Prognosis of Depression in the Elderly (PRODE). A Multicentre, Longitudinal Study of Elderly Depressed Patients.: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Prognosis of Depression in the Elderly (PRODE). A Multicentre, Longitudinal Study of Elderly Depressed Patients. (NCT01952366), a registered phase not stated study. The primary outcome is Depression.

2. Clinical Question

The study is framed as a prognosis investigation, rather than a test of a treatment against a control. Its summary states a hypothesis that elderly patients referred to specialist health services have a poor long-term prognosis. The registry also identifies dementia diagnoses at one year and three years as secondary outcomes. Those measures concern diagnoses according to ICD-10, while the stated primary measure concerns depression relapse or recurrence.

These questions are descriptive and longitudinal: they concern outcomes observed over time in a clinical group. Without a reported control comparison, the study cannot establish how the observed course differs from what would have occurred under another treatment or in another population. The outcome counts and analysis results needed to answer the clinical questions are not reported in the registry record.

3. Trial Design

PRODE is described as a Norwegian multicentre, longitudinal study of elderly depressed patients. The study record lists 169 enrolled patients and describes the group as patients admitted to specialist health care services of old age psychiatry. The registry status is completed. The listed study dates are a start in 2009-12 and primary completion in 2013-01.

The study summary describes assessments after one and three years. The primary outcome is relapse or recurrence of depression one year after inclusion, expressed as a number of participants among inpatients. The secondary outcomes include the number of patients with a diagnosis of dementia according to ICD-10 one year and three years after inclusion. The record indicates four outcome measures in all, but the details of every measure are not reported in the registry record.

This is not described as a randomized trial. The registry explicitly notes that allocation is not stated and that the arms are not a like-for-like control comparison. The listed group is depressed patients admitted to specialist old age psychiatry care; a separate valid comparison group is not described. Accordingly, the design supports a prognosis-focused description of outcomes in the recorded clinical population, not a randomized estimate of a treatment effect.

The registry record does not report a protocol, detailed recruitment procedures, follow-up completion, or a statistical analysis plan. It also does not state how the one-year and three-year assessments were conducted or how missing observations were handled. These omissions matter when interpreting longitudinal outcome counts: the record does not establish whether all enrolled patients contributed information at each assessment.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Inpatients

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 Depression, measured over 1 year after inclusion to the study.

The primary endpoint is relapse or recurrence of depression one year after inclusion to the study. The registry specifies the measure as a number of participants and names the population as inpatients. It therefore describes a count of people meeting the outcome definition, rather than a continuous score or a time-to-event estimate.

A relapse or recurrence endpoint is used to describe whether depression returns or recurs during the specified follow-up period. In a prognosis study, this can help characterize the clinical course of the population being followed. The meaning of the count depends on a clear operational definition of relapse or recurrence, consistent outcome assessment, and clarity about which patients were assessed. The precise diagnostic criteria and assessment procedures are not reported in the registry record.

The one-year timeframe is part of the endpoint definition. It should not be read as a measure of depression at every point during follow-up, nor as a comparison with an untreated or differently treated group. The registry record does not provide the number of participants with the endpoint, a denominator for those assessed, an effect estimate, or an uncertainty interval. As a result, it does not quantify how often relapse or recurrence was observed or how precisely that frequency is known.

The record separately lists dementia diagnoses at one year and three years as secondary outcomes. Those are not substitutes for the primary depression endpoint; they address a different clinical outcome and different follow-up times.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a binary primary outcome as a number of participants with an event. In this setting, the event is relapse or recurrence of depression at one year. A binary outcome records whether each assessed participant meets the outcome definition or does not. Reporting a count is useful, but interpretation also requires knowing the number assessed and how the endpoint was determined. Those details and the primary outcome count are not reported in the registry record.

What does a participant count tell us?

A count describes the number of people meeting an endpoint, but it does not by itself express how common that endpoint was among those assessed. The denominator must match the population contributing outcome data at the relevant time. Enrollment is not automatically the denominator at follow-up: some participants may not have a recorded assessment, and the registry record does not report follow-up completion or the number assessed. No frequency should therefore be inferred from the enrollment figure alone.

The registry’s primary outcome is not described as a time-to-event analysis. It is specified as a participant count at one year after inclusion. General methods for binary outcomes can compare event frequencies, estimate a proportion, or model the chance of an event, but the record does not report which statistical method was used. It lists 0 analyses. It would be inappropriate to attribute a particular model, adjustment strategy, or hypothesis test to the study.

Why does the comparison structure matter?

