Using D-cycloserine to Enhance the Benefits of Cognitive Behavioral Therapy for Schizophrenia: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Using D-cycloserine to Enhance the Benefits of Cognitive Behavioral Therapy for Schizophrenia (NCT00742079), a randomized phase 4 study. The primary outcome is Change in Alternative Beliefs Assessment.

2. Clinical Question

The clinical question is about whether pretreatment before therapy is associated with a change in a task-based measure of cognitive flexibility. It is not a direct measure of symptom remission or a broad measure of functioning. The endpoint records the number of alternative explanations generated for social scenarios, including scenarios tailored to a participant's delusions. A higher score reflects more alternative beliefs on this assessment.

The registry record lists four secondary outcomes concerning delusion ratings, cognitive insight, probabilistic reasoning, and delusion assessment. These measures broaden the questions considered, but their results do not replace the primary endpoint. The record does not report an analysis of participant traits that might predict a response.

3. Trial Design

The registry record describes a Phase 4, randomized, quadruple-masked crossover study sponsored by Massachusetts General Hospital. Its status is completed. The recorded study start is 2006-09, and primary completion is recorded as 2010-07. The enrollment listed in the record is 21.

The two sequences differed in the order of pretreatment. In the D-cycloserine-then-placebo sequence, participants received D-cycloserine before a cognitive behavioral therapy session on Week 1 and placebo before a session on Week 2. In the other sequence, placebo came before the Week 1 session and D-cycloserine before the Week 2 session. Thus, each sequence included both pretreatments, with their order reversed.

A crossover design compares conditions experienced at different times, rather than assigning each participant to only one condition throughout. In general, this can make within-person comparisons informative, but interpretation can depend on the timing of measurements and on possible carryover between periods. The registry record does not report a washout interval, a carryover assessment, or a detailed analysis accounting for paired observations. It also does not report the original design assumptions or a sample-size justification.

Posted arm summaries give the primary outcome mean and standard deviation for D-cycloserine and placebo, each with n of 20. Those aggregate summaries do not describe how individual participants' scores changed between conditions. The registry record lists no reported analyses for the secondary outcomes. Therefore, the posted summary statistics can be described, but they do not reveal the full analysis strategy or whether a model used the crossover structure.

Quadruple masking is the registry's description of masking; the record does not detail which roles were masked or how masking was maintained. Randomized allocation and crossover sequencing are recorded, but the method used to generate or conceal the allocation is not reported in the registry record.

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: 31 participants were screened, 10 were excluded (7 did not meet inclusion criteria and 2 refused to participate, 1 excluded for reasons not listed in study publication)

Overall Study

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 Change in Alternative Beliefs Assessment, measured over Baseline to Week 2.

The primary endpoint is change in the Alternative Beliefs Assessment from baseline to Week 2. The assessment uses nine vignettes about social interactions: three with neutral content, three with negatively-valenced content, and three tailored to the participant's specific delusions. For each vignette, participants were asked to generate as many explanations as they could, and the number produced for each item was recorded.

The total score adds the alternative beliefs generated across the vignettes. It has no fixed maximum: the score can range from 0 to as many explanations as a person can produce. The endpoint is reported in units on a scale, as a mean with standard deviation. The registry record identifies a higher number of generated alternatives with greater cognitive flexibility.

This measure was used to assess a cognitive process that the study's rationale connects to cognitive behavioral therapy. Generating alternative explanations is relevant to examining whether participants can consider interpretations beyond an initial belief, including beliefs linked to delusions. That makes the assessment a task-based measure of cognitive flexibility, rather than a direct rating of clinical improvement.

The endpoint description explains how the score was constructed, but the registry record does not report additional information about its measurement properties, its interpretation in clinical practice, or a threshold for meaningful change. Accordingly, the posted result describes a difference in this assessment score; it does not by itself establish the meaning of that difference for symptoms or daily life.

7. Results Posted in the Registry

• D-cycloserine: mean 14.05 versus 10.70 on control; difference 3.35 (95% CI -5.63 to 12.33), standardized effect d = 0.23; z-test p = 0.465.

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 Psychotic Rating Scales (PSYRATS) Delusion Score

• 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:
  • D-cycloserine: mean -0.89 versus -0.47 on control; difference -0.42 (95% CI -2.20 to 1.36), standardized effect d = -0.15; z-test p = 0.644.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between D-cycloserine and the control. The interval gives the range of effects that remain compatible with the data.

