The Impact of the COVID-19 (SARS-CoV-2 Disease) on Psychopathology: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for The Impact of the COVID-19 (SARS-CoV-2 Disease) on Psychopathology (NCT04694482), a registered phase not stated study. The primary outcome is Impact of Event Scale - Revised Version (IES-R).

2. Clinical Question

The study was motivated by the possibility that the pandemic could be experienced as a traumatic phenomenon. Its stated hypothesis was that psychiatric outpatients might experience psychopathological worsening and have more PTSD symptoms than the general population. Those statements describe the research hypothesis, not a finding. The record identifies the groups and measures but does not provide results that would establish whether the expected patterns were observed.

3. Trial Design

The registry describes a completed study sponsored by the University of Milano Bicocca. The recorded start date is 2020-11-12, and the primary completion date is 2021-01-31. Enrollment is recorded as 270. The record does not state how many participants were psychiatric patients, how many were healthy controls, or whether all enrolled participants completed both assessments.

The study used psychometric scale administration rather than a treatment intervention. Psychiatric patients and healthy controls were assessed for the primary outcome, the IES-R. The stated timepoints were T1, during the 2 months of lockdown, and T2, during the 2 months of reopening. The registry also lists several secondary measures: the Disability Scale, Hamilton Depression Rating Scale, Montgomery and Asberg Depression Rating Scale, Young Mania Rating Scale, Yale-Brown Obsessive-Compulsive Scale, and Positive And Negative Syndrome Scale.

The registry says this is not a randomized comparison and that allocation is not stated. It also cautions that the arms are not a like-for-like control comparison. Consequently, the group contrast should not be interpreted as though participants had been randomly assigned to comparable conditions. Differences between psychiatric patients and healthy controls could reflect characteristics of the groups as well as any difference in responses to the pandemic. The record does not describe a recruitment procedure, eligibility criteria, matching, or adjustment for differences between groups.

The record lists 11 outcome measures but records 0 analyses. It does not give a detailed statistical analysis plan, explain how repeated observations were handled, or report outcome values. The design description therefore establishes the intended assessments and broad study groups, but does not support a numerical conclusion about change over time or differences between groups.

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

Analysis population for the primary outcome, as defined in the registry: Only psychiatric patients were assessed for this outcome; data not collected for healthy controls.

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 Impact of Event Scale - Revised Version (IES-R), measured over 2 months of lockdown period (T1) and 2 months of reopening phase (T2).

The primary endpoint is the Impact of Event Scale - Revised Version (IES-R), recorded as a mean score with standard deviation. It is a self-report measure of current subjective distress in response to a specific traumatic event. The registry gives a score range of 0-88 and states that higher scores mean a worse outcome. The scale covers intrusion, avoidance, and hyper-arousal, described as symptom clusters associated with post-traumatic stress.

The IES-R was selected to assess PTSD symptoms in the context of the pandemic. The registry specifies measurement at T1, during the 2 months of lockdown, and T2, during the 2 months of reopening. Both psychiatric patients and healthy controls were assessed. This structure could support descriptions of scores at each timepoint and, if participant-level data and an appropriate analysis were available, assessment of change over time and comparison between groups. The registry record does not report the actual means, standard deviations, changes, or group contrasts.

As a self-report measure, the score represents participants’ reported distress rather than a diagnosis established by the scale alone. A higher score indicates more reported distress on the instrument; it does not, on its own, identify the cause of distress or establish a clinical diagnosis. The record does not report a threshold used to classify participants, nor does it state whether the IES-R was administered in a particular language or under a specified assessment procedure.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry specifies the primary outcome as a continuous score summarized by a mean and standard deviation. It does not state which inferential statistical methods were used. Because the record contains 0 analyses and no outcome estimates, the statistical concepts below describe how such data may generally be interpreted; they do not describe analyses confirmed to have been performed in this study.

What does a mean describe?

In general, a mean is the arithmetic average of observed scores. For the IES-R, it would describe the average reported distress score in a defined group at a specified assessment period. A mean can make group-level patterns easier to communicate, but it does not show the full distribution. Participants can have quite different scores even when their group averages are similar.

A standard deviation describes the spread of scores around a mean. A larger standard deviation indicates greater variation among participants; it does not measure uncertainty in the estimated mean. The standard deviation and the mean answer different questions, so both are useful when describing a continuous measure. The registry identifies standard deviation as the intended dispersion measure but does not report observed values.

What would a group contrast mean?

In general, a difference between group means describes how far apart the group averages are on the score scale. For this study, a contrast might compare psychiatric patients with healthy controls at one assessment period, or compare changes across periods. These are distinct questions. A single-period contrast concerns the groups’ scores at that time; a change contrast concerns whether the pattern from T1 to T2 differs between groups.

