Effect of Intranasal Neuropeptide on Emotion Perception in Trait Anxiety: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Effect of Intranasal Neuropeptide on Emotion Perception in Trait Anxiety (NCT01551303), a randomized na study. The primary outcome is Affective Ratings in Affective Learning Task.

2. Clinical Question

The posted comparison concerns an average rating, rather than a clinical event or a diagnosis. It describes the difference between group means at the specified assessment time. It does not, by itself, establish how individual participants responded, whether an observed difference would persist beyond that assessment, or how the result relates to other measures of emotion perception. Those details are not reported in the registry record.

3. Trial Design

The registry describes a randomized, double-masked, parallel-group study with 47 participants enrolled. The listed arms are oxytocin and placebo: 25 participants are recorded in the oxytocin arm and 22 in the placebo arm. The record lists Massachusetts General Hospital as the sponsor and gives the study start as 2009-02 and primary completion as 2012-12. Its status is completed.

In the oxytocin arm, participants received liquid intranasal oxytocin administered in a nasal spray. The comparator was a matched nasal spray placebo. The record does not specify the oxytocin dose, the timing details beyond the primary outcome assessment, or further procedures for administering either spray. It also does not explain which people were masked or how masking was maintained. The terms randomized, double-masked, and parallel-group describe the recorded design, but do not supply those operational details.

The primary outcome was assessed 30 minutes after drug administration. It was based on ratings made during an Affective Learning Task in which participants viewed 30 neutral faces. Each face was paired with a sentence describing a negative, positive, or neutral behavior, with those pairings counterbalanced across participants. In a test phase, participants rated faces as negative, neutral, or positive; the ratings were averaged.

The title places the study in a trait-anxiety context, but detailed eligibility criteria, participant characteristics, recruitment procedures, and the number screened or excluded are not reported in the registry record. The record also does not report the original design assumptions, the planned sample-size rationale, or further details of the protocol. The enrollment count describes the participants recorded for the study; it does not reveal whether every enrolled participant contributed data to the primary outcome.

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: No enrolled participants were excluded before group assignment.

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 Affective Ratings in Affective Learning Task, measured over 30 minutes after drug administration.

The primary endpoint is the mean affective rating in the Affective Learning Task, reported in units on a scale. Participants viewed 30 neutral faces, each paired with a sentence describing negative, positive, or neutral behavior. The pairings were counterbalanced across participants. During the test phase, participants rated each face as negative, neutral, or positive, and the responses were averaged.

The coding assigns -1 to a negative rating, 0 to a neutral rating, and 1 to a positive rating. The averaged score therefore has a possible range from -1 to 1. The posted arm means are -0.096 for oxytocin and -0.12 for placebo. This measure is used to summarize the direction and average level of the participants’ affective ratings in the task, rather than to count clinical events or assess a disease outcome. The assessment was made 30 minutes after drug administration.

The registry describes the endpoint as a measure of affective learning. It does not define a clinically meaningful difference or identify a direction as better or worse. Consequently, the mean rating can be interpreted as a task outcome, but not as a direct measure of benefit or harm. Information about the scale’s validation, reliability, or relationship to other outcomes is not reported in the registry record.

7. Results Posted in the Registry

• Oxytocin: mean -0.10 versus -0.12 on control; difference 0.02 (95% CI -0.12 to 0.17), standardized effect d = 0.10; z-test p = 0.744.

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is a continuous measure, and the registry reports a mean for each arm. A mean is the arithmetic average of the recorded task ratings. In this study, each participant’s ratings were averaged after responses were coded as negative = -1, neutral = 0, and positive = 1. The resulting group mean describes the average task score among the participants contributing to that arm’s reported result. It does not describe every participant or show the full distribution of scores.

What does the standard error describe?

The posted dispersion measure is the standard error. In general, a standard error describes the sampling uncertainty of an estimated statistic, such as a mean. It is not the standard deviation of participants’ scores and should not be read as a range containing most participants. A standard error is useful for understanding how precisely a group mean has been estimated. The registry reports standard errors of 0.05 for the oxytocin mean and 0.054 for the placebo mean.

The standard error depends on both the variability in the observations and the number of observations contributing to an estimate. However, the record does not provide the participant-level scores or an explicit standard deviation for each arm. It is therefore not possible to reconstruct the full distribution of ratings from the displayed means and standard errors alone. Nor does the record state how missing scores, if any, were handled.

