Efficacy and Safety Trial to Evaluate the Effect of SCH 497079 on Weight in Obese and Overweight Participants (Study P05483)(COMPLETED): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety Trial to Evaluate the Effect of SCH 497079 on Weight in Obese and Overweight Participants (Study P05483)(COMPLETED) (NCT00642993), a randomized phase 2 study. The primary outcome is Mean Change From Baseline in Body Weight at Week 12.

2. Clinical Question

The clinical question is framed as a comparison of average change, not as whether every participant lost weight or whether a particular individual reached a target. The registry record identifies body-weight change as the primary effectiveness measure and states the hypothesis that SCH 497079 would be more efficacious than placebo on that measure. The posted results report a mean change of -0.51 kilograms in the SCH 497079 arm and -0.92 kilograms in the placebo arm. The reported between-group difference was 0.41 kilograms, with the positive direction reflecting the SCH 497079 mean minus the placebo mean.

The record also lists weight-loss thresholds, waist circumference, and body mass index as additional measures. Those outcomes provide related but distinct views of change during treatment. The primary endpoint remains the average body-weight change, and the central statistical question is whether the observed between-group estimate is sufficiently precise to distinguish a group difference from values compatible with no difference. The registry record does not report the clinical threshold, if any, that would define a meaningful difference in weight.

3. Trial Design

The registry record describes a Phase 2, randomized, triple-masked, parallel-group, placebo-controlled trial. It lists 401 participants as enrolled and identifies the study as completed. The recorded start date is 2008-06-09, and the primary completion date is 2009-01-30. The sponsor is Merck Sharp & Dohme LLC. These registry entries describe the trial's design and administrative record, but do not establish why the trial was designed with its particular sample size or duration.

Participants were assigned to SCH 497079 or placebo. Both were administered orally once daily according to the arm descriptions. The parallel-group structure means that each participant was assigned to one treatment group, and the reported primary comparison is between the groups' average changes. Triple masking indicates the masking category recorded in the registry; further details about which roles were masked or how masking was implemented are not reported in the registry record.

The primary outcome was mean change from baseline in body weight at Week 12, measured in kilograms. The primary analysis population is described as the intent-to-treat population consisting of participants who received randomized treatment assignment and had a baseline body-weight measurement and at least one post-baseline body-weight measurement. The endpoint description also says that last observation carried forward was applied for participants who discontinued, and that a dropout before Week 12 could be included if the participant had a valid baseline and at least one post-baseline value.

The registry record does not report the original sample-size justification, the planned allocation ratio, or a detailed statistical analysis plan. The posted primary arm counts are 255 for SCH 497079 and 130 for placebo; the record does not explain the difference between those outcome-analysis counts and the total enrollment.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-treat population consisted of all participants who received randomized treatment assignment and had the baseline body weight measurement and at least one post-baseline body weight measurement.

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 Mean Change From Baseline in Body Weight at Week 12, measured over Baseline and Week 12.

The primary endpoint is mean change from baseline in body weight at Week 12, with weight measured in kilograms. Change from baseline expresses the follow-up measurement relative to each participant's starting measurement, while the group mean describes the average change among participants included in the analysis. The reported endpoint is therefore a continuous outcome, rather than a count of participants crossing a weight-loss threshold.

This endpoint is used to compare average weight change between the randomized groups. A mean difference summarizes the contrast in the same measurement units as the endpoint, which makes its direction and scale interpretable in kilograms. The arm means were -0.51 kilograms for SCH 497079 and -0.92 kilograms for placebo. The posted comparison, calculated as SCH 497079 minus placebo, was 0.41 kilograms. A positive difference in this setup indicates that the SCH 497079 mean change was higher, or less negative, than the placebo mean change; it does not by itself determine whether the difference is statistically persuasive or clinically important.

The endpoint description specifies that dropouts before Week 12 could contribute if they had a valid baseline and at least one post-baseline body-weight measurement, with last observation carried forward applied to participants who discontinued. Such an approach uses an earlier observed value to stand in for a later one. As a general statistical consideration, that assumption can affect the estimate if participants' outcomes would have continued to change after the last observation. The registry record does not report additional details about how this assumption was assessed.

