Role of Apathy in the Effectiveness of Weight Loss Interventions: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Role of Apathy in the Effectiveness of Weight Loss Interventions (NCT00548652), a randomized na study. The primary outcome is Apathy Evaluation Scale.

2. Clinical Question

The study is registered as NCT00548652 and is titled “Role of Apathy in the Effectiveness of Weight Loss Interventions.” Its stated rationale connects apathy treatment with adherence to weight-loss programs, but the posted primary measure is apathy rather than adherence. Change in Weight is listed as a secondary outcome. Thus, the registry record offers results relevant to apathy and weight, but the outcomes alone do not establish whether any change in apathy altered adherence or the effectiveness of a weight-loss program. The record does not report an adherence measure among the posted outcomes.

3. Trial Design

The registry describes a randomized, parallel study with no masking and a completed status. Enrollment is listed as 101. The sponsor is VA Nebraska Western Iowa Health Care System. The recorded study start is 2007-08, and primary completion is 2009-05. The phase is listed as NA.

The intervention descriptions include MOVE, medical crisis counselling, and methylphenidate. The arm descriptions specify standard nutrition counselling; MOVE; MOVE plus medical crisis counselling; MOVE plus methylphenidate; and MOVE plus methylphenidate plus medical crisis counselling. The registry also includes repeated intervention entries, so the intervention list alone does not establish the mapping of each listed entry to a participant group.

For the posted outcomes, results are organized under Usual Care, VA MOVE, and Intervention. The record gives outcome group sizes of 16, 29, and 34, respectively, for the Apathy Evaluation Scale and Change in Weight. It does not explain how the three outcome labels correspond to the fuller set of arm descriptions. The analysis should therefore be read in terms of the posted outcome labels, rather than assuming that the result labeled Intervention refers to a particular one of the described combinations.

Randomization is recorded, but the allocation procedure and any stratification details are not reported in the registry record. Masking is listed as none. The record does not report the original sample-size justification, interim analyses, the trial's original statistical analysis plan, or further details about the study procedures. Although the registry lists enrollment, that figure should not be treated as a count of participants contributing to every outcome: the posted outcome group sizes differ, and the record does not explain the reasons for that difference.

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

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 Apathy Evaluation Scale, measured over 6 months.

The primary endpoint is the Apathy Evaluation Scale, reported as a mean with standard deviation at six months. The registry describes the scale as measuring apathy over the previous four weeks. Its range is 18 (minimum score) to 72 (maximum score), and higher scores indicate higher apathy. The registry identifies reduction in the score as a better outcome.

This measure is relevant to the study's stated question because the intervention rationale is to treat apathy in the context of weight-loss programs. It captures apathy on a defined scale, while the secondary Change in Weight outcome addresses weight directly. These measures therefore reflect related but distinct aspects of the study's stated aims. The posted primary results compare mean values for Usual Care with VA MOVE and with Intervention.

The record does not explicitly label the posted AES values as change from baseline, nor does it provide baseline scores in the outcome information. The values are negative, but the precise meaning of that sign is not explained in the endpoint description. The scale description supports interpreting lower scores as less apathy; it does not by itself resolve whether the reported negative values represent change scores, another derived measure, or a reporting convention. That distinction limits how confidently the numerical direction can be described as improvement.

7. Results Posted in the Registry

• VA MOVE: mean -6.40 versus -7.69 on control; difference 1.29 (95% CI -2.97 to 5.55), standardized effect d = 0.18; z-test p = 0.553.
• Intervention: mean -6.15 versus -7.69 on control; difference 1.54 (95% CI -2.79 to 5.87), standardized effect d = 0.20; z-test p = 0.486.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change in Weight

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard deviations.
• Result:
  • VA MOVE: mean -0.61 versus -0.60 on control; difference -0.01 (95% CI -3.19 to 3.17), standardized effect d = -0.00; z-test p = 0.995.
  • Intervention: mean -4.61 versus -0.60 on control; difference -4.01 (95% CI -7.67 to -0.35), standardized effect d = -0.50; z-test p = 0.032.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between VA MOVE and the control. The interval gives the range of effects that remain compatible with the data.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Intervention than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change in Weight is the posted secondary outcome. Its group means are -0.6 kg for Usual Care, -0.61 kg for VA MOVE, and -4.61 kg for Intervention. Across the pairwise recalculations, the VA MOVE comparison is close to zero and its interval is broad enough to include values on either side of zero. The Intervention comparison is more separated from Usual Care in the posted summaries, and its unadjusted interval excludes zero. These patterns differ from the primary AES comparisons, whose intervals both include zero.

