Treatment of Depressed Chronic Obstructive Pulmonary Disease Patients: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Treatment of Depressed Chronic Obstructive Pulmonary Disease Patients (NCT00151372), a randomized na study. The primary outcome is Composite Antidepressant Score Scale (CAD).

2. Clinical Question

The study description proposes that helping patients overcome adherence obstacles could affect physicians' prescribing of adequate antidepressant treatment, patients' adherence, depressive symptoms, suicidal ideation, and disability. These are stated hypotheses, not reported findings. The primary endpoint focuses on the adequacy of antidepressant dosage rather than directly measuring adherence, depressive symptoms, or disability. The registry lists the Hamilton Depression Rating Scale as a secondary outcome, but does not report its results.

Accordingly, the clinical question can be identified, but the posted record does not establish the direction or size of any between-group difference. Without endpoint results and an analysis, it is not possible to assess how the groups compared at follow-up or how precisely any difference was estimated.

3. Trial Design

This was a randomized, parallel-group trial with no masking. The registry lists 141 participants and marks the study as completed. The sponsor was Weill Medical College of Cornell University. The recorded start was 2002-03 and primary completion was 2008-07. The phase is listed as not applicable.

Participants were assigned to Treatment Adherence Intervention or Enhanced Care. In the intervention arm, a study therapist regularly met with participants to identify obstacles to adhering to depression and chronic obstructive pulmonary disease treatment and help them overcome those obstacles. In the comparator arm, physicians providing aftercare received written information about the patients' diagnosis but no clinical instructions from the research team. The registry labels both interventions behavioral.

Random allocation helps make groups comparable on average at assignment, but it does not guarantee that the groups will be alike on every characteristic. Because masking was absent, participants and study personnel were not masked to assignment. The registry does not describe who generated or implemented the allocation sequence, whether assignment was concealed before enrollment, or which outcome assessors knew the assignments. Those details are not reported in the registry record.

The primary outcome was assessed at 28 weeks. Its population description states that the analysis included subjects actively participating at that assessment and equates this with the number marked as completed in Participant Flow. The number analyzed and the flow of participants by arm are not reported in the registry record. The record also does not provide a more detailed schedule of assessments, intervention duration, adherence measurement, or follow-up procedures.

The study description says the intervention was intended to facilitate adherence to an algorithm based on Agency for Health Care Policy and Research guidelines. It does not provide enough detail to reconstruct the algorithm, clinical care received in each arm, or implementation fidelity. Those protocol details are not reported in the registry record.

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: Analysis was conducted on subjects actively participating in the study at the 28-week assessment. The number corresponds to "Completed" in the "Participant Flow" section.

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 Composite Antidepressant Score Scale (CAD), measured over 28 Weeks.

The primary endpoint is the Composite Antidepressant Score scale (CAD), assessed at 28 Weeks. It describes the adequacy of an antidepressant's dosage. Scores range from 0-4: scores of 0, 1, and 2 indicate subthreshold or non-adequate therapeutic dosages, while scores of 3 and 4 indicate a therapeutic/adequate dosage. The best value is 4 and the worst value is 0.

The registry characterizes the endpoint as a number of participants. This makes the intended outcome a count of participants in endpoint categories, rather than a mean score or a time-to-event measure. The endpoint is relevant to the stated intervention pathway because the study aims to support treatment adherence and adequate antidepressant treatment. It captures dosage adequacy, however, and is not itself a direct measure of whether a participant took medication as prescribed or experienced an improvement in depressive symptoms.

For a useful group comparison, the outcome would need to be reported in a way that identifies the relevant categories and denominators, along with an analysis appropriate to the chosen contrast. The registry record does not report the category counts, denominator for each group, or comparative estimate. It therefore does not support a conclusion about the primary endpoint's observed distribution or the precision of a difference between groups.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does randomization contribute?

General: Random allocation is intended to reduce systematic differences between groups at the time of assignment. If assignment is implemented as planned, measured and unmeasured participant characteristics are balanced on average across repeated versions of the trial. In a particular trial, chance imbalances can still occur. Randomization does not correct for missing outcome data, departures from assigned care, measurement problems, or selective reporting after assignment.

The registry identifies the study as randomized but does not describe the sequence-generation method, allocation concealment, or the analysis population in sufficient detail to assess those procedures. It also records no masking. Lack of masking can matter when participants or personnel influence treatment delivery, reporting, or outcome assessment. Whether that occurred in this trial cannot be determined from the registry record.