Change in Bead Task Score Measuring Probabilistic Reasoning

• 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:
  • D-cycloserine: mean 0.45 versus 0.10 on control; difference 0.35 (95% CI -2.64 to 3.34), standardized effect d = 0.07; z-test p = 0.819.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between D-cycloserine and the control. The interval gives the range of effects that remain compatible with the data.

Change in the Maudsley Assessment of Delusions Scale

• 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:
  • D-cycloserine: mean 0.05 versus -0.16 on control; difference 0.21 (95% CI -0.04 to 0.46), standardized effect d = 0.55; z-test p = 0.093.
• Interpretation:
  • The 95% confidence interval includes no difference, so these data do not show a statistically significant difference between D-cycloserine and the control. The interval gives the range of effects that remain compatible with the data.

The secondary outcomes cover several related but distinct constructs: delusion severity, cognitive insight, probabilistic reasoning, and delusion assessment. Across the posted unadjusted mean differences, the estimates vary in direction and size. Their reported intervals include zero, and the unadjusted p-values vary. This pattern does not form a consistent, precise signal across all measures.

The primary endpoint concerns the generation of alternative beliefs, while the secondary measures assess other aspects of delusions and reasoning. They can add context to the primary result, but they are not interchangeable measures of the same outcome. Similarity or difference in their results would not by itself validate or overturn the primary comparison. The secondary results should be interpreted as exploratory context rather than as independent confirmation of the primary finding.

There are four posted secondary outcomes. When several outcomes are examined, the chance of finding at least one apparently notable result by chance can increase. In general, a multiplicity adjustment can address this issue, or a study can specify in advance how multiple outcomes will be interpreted. The registry record does not report a multiplicity adjustment, a hierarchy for secondary outcomes, or the analysis plan used for them. Their unadjusted results therefore carry less inferential weight than a prespecified, appropriately controlled set of analyses would.

The registry record lists no reported analyses for these secondary outcomes, and the posted comparisons are unadjusted recalculations from summary statistics. Their intervals and p-values should not be treated as sponsor-confirmed findings. The differing endpoint sample sizes also make it important not to assume that every measure has identical data availability or was analyzed in the same way. Reasons for any differences in endpoint sample size are not reported in the registry record.

Overall, the secondary findings broaden the descriptive picture but do not resolve the uncertainty in the primary result. The record does not report whether secondary analyses were prespecified, how missing data were handled, or whether a formal correction for multiple testing was used.

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

• Change in Psychotic Rating Scales (PSYRATS) Delusion Score
• Change in Beck Cognitive Insight Scale (BCIS)
• Change in Bead Task Score Measuring Probabilistic Reasoning
• Change in the Maudsley Assessment of Delusions Scale

9. Statistical Interpretation

10. Statistical Methods Explained

The primary outcome is continuous: it is a numerical score rather than a count of participants with or without an event. The registry record reports each condition's mean and standard deviation. A mean describes the central value of the observed scores, while the standard deviation describes how spread out scores are around that mean. The means are useful for seeing the direction of the observed contrast; the standard deviations help show how variable the scores were.

The primary comparison is a mean difference. In plain terms, it subtracts the placebo mean from the D-cycloserine mean. The posted summary statistics yield a recalculated difference of 3.35 units. This is an unadjusted contrast: it does not account for covariates or make adjustments for other features of the trial. The registry record does not report a model-based or sponsor-reported primary analysis. Since the design is crossover, the simple contrast based on group summaries cannot represent the within-person relationship between scores unless the required paired information is available.

The reported interval around the mean difference communicates uncertainty about the estimate. In general, a confidence interval is a range of values compatible with the data and the method used to calculate it. A narrow interval indicates greater precision than a wide interval, while an interval spanning zero means the data do not clearly distinguish a positive difference from a negative one under the stated method. The registry record does not state the confidence level or calculation method for the posted interval, so those details cannot be assessed from the record.

The unadjusted p-value is 0.465. In general, a p-value measures how unusual data at least as incompatible with a specified null hypothesis would be if that null hypothesis and the test assumptions were true. It is not the probability that the null hypothesis is true, and it is not a measure of effect size. The registry record does not report the test used or a prespecified primary analysis plan, so the p-value should be interpreted as a posted unadjusted value rather than as a complete account of the analysis.