The record does not describe a randomized comparison. It states that allocation is not stated and that the arms are not a like-for-like control comparison. Random assignment, when used, can help make groups comparable on average, while an observational prognosis study describes outcomes in the population followed. Without a suitable comparator, the main interpretation is about the recorded clinical group, not a causal contrast between treatments. The registry does not report an intervention effect.

Any comparisons between groups would require a clear account of how those groups were formed and what factors might differ between them. The record does not provide such an account or a group-comparison analysis. The arm information should not be treated as evidence of a valid control condition.

What do confidence intervals and tests contribute?

In general, a confidence interval conveys uncertainty around an estimate under the assumptions of the analysis. A statistical test addresses compatibility between data and a specified null hypothesis, also under assumptions. Neither can be interpreted in isolation from the estimate, study design, and analysis population. The registry record reports no primary estimate, confidence interval, or p-value, so it is not possible to assess statistical precision or evidence against a null hypothesis for the primary endpoint.

Statistical significance, in general, does not describe the clinical importance of an effect. Conversely, a result that is not statistically significant would not establish the absence of an effect. Those distinctions cannot be applied to a particular PRODE result because no analysis result is reported in the registry record.

How should planning illustrations be read?

Planning illustrations are not observed results and do not describe the study’s actual power. The stated illustration assumptions use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is expressed as a fraction of the observed effect. For time-to-event illustrations, the stated quantity is a total number of events; for other illustrations, it is participants per arm. These are planning assumptions, not evidence that PRODE randomized participants or had two comparable arms. The registry says allocation is not stated and flags the arms as not a like-for-like control comparison.

A sample-size calculation based on an observed effect is a planning exercise that asks what study size might be needed to detect an effect under stated assumptions. It is not a measure of the probability that this completed study found a true effect. The registry record does not report an observed effect or analysis results, so the planning illustration cannot be read as a trial finding or as observed power.

General statistical caution also applies to follow-up studies: missing outcome observations can affect both the count and the population to which it applies. The record does not describe missing-data methods, analysis populations, or sensitivity analyses. These methods should not be assumed from the outcome definitions or study status.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Depressed Patients")
n      <- c(146)
events <- c(48)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Depressed Patients  146  48  32.9  25.3  41.1  25.8  40.9  25.8  40.9

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures. It identifies depression relapse or recurrence at one year as the primary endpoint and lists dementia diagnoses according to ICD-10 at one year and three years as secondary outcomes. The details of every listed measure are not reported in the registry record, and no outcome analyses are reported.

When a study examines several outcomes or timepoints, the chance of at least one apparently notable result can increase if each is tested separately. This is a general multiplicity issue, not evidence that PRODE used a particular adjustment. The registry record does not report whether the analysis plan prespecified a hierarchy, adjusted for multiple comparisons, or treated secondary outcomes as exploratory. With no analyses reported, it is not possible to assess how multiplicity was handled in practice.

Missing-data methods are also not reported in the registry record. It does not state how patients without an assessment at one year or three years were handled, whether missingness was described, or whether any sensitivity analyses were conducted. Those omissions limit interpretation of any follow-up count because the number enrolled may differ from the number with an observed outcome. No follow-up denominator is reported for the listed endpoints.

The record does not specify analysis populations, such as whether analyses included all enrolled patients or only those with observed outcome data. It also does not report an intention-to-treat approach or any other population definition. These details should not be inferred from the completed status, the enrollment count, or the endpoint descriptions.

Overall, the registry record does not provide the information needed to assess multiplicity control, missing-data handling, or analysis-population choices. These are reporting gaps, not proof that the study lacked methods for addressing them.

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 2% reporting threshold.

The registry’s serious adverse event listing for depressed patients reports 169 at risk and 0 affected. It does not list any top serious adverse event terms. The deaths field is not reported in the registry record. These entries describe the safety information recorded in this listing; they do not establish that no serious adverse events occurred outside the recorded reporting scope or period.

A count of 0 affected should be read alongside its at-risk count and the way adverse events were collected and reported. The registry record does not describe the event collection procedures, the safety observation period, or whether the listing covers all events throughout follow-up. It also does not explain the separate adverse-event categories in enough detail to interpret them beyond their recorded figures.

Zero recorded events is not proof of zero risk. It may reflect the events recorded under the registry’s definitions and reporting process, and the record does not give a statistical estimate of uncertainty around the safety count. The safety listing also does not provide a randomized comparison that would allow attribution of events to a treatment relative to a control.

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

PRODE addresses an important descriptive question: the course of depression in elderly patients admitted to specialist old age psychiatry services. The registry identifies relapse or recurrence at one year as the primary outcome and dementia diagnoses at one year and three years as secondary outcomes. These definitions establish what the study intended to assess, but they do not provide the observed outcome frequencies.