The secondary result can complement the primary outcome by addressing weight directly, while AES measures apathy. The pattern does not show that change in apathy caused or accompanied a change in weight: the registry does not report an analysis linking the outcomes, nor does it report adherence results. It also does not establish that the treatment combinations were represented identically across the intervention descriptions and the three outcome labels.

Unadjusted secondary results carry less weight when multiple outcomes or comparisons may have been examined, because the chance of seeing an apparently notable result can increase as the number of analyses grows. General statistical practice may address this with a prespecified hierarchy or multiplicity adjustment, but the registry record does not report such a plan. The record lists the primary AES outcome and Change in Weight as a secondary outcome, but it does not specify whether additional outcomes or analyses were planned and not posted. For that reason, the secondary pattern is informative but should not be treated as a stand-alone confirmation of an intervention effect.

The registry lists no reported analyses. The numerical comparisons are simple unadjusted recalculations from the posted group means and standard deviations. They do not establish what the original analysis plan specified or whether any adjusted sponsor analysis was conducted. The secondary findings should therefore be considered alongside the primary uncertainty and the reporting limitations, rather than used to override them.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change in Weight

9. Statistical Interpretation

10. Statistical Methods Explained

The posted outcomes are continuous measures summarized by group means and standard deviations. A mean describes the average recorded value in a group; a standard deviation describes how spread out individual values are around that average. These summaries provide a useful starting point for comparing groups, but they do not reveal the full distribution of participant results or how missing observations were handled.

What does a mean difference represent?

A mean difference compares the average in an intervention-labeled group with the average in Usual Care. The reported recalculated AES difference is 1.29 for VA MOVE versus Usual Care and 1.54 for Intervention versus Usual Care. These are unadjusted differences derived from the posted summaries. A positive difference means the intervention-labeled group has a higher posted mean than Usual Care under the subtraction order used. Whether that direction corresponds to more or less change in apathy depends on what the negative AES values represent; the record does not explicitly identify them as baseline change.

For Change in Weight, the corresponding recalculated differences are -0.01 kg for VA MOVE and -4.01 kg for Intervention, each compared with Usual Care. A negative difference indicates a lower group mean under that subtraction order. The outcome is named Change in Weight, and the registry lists kilograms as its unit. Statistical direction alone does not establish the clinical meaning of the difference or whether the result reflects a treatment effect.

Why are confidence intervals useful?

A confidence interval expresses the uncertainty around an estimated difference under the assumptions of the calculation. A narrower interval indicates greater precision; a wider interval indicates that a broader range of differences remains compatible with the data and method. For the primary comparisons, the intervals run from -2.971 to 5.551 and from -2.794 to 5.874. Both include zero. This means the posted summaries do not sharply distinguish a difference from no difference. It does not prove that the groups are the same.

For the secondary Intervention comparison, the interval runs from -7.666 to -0.354, while the VA MOVE interval runs from -3.187 to 3.167. These are unadjusted intervals calculated from posted summaries. An interval that excludes zero can be evidence of a difference under the stated calculation, but interpretation also depends on the analysis plan, outcome selection, and multiplicity. Those details are not reported in the registry record.

What does an unadjusted p-value say?

A p-value measures how incompatible the observed data are with a specified null model, assuming the model and calculation are appropriate. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. The primary unadjusted p-values are 0.553 and 0.486. For weight, they are 0.995 for VA MOVE and 0.032 for Intervention. The values accompany the recalculated comparisons; the registry record lists no reported analyses. They should not be read as a complete account of the trial's original analysis.

These recalculations use the posted group summaries and are unadjusted. They do not account for covariates or any unreported features of the original design. The discrepancy flag is false. If a sponsor's own analysis were available, that analysis would take precedence over a simple recalculation; the registry record does not list a reported analysis to compare with these results.

Why can variation matter?