Why does the crossover structure matter?

In a crossover study, participants receive conditions in sequence, so measurements from the same person can be related. A paired analysis can use this relationship and may differ from a comparison based only on separate means and standard deviations. The registry record identifies a crossover model and two reversed sequences, but does not report paired differences, within-person correlations, period effects, sequence effects, or carryover analyses. A simple unadjusted recalculation from marginal summaries cannot recreate those details.

Carryover is a general concern when an earlier condition could influence measurements during a later period. Period effects are general changes related to when a condition is received or when an outcome is measured. A crossover analysis may need to consider such features, depending on the design and assumptions. The registry record does not say whether these issues were evaluated, so no conclusion about their presence or absence is warranted.

What do variability and over-dispersion mean?

For a continuous score, standard deviation is a descriptive measure of spread. The primary endpoint is an unbounded count of explanations, but it is reported as a continuous mean and standard deviation. In general, count outcomes can have variability that differs from what a simple model assumes; over-dispersion means the observed variability is greater than the model's expected variability. That issue can affect standard errors and inference if a count model is used. The registry record does not say that a count model was used, and it does not report an over-dispersion assessment. The posted analysis should therefore not be described as having addressed or failed to address over-dispersion.

For inference, an analysis needs a clearly specified unit of analysis, outcome definition, comparison, and assumptions. The endpoint description identifies the measure and timeframe, and the registry identifies the crossover design, but detailed statistical methods are not reported. The registry record lists no reported analyses for the secondary outcomes. It also does not report the handling of missing observations, the analysis population, or a multiplicity procedure.

All recalculated comparisons on the page are unadjusted calculations from the posted summary statistics. The discrepancy indicator is false, so there is no stated conflict that would cause a recalculated result to take precedence over a sponsor analysis. Nevertheless, no sponsor-reported analysis is listed for the primary endpoint. These calculations are useful for transparent description of the posted means, but they cannot supply details absent from the registry record.

11. Confidence Intervals and Precision

The primary mean difference is 3.35 units, with a reported interval from -5.633 to 12.33. The interval includes zero, extends into negative values, and also extends to positive values well above the point estimate. This width indicates that the estimate is imprecise: the posted summary data do not pin down the size or direction of the difference closely.

In general, an interval around an estimate conveys a range of values that remain compatible with the data and the calculation method. The interval is more informative than the point estimate alone because it shows the uncertainty around that estimate. However, the registry record does not report the interval's confidence level or the method used to calculate it. The interval should not be assigned a particular confidence level without that information.

The primary outcome standard deviations are 12.71 for D-cycloserine and 16.08 for placebo, compared with a mean difference of 3.35. This contrast in scale suggests that individual scores varied considerably in relation to the estimated difference. The endpoint sample summaries list n of 20 for each condition, but the record does not report how missing measurements were handled or how the crossover pairing was used in the inferential calculation.

Imprecision is not evidence that the conditions are identical. It means the available result leaves a broad range of possibilities unresolved. The estimate could be consistent with a negative difference, little difference, or a positive difference. Interpreting which values would matter clinically also requires a meaningful-change threshold, and the registry record does not report one.

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, not total events. They are illustrations based on the observed effect, rather than the original trial's design assumptions. The planning assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. Each scenario targets the stated fraction of the observed effect. The registry record does not report the trial's own original sample-size assumptions or justification.

The 80% power column describes the number of participants per arm that the planning calculation estimates would be needed for an 80% chance of detecting the target effect under those assumptions, if that effect and the assumptions were correct. The 90% power column gives the corresponding planning figure for a 90% chance. These are design-planning concepts, not guarantees about what a future study will find. The planning numbers are based on the posted observed effect, which itself is uncertain.

The scenarios consider planning for 100% of the observed effect, 75% of the observed effect, and 50% of the observed effect. Smaller effects need more participants to detect under the same assumptions. The figures can therefore be used to see how planning requirements change when a future study aims to detect a smaller effect than the observed estimate. They should not be treated as evidence about the probability that this completed trial detected an effect; this is not observed power.

Any curve associated with the planning exercise should be read as a representation of these assumptions and scenarios, not as observed trial results. The planning exercise uses a normal approximation and equal allocation, while the registry describes a crossover design. The registry record does not report whether the original design used these assumptions, and the illustrations do not establish the sample size needed for a crossover analysis.