Body weight is the primary measure identified in the record; waist circumference, body mass index, and weight-loss thresholds are listed as additional measures. These outcomes can complement the primary mean-change comparison, but they do not replace it.

7. Results Posted in the Registry

• SCH 497079: mean -0.51 versus -0.92 on control; difference 0.41 (95% CI -0.22 to 1.04), standardized effect d = 0.14; z-test p = 0.203.

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.

Percentage of Participants Demonstrating a Weight Loss ≥5% at Week 12

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • SCH 497079: 7.1% (18/255) versus 11.5% (15/130) on control; risk difference -4.5 percentage points (95% CI -10.8 to 1.8), risk ratio 0.61 (0.32–1.17); unadjusted two-proportion z-test p = 0.138.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between SCH 497079 and the control. The interval gives the range of effects that remain compatible with the data.

Percentage of Participants Demonstrating a Weight Loss ≥10% at Week 12

• Endpoint type: Binary: the percentage of participants with the event (counts rebuilt from the posted percentages and group sizes).
• Test: Unadjusted two-proportion z-test, with a Wald 95% confidence interval for the risk difference.
• Result:
  • SCH 497079: 1.6% (4/255) versus 0.8% (1/130) on control; risk difference 0.8 percentage points (95% CI -1.3 to 2.9), risk ratio 2.04 (0.23–18.06); unadjusted two-proportion z-test p = 0.512.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between SCH 497079 and the control. The interval gives the range of effects that remain compatible with the data.

Mean Change From Baseline in Waist Circumference at Week 12

• 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 errors.
• Result:
  • SCH 497079: mean -1.22 versus -0.94 on control; difference -0.28 (95% CI -1.23 to 0.67), standardized effect d = -0.06; z-test p = 0.565.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between SCH 497079 and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover two types of questions: whether participants met specified weight-loss thresholds by Week 12, and how average waist circumference and body mass index changed. Taken together, these measures do not present a uniform pattern that clearly reinforces the primary comparison. The posted estimates vary in direction across the different outcomes, and the estimates are generally uncertain. The primary mean-change result remains the principal effectiveness comparison identified by the registry.

Secondary outcomes can add context because a group mean and the share of participants crossing a threshold answer different questions. A mean may shift even when relatively few participants cross a chosen cutoff, while threshold outcomes discard information about the amount of change within each category. Waist circumference and body mass index likewise describe different aspects of body size from body weight itself. These outcomes can therefore complement, but not replace, the primary endpoint.

The registry reports unadjusted secondary analyses and does not report a multiplicity adjustment or a planned hierarchy for interpreting them. As a general statistical consideration, evaluating several outcomes separately increases the chance that at least one result may appear notable through chance alone. This makes isolated secondary p-values weaker evidence than a prespecified primary test, especially when there is no reported adjustment or confirmatory plan.

The overall pattern should consequently be read as exploratory context around the primary result. It does not establish a consistent effect across measures, and it does not resolve the uncertainty in the primary estimate. The registry record does not report whether particular secondary findings were intended to be confirmatory or how they were prioritized.

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

• Percentage of Participants Demonstrating a Weight Loss ≥5% at Week 12
• Percentage of Participants Demonstrating a Weight Loss ≥10% at Week 12
• Mean Change From Baseline in Waist Circumference at Week 12
• Mean Change From Baseline in Body Mass Index (BMI) at Week 12

9. Statistical Interpretation

10. Statistical Methods Explained

For the primary outcome, the registry reports an analysis of variance (ANOVA) and a difference in means. The reported estimate compares the mean body-weight change in the SCH 497079 group with the mean change in the placebo group. The posted value is 0.41 kilograms. In this contrast, the arm order is SCH 497079 minus placebo, so positive values mean the SCH 497079 mean is higher than the placebo mean. Since the arm means are negative, the positive contrast corresponds to a less negative mean change in the SCH 497079 group.

