assessment, and the primary endpoint is a continuous HbA1c change rather than an event count.

The posted outcome does not state whether the analysis compared change scores directly, adjusted for baseline HbA1c, or used another model. It also does not describe distributional checks, covariate selection, handling of extreme values, or robustness analyses. These methods can affect estimates and uncertainty, so their absence limits the ability to reproduce or evaluate a formal primary comparison.

For the same reason, the reported arm summaries cannot be used to reconstruct a sponsor analysis that is not posted. A simple recalculation from summaries would not be a substitute for the trial’s prespecified analysis and would not account for unreported design or data-handling decisions. The registry record does not report a sponsor comparison result to take precedence over any such recalculation.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure, identifies the HbA1c change as primary, and posts no secondary outcomes. It reports no analysis for the primary outcome. The number and structure of all outcomes originally planned in the protocol, however, are not reported in the registry record. Nor are multiplicity procedures, such as a hierarchy of tests or an adjustment for multiple comparisons, reported.

Multiplicity matters in general when several outcomes, time points, subgroups, or analyses are tested: the chance of at least one apparently unusual result can increase as the number of tests grows. The registry lists HbA1c measurements at baseline, 6 weeks, and 6 months, while identifying the six-month change as the primary endpoint. It does not report whether the 6-week measurement was analyzed, whether additional outcomes were collected, or how any such analyses were handled. No conclusion about the overall testing strategy is possible from the posted record.

The primary result is labeled per protocol. The record does not define that population, list exclusions, provide a participant flow account, or report the number of missing measurements and their reasons. It does not describe imputation, complete-case analysis, sensitivity analyses, or another missing-data method. The enrollment total and per-protocol group sizes are both reported, but the record does not reconcile them.

These gaps matter because missing outcomes and population definitions can affect both the estimate and its uncertainty. They do not establish that the analysis was biased; they mean that readers cannot evaluate the potential impact from the registry results alone. An intention-to-treat result, a prespecified missing-data strategy, and sensitivity analyses are not reported in the registry record.

11. 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.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: abdominal pain, nausea, loose stool (6.5%), blood pressure and pulse (4.3%), prostate cancer (2.2%), renal failure (2.2%), cellulitis (2.2%).

The serious adverse event figures are reported separately for the two arms. The methylphenidate group had 7 participants affected among 46 at risk, and the placebo group had 6 among 46 at risk. The registry also reports other adverse events as 28 among 46 at risk in the methylphenidate group and 25 among 46 in the placebo group. These are posted counts, not estimates of a treatment effect.

The registry lists serious-event terms with percentages: “abdominal pain, nausea, loose stool” at 6.5%, “Blood Pressure and pulse” at 4.3%, “Prostate Cancer” at 2.2%, “renal failure” at 2.2%, and “cellulitis” at 2.2%. The record does not assign these listed terms to particular arms or clarify whether the percentages refer to participants, events, or another denominator. They should not be interpreted as arm-specific rates.

The record does not report deaths. It does not provide event-level timing, duration, severity details beyond the serious classification, relatedness assessments, or a statistical comparison of safety outcomes. Counts alone do not indicate whether an event was caused by a study treatment. The figures describe what is posted in the registry and should be interpreted with these reporting limits in mind.

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

The posted data describe a completed randomized, parallel-group trial comparing methylphenidate tablets with placebo tablets. For the per-protocol primary outcome, the registry reports median six-month HbA1c changes of -1.0 and -0.1, respectively, with 46 participants in each arm. It also reports standard deviations of 1.02 and 1.04. These are descriptive summaries at the specified follow-up time.

They do not, by themselves, establish a causal effect or the precision of a between-arm difference. The registry record contains no reported primary analysis, confidence interval, or p-value. It also does not report the details needed to assess the per-protocol population, missing outcomes, or the analysis model. The numerical contrast should therefore not be treated as proof of a treatment benefit, proof of no effect, or evidence that the arms are equivalent.

The clinical rationale concerns apathy and self-care, but the posted primary outcome is HbA1c change. The record does not post an apathy outcome or a result for self-care behaviors. It therefore does not establish from the listed endpoint whether apathy changed, whether self-care changed, or how either might relate to HbA1c.