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 = 3.350; pooled standard deviation σ = 14.493.
2. n = 2 × (1.96 + 0.842)² × 14.493² / 3.350² = 293.8, rounded up to 294 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 <- 3.35                      # observed difference in means
sigma <- 14.4932829269286                     # 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(742079)
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 = 294 (80% power), 394 (90% power)
 75% of observed effect: n per arm = 523 (80% power), 700 (90% power)
 50% of observed effect: n per arm = 1,176 (80% power), 1,574 (90% power)
power.t.test: 294.8 
Simulated power at n = 294 per arm: 0.797 (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 record identifies a primary endpoint and four secondary outcomes. It does not report a statistical plan describing how the primary and secondary outcomes were prioritized, whether any secondary outcome was designated as confirmatory, or how multiplicity was addressed. A multiplicity method matters because conducting several tests can raise the likelihood of at least one apparently unusual result even when none of the underlying effects is real. Without a stated procedure, the secondary p-values should be read as unadjusted and exploratory rather than as a family of controlled confirmatory tests.

Missing-data handling is also not reported in the registry record. Posted sample sizes differ across outcomes: the primary outcome and Bead Task summaries list n of 20 for each condition, while the PSYRATS and Maudsley summaries list n of 19 for each condition. The record does not explain why these endpoint counts differ, whether missingness occurred, what caused any missing measurements, or whether an imputation or other method was used. These counts alone do not establish the number of people with complete paired data in the crossover design.

The analysis populations are not reported in the registry record. It is not clear whether an intention-to-treat, per-protocol, or other population was used, or how participants who did not complete both periods were handled. No participant flow or endpoint-specific disposition information is reported in the registry record from the registry record.

The crossover design makes the analysis population and missingness particularly relevant in general, because paired comparisons depend on observations across periods. The registry record does not report whether the posted comparisons include paired data, how period or sequence was handled, or whether a carryover assessment was made. These omissions limit the ability to assess the precision and potential bias of the posted comparisons.

These are reporting gaps, not evidence that a particular method was or was not used. The registry record does not report interim analyses, a detailed statistical analysis plan, or the original sample-size justification.

15. 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 registry record lists serious adverse events for the two treatment-order groups. In the D-cycloserine-then-placebo group, 0 serious adverse events are recorded among 11 at risk. In the placebo-then-D-cycloserine group, 0 serious adverse events are recorded among 10 at risk. The record also lists 0 other adverse events among 11 at risk in the first group and 0 among 10 at risk in the second group.

These are group-level registry counts. The order labels describe the sequences, so the figures should not be interpreted as a separate, direct comparison of exposure-specific risks for D-cycloserine and placebo. The registry record does not provide event-level detail or an analysis comparing safety between conditions. Death counts are not reported in the registry record.

A zero count in these summaries means that no events of that category were recorded for the listed group in the registry results. It does not prove that the risk is zero, particularly when the number at risk is limited. The record's safety figures should be read as descriptive counts, not as evidence that an intervention is safe or unsafe.

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

The posted primary result describes a mean difference in the Alternative Beliefs Assessment, a task-based measure of how many alternative explanations participants generated for social vignettes. The D-cycloserine condition had a higher posted mean than placebo, and the recalculated unadjusted difference was 3.35 units. The reported interval is broad and includes both negative and positive differences. The result therefore leaves substantial uncertainty about the direction and size of the contrast.

This finding does not establish that D-cycloserine improves outcomes, and it does not establish that it has no effect. The interval and unadjusted p-value do not support a definitive conclusion about the presence or absence of a difference. A statistically nonsignificant result is not proof of equivalence. Equivalence would require a prespecified margin and an analysis designed to assess it; neither is reported in the registry record.

The endpoint is not a direct symptom score, a measure of functioning, or a patient-centered threshold. Although the assessment is described as reflecting cognitive flexibility, the registry record does not state what size of change would be meaningful to participants or clinicians. The result cannot be translated into a clinical benefit or harm from the posted statistics alone.

The timeframe is baseline to Week 2, in a crossover study where D-cycloserine or placebo preceded cognitive behavioral therapy sessions. The registry record does not report longer-term outcomes or a detailed analysis of carryover and period effects. It also does not report an analysis of which participant traits might predict response, despite the brief summary's stated interest in that question.