As a general statistical explanation, a mean difference is useful for continuous outcomes because it preserves the endpoint's units. Here, the units are kilograms. The difference describes the average contrast between groups; it does not describe the range of individual responses, the proportion of participants with a particular outcome, or what happened to every participant. The standard errors reported beside the arm means describe uncertainty in those estimated means, not the spread of all individual measurements.

The sponsor-reported analysis gives a 95% confidence interval from -0.20 to 1.03 and p = 0.187. As a general explanation, a confidence interval describes a range of effect estimates reasonably compatible with the data under the method's assumptions. It is not a range containing a stated proportion of individual participant outcomes. Because this interval includes zero, the result is compatible with no mean difference, while also allowing differences in either direction across its span. A p-value describes how unusual the data, or more extreme data, would be under a specified null hypothesis and model. It is not the probability that the null hypothesis is true.

A simple unadjusted recalculation based on the posted means and standard errors gives the same point estimate, 0.41 kilograms, and p = 0.203. That recalculation is not a substitute for the trial's own analysis. It uses summary statistics and does not reproduce any unreported adjustments or analysis details. The sponsor's reported analysis remains the reference result. The recalculated uncertainty interval also crosses zero, so the broad interpretation is not changed.

What does randomization contribute?

As a general statistical principle, random assignment is intended to make treatment groups comparable on average with respect to measured and unmeasured characteristics at the start of a trial. It supports a between-group comparison, but does not guarantee that every characteristic is balanced in a particular realized sample. The registry record identifies the trial as randomized; it does not report the randomization procedure or any stratification factors.

The record describes triple masking, but details about who was masked and how masking was maintained are not reported in the registry record. Masking can generally reduce the influence of expectations on participant behavior, care, measurement, or analysis. The registry's masking label alone does not establish which of these processes occurred in this trial.

How should the analysis population and missing values be understood?

The intent-to-treat population is described as participants who received randomized treatment assignment and had baseline weight plus at least one post-baseline body-weight value. The endpoint description says that a participant who discontinued before Week 12 could be included if those measurements were available. It also specifies last observation carried forward for participants who discontinued. In general, this method carries a participant's last observed value forward to represent a later time point. Its validity depends on assumptions about what would have happened after the last measurement; the registry record does not report a sensitivity analysis or further justification for that assumption.

The record reports 255 participants in the SCH 497079 primary outcome group and 130 in the placebo group. The safety group denominators differ, at 267 and 134. The registry record does not explain the differences, so these counts should be understood in the context of their respective reported analyses rather than treated as interchangeable.

What do the secondary analyses add?

The secondary outcomes include binary weight-loss thresholds and continuous measures of waist circumference and body mass index. Binary outcomes count whether participants meet a defined threshold; continuous outcomes compare average measured changes. The posted analyses use different methods for these kinds of outcomes. The weight-threshold results report Cochran-Mantel-Haenszel odds ratios, while the waist-circumference analysis reports ANOVA and a mean difference. The methods and scales differ, so the estimates are not directly interchangeable with the primary mean difference.

As a general statistical consideration, multiple analyses create more opportunities for chance findings when each is assessed separately. The registry record does not report a multiplicity adjustment or a prespecified hierarchy for interpreting the secondary outcomes. Their reported p-values should therefore be read as unadjusted evidence for their individual comparisons, not as a single confirmatory test of the overall study question.

11. Confidence Intervals and Precision

The primary sponsor-reported estimate is a difference in mean change of 0.41 kilograms. Its 95% confidence interval runs from -0.20 to 1.03. This interval is wide enough to include zero and values on both sides of zero, so the direction and size of the underlying group difference remain uncertain. The interval is more informative than the point estimate alone because it shows a range of effect estimates compatible with the posted analysis.

As a general statistical explanation, precision concerns how narrowly an estimate is determined by the data and analysis. A narrower confidence interval indicates greater precision under the model used; it does not by itself establish that the estimate is unbiased or clinically important. An interval that includes zero does not prove there is no difference. It indicates that the data do not exclude zero at the confidence level used, while other values within the interval remain compatible with the result.

