Pilot Study of Duloxetine in Psychological Resilience: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Pilot Study of Duloxetine in Psychological Resilience (NCT00331799), a na phase 2 study. The primary outcome is Change in Connor Davidson Resilience Scale (CD-RISC) From Baseline to 8 Weeks.

2. Clinical Question

This is a within-group question about change over time, not a randomized estimate of a treatment effect against a control. Even if a mean change had been reported, change during treatment alone would not establish that duloxetine caused the change. Without a comparator, other explanations for change cannot be separated from a treatment effect. The record’s stated interest in transporter blockade is part of the study purpose; it does not provide a reported result linking transporter inhibition to resilience or therapeutic response.

3. Trial Design

The registry identifies this as a Phase 2 pilot study of duloxetine in psychological resilience. It is listed as a single-group, open-label study, with allocation recorded as NA and masking recorded as NONE. The intervention description specifies 8 weeks of duloxetine treatment with dosing from 30-60 mg. The registry lists major depressive disorder as the condition and enrollment of 18 participants.

The primary outcome is a continuous measure: change in the Connor Davidson Resilience Scale (CD-RISC) from baseline to 8 weeks. The stated summary parameter is the mean, with standard deviation as the dispersion measure. The outcome’s timeframe is baseline and 8 weeks. However, the registry record does not report the numerical outcome values or the number of participants contributing data at either assessment.

The study began in 2007-04, had a primary completion date of 2008-05, and is listed as COMPLETED. These administrative details do not establish that all enrolled participants completed treatment or had outcome measurements available. The number who completed follow-up, the amount of missing outcome data, and the analysis population are not reported in the registry record.

Because the study has no concurrent control group, it cannot directly compare duloxetine with placebo, usual care, or another intervention. The before-and-after measurement can describe change within the observed group if results are available, but it does not by itself distinguish treatment-related change from changes that might occur over time or from other influences. The registry record does not report a protocol, a sample-size justification, interim analyses, or further details of the statistical plan.

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:

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 Connor Davidson Resilience Scale (CD-RISC) From Baseline to 8 Weeks, measured over baseline and 8 weeks.

The primary endpoint is change in the Connor Davidson Resilience Scale (CD-RISC) from baseline to 8 weeks. It is a continuous score, and the registry describes the analysis parameter as a mean with standard deviation. The scale’s total score ranges from 0-100, with higher scores indicating greater resilience.

The registry description says that the scale has been psychometrically validated and studied in general and clinical populations. It also states that changes in CD-RISC scores have been found to be sensitive to treatment effects and that impaired resilience has been demonstrated in subjects with depression relative to normal controls using the scale. These statements explain why the measure was selected; they are not findings from this study.

A baseline-to-follow-up change score captures how the group’s measured resilience differs over the treatment period. The mean describes the average change, while a standard deviation can describe how variable individual scores are around that average. Neither statistic is reported in the registry record. The record also does not report a confidence interval or other measure of uncertainty for the mean change. As a result, the endpoint definition is available, but the observed change and its precision cannot be evaluated.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary endpoint is continuous, and the registry specifies a mean as the summary parameter and standard deviation as the measure of dispersion. In general, a mean describes the average value in a group. A standard deviation describes how spread out individual values are around the group mean. These answer different questions: the mean concerns the group’s average, while the standard deviation concerns variation among individuals. The registry record provides neither statistic for the CD-RISC endpoint.

What would a mean change describe?

In general, a within-group mean change summarizes the average difference between participants’ measurements at two time points. For this study, those time points are baseline and 8 weeks. The change can be useful for describing how scores evolved in the observed group. It is not automatically a causal treatment effect. A causal comparison requires a credible estimate of what would have happened over the same period without the intervention, and this study is listed as single-group with no concurrent comparator.

The registry record does not specify the exact calculation or statistical test used for the endpoint. Although it identifies the mean and standard deviation, that information alone does not say whether the analysis used participant-level change scores, a model of repeated measurements, or another method. The statistical plan, handling of repeated measurements, and any adjustments are not reported in the registry record. No particular analysis method should be inferred from the endpoint description alone.

How does uncertainty affect interpretation?

In general, a confidence interval gives a range of values compatible with the data and the method used to calculate it. It conveys uncertainty around an estimate; it does not guarantee that the true value lies in the interval. A narrow interval indicates greater precision than a wide interval, considered under the same method and assumptions. No confidence interval for the primary outcome is reported, so the precision of the mean change cannot be assessed.

A p-value, when reported, addresses how compatible the observed data are with a specified null model under the assumptions of the statistical test. It is not a measure of effect size, clinical importance, or the probability that a hypothesis is true. The registry record does not report a p-value or name a primary-outcome test. There is therefore no basis for describing the primary result as statistically significant or not statistically significant.