Standard deviations describe variability within groups, and the posted values show that group outcomes vary. In general, greater variation makes it harder to estimate a group difference precisely, because individual results are less tightly clustered around the average. The recalculations use pooled standard deviations and also report standardized effect-size estimates. A standardized effect expresses a mean difference in relation to the variability used in the calculation; it can help describe magnitude on a common scale, but it does not remove uncertainty or make an outcome clinically important by itself.

General statistical caution is especially important when group sizes are limited or unequal, or when a summary statistic does not adequately describe a distribution. The record does not provide participant-level data, distributional plots, or details of model diagnostics. It therefore is not possible to check assumptions about outliers, skewness, or the shape of outcome distributions from the registry summary alone. The normal-approximation planning calculations are a separate exercise and should not be mistaken for a validation of the outcome analysis.

What can randomization establish?

Randomization is recorded, which is a design feature intended to reduce systematic differences between assigned groups. The registry does not report the allocation sequence, concealment details, adherence to assigned treatment, or analysis population. It also does not state whether results were analyzed according to randomized assignment. Those omissions prevent a fuller assessment of how the randomized design was implemented and how closely the posted comparisons preserve it.

Finally, the record describes a parallel design and no masking. In general, lack of masking can matter when outcomes involve participant experience, reporting, or behavior, although the AES is a scored measure and the record does not explain who administered or scored it. No claim about bias should be inferred from that missing information alone. The appropriate reading is that these summaries offer unadjusted estimates with substantial uncertainty for the primary comparisons, while important details needed to evaluate the original statistical analysis are not reported in the registry record.

11. Confidence Intervals and Precision

The primary estimates are uncertain. For VA MOVE compared with Usual Care, the recalculated mean difference is 1.29 and its 95% confidence interval extends from -2.971 to 5.551. For Intervention compared with Usual Care, the difference is 1.54 and the interval extends from -2.794 to 5.874. Each interval includes zero and allows for differences in either direction. The posted results therefore do not pin down a precise primary effect.

Confidence intervals are not a range containing a known fixed proportion of individual participants' scores. They describe uncertainty in the estimated group difference under the calculation's assumptions. They also do not establish that every value in the interval is equally plausible. The intervals provide a useful sense of the range of values compatible with the summaries and method, while the underlying unadjusted nature of the calculations and unreported analysis details remain relevant.

The secondary weight estimates illustrate that precision can differ by comparison. The VA MOVE interval ranges from -3.187 to 3.167 kg and includes zero. The Intervention interval ranges from -7.666 to -0.354 kg and excludes zero under the unadjusted calculation. That interval still has meaningful width, and its interpretation is affected by its status as a secondary result and the absence of a reported multiplicity plan.

Standard deviations and group sizes influence the precision of a mean difference: more variable outcomes and less information generally yield wider uncertainty. The posted group sizes and spreads are therefore relevant context, but the registry record does not provide enough detail to assess missing observations or the original model. Precision should be judged from the intervals alongside those reporting limitations, not from the point estimates alone.

12. Planning a Similar Trial: Sample Size

This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.

The sample-size figures are planning illustrations based on the observed effect, not the trial's original design assumptions. The registry record does not report the original sample-size justification or its planning assumptions. The stated illustration uses a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. It considers the effect to detect as a stated fraction of the observed effect. These figures are participants per arm; the note that applies to time-to-event outcomes would instead express total events, but these outcomes are continuous.

The 80% power column describes the number of participants per arm estimated to give an 80% chance of detecting the specified effect under those planning assumptions, if that effect and the assumptions hold. The 90% power column describes the corresponding planning count for a 90% chance. These are design calculations for hypothetical future studies, not outcome results. They do not indicate the probability that the current trial's findings are correct.

The rows considering 100%, 75%, and 50% of the observed effect show how the planning count changes when the assumed effect is smaller. Smaller effects are harder to distinguish from random variation, so more participants are needed for the same target power. This pattern is especially consequential when the observed effect is close to zero, as in the VA MOVE weight comparison; the resulting planning figures become very large. Such estimates should be read as illustrations sensitive to the effect-size assumption, not as firm requirements or evidence that a future study would achieve its intended result.

This is not observed power. Observed power is not a useful substitute for interpreting the confidence interval and estimate from the completed trial. The planning figures answer a different question: under the specified assumptions, what group size would be needed to target a stated power for a chosen effect? They do not repair uncertainty in the current estimates or establish whether the trial was adequately designed.