How should the arm comparison be read?

The comparison is expressed as an unadjusted mean difference, with oxytocin compared with placebo. A positive difference means that the oxytocin group mean is numerically higher on the coded scale; a negative difference would mean that it is numerically lower. The posted estimate is 0.024 units. This is an arithmetic contrast between the group means, not a comparison of every participant with another participant, and not an adjusted estimate accounting for other variables.

The registry posts an unadjusted p-value of 0.744 and a confidence interval for the difference. General statistical interpretation treats the p-value as a measure of how unusual data at least this discrepant would be under a specified null model and its assumptions. It is not an effect-size measure. The interval communicates uncertainty around the estimated difference and includes zero. The exact statistical procedure used to construct the interval, including any distributional or variance assumptions, is not reported in the registry record.

What does randomization contribute?

Random allocation is intended, in general, to make treatment assignment independent of participant characteristics, on average, and thus to support a fair comparison between groups. It does not ensure that the arms are identical in every observed or unobserved characteristic, particularly in a relatively small study. The registry states that allocation was randomized, but does not report the sequence-generation method, allocation-concealment procedures, or whether the analysis followed an intention-to-treat principle.

The study is also described as double-masked and parallel-group. In general, masking can reduce the influence of treatment knowledge on participant behavior, outcome assessment, and study conduct. The registry does not specify who was masked or provide details of how the masking was implemented. A parallel-group design means that the comparison is between separate groups assigned to the two interventions; details of the protocol beyond that design label are not reported.

What can be concluded from the reported test?

The posted p-value is unadjusted. This identifies it as a result without a reported multiplicity adjustment, but the registry does not provide a full statistical analysis plan or say whether any adjustment was planned. In general, when several hypotheses are tested, multiplicity can raise the chance that at least one result appears statistically unusual even if no underlying effects exist. Whether that concern applies, and how it was addressed, cannot be established from the record because the planned testing strategy is not reported.

The registry lists one outcome measure and no posted secondary outcomes. It lists no analysis entries, although a primary group comparison is posted. There is no further description of model specification, covariate adjustment, handling of missing data, outlier procedures, or analysis population. Those choices can affect estimates and uncertainty, so they should not be inferred from the summary statistics alone.

General statistical concepts can clarify what the estimates mean, but the record’s summaries do not reveal the underlying observations or the full analysis process. The mean and mean difference address the average coded response; the standard errors and confidence interval describe uncertainty in those averages and their contrast. None of these quantities alone indicates whether a difference has practical importance. The registry gives no threshold for meaningful change on the task scale.

10. Confidence Intervals and Precision

The mean difference is estimated as 0.024 units, with an unadjusted p-value of 0.744. The posted confidence interval crosses zero, extending to both negative and positive differences. That span means the data do not pinpoint the comparison to one direction. The interval is the most direct posted summary of the uncertainty around the mean difference; the p-value alone does not show the range of effect sizes compatible with the data.

In general, a confidence interval combines a point estimate with information about its uncertainty under a statistical procedure and its assumptions. A narrower interval indicates greater precision, while a wider interval indicates less precision. An interval that includes zero does not establish that the true difference is exactly zero. It indicates that zero is among the values compatible with the interval procedure, along with values on either side. The registry does not report the method used to calculate the interval or a threshold for a meaningful difference on this endpoint.

The arm-specific standard errors are 0.05 for oxytocin and 0.054 for placebo. These quantify uncertainty in the estimated means, not participant-to-participant spread. The record provides neither the individual ratings nor detailed outcome completeness, so the displayed precision cannot show whether a small number of unusual observations influenced the result or whether every enrolled participant contributed to the outcome.

The sample enrolled 47 participants, with 25 recorded in the oxytocin arm and 22 in the placebo arm. A modest sample can leave substantial uncertainty, but the registry does not report the original sample-size rationale or the assumptions used to plan the trial. The uncertainty in this estimate should therefore be read from the posted interval and standard errors, not attributed to a particular planning decision that is absent from the record.

11. 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 expressed as participants per arm, not total events. They are based on the observed mean difference and show the participant count associated with planning for 80% or 90% power under stated assumptions. The figures are not the number enrolled in the trial: the recorded arm sizes are 25 for oxytocin and 22 for placebo.