What do the planning assumptions mean?

General planning illustrations described for the analysis use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the target effect expressed as a stated fraction of the observed effect. The described approach uses total events for time-to-event outcomes and participants per arm for other outcomes. These are planning conventions, not evidence about the study’s actual design or results. In particular, this trial is recorded as single-group, so an equal-allocation, two-arm illustration does not describe its intervention design.

Planning sample sizes based on an observed effect are illustrations of what a later study might require under stated assumptions. They are not observed power and do not show that the present study had a particular probability of detecting an effect. No numerical planning result or observed CD-RISC effect is reported in the registry record. Consequently, there is no reported effect estimate to use when interpreting a planning illustration, and no sample-size justification for this trial is reported.

Why might over-dispersion matter?

In general, over-dispersion means that observed variability is greater than a statistical model assumes. If a model understates variability, standard errors may be too small and confidence intervals too narrow, making results appear more precise than they are. This concern is relevant only when a model and its assumptions are specified. The primary endpoint is described as a continuous mean with standard deviation, but no model, variance assumption, or diagnostic assessment is reported. It would not be appropriate to claim that over-dispersion was present or that it affected the analysis.

Overall, the registry provides enough information to identify the endpoint and its intended summary form, but not enough to reconstruct or evaluate the primary statistical analysis. The outcome estimate, its uncertainty, the test or model, and relevant analysis decisions are not reported in the registry record.

10. Confidence Intervals for Each Arm

No two-arm comparison is shown for this trial, but each arm's mean can be given with a t-based 95% confidence interval computed from the posted mean, spread and number of participants.

R code and output

arm <- c("Duloxetine")
n   <- c(18)
m   <- c(52.62)
sp  <- c(16.61)
sd  <- sp      # posted standard deviations
for (i in seq_along(n)) {
  se <- sd[i] / sqrt(n[i]); h <- qt(0.975, n[i] - 1) * se
  cat(sprintf("CARM|%s|%d|%.3f|%.3f|%.3f|%.3f\n", arm[i], n[i], m[i], sd[i], m[i] - h, m[i] + h))
}

CARM  Duloxetine  18  52.620  16.610  44.360  60.880

11. Multiplicity, Missing Data and Analysis Populations

The registry identifies a primary outcome and lists one outcome measure and one analysis. Those counts do not explain whether other outcomes were collected, whether other analyses were performed, or whether the listed analysis was selected from a broader set. A multiplicity adjustment, a prespecified hierarchy of outcomes, and the handling of multiple statistical tests are not reported in the registry record. It is therefore not possible to evaluate how multiplicity was addressed.

The record does not report how missing CD-RISC measurements were handled. It does not give the number of participants with baseline data, the number with 8-week data, reasons for missingness, or whether any imputation or model-based method was used. Enrollment of 18 does not establish that all participants contributed complete endpoint data. Without these details, readers cannot assess whether missing observations might affect the estimated mean change or its precision.

The analysis population is also not reported. The registry does not state whether the endpoint analysis included all enrolled participants, only participants who completed treatment, or another defined group. It does not describe exclusions from analysis or deviations from the treatment plan. These omissions limit reproducibility and make it difficult to connect enrollment with the data underlying the endpoint.

These are reporting gaps, not proof that the investigators did not make analysis decisions or that data were missing. The registry record does not provide enough information to determine the decisions made or their consequences.

12. 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.

The registry lists 18 participants at risk for serious adverse events and 0 affected. In plain terms, the posted safety figures record no serious adverse events in that group during the reporting period represented by the registry. The record also lists 18 at risk and 0 affected for the other adverse-event category. These figures should be read as counts recorded in the registry, not as a guarantee that an event is impossible or that risk is absent.

The deaths field is null, so deaths are not reported in the registry record. The safety listing does not provide additional detail about event definitions, collection procedures, duration of safety follow-up, or whether participants experienced events that were not classified as serious. The record’s zero affected count for serious adverse events does not provide a complete description of tolerability or of every possible safety outcome.

Because the study is single-group and has enrollment of 18, these counts are descriptive. They do not support a comparative safety estimate against another treatment or a control group. No rate or comparison should be inferred from the counts alone. The posted figures are limited to the adverse-event categories and reporting information in the registry.

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

The record establishes that a Phase 2 pilot study examined open-label duloxetine in relation to psychological resilience in major depressive disorder. It identifies a primary measure, the CD-RISC, and defines the comparison as change from baseline to 8 weeks. It also states that higher scale scores indicate greater resilience. These details clarify what the study intended to measure.

