Epidemiology of Depression, Anxiety, and Cognitive Impairment: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Epidemiology of Depression, Anxiety, and Cognitive Impairment (NCT00717041), a registered phase not stated study. The primary outcome is Participants With Depression by Patient Health Questionnaire - 9.

2. Clinical Question

The registry record asks whether depression and cognitive impairment are common among older adults presenting to an emergency department, and whether their prevalence differs according to how patients arrive. It also raises a measurement question: whether screening during an acute illness can validly identify these conditions. These are descriptive and assessment questions, rather than questions about the comparative effect of two assigned treatments.

The listed primary endpoint concerns depression measured with the Patient Health Questionnaire - 9. It counts participants whose score meets the stated threshold of at least 10, with a registry timeframe of 2 hours. The record also lists a secondary outcome concerning depression and cognitive impairment at 2 weeks. Anxiety appears among the study conditions and in the study title, but the registry record does not report a specific anxiety endpoint in the outcome details described.

The study is framed around emergency department patients and the possible role of the emergency department as a place to identify unmet health needs. The description highlights concerns that some older adults have undetected problems and that screening based in primary care may not reach everyone. It does not establish that emergency department screening is effective or valid; those are questions the study description identifies as relevant.

The registry record does not report the observed depression count, the distribution of screening scores, or estimates comparing arrival modes. It also does not report results from the 2-week outcome. Consequently, the clinical question can be described from the stated aims and endpoints, but the posted information does not show an answer to those questions.

3. Trial Design

NCT00717041, titled Epidemiology of Depression, Anxiety, and Cognitive Impairment, is recorded as completed and sponsored by the University of Rochester. The registry lists enrollment of 1206 and study dates from 2008-05 to 2008-09. Its description concerns older adults presenting to an emergency department and the epidemiology of depression, anxiety, and cognitive impairment in that setting.

The design information does not describe a randomized treatment comparison. The record lists one arm, called Presenting to the ED, with the description Patients who present to the ED. It does not state an allocation method, and the registry record specifically does not present the arms as a like-for-like control comparison. The information therefore supports reading this as an epidemiologic study, not as a controlled trial estimating the effect of a treatment.

The stated primary endpoint is a count of participants meeting a depression screening threshold on the Patient Health Questionnaire - 9, with a timeframe of 2 hours. A secondary outcome is listed for depression and cognitive impairment at 2 weeks. The study description identifies interest in whether prevalence differs by mode of arrival and in whether screening during acute illness is valid. The record does not provide the arrival-mode categories or a detailed schedule of data collection.

Important design details are not reported in the registry record. These include the eligibility criteria, recruitment procedures, setting details beyond the emergency department, the approach to choosing or defining arrival groups, and the planned statistical analysis. A sample-size justification for the original study is also not reported in the registry record. The record lists 4 outcome measures and 0 analyses, so the design description should not be mistaken for a full results report.

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

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 Participants With Depression by Patient Health Questionnaire - 9, measured over 2 hours.

The primary endpoint is the number of participants classified as having depression according to the Patient Health Questionnaire - 9. The registry definition uses a score of at least 10. The endpoint is listed in participants, with a timeframe of 2 hours. This makes the outcome a binary classification at the participant level: each person either meets the stated threshold or does not. The primary result would ordinarily be interpretable as a count, and, when paired with the number assessed, as a measure of how frequently the threshold was met in the studied group.

Screening questionnaires provide a standardized way to define an outcome for descriptive research. A threshold turns a score that can vary across people into a category that can be counted. That can help describe the burden of screening-positive results in a particular setting. It does not, by itself, establish a clinical diagnosis, explain why a participant has a particular score, or show how accurately the measure performs during acute illness.

The registry description makes the timing relevant: it explicitly raises whether screening during acute illness is valid, and lists a later outcome concerning depression and cognitive impairment at 2 weeks. Comparing assessments at different times could be informative only if the corresponding results and analysis were reported. The registry record does not report the primary count or the later outcome values, nor does it report diagnostic validation data. The endpoint is therefore defined, but its observed value and precision cannot be evaluated from the posted results described in the record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is listed?