The 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 at the stated fraction of the observed effect. The table gives participants per arm for 80% power and participants per arm for 90% power. In plain terms, the 80% column refers to the planned chance of detecting the specified effect at that significance level if the assumptions hold and that effect is real; the 90% column uses a higher target probability of detection. These are design quantities, not descriptions of what happened in this trial.

For 100% of the observed effect, the illustration lists 1,725 participants per arm for 80% power and 2,309 for 90% power. For 75% of the observed effect, it lists 3,066 and 4,104 participants per arm, respectively. For 50% of the observed effect, it lists 6,898 and 9,234 participants per arm, respectively. The curve expresses the same planning relationship visually: as the effect to detect becomes smaller, the required sample size increases.

These calculations use the observed effect as their reference and are planning illustrations, not observed power. The original trial’s sample-size assumptions and justification are not reported in the registry record, so these illustrations should not be mistaken for the study’s prospective design plan.

12. 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 = 0.024; pooled standard deviation σ = 0.252.
2. n = 2 × (1.96 + 0.842)² × 0.252² / 0.024² = 1,724.3, rounded up to 1,725 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 <- 0.024                      # observed difference in means
sigma <- 0.251537141061381                     # 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(1551303)
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 = 1,725 (80% power), 2,309 (90% power)
 75% of observed effect: n per arm = 3,066 (80% power), 4,104 (90% power)
 50% of observed effect: n per arm = 6,898 (80% power), 9,234 (90% power)
power.t.test: 1725.3 
Simulated power at n = 1,725 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.

13. Multiplicity, Missing Data and Analysis Populations

The registry lists one primary outcome measure and no posted secondary outcomes. It also lists no analysis entries, although a primary comparison is reported. The posted p-value is unadjusted. The registry record does not describe a full statistical analysis plan, specify the intended family of hypotheses, or report a multiplicity-adjustment procedure. It is therefore not possible to determine from the record whether the primary comparison was the only planned analysis or how any additional planned tests would have been handled.

In general, multiplicity arises when several hypotheses are assessed, because repeated testing can increase the chance of at least one apparently unusual result. Adjustment methods can control that issue under specified conditions, but they may also affect precision and interpretation. No adjustment should be presumed from the trial’s design labels or the fact that one outcome is posted. The unadjusted result should be interpreted as an unadjusted comparison.

The record does not report counts of missing primary outcomes, reasons for missingness, or procedures for handling incomplete ratings. It does not state whether participants were analyzed according to randomized assignment, whether any participants were excluded after allocation, or whether the posted arm sizes are the numbers contributing to the endpoint analysis. The enrollment and arm counts alone cannot answer those questions.

Analysis-population definitions, handling of protocol deviations, and any sensitivity analyses are not reported in the registry record. Nor are subgroup analyses or covariate-adjusted models described. Such details can matter when evaluating how robust an estimate is, but they cannot be reconstructed from the posted group means and comparison. In the absence of these details, interpretation should remain focused on the reported unadjusted mean difference, its uncertainty, and the recorded endpoint.

14. 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 1% reporting threshold.

Most frequent non-serious adverse event terms

The registry records 0 serious adverse events among 22 participants at risk in the placebo group and 0 among 25 participants at risk in the oxytocin group. For other adverse events, it records 0 among 22 participants at risk in the placebo group and 1 among 25 participants at risk in the oxytocin group. The record does not identify a serious-event term in either arm. Death counts are not reported in the registry record.

These are counts recorded in the registry, not evidence that an event was or was not caused by an assigned spray. The record does not provide details of event definitions, the period of collection, severity classifications for the other event, or an assessment of relatedness. A zero count in a group means no events of that category are recorded for that group in this result; it does not establish that the risk is absent. With the reported group sizes, the counts should be interpreted as descriptive safety information rather than as a precise comparison of risks.

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

The posted result describes average affective ratings in one task, assessed 30 minutes after administration of intranasal oxytocin or matched placebo. The mean difference is 0.024 units, with an unadjusted p-value of 0.744. The confidence interval spans zero and values on both sides, so the estimate is uncertain in direction and does not rule out either a negative or positive difference under the interval’s assumptions.

This is not evidence of equivalence. A conclusion of equivalence requires a defined margin for differences considered sufficiently small, as well as an analysis designed to assess that margin. The registry does not report such a margin or an equivalence analysis. Likewise, a p-value of 0.744 is not the probability that there is no effect and does not quantify the probability of a meaningful effect. The study’s posted result is best read as an imprecise estimate for this specific endpoint, rather than a definitive statement that the groups are identical.