The unadjusted recalculation gives the same point estimate, 0.41 kilograms, but its p-value is 0.203 rather than the sponsor-reported 0.187. Differences between summary-statistic recalculation and the trial's reported model can occur because the exact analysis details may differ. The registry record reports ANOVA for the sponsor analysis but does not provide enough detail to reconstruct every model component. The sponsor interval and p-value should therefore be used as the principal account of the trial's own result.

The secondary estimates also have uncertainty. The registry reports confidence intervals for the weight-threshold comparisons and waist-circumference comparison; these intervals are broad and include values compatible with no difference. For example, the reported odds ratio for reaching at least 5% weight loss is 0.58, with a 95% confidence interval from 0.28 to 1.20. The reported odds ratio for reaching at least 10% weight loss is 1.55, with a 95% confidence interval from 0.24 to 9.93. Such intervals show why a point estimate alone should not carry the interpretation.

Uncertainty also reflects the number of analyzed participants and the variability of outcomes. The primary outcome counts were 255 and 130, while the record does not fully explain the difference from enrollment. Confidence intervals quantify statistical uncertainty under the analysis; they do not resolve unreported details about missing data, clinical relevance, or the generalizability of the trial population.

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 planning figures are participants per arm, rather than total participants or total events. They are illustrations calculated from the observed effect, not the trial's original design calculation. The stated planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect to detect is set to the stated fraction of the observed effect. The original trial's own sample-size assumptions are not reported in the registry record.

The 80% power column gives the number of participants per arm that the planning calculation associates with an 80% chance of detecting the chosen effect under those assumptions, if that effect is the true one and the calculation's model applies. The 90% power column uses a higher target chance of detection, so it requires more participants per arm for the same assumed effect. These are planning concepts, not guarantees about what a future study would find.

Planning for 100% of the observed effect uses the effect estimate from this trial as the target. Planning for 75% or 50% of the observed effect assumes a smaller target effect. Smaller effects are harder to distinguish from random variation, so they require more participants per arm for the same target power. This general relationship is reflected across the planning illustrations for the primary and secondary outcomes.

These figures are not observed power. They do not describe the probability that the completed trial's result is true, nor do they change the interpretation of the confidence interval or p-value. They are hypothetical design illustrations, and the values depend on the planning assumptions and on treating the observed effect as the starting point. The registry record does not report the assumptions used when the original trial was planned.

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 = 0.410; pooled standard deviation σ = 3.011.
2. n = 2 × (1.96 + 0.842)² × 3.011² / 0.410² = 846.5, rounded up to 847 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 <- 0.41                      # observed difference in means
sigma <- 3.01079389788829                     # 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(642993)
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 = 847 (80% power), 1,134 (90% power)
 75% of observed effect: n per arm = 1,505 (80% power), 2,015 (90% power)
 50% of observed effect: n per arm = 3,387 (80% power), 4,533 (90% power)
power.t.test: 847.5 
Simulated power at n = 847 per arm: 0.798 (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. Analyses Reported by the Sponsor

The registry's reported primary analysis uses ANOVA and gives a difference in means of 0.41 kilograms, with a 95% confidence interval from -0.20 to 1.03 and p = 0.187. A simple unadjusted recalculation from the posted arm means and standard errors gives the same difference, 0.41 kilograms, and p = 0.203. The point estimates therefore agree, while the p-values are close but not identical.

The recalculation uses only the posted summary statistics and is not a reconstruction of every detail of the sponsor's analysis. The registry record does not provide enough information to reproduce all analysis choices. The sponsor-reported model and result are the appropriate primary account of the trial's own analysis. In this case, the small difference between the reported and recalculated p-values does not alter the broad interpretation: the reported confidence interval includes zero, and the unadjusted recalculation's uncertainty interval also crosses zero.

The results record does not flag a discrepancy between the posted result and the recalculation. The recalculated value is best treated as a basic consistency check, not as a replacement analysis. Neither estimate should be read without its uncertainty interval or as a direct statement about clinical importance.