The primary endpoint is a binary participant-level outcome. A participant is classified according to whether the Patient Health Questionnaire - 9 score reaches at least 10. General statistical explanation: binary outcomes are often described by reporting the number meeting the definition together with the number assessed. The count gives the numerator; the assessed participants supply the denominator. A percentage or prevalence estimate can then describe the frequency in that group. The registry record does not report the observed count, the number assessed, or a prevalence estimate, so none can be interpreted for this study.

The endpoint is a screening classification, not a continuous score as presented in the registry outcome definition. That distinction matters because a threshold discards information about how far individual scores lie above or below the cutoff. It also means results depend on the stated cutoff and on whether the questionnaire was completed and scored as intended. General statistical explanation: a screening threshold is a rule for classifying results; classification alone does not establish diagnostic accuracy. The registry record does not report validation against a diagnostic assessment or details of how incomplete questionnaires were handled.

What would a prevalence estimate mean?

General statistical explanation: prevalence is a description of how common a defined condition or screening classification is in a specified population at a specified time. Its interpretation depends on the population sampled, the outcome definition, and the denominator. A prevalence estimate from emergency department patients would describe the assessed study population; it would not automatically represent all older adults, all emergency department patients, or people in other settings. The registry description identifies older adults presenting to the emergency department as the intended population, but eligibility rules, sampling procedures, and the final analysis population are not reported in the registry record.

A confidence interval is a way to express the uncertainty associated with an estimate under a statistical model and its assumptions. General statistical explanation: a narrower interval indicates greater precision, while a wider interval indicates less precision. Precision is not the same as freedom from bias: an estimate can be precise and still be affected by selection, measurement, or missing-data problems. No confidence interval for the primary endpoint is reported in the registry record, so its precision cannot be assessed.

How should arrival-mode comparisons be understood?

The description asks whether depression and cognitive impairment differ by mode of arrival. General statistical explanation: a comparison requires a defined measure for each group and a contrast that expresses how the groups differ. The contrast might be a difference in proportions or another prespecified measure, but the registry record does not state which comparison was planned or report its results. The arrival categories and group denominators are also not reported.

Because the registry record does not describe randomized allocation and does not identify a like-for-like control group, any arrival-mode comparison should be read as observational. General statistical explanation: in observational comparisons, group membership is not assigned at random, so other characteristics may vary between groups. Statistical adjustment can sometimes address measured differences, but cannot guarantee removal of unmeasured confounding. The registry record does not report an adjustment plan, covariates, or adjusted estimates. No causal interpretation is justified by the design information available.

What can a later assessment add?

A secondary outcome is listed for depression and cognitive impairment at 2 weeks. General statistical explanation: repeated assessment can describe whether classifications or scores differ over time, but interpretation depends on whether the same participants are measured, how the measures are defined, and how incomplete follow-up is handled. A change in classification can reflect a true change, measurement variability, or differences in who was assessed. The registry record does not report the later outcome values, paired data, follow-up completion, or an analysis of agreement or change.

The study description raises whether screening during acute illness is valid. Validity is a measurement property: it concerns whether an instrument or classification adequately reflects the condition it is intended to identify. General statistical explanation: assessing validity commonly requires a suitable reference measure or a clearly stated validation approach. A later screening result alone is not necessarily a reference standard. No validation method or accuracy estimate is reported in the registry record.

What do analysis and planning details establish?

The registry lists 0 analyses. It therefore does not report model estimates, standard errors, confidence intervals, hypothesis tests, or analysis populations. The original statistical analysis plan, treatment of clustering or over-dispersion, and interim analyses are not reported in the registry record. General statistical explanation: over-dispersion matters when observed variability exceeds what a chosen count model expects; if relevant, the model may need to account for that extra variability. The registry record does not establish that a count model was used or that over-dispersion was present.