The task outcome is a coded average of participants’ judgments about faces paired with behavioral descriptions. The record does not define a clinically or practically important change, and it explicitly notes that there is no better or worse outcome direction because the study is not a disease-treatment study. The numerical direction of the difference therefore should not be translated into benefit or harm.

The result does not establish effects on other measures, settings, time points, or populations. It does not show whether an outcome difference persisted beyond 30 minutes, and the registry does not report follow-up assessments for this endpoint. It also does not provide detailed participant characteristics or eligibility criteria, so generalization beyond the studied sample is limited. The findings should be kept within the bounds of the posted task, time point, and group comparison.

Finally, the trial’s summary data do not reveal individual response patterns, missing-data handling, or the full analysis process. They support a description of the observed group means and their uncertainty, but not a claim about how any particular participant would respond or what would occur in a different study.

16. Why This Trial Matters Statistically

This trial illustrates why a point estimate and a measure of precision should be considered together. The mean difference is 0.024 units, but the confidence interval crosses zero and extends in both directions. The estimate alone gives a single value; the interval makes clear that the posted data leave substantial uncertainty about the direction and size of the group difference.

It also shows why a large p-value should not be equated with proof of no effect. The unadjusted p-value is 0.744, but that value does not establish equivalence or identify a range of effects that can be ruled out. Interpretation depends on the interval, the outcome scale, and whether any difference would be meaningful. The registry gives no meaningful-difference threshold for the task score, which limits the practical interpretation of the contrast.

The sample-size illustration highlights the relationship between effect size and planning requirements. Under the stated assumptions, planning to detect a smaller fraction of the observed effect requires more participants per arm. These figures are not evidence about the original design rationale or the result’s observed power. The trial’s original sample-size assumptions are not reported in the registry record.

Finally, the record demonstrates the limits of registry summaries. The listed means, standard errors, comparison, and adverse-event counts are useful for understanding what was posted, while details such as missing outcomes, analysis populations, and the full statistical plan are not reported. That distinction helps keep conclusions anchored to the available endpoint and analysis rather than extending beyond the documented evidence.

17. 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 provides limited detail about who participated. Although the title refers to trait anxiety and Social Intelligence is listed as a condition, eligibility criteria, participant characteristics, and recruitment details are not reported. The extent to which the enrolled participants represent a broader population cannot be assessed from the record.

Important intervention details are also absent. The oxytocin dose, the precise administration procedure, and further information about the placebo are not reported. The record identifies the study as double-masked but does not specify who was masked or how masking was maintained. These omissions limit assessment of intervention implementation and the possibility of unmasking.

The primary endpoint is described as an average from a task, but the record does not report validation or reliability information, participant-level distributions, or a threshold for a meaningful difference. The assessment is specified at 30 minutes after administration; persistence at other time points is not reported. Detailed missing-data counts, outcome completeness, analysis-population definitions, and sensitivity analyses are also not reported.

The registry does not provide the original sample-size rationale, the planned statistical analysis, or details about interval construction. It lists an unadjusted p-value, but the planned multiplicity strategy is not reported. These omissions do not change the posted summary statistics, but they constrain evaluation of the analysis process and interpretation of uncertainty. The posted data should therefore be understood as a limited summary of one primary task outcome in this randomized comparison.

18. Related Tutorials

19. Related Statistical Calculators

20. Sources

• ClinicalTrials.gov: Effect of Intranasal Neuropeptide on Emotion Perception in Trait Anxiety — NCT01551303.
• Registry record last updated 2014-06-30; status last verified 2014-03.
• Results first posted 2014-06-30.
• 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.

21. Record Summary

The completed study, sponsored by Massachusetts General Hospital, is titled Effect of Intranasal Neuropeptide on Emotion Perception in Trait Anxiety. The registry records a randomized, double-masked, parallel-group comparison of intranasal oxytocin with matched nasal spray placebo, with 47 participants enrolled. The primary outcome is the mean affective rating in an Affective Learning Task, assessed 30 minutes after drug administration.

The posted means are -0.096 for oxytocin and -0.12 for placebo. The mean difference is 0.024 units, with an unadjusted p-value of 0.744 and a confidence interval that spans zero. The record also lists 0 serious adverse events in each arm and 1 other adverse event in the oxytocin arm, compared with 0 in the placebo arm. The registry does not report detailed analysis-population, missing-data, or original sample-size-planning information.