13. How the Sample Size Is Derived

Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z_1−α/2 = 1.960) and the desired power (z_1−β = 0.842 for 80% and 1.282 for 90%).

Formula

n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.

Worked calculation for this trial

1. Observed difference Δ = 1.290; pooled standard deviation σ = 7.153.
2. n = 2 × (1.96 + 0.842)² × 7.153² / 1.290² = 482.7, rounded up to 483 participants per arm for 80% power.

The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).

R code

alpha <- 0.05
z_a   <- qnorm(1 - alpha / 2)          # two-sided
delta <- 1.29                      # observed difference in means
sigma <- 7.15301774013581                     # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
  ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
  cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
              format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))

# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")

# Simulation: exact two-sample t-test using simulated means and variances
set.seed(548652)
n    <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n))             # difference in sample means
s2     <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1))   # pooled sample variance
tstat  <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))

Output from running the code

100% of observed effect: n per arm = 483 (80% power), 647 (90% power)
 75% of observed effect: n per arm = 859 (80% power), 1,149 (90% power)
 50% of observed effect: n per arm = 1,931 (80% power), 2,585 (90% power)
power.t.test: 483.6 
Simulated power at n = 483 per arm: 0.799 (20000 replicates)

The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.

14. Multiplicity, Missing Data and Analysis Populations

The registry identifies the Apathy Evaluation Scale as the primary outcome and Change in Weight as a secondary outcome. It does not report a multiplicity strategy, such as a hierarchy for testing outcomes, a correction for multiple comparisons, or a statement that the secondary outcome is exploratory. The p-values described for the pairwise comparisons are unadjusted. When several outcomes or comparisons are considered, unadjusted results can overstate the strength of evidence if they are interpreted without regard to how many opportunities there were to find a result.

The registry record lists no reported analyses and does not include the original statistical analysis plan. It therefore does not establish which comparisons were prespecified, whether there were other planned analyses, or whether any interim analysis occurred. Interim analyses and the original analysis plan are not reported in the registry record. These omissions make it difficult to distinguish a confirmatory finding from an exploratory result using the posted information alone.

Missing-data procedures are also not reported. The record does not explain whether all randomized participants contributed outcome data, how missing measurements were handled, or whether imputation or another method was used. The outcome group sizes differ from the enrollment figure, but the record does not explain the relationship among enrollment, randomized groups, and participants with available outcome measurements. No analysis population is specified, such as an intention-to-treat or per-protocol population.

These gaps matter because missingness and analysis choices can affect both estimated differences and uncertainty. This is a general concern, not evidence that a particular method was used or that missing data biased the results. The posted summaries support descriptive comparisons, but the registry record does not provide enough information to evaluate the full analysis process or the robustness of results to alternative assumptions.

15. Safety Results

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

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

The adverse-event record reports serious adverse events for Usual Care, VA MOVE, and Intervention. The numbers listed as at risk are 18, 38, and 45, respectively; the number affected is 0 in each group. For other adverse events, the numbers at risk are also 18, 38, and 45, and the number affected is 0 in each group. Deaths are listed as 0 in all three groups. No serious adverse-event terms are listed.

These figures describe what the registry record reports, not proof that no adverse events occurred outside the recorded categories or observation process. The record does not explain why the at-risk counts differ from the outcome group sizes, define the event-collection procedures, or provide details about event severity beyond the serious/other categories. The absence of listed events should therefore be read narrowly as zero affected among the recorded at-risk counts, not as a comprehensive guarantee of safety.

The safety categories use the same three labels as the posted outcomes. Because the registry does not fully map those labels to every intervention combination described in the study, the adverse-event results should be interpreted by their recorded group labels rather than assigned to a particular combination not explicitly identified.

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

The posted primary results estimate modest differences in mean AES values between Usual Care and the other outcome categories, but the confidence intervals are broad and include zero. The results do not precisely establish the direction or size of a difference in the primary outcome. The registry identifies a lower AES score as better, but does not explicitly state that the posted negative mean values are changes from baseline. This reporting ambiguity further limits claims about improvement.

The secondary weight comparison for Intervention has an unadjusted interval that excludes zero, while the VA MOVE comparison has an interval that includes zero. This is a statistical pattern in the posted summaries, not proof that an intervention works or does not work. The secondary status of the outcome, unreported multiplicity plan, and absence of a reported sponsor analysis all matter when weighing that result.