How should the endpoint be understood?

General: A count endpoint records how many participants fall into a defined category. Interpreting a count requires knowing the category definition and the number of participants eligible for that count. Counts alone do not account for different group sizes. A comparison may therefore use group-specific proportions or another prespecified statistical model, depending on the outcome structure and analysis plan.

Here, the CAD scale defines dosage adequacy by score categories, and the primary outcome is described as a number of participants. However, the registry does not report the number of participants in each category or the denominators used for the comparison. It also does not report whether categories were analyzed separately, combined, or treated in another way. The skip note indicates that the primary outcome has several categories or time points and was not reduced to a single comparison. The analysis that would connect those categories to an overall treatment contrast is not reported in the registry record.

What would an effect estimate and confidence interval add?

General: An effect estimate quantifies the contrast between groups using a specified scale. Depending on the endpoint and analysis plan, that scale might be a difference in proportions, a relative measure, or another contrast. The estimate's meaning depends on the outcome definition, denominator, and analysis population. A confidence interval communicates uncertainty around the estimate; a wider interval indicates less precision than a narrower interval, without by itself deciding whether an effect is clinically important.

No primary estimate or confidence interval is reported in this registry record. There is also no reported p-value for the primary comparison. Consequently, readers cannot infer the magnitude, direction, precision, or statistical compatibility of the group difference from the endpoint description alone. A non-significant result cannot be assumed, because no such result is reported; a statistically significant result cannot be assumed either.

Why do analysis population and missing outcomes matter?

General: An intention-to-treat analysis generally compares participants according to their randomized assignment, preserving the initial randomized groups. Other analysis populations may include only participants who received treatment or completed follow-up. These approaches answer different questions and can be affected differently by nonadherence and attrition. An analysis restricted to participants with observed outcomes may be biased if outcome availability is related to group assignment or to the outcome itself.

The primary outcome description says the analysis was conducted on subjects actively participating at the 28-week assessment and refers to those marked as completed in Participant Flow. This does not, on its own, specify an intention-to-treat analysis or explain how missing outcomes were handled. Group-specific numbers completing assessment, reasons for noncompletion, imputation methods, and sensitivity analyses are not reported in the registry record. The safety at-risk counts should not be assumed to be the primary efficacy analysis denominators.

What can be said about planning and multiplicity?

General: Sample-size planning estimates how many participants may be needed to detect a prespecified effect under chosen assumptions. Such calculations are planning illustrations; they are not observed power and do not establish what effect occurred. An illustration based on an observed effect is especially dependent on the estimate used and should not be mistaken for a prospective design justification or a trial result.

The record describes planning assumptions including a two-sided significance level of 0.05, equal allocation, and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. It does not report a sample-size justification or the numerical planning outputs. The registry does not report an observed primary effect from which readers could assess the illustration.

General: Multiplicity arises when several outcomes, time points, categories, or statistical comparisons are examined. The more analyses considered, the greater the chance of at least one apparently unusual result if no adjustment or interpretation plan accounts for the number of comparisons. The record lists a primary outcome with several categories or time points and a secondary outcome, but does not report a multiplicity strategy, statistical analysis plan, or completed analysis. The implications cannot be evaluated from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The registry identifies the CAD outcome as primary and lists the Hamilton Depression Rating Scale as a secondary outcome. The primary outcome description includes several categories or time points, and the record does not reduce it to a single comparison. The registry reports no analyses. A multiplicity plan, including whether any outcomes, categories, or time points were designated for confirmatory testing or adjusted for multiple comparisons, is not reported in the registry record.

General: Testing several outcomes or contrasts can increase the chance that at least one result appears notable by chance. Prespecifying a primary contrast and controlling or transparently addressing multiplicity can help readers interpret a set of tests. Without a statistical analysis plan or reported tests, it is not possible to establish how multiplicity was handled in this trial.

The endpoint population is described as subjects actively participating at the 28-week assessment, with the number corresponding to participants marked completed in Participant Flow. The analyzed count by group is not reported in the registry record. The record does not specify whether participants were analyzed according to their assigned group, how missing primary outcomes were handled, why participants may not have completed follow-up, or whether any sensitivity analyses were conducted.