Any sample-size calculation based on an observed effect is a planning illustration, not an account of the original study design and not observed power. The registry record does not report the original sample-size justification. A planning calculation cannot replace estimates and uncertainty from the completed study, and it cannot show whether the study detected a meaningful difference. No outcome effect estimate is reported in the registry record for interpreting such planning calculations.

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("Presenting to the ED")
n      <- c(1206)
events <- c(177)
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  Presenting to the ED  1206  177  14.7  12.7  16.8  12.8  16.8  12.8  16.8

11. Multiplicity, Missing Data and Analysis Populations

The registry record lists 4 outcome measures, including the primary depression endpoint and a secondary outcome concerning depression and cognitive impairment at 2 weeks. It lists 0 analyses. The complete list of outcome definitions and the analytic hierarchy beyond the endpoint details described are not reported in the registry record. Nor is a plan for prioritizing outcomes or handling multiple comparisons reported.

General statistical explanation: when many outcomes or comparisons are examined, the chance of finding an apparently notable result by chance can increase. A prespecified primary outcome, a clear hierarchy, or an adjustment procedure can help readers understand how multiple testing was addressed. The registry record does not say whether any such procedure was planned or used. With no reported analyses, there are no posted p-values or confidence intervals to assess for multiplicity.

Missing-data information is also not reported in the registry record. The enrollment figure of 1206 does not establish how many participants completed the primary questionnaire, had evaluable scores, or returned for the 2-week assessment. The record does not describe missing-item rules, exclusions, imputation, or sensitivity analyses. General statistical explanation: missingness can affect both the denominator and the representativeness of an estimate, particularly if the likelihood of missing data is related to participants' health or study outcomes.

The analysis population is not defined in the registry record. It is not stated whether outcome summaries include all enrolled participants, only those completing screening, or another subset. These omissions limit assessment of both outcome completeness and the relationship between the enrolled group and the analyzed group.

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 0% reporting threshold.

The serious adverse event figures list 1206 participants at risk and 0 affected in the Presenting to the ED group. The other adverse event figures also list 1206 at risk and 0 affected. No serious adverse event terms are listed. These are the figures recorded for this study; they are not a comparison between a treatment group and a control group.

The record does not report a death count. A missing death value should not be read as zero deaths. The adverse event figures also do not establish that every participant was assessed in the same way or that every possible event was captured; details of collection and reporting procedures are not reported in the registry record.

General statistical explanation: an observed count of zero is a statement about what was recorded in the reported group, not proof that an event is impossible or that risk is absent. Interpretation depends on the definition of reportable events, follow-up, ascertainment, and completeness. Those details are not reported in the registry record. Since the study description is epidemiologic and does not present a treatment comparison, these figures should not be interpreted as evidence about the safety of a treatment.

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

The registry record describes an epidemiologic study of older adults presenting to an emergency department, with interest in depression, anxiety, cognitive impairment, arrival mode, and screening during acute illness. It defines a primary depression screening endpoint and lists a later outcome concerning depression and cognitive impairment. These details establish what the study was intended to examine, but they do not show what was observed.

The enrollment figure is 1206, and the study is recorded as completed. However, the record does not report the number who met the depression screening threshold, the proportion assessed, or the relevant confidence interval. It also does not report results comparing arrival modes or values for the 2-week outcome. Thus, the record cannot quantify how common a positive depression screen was in the study group or how precisely any prevalence estimate was measured.

The record also cannot establish whether screening during acute illness was valid. That question would require relevant outcome data and a stated method for assessing validity. The endpoint definition and the existence of a later assessment do not substitute for those results. Similarly, the study does not provide a randomized comparison that could estimate a treatment effect. Its stated questions concern description and measurement, not whether a treatment caused an outcome.

General statistical explanation: descriptive estimates characterize the people who were assessed, while causal conclusions require a design and analysis capable of addressing alternative explanations. Even a complete descriptive result would not automatically generalize beyond the population and setting studied. Here, recruitment, eligibility, analysis population, and outcome estimates are not reported in the registry record, so both the scope and precision of any conclusion remain unclear.