The record does not report adherence results, despite the study rationale linking apathy treatment to adherence to weight-loss programs. Nor does it report an analysis relating AES and weight outcomes. The outcome summaries therefore cannot establish that reducing apathy led to greater adherence or that adherence mediated a change in weight.

Randomization is recorded, but details about allocation, analysis population, missing data, and treatment-label mapping are not. These limits make it difficult to assess how fully the posted comparisons reflect randomized assignment. The record describes the study as completed, but completion status does not fill those gaps. The results are best understood as uncertain estimates from posted group summaries, with the limits of the registry reporting kept in view. They should not be converted into medical advice or a general claim about treatment effects in other populations.

17. Why This Trial Matters Statistically

This trial raises a useful statistical distinction between a study's motivating question and the outcomes available for analysis. The stated rationale connects apathy treatment with adherence and weight-loss program effectiveness, while the listed primary measure is apathy and the secondary measure is weight change. Without posted adherence results or an analysis linking apathy to weight, those outcomes cannot by themselves answer the full pathway described in the rationale.

The primary estimates also illustrate why a point estimate should not be interpreted alone. Their confidence intervals include zero and span differences in both directions. The associated unadjusted p-values do not establish equivalence, and the record gives no equivalence margin. In contrast, the secondary Intervention weight comparison has an unadjusted interval that excludes zero. That contrast makes clear why outcome hierarchy, multiplicity planning, and prespecification are important to interpretation.

The record further shows how outcome labels and intervention descriptions affect reproducibility. The study describes several treatment combinations, while results are posted under three group labels and the mapping is not fully explained. A reader can accurately describe the comparisons as labeled, but cannot safely assign every result to a particular intervention combination.

Finally, planning illustrations based on observed effects can be sensitive to the chosen effect fraction, especially when an observed difference is near zero. They help frame possible future designs, but are not a measure of the completed study's success or adequacy. Taken together, the case emphasizes the value of complete reporting of outcome definitions, analysis plans, missing-data handling, group mapping, and precision.

18. 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 registry record does not clearly define the primary AES values as change from baseline, despite describing reduction in score as better. This makes the interpretation of the negative means uncertain. Baseline AES values are not included in the posted outcome information, so change over time cannot be reconstructed from the registry summaries.

The arm descriptions name several combinations of MOVE, medical crisis counselling, and methylphenidate, but the posted outcomes are grouped as Usual Care, VA MOVE, and Intervention. The record does not explain the mapping between the described combinations and outcome categories. Consequently, the result labeled Intervention cannot be attributed confidently to one specific combination from the record alone.

Enrollment is listed as 101, while the outcome group sizes and adverse-event at-risk counts differ across outcomes. The registry does not explain these differences, report participant flow, or describe outcome completion. Reasons for missing measurements and the method used to address them are not reported. The analysis population is also not specified.

There is no reported statistical analysis plan or sponsor analysis in the registry record, and no multiplicity approach is described. The estimates discussed are unadjusted recalculations from group summaries. The record also does not provide participant-level distributions, baseline characteristics, adherence outcomes, or an analysis relating apathy to weight. These limitations constrain both statistical appraisal and interpretation of how the findings address the study's stated rationale.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Role of Apathy in the Effectiveness of Weight Loss Interventions — NCT00548652.
• Registry record last updated 2019-10-04; status last verified 2019-10.
• Results first posted 2019-10-04.
• 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.

22. Record Summary

NCT00548652 is a completed, randomized, parallel study with no masking, sponsored by VA Nebraska Western Iowa Health Care System. The registry records enrollment of 101, a start of 2007-08, and primary completion in 2009-05. It describes interventions involving MOVE, medical crisis counselling, and methylphenidate.

The primary outcome is the Apathy Evaluation Scale at six months; Change in Weight is listed as a secondary outcome. Recalculated unadjusted primary comparisons have confidence intervals that include zero. The secondary weight comparison labeled Intervention has an unadjusted interval that excludes zero, while the VA MOVE comparison interval includes zero. The registry record does not report analyses, multiplicity handling, missing-data methods, an original sample-size justification, or a complete mapping from described treatment combinations to outcome labels.