15. Multiplicity, Missing Data and Analysis Populations

The registry record lists one primary outcome and four posted secondary outcomes. It reports five outcome measures and five analyses. Although that accounting describes the posted results, it does not specify how the analyses were prioritized or whether statistical significance was adjusted for testing multiple outcomes. A multiplicity adjustment, if planned and applied, is not reported in the registry record.

As a general statistical explanation, testing several outcomes increases the opportunity for a chance result to look noteworthy when each test is considered separately. Adjustment methods or a prespecified testing sequence can address that issue, but the record does not identify such a method or sequence. The secondary p-values should therefore be regarded as unadjusted comparisons. Their interpretation is more cautious than that of a single primary endpoint selected in advance, although details of the prespecified plan are not reported.

The registry does report an intent-to-treat population definition for the primary outcome and describes last observation carried forward for participants who discontinued. It says participants needed a baseline measurement and at least one post-baseline measurement to enter that population. It also says dropouts before Week 12 could be included when those measurements were available. Further information about missingness patterns, reasons for missing measurements, alternative imputation methods, or sensitivity analyses is not reported in the registry record.

As a general consideration, missing-data methods rely on assumptions about the unobserved outcomes. Last observation carried forward treats a participant's last recorded value as a stand-in for a later outcome; that may not reflect the participant's actual subsequent course. The record does not report analyses testing how conclusions would change under different assumptions.

The primary description identifies ANOVA as the sponsor's method, but a fuller statistical analysis plan, including covariate adjustment, treatment of protocol deviations, and any interim analyses, is not reported in the registry record. The randomization procedure and details of masking are also not reported. These omissions limit independent reconstruction of the analysis, not the ability to describe the posted estimate and interval.

16. 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: cartilage injury (0.7%), chest pain (0.4%), pneumonia (0.4%), femur fracture (0.4%), breast cancer (0.4%).

The safety record lists 267 participants at risk in the SCH 497079 group and 134 in the placebo group. Serious adverse events were reported for 5 participants in the SCH 497079 group and 1 in the placebo group. Other adverse events were reported for 142 participants and 26 participants, respectively. These denominators differ from the primary efficacy outcome counts of 255 and 130; the registry record does not explain the difference.

The serious-event terms listed include cartilage injury, chest pain, pneumonia, femur fracture, breast cancer, and cerebrovascular accident. The registry record gives 0.7% for cartilage injury and 0.4% for each of the other listed terms. These are descriptive safety listings. The record does not provide enough detail to determine causal attribution, event timing, severity beyond the serious-event classification, or whether events overlapped within participants.

Deaths are not reported in the registry record. The listed adverse-event counts should not be interpreted as a complete comparison of risk without the event definitions, follow-up details, and analysis methods. They describe the posted safety figures, not a causal conclusion about treatment.

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

The primary result estimates a between-group difference in mean body-weight change of 0.41 kilograms, with the SCH 497079 mean higher, or less negative, than the placebo mean. The sponsor-reported 95% confidence interval extends from -0.20 to 1.03, and the reported p-value is 0.187. These results indicate substantial uncertainty about the size and direction of the underlying difference. The interval includes zero, so the data do not rule out no mean difference under the reported analysis.

This does not prove that the treatments were equivalent. Demonstrating equivalence would require a prespecified equivalence margin and an analysis designed to assess whether the interval falls within that margin. Such a margin and an equivalence analysis are not reported in the registry record. Nor does a p-value above a conventional threshold establish that there is no effect.

The result also does not show whether a difference is clinically important. The registry record does not report a threshold for a meaningful change in body weight. Statistical uncertainty and clinical importance are distinct: a confidence interval describes the range of effect estimates compatible with the analysis, while judging importance requires a relevant clinical criterion that is not recorded.

The secondary outcomes add information about weight-loss thresholds and other body-size measures, but they do not yield a consistent, precise pattern that resolves the primary uncertainty. Their unadjusted status and the absence of a reported multiplicity plan further limit how strongly isolated secondary findings can be interpreted. Safety figures are descriptive and do not establish whether events were caused by treatment.