The most defensible interpretation is therefore limited: NCT00717041 records an intended epidemiologic investigation and defined outcome measures, but the posted registry information does not report the analyses needed to answer its stated questions. Absence of reported results is not evidence that the outcomes were absent or that a particular comparison was null.

14. Why This Trial Matters Statistically

This study raises statistical questions that arise when researchers use a busy clinical setting to describe health needs. Emergency departments may encounter people who are not reached by conventional screening routes, as the study description notes. Estimating the frequency of screening-positive results in such a setting requires a clearly defined population, consistent measurement, and transparent denominators. Without those details and the outcome counts, readers cannot judge the size or precision of the estimated burden.

The study also connects epidemiology with measurement. Screening during acute illness may not have the same interpretation as assessment outside an acute episode. A threshold-based questionnaire can support consistent classification, but its meaning depends on validity in the setting where it is used. The study description explicitly identifies this as an open question. The registry record does not report validation results, so the concern remains a motivation rather than a conclusion.

Arrival mode presents a further design issue. Differences between people arriving in different ways can be described statistically, but observational differences do not establish that the mode of arrival itself explains those differences. Clear group definitions, denominators, and methods for handling confounding are needed to interpret such comparisons. Those analysis details and results are not reported in the registry record.

Finally, the record illustrates why a completed status and an enrollment figure are not substitutes for results. Statistical interpretation requires outcome estimates, uncertainty, analysis populations, and missing-data information. With 0 analyses listed, the registry information identifies questions worth examining but does not quantify answers. This distinction is important for readers evaluating what an epidemiologic study establishes and what remains unknown.

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 interpretation is that the registry record does not report numerical outcomes or analyses. The primary endpoint is defined, but its observed count and denominator are not stated. No prevalence estimate, confidence interval, p-value, or comparison by arrival mode is reported. The secondary outcome at 2 weeks is listed without outcome values.

The study population is described broadly as older adults presenting to the emergency department, but eligibility criteria, recruitment methods, and the characteristics of participants are not reported in the registry record. The enrollment figure of 1206 does not reveal how many participants contributed data to each outcome. The analysis population and the handling of incomplete questionnaires or follow-up are also not reported, limiting assessment of selection and missing-data concerns.

The record does not specify the arrival-mode categories or the planned comparison. It does not report whether estimates were adjusted for other participant characteristics. Because the record does not describe randomized allocation or a like-for-like control comparison, any comparison by arrival mode would need to be interpreted as observational, with potential for confounding. No adjusted analysis is reported.

Although the study description asks whether screening during acute illness is valid, the registry record does not report a reference assessment, validation procedure, or diagnostic accuracy results. The existence of a later outcome does not resolve that limitation without information about follow-up and analysis. The original statistical analysis plan, multiplicity strategy, sample-size justification, and interim analyses are not reported in the registry record.

These limitations mean that the record can identify the study's purpose and endpoint structure but cannot support a quantitative conclusion about prevalence, group differences, or screening validity. They should not be mistaken for evidence that the study found no effect or no cases.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Epidemiology of Depression, Anxiety, and Cognitive Impairment — NCT00717041.
• Registry record last updated 2015-06-15; status last verified 2015-06.
• Results first posted 2015-06-15.
• 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

NCT00717041 is a completed epidemiologic study sponsored by the University of Rochester, with enrollment listed as 1206 and dates from 2008-05 to 2008-09. It concerns depression, anxiety, and cognitive impairment among emergency department patients, with the description focused on older adults.

The primary endpoint counts participants meeting the depression threshold on the Patient Health Questionnaire - 9, defined as a score of at least 10, with a timeframe of 2 hours. A secondary outcome concerns depression and cognitive impairment at 2 weeks. The study description raises questions about prevalence by arrival mode and the validity of screening during acute illness.

The registry record lists 4 outcome measures and 0 analyses. It does not report the primary count, outcome estimates, comparisons, or analysis details. Serious and other adverse event figures each list 0 affected among 1206 at risk; the death count is not reported.