The secondary outcomes provide additional descriptive measures but do not eliminate the primary endpoint's uncertainty. Their analyses are unadjusted, and a multiplicity procedure is not reported. Taken together, the record supports a cautious description of the observed summaries, not a treatment recommendation or a conclusion about clinical effectiveness.

17. Why This Trial Matters Statistically

This trial is statistically informative because it combines a randomized, masked comparison with a crossover structure and a cognitive task outcome. The crossover arrangement means that the order of D-cycloserine and placebo matters to the interpretation: measurements within a participant may be related, and period or carryover effects can be relevant. The registry record identifies the design but does not provide the paired analysis details needed to evaluate those issues.

The primary outcome also illustrates the distinction between an estimate and its precision. The recalculated mean difference is positive, but the interval is wide and extends across zero. Reading the point estimate without its uncertainty could overstate what the results establish. The posted summaries support a description of the observed direction, while the interval shows that the magnitude and even direction of the underlying contrast remain uncertain.

The outcome is a count of alternative beliefs with no fixed maximum, yet it is presented as a continuous mean with standard deviation. This makes the modeling and distributional assumptions relevant. The registry record does not report a detailed statistical method, so readers cannot determine whether the analysis matched the endpoint's distribution or accounted for the crossover pairing.

The study also has multiple secondary outcomes, but the registry record does not report a multiplicity strategy or detailed analysis plan. This highlights why a result's apparent strength should be considered alongside prespecification, analytic transparency, and the number of outcomes examined. The record offers useful descriptive summaries, but key inferential details remain unavailable.

Finally, the planning illustrations demonstrate how sample-size requirements depend on the effect a future study aims to detect. They are not a retrospective measure of whether this study had adequate power. Together, these features make the study a useful case for separating observed differences, uncertainty, design structure, and planning assumptions.

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 report the original sample-size justification, detailed eligibility criteria, or endpoint population description. Although the brief summary describes stable cases of schizophrenia, other population characteristics and the basis for the endpoint sample are not reported. This limits assessment of how broadly the results might apply.

The trial is identified as crossover, but the registry record does not report a washout interval, paired estimates, within-participant covariance, period or sequence effects, or carryover analyses. The posted summaries are marginal means and standard deviations, so the simple recalculated contrasts cannot fully represent the crossover comparison. No sponsor-reported primary analysis is listed.

Important statistical details are not reported, including the primary model, confidence-interval method and level, missing-data approach, analysis population, and multiplicity procedure. The registry also lists no reported analyses for the secondary outcomes. Differences in endpoint sample sizes are visible in the posted summaries, but reasons for those differences are not reported.

The primary endpoint is a task-based score with no fixed maximum. The record does not report a threshold for meaningful change or additional measurement properties, so the clinical interpretation of a difference in score remains uncertain. The posted timeframe ends at Week 2; longer-term results are not reported in the registry record.

Safety results are limited to group-level event counts. The record does not report event details, an exposure-specific comparison, or death counts. These reporting limits mean the posted safety figures should not be taken as a complete assessment of risk.

19. Related Tutorials

20. Related Statistical Calculators

21. Sources

• ClinicalTrials.gov: Using D-cycloserine to Enhance the Benefits of Cognitive Behavioral Therapy for Schizophrenia — NCT00742079.
• Registry record last updated 2017-12-19; status last verified 2014-09.
• Results first posted 2014-09-05.
• 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

NCT00742079 is a completed, randomized, quadruple-masked, Phase 4 crossover study sponsored by Massachusetts General Hospital. The registry record lists an enrollment of 21 and a study period beginning 2006-09, with primary completion in 2010-07. The study examined D-cycloserine or placebo given before cognitive behavioral therapy sessions for schizophrenia.

The primary outcome was change from baseline to Week 2 in the number of alternative beliefs generated on a vignette assessment. Posted means were 14.05 for D-cycloserine and 10.7 for placebo; the recalculated unadjusted mean difference was 3.35, with a reported interval from -5.633 to 12.33 and an unadjusted p-value of 0.465.

Four secondary outcomes are posted, but the registry record lists no reported analyses for them. The posted summaries and safety counts are descriptive; key analysis details, missing-data methods, and multiplicity handling are not reported in the registry record.