The registry record reports an enrollment of 169 and a completed study status, but no outcome analyses. It therefore does not establish how many participants had depression relapse or recurrence, how many received a dementia diagnosis, or how certain any estimate might be. The absence of reported results should not be interpreted as a finding of no events or as confirmation of the study’s prognosis hypothesis.

The design description also sets limits on what the study can mean. It is not a randomized comparison, allocation is not stated, and the registry warns that the arms are not a like-for-like control comparison. The record consequently does not support a causal treatment conclusion or a comparison of prognosis against a valid control group. Its stated purpose is prognostic, and its summary hypothesis should be kept distinct from evidence of an observed result.

In general, longitudinal observational findings can describe outcomes in the population actually followed. Their broader relevance depends on how participants were selected, how complete follow-up was, and how outcomes were assessed. The registry record does not report enough detail to evaluate these features fully. It also does not describe the statistical analysis or handling of missing data.

The useful conclusion from the available record is therefore about the study’s scope and its reporting status: it planned follow-up assessments of depression and dementia in a specialist-care population, but the posted record does not provide the analyses needed to estimate prognosis. It cannot establish whether outcomes were common or uncommon, whether estimates were precise, or why any outcome occurred.

14. Why This Trial Matters Statistically

PRODE is statistically interesting because it focuses on prognosis over time rather than a randomized treatment contrast. Prognosis studies can help describe the course of a condition in a defined clinical population. Interpreting such work requires close attention to who entered the study, who remained under observation, how outcomes were defined, and what population contributed data at each follow-up time.

The registry distinguishes a primary depression outcome at one year from secondary dementia outcomes at one year and three years. This makes outcome definition and follow-up timing central to interpretation. A count for one endpoint cannot be substituted for another, and the enrollment count cannot be assumed to represent the denominator at every assessment. The registry does not report the outcome counts or follow-up denominators needed to make those distinctions empirically.

The study also illustrates why design and analysis reporting matter. The registry says the study is not a randomized comparison, allocation is not stated, and the arms are not a like-for-like control comparison. Those statements preclude treating the listed groups as a conventional randomized treatment comparison. A prognosis question can still be meaningful, but its interpretation depends on transparent reporting of the observed course and the population followed.

Finally, completion status alone is not a statistical result. The record lists 0 analyses and does not report effect estimates or uncertainty. That gap prevents readers from judging the frequency and precision of the outcomes or assessing the study hypothesis. Statistically, the record is most informative about the intended questions and the limits on inference, rather than about the outcomes themselves.

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.

A central limitation of the registry record is that it reports no analyses or outcome results. The primary endpoint is named, but there is no event count, follow-up denominator, effect estimate, confidence interval, or test result. The dementia outcome counts are also not reported. As a result, the record cannot quantify the outcomes it describes.

The registry does not report the diagnostic criteria or assessment procedures for depression relapse or recurrence. Although dementia outcomes are described as diagnoses according to ICD-10, details of ascertainment and assessment are not reported. The record also does not state whether the one-year and three-year assessments were completed for all enrolled patients or how missing observations were treated.

The population is described as elderly depressed patients admitted to specialist old age psychiatry services. The record does not provide additional participant characteristics or recruitment details that would allow readers to judge how well this group represents other populations. It also does not report a valid control comparison: allocation is not stated, and the listed arms are not a like-for-like control comparison. Causal claims about treatment are therefore not supported by the design information in the record.

The registry does not report a statistical analysis plan, the analysis populations, multiplicity procedures, or sensitivity analyses. It lists four outcome measures, but not every outcome’s details. These omissions limit assessment of prespecification and analytical choices. The completed status and enrollment figure do not resolve these uncertainties or show whether follow-up data were complete.

These are limitations of what is reported in the registry record; they do not establish that the study did not collect further information or conduct analyses outside the record.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Prognosis of Depression in the Elderly (PRODE). A Multicentre, Longitudinal Study of Elderly Depressed Patients. — NCT01952366.
• Registry record last updated 2026-04-13; status last verified 2026-03.
• Results first posted 2016-09-22.
• 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

PRODE is a completed Norwegian multicentre longitudinal study of elderly depressed patients admitted to specialist old age psychiatry services. The registry lists an enrollment of 169, a start date of 2009-12, and primary completion in 2013-01.

The primary outcome is the number of inpatients with relapse or recurrence of depression one year after inclusion. Secondary outcomes include dementia diagnoses according to ICD-10 at one year and three years. The record lists four outcome measures overall.

The registry reports 0 analyses and does not report outcome results. It states that the study is not a randomized comparison, allocation is not stated, and the listed arms are not a like-for-like control comparison. Thus, the posted record describes the study questions and design but does not provide estimates of the outcomes or their uncertainty.