The record does not report the CD-RISC outcome values. Without a baseline score, a follow-up score, or a mean change, there is no reported direction or magnitude of change to interpret. Without a standard deviation or confidence interval, the variability and precision of an estimate cannot be assessed. Without a reported statistical test or p-value, statistical evidence against a null hypothesis cannot be characterized. The result therefore cannot be described as showing improvement, decline, or no change.

Even a reported within-group change would not, on its own, establish that duloxetine caused the change. This study has no concurrent comparator group, and the registry lists it as open-label. A before-and-after comparison can describe what happened in the observed group, but it does not directly compare that trajectory with what would have happened without treatment. The registry’s mechanistic interest in serotonin and norepinephrine transporter inhibition likewise does not establish a mechanistic finding; no relevant result is reported.

The absence of outcome results in the registry should not be taken as evidence that the study found no change, or that no analysis was conducted. It means the posted record does not provide the information needed to evaluate the primary endpoint. The distinction is important: an unavailable result is not a null result.

The safety figures report 0 serious adverse events among 18 participants listed at risk, while the deaths field is not reported. These counts are descriptive and do not provide a comparison with another group. Overall, the record supports conclusions about the study’s design, intended endpoint, and recorded safety counts, but not about the size, precision, or causal meaning of any resilience change.

14. Why This Trial Matters Statistically

This study illustrates a basic distinction between defining an endpoint and reporting its result. The registry describes the CD-RISC, its score direction, and the baseline-to-8-week timeframe. Those details allow readers to understand what the investigators intended to measure. They do not substitute for the mean change, variability, or uncertainty needed to assess what was observed.

It also highlights why design determines the question that can be answered. A single-group study can describe change over time in the participants observed. Without a concurrent comparator, it cannot make a direct between-group estimate of what duloxetine changed relative to an alternative. The open-label design is another feature relevant to interpretation, while the registry record does not describe additional methods to address its possible influence.

The pilot designation and enrollment of 18 place the study in a small-study context, but enrollment alone cannot establish precision or adequacy. Those judgments require the outcome estimate, its variability, completeness of follow-up, and the study’s design assumptions. The registry record does not report the sample-size justification or the information needed to assess the precision of the primary result.

Finally, the record demonstrates the value of separating a study’s stated rationale from its empirical findings. The stated interest in psychological resilience and transporter inhibition explains the research question. Since the endpoint results and any analysis of transporter blockade are not reported, readers cannot use that rationale as evidence of a particular response or mechanism. Statistical interpretation depends on results and methods being reported, not only on a plausible question and a defined measure.

15. 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 main limitation for interpreting this study is that the registry record does not report the primary endpoint results. Although it defines the CD-RISC change measure and its timeframe, it gives no numerical baseline or follow-up values, mean change, standard deviation, confidence interval, or p-value. The magnitude, direction, and precision of any change therefore cannot be assessed.

The single-group design limits causal interpretation independently of the missing results. There is no concurrent control group, and allocation is listed as NA. The study is open-label, with masking listed as NONE. A within-group change, if available, would not establish that duloxetine caused that change or separate treatment-related change from other changes over time.

The registry record does not report participant characteristics beyond the listed condition, enrollment, and study design. It does not describe the endpoint analysis population, the number with measurements at each time point, follow-up completion, or missing-data methods. The statistical plan, sample-size justification, and any interim analyses are also not reported in the registry record. These omissions restrict evaluation of the analysis and its reproducibility.

Safety interpretation is limited as well. The record gives counts for serious and other adverse events, but does not report the deaths field, event definitions, collection procedures, or further follow-up details. The counts are descriptive and cannot support a comparative safety conclusion.

These limits concern what the registry record reports. They do not establish that outcome data were never collected, that the analysis was not performed, or that no change occurred. They do mean that the posted record does not support an assessment of the primary outcome’s statistical result.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Pilot Study of Duloxetine in Psychological Resilience — NCT00331799.
• Registry record last updated 2013-08-02; status last verified 2013-06.
• Results first posted 2013-08-02.
• 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.

19. Record Summary

NCT00331799 is a completed Phase 2 pilot study titled “Pilot Study of Duloxetine in Psychological Resilience.” The registry lists Duke University as sponsor, major depressive disorder as the condition, and enrollment of 18. The study began in 2007-04 and had a primary completion date of 2008-05.

The design is recorded as single-group and open-label, with no concurrent comparator. The intervention was duloxetine for 8 weeks, with dosing from 30-60 mg. The primary endpoint was mean change in CD-RISC score from baseline to 8 weeks. The scale ranges from 0-100, with higher scores indicating greater resilience.

The registry record does not report the primary outcome values or the statistical uncertainty around them. It lists 0 serious adverse events among 18 participants at risk; the deaths field is not reported. The available information describes the study’s design and intended outcome, but does not permit evaluation of the observed resilience change.