Because the registry describes a non-randomized comparison, any group contrast would need to be interpreted as an association rather than a treatment effect. Random allocation is one method for balancing measured and unmeasured characteristics between groups, but the record says this was not a randomized comparison. It does not state whether participants were matched or whether statistical adjustment was planned. General statistical reasoning therefore cautions that group differences can reflect both the characteristic of interest and other differences between the groups.

Why does repeated measurement matter?

General statistical methods for repeated measurements account for the fact that scores from the same participant may be related. Treating observations from one person as fully independent can misrepresent uncertainty. An analysis might compare within-person changes, model scores over time, or estimate differences in change between groups. The suitable choice depends on the research question, the data structure, and assumptions about missing observations. The registry record does not report which approach, if any, was used.

The timepoints are described as T1 during the 2 months of lockdown and T2 during the 2 months of reopening. That description identifies the assessment windows, but it does not provide exact individual assessment dates or explain whether all participants were measured in comparable circumstances. Nor does the record report a distribution of follow-up times or confirm that every enrolled participant completed both assessments.

How should uncertainty be understood?

In general, a confidence interval expresses uncertainty around an estimate under the statistical model and assumptions used. A narrow interval indicates greater precision than a wide interval, while the interval’s location indicates which effect sizes remain compatible with the data and method. A p-value, when reported, addresses how compatible the observed data are with a specified null hypothesis under a model. Neither measure indicates the clinical importance of an effect by itself. No confidence interval or p-value for the primary outcome is reported in the registry record.

The registry describes mean and standard deviation but does not report a model, adjustment variables, tests, or assumptions. It also does not report an analysis of the secondary measures. Those omissions prevent a reader from checking whether estimates account for the study’s repeated assessments, group structure, or potential differences among participants.

What do the planning illustrations represent?

The stated planning assumptions describe illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. Such calculations are planning illustrations, not evidence that the study had a particular probability of detecting an effect after data collection. They are not observed power.

For outcomes other than time-to-event outcomes, the stated planning quantity is participants per arm for a specified power. The registry record does not report the numerical planning outputs or the effect value underlying them in the information available for interpretation. It also does not report whether these illustrations were part of the study’s original design. They should not be mistaken for the trial’s actual enrollment by group, an analysis result, or a justification documented by the investigators.

More generally, statistical interpretation depends on the estimand: the exact quantity an analysis aims to estimate, such as an average score at a particular period or a between-group difference in change. The registry record does not define an estimand or state how deviations from the intended assessment schedule were handled. Without those details and the outcome estimates, the methods cannot be reconstructed from the record.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists 11 outcome measures, including the IES-R as the primary outcome and six named secondary scales: the Disability Scale, Hamilton Depression Rating Scale, Montgomery and Asberg Depression Rating Scale, Young Mania Rating Scale, Yale-Brown Obsessive-Compulsive Scale, and Positive And Negative Syndrome Scale. The record also describes assessment of psychopathological status and PTSD symptoms. It records 0 analyses and does not report results for any of the listed measures.

Multiplicity arises when several outcomes, timepoints, or group contrasts are examined. In general, conducting many statistical tests can increase the chance that at least one appears noteworthy by chance. A prespecified primary outcome can help focus interpretation, and statistical methods can address multiple testing when appropriate. The registry record does not report a multiplicity adjustment, a hierarchy among secondary outcomes, or which comparisons were planned. It is therefore not possible to determine how the family of outcomes was handled.

Missing-data methods are also not reported in the registry record. The enrollment is 270, but the record does not provide the number with outcome data at each timepoint, reasons for missing assessments, or an analysis population. It does not say whether analyses used complete cases, imputation, or another approach. The handling of incomplete follow-up can affect both the estimate and its precision, particularly when missingness is related to participant characteristics or measured outcomes.

The record does not define whether all enrolled participants were intended for analysis or describe exclusions after enrollment. It also does not report a protocol-deviation strategy or a sensitivity analysis for missing observations. Accordingly, the completeness and representativeness of the posted outcome data cannot be assessed from this record.

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

The study’s stated aim was to assess psychopathological status and PTSD symptoms in psychiatric patients over time and to compare PTSD symptoms with those in healthy controls. The IES-R was assessed in both groups at T1 during the 2 months of lockdown and T2 during the 2 months of reopening. These details explain what the study sought to measure and when.

The registry record does not report IES-R scores, group differences, changes between assessments, or inferential analyses. It therefore does not establish whether distress scores changed over time, whether psychiatric patients had higher scores than healthy controls, or whether the stated hypothesis was supported. No conclusion about the size, direction, or precision of an observed effect can be drawn from the available results information.