Safety counts provide a separate descriptive account: 7 serious adverse event-affected participants are reported in the methylphenidate group and 6 in placebo, with other-event counts of 28 and 25. The record does not provide a formal safety comparison or sufficient event detail to attribute events to treatment. These counts should not be used alone to claim that one arm is safer.

The appropriate reading is narrow: the registry reports the stated outcome summaries and adverse-event counts for the stated groups. Statistical uncertainty, completeness of follow-up, and the consequences of analysis choices remain unclear in the registry record. Additional protocol and analysis information would be needed to make a fuller assessment.

13. Why This Trial Matters Statistically

This trial illustrates why a result needs more than two arm-level summaries to support a statistical comparison. The posted medians describe the observed per-protocol groups, but without a comparative estimate and its uncertainty, readers cannot judge how stable the apparent difference may be. A confidence interval and a clearly specified test would help communicate what the data say about the treatment contrast under the analysis assumptions.

It also highlights the importance of defining the analysis population. The registry reports enrollment of 106 and primary endpoint group sizes of 46 in each arm, but does not explain the relationship between those counts. Because the outcome is labeled per protocol, its interpretation depends on how that population was defined and how participants without usable endpoint data were handled. Those details are not reported.

The endpoint and the rationale are related but distinct. The study summary proposes that apathy may interfere with diabetes self-care, while the primary posted outcome measures HbA1c change. A direct assessment of apathy or the proposed behaviors could help explain the pathway under investigation, but those results are not posted in the registry record. Separating a mechanistic hypothesis from the measured primary outcome keeps interpretation aligned with the evidence actually reported.

Finally, the record demonstrates the difference between an outcome summary and a complete statistical account. The trial is labeled randomized and quadruple masked, but allocation details, masking roles, the formal analysis, multiplicity handling, and missing-data procedures are not reported. These omissions do not prove that the methods were inadequate; they limit what can be evaluated from the registry. Planning illustrations based on the observed effect likewise answer a design question for hypothetical studies, not whether the completed trial produced a precise or conclusive estimate.

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 principal limitation of the posted efficacy result is that it provides arm-level summaries without a formal comparison, confidence interval, or p-value. Consequently, the precision and statistical compatibility of a between-arm difference cannot be assessed from the registry result. The endpoint is described as a median with a standard deviation, but the registry does not explain the choice or how the spread measure relates to the analysis.

The outcome population is per protocol, but the definition of that population and participant exclusions are not reported. Although the registry states enrollment of 106 and reports 46 participants per arm for the primary endpoint, it does not explain the flow from enrollment to analysis or describe missing measurements. No missing-data strategy or sensitivity analysis is reported. The possible effect of these issues on the posted summaries cannot be assessed.

Other analysis details are also absent: the statistical model, baseline adjustment, prespecified testing strategy, multiplicity procedures, and any interim analyses are not reported in the registry record. The record does not state whether additional endpoints or subgroup analyses were planned. These are limits on interpretation, not evidence that any particular analysis was or was not performed.

The study summary motivates treatment of apathy, but the posted primary result is HbA1c change. No apathy outcome or self-care behavior result is posted. The registry does not report the roles covered by quadruple masking, the randomization procedure, or baseline group characteristics for this endpoint. Safety reporting is similarly limited by absent event-level detail and no formal comparison; deaths are not reported in the registry record.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: The Role of Apathy in Glycemic Control — NCT00844090.
• Registry record last updated 2014-04-21; status last verified 2014-03.
• Results first posted 2014-04-21.
• 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 lists NCT00844090, “The Role of Apathy in Glycemic Control,” as a completed randomized, quadruple-masked, parallel-group study sponsored by the US Department of Veterans Affairs. Enrollment was 106. The study summary describes methylphenidate or placebo over 6 months.

The primary outcome is change in HbA1c over baseline at 6 months, reported as a median with standard deviation in a per-protocol population. The methylphenidate arm had a median change of -1.0 and standard deviation of 1.02; the placebo arm had a median change of -0.1 and standard deviation of 1.04. Each posted group includes 46 participants. No formal primary analysis, confidence interval, or p-value is reported.

The registry lists serious adverse event counts of 7 in the methylphenidate group and 6 in placebo, and other adverse event counts of 28 and 25, respectively. The record does not report deaths, secondary outcomes, a detailed missing-data approach, or the analysis plan.