As a general interpretation principle, a trial result applies most directly to its enrolled participants and the conditions under which the trial was conducted. The registry record describes an obese and overweight population and a once-daily oral intervention, but does not provide detailed demographic characteristics or sufficient information to judge how well the findings extend to other populations or settings. The posted results should be read as estimates with limits, rather than as proof of benefit, absence of effect, or safety.

18. Why This Trial Matters Statistically

This trial illustrates why an estimated difference should be read alongside its uncertainty. The primary point estimate is 0.41 kilograms, but the 95% confidence interval ranges from -0.20 to 1.03. The interval crosses zero, meaning that the posted analysis is compatible with no difference and with effects in either direction. The p-value alone cannot communicate that full range of plausible estimates.

It also illustrates the distinction between a group mean and individual outcomes. A mean body-weight change summarizes the average contrast, while the secondary threshold measures count participants reaching specified cutoffs. Those measures can tell different stories because they represent different features of the outcome. Interpreting one as if it directly described the other would lose important information.

The registry includes simple planning illustrations based on the observed effect. These show how sample-size requirements depend on the target effect and desired power under stated assumptions. They are not the original design justification and are not observed power. Keeping planning calculations separate from the completed trial's evidence helps avoid treating a post hoc illustration as a design fact.

Finally, the record offers a useful example of the limits of registry-level reporting. It identifies the primary analysis method, endpoint population, and missing-value approach, but does not report the full statistical plan, multiplicity strategy, or original sample-size assumptions. The posted data still permit a clear description of the main estimate and its precision, while leaving important questions about analysis details and interpretation unresolved.

19. 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 report the original sample-size justification or the assumptions used to plan enrollment. The planning illustrations are based on the observed effects and cannot establish what effect the trial was designed to detect. The record also does not describe a multiplicity adjustment or hierarchy for the secondary endpoints, limiting their confirmatory interpretation.

Missing-data handling is a further limitation. The primary description specifies last observation carried forward for participants who discontinued, but does not report missingness patterns, reasons for discontinuation, or sensitivity analyses using alternative assumptions. Because the method carries an earlier measurement forward, the analysis can depend on whether that value reasonably represents the later outcome.

The efficacy and safety counts differ: the primary outcome includes 255 participants in the SCH 497079 arm and 130 in placebo, while the safety denominators are 267 and 134. The registry record does not explain the difference. This prevents a complete assessment of how the analysis populations relate to total enrollment. The record also does not report detailed participant characteristics, which limits assessment of how broadly the results may apply.

The sponsor's primary analysis is reported as ANOVA, but full model details are not reported in the registry record. The randomization procedure, masking implementation, interim analyses, and broader statistical analysis plan are also not reported. These gaps limit independent reproduction of the analysis. In addition, no clinical threshold for a meaningful weight difference is reported, so the clinical importance of the estimate cannot be judged from the record alone.

Safety reporting is also limited to descriptive counts and listed serious-event terms. Deaths are not reported in the registry record, and details needed to assess event timing, overlap, and causal attribution are not included in the posted information.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy and Safety Trial to Evaluate the Effect of SCH 497079 on Weight in Obese and Overweight Participants (Study P05483)(COMPLETED) — NCT00642993.
• Registry record last updated 2018-09-10; status last verified 2018-08.
• Results first posted 2016-10-27.
• 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.

23. Record Summary

The record describes a completed Phase 2, randomized, triple-masked, parallel-group, placebo-controlled trial of once-daily oral SCH 497079 in obese and overweight participants. It lists 401 participants enrolled. The primary endpoint was mean change from baseline in body weight at Week 12.

The sponsor-reported difference in mean change was 0.41 kilograms, with a 95% confidence interval from -0.20 to 1.03 and p = 0.187. The interval includes zero, and the registry record does not report a threshold for clinical importance. Secondary outcomes address weight-loss thresholds, waist circumference, and body mass index; their results are less conclusive and are not reported as multiplicity-adjusted.

The primary analysis description specifies an intent-to-treat population with baseline and at least one post-baseline measurement, and last observation carried forward for participants who discontinued. Safety figures are reported separately, with deaths not reported in the registry record. The original sample-size justification, detailed statistical plan, and multiplicity strategy are not reported.