Even if a difference in scores were reported, the comparison would need to be interpreted in light of the design. The registry states that this was not a randomized comparison, that allocation is not stated, and that the arms are not a like-for-like control comparison. An observed difference between these groups would not by itself show that the pandemic caused the difference. Other distinctions between psychiatric patients and healthy controls could contribute, and the record does not describe adjustment for such factors.

The IES-R is a self-report measure of current subjective distress associated with a specific traumatic event. Its score can describe reported symptoms on the instrument, but a score alone does not establish a diagnosis or identify the cause of distress. The record does not report a diagnostic threshold or clinical interpretation rule.

The enrollment figure and completed status describe the registry record, not the amount of analyzable outcome data. The record does not report group-specific enrollment, completion at each assessment, missing-data handling, or outcome estimates. The defensible interpretation is therefore about the study question and measurement plan, not about a treatment effect or a demonstrated clinical outcome.

12. Why This Trial Matters Statistically

The study is statistically interesting because it combines a comparison between psychiatric patients and healthy controls with assessments across two pandemic phases. These are different sources of information: group differences describe contrasts between populations, while repeated assessments can describe temporal patterns. Separating those questions is important for interpreting any reported score differences.

The registry identifies a continuous primary measure and specifies both a mean and standard deviation as summary statistics. That makes it possible, in principle, to describe average symptom scores alongside variation among participants. The IES-R also has a stated direction, with higher scores representing worse outcome, and includes intrusion, avoidance, and hyper-arousal subscales. Those details give statistical summaries a clear measurement context.

The non-randomized nature of the comparison is central to interpretation. Healthy controls and psychiatric patients are not interchangeable groups by design, and the registry explicitly notes that the arms are not a like-for-like control comparison. Statistical adjustment can sometimes address measured differences, but it cannot automatically remove bias from unmeasured factors. The record does not report whether adjustment was conducted.

Repeated measurement raises further questions about participant-level correlation, incomplete follow-up, and whether changes are comparable across groups. These are general considerations for longitudinal data, not methods confirmed in this record. The registry does not report the analysis strategy needed to assess them.

Finally, the distinction between a hypothesis and a result matters. The study description proposes that psychiatric outpatients might have worsening psychopathology and greater PTSD symptom prevalence. Because the registry record reports no analyses or outcome values, its statistical contribution cannot be judged from numerical findings. The record is informative about the question, measures, and design limitations, while leaving the empirical answer unreported.

13. 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 trial-specific limitation for interpreting the registry record is the absence of posted outcome estimates. Although the primary measure, summary format, groups, and assessment windows are identified, no means, standard deviations, group contrasts, changes, confidence intervals, or p-values are reported. The record also lists 0 analyses. The stated hypothesis therefore cannot be evaluated from the recorded results.

The group comparison is non-randomized, and the registry warns that the arms are not a like-for-like control comparison. Allocation is not stated. The record does not describe matching, recruitment, eligibility criteria, or adjustment for group differences. These omissions limit what could be concluded from any unadjusted contrast between psychiatric patients and healthy controls.

The registry gives enrollment as 270 but does not report group-specific counts or how many participants contributed data at T1 and T2. It does not state whether observations were paired across assessments, how missing data were handled, or which participants were included in analyses. Consequently, the completeness of follow-up and the representativeness of analyzed participants are not reported.

The record lists multiple outcomes but does not report a statistical plan, specify which secondary comparisons were prioritized, or describe control of multiplicity. It does not explain how the repeated measurements were modeled. These details matter when interpreting uncertainty and selecting among several possible comparisons.

Finally, the primary outcome is a self-report measure of subjective distress. The registry does not report a diagnostic threshold or describe a clinical assessment used to validate scores. The listed measurement information supports interpretation of the scale as a symptom measure, but not as a standalone diagnosis or a causal measure of the pandemic’s effects.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: The Impact of the COVID-19 (SARS-CoV-2 Disease) on Psychopathology — NCT04694482.
• Registry record last updated 2023-09-07; status last verified 2022-10.
• Results first posted 2023-09-07.
• 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.

17. Record Summary

The registry record describes a completed study sponsored by the University of Milano Bicocca, with enrollment of 270. It lists psychiatric patients and healthy controls who received psychometric scale assessments. The primary outcome is the IES-R, summarized as a mean and standard deviation, with assessments at T1 during the 2 months of lockdown and T2 during the 2 months of reopening. Higher scores on its 0-88 scale mean worse outcome.

The record names several psychiatric conditions and secondary measures, and states that the comparison was not randomized, allocation is not stated, and the arms are not a like-for-like control comparison. It lists 11 outcome measures and records 0 analyses. The registry record does not report group-specific enrollment, outcome values, statistical estimates, missing-data methods, or a detailed analysis plan. The study aims and measurement schedule are therefore documented, but the results needed to assess its stated hypothesis are not reported in the registry record.