General: Missing outcomes can affect both precision and validity. If outcome availability differs between groups or is related to participants' likely outcomes, an analysis limited to observed measurements may not represent the original randomized groups. The safety at-risk counts do not resolve this issue for the primary endpoint, because the record does not identify them as its analysis denominators. The available information is therefore insufficient to assess attrition, missing-data assumptions, or the robustness of an efficacy comparison.

11. 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.

Most frequent serious adverse event terms

Serious events with the highest arm-level rate: exacerbation of chronic obstructive pulmonary disease (45.9%), pneumonia (6.8%), heart surgery (4.5%), staph infection (4.1%), congestive heart failure (3.0%).

The registry lists serious adverse events for both study groups. For Treatment Adherence Intervention, 67 participants are listed as at risk and 38 as affected. For Enhanced Care, 74 are listed as at risk and 46 as affected. Other adverse events are listed as 0 affected in each group. Death counts are not reported in the registry record.

These entries are descriptive safety counts. They do not establish that the groups had comparable exposure periods, and they are not the primary CAD endpoint. The registry record does not define the serious-event counting unit in further detail or report an adjusted comparison. The counts should therefore be read as entries for the stated groups, not as evidence of a causal difference.

The record lists the following serious adverse event terms and percentages: exacerbation of chronic obstructive pulmonary disease, 45.9%; pneumonia, 6.8%; heart surgery, 4.5%; Staph infection, 4.1%; congestive Heart Failure, 3.0%; and fall, 3.0%. The denominator and method used to calculate those percentages are not reported in the registry record. These percentages cannot be interpreted as group-specific risks or compared with the at-risk counts without that information. The safety record is not, by itself, enough to determine how the intervention affected safety.

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

The registry record establishes that a randomized, non-masked, parallel-group trial compared a therapist-led treatment-adherence intervention with enhanced care in patients with chronic obstructive pulmonary disease and major depression. It describes the interventions, identifies a primary measure of antidepressant dosage adequacy at 28 weeks, and records serious adverse event counts.

It does not report the CAD category counts, the primary comparison, an effect estimate, a confidence interval, or a p-value. It also does not report the number of participants analyzed for the primary endpoint by group. The registry lists the Hamilton Depression Rating Scale as a secondary outcome but does not provide its result. The study's hypotheses about prescribing, adherence, depressive symptoms, suicidal ideation, and disability should not be mistaken for observed findings.

As a result, the posted information cannot establish whether the primary endpoint differed between groups, how large any difference was, or how precisely it was estimated. Missing statistical results do not imply that there was no difference; they also do not support a conclusion that there was one. The absence of a reported analysis is a limit on what can be concluded from this registry record.

General: A trial's result is best interpreted by considering the estimated contrast, its uncertainty, the outcome's clinical meaning, and the completeness of follow-up together. A result on dosage adequacy would not automatically answer every question about medication adherence, depressive symptoms, disability, or safety. Those are distinct outcomes and require their own reported measurements and analyses.

The safety counts are also not a substitute for efficacy results, and the serious-event percentages lack a reported denominator. The record supports a description of the trial's design and listed safety entries, but not a claim that either treatment strategy improved or worsened an outcome.

13. Why This Trial Matters Statistically

This trial is statistically notable because it sets out a randomized comparison in a population with both chronic obstructive pulmonary disease and major depression, while targeting obstacles to adherence through regular therapist meetings. Its comparator was not described as no care: physicians in Enhanced Care received written information about the diagnosis, but no clinical instructions from the research team. Keeping that distinction clear is important when defining the contrast the randomization was intended to estimate.

The primary measure also illustrates the difference between a clinically motivated construct and a reported statistical result. The CAD scale concerns antidepressant dosage adequacy, with a defined range and categories, but the registry does not provide the participant counts in those categories or the comparison between groups. A complete result requires more than naming the measure: readers need denominators, outcome values, an analysis, and an indication of uncertainty.

The record also highlights why analysis populations and follow-up matter. Its endpoint description refers to participants active at the 28-week assessment, but the number analyzed and the handling of missing outcomes are not reported. Without those details, readers cannot determine how closely the endpoint analysis reflects the randomized groups.

Finally, the record gives safety counts but not a primary efficacy analysis. This distinction is important: descriptive safety entries and a planned clinical hypothesis answer different questions. For biostatisticians and clinical researchers, the case underscores the need for complete outcome reporting, transparent denominators, and an interpretable analysis plan. Here, those missing elements limit statistical interpretation regardless of the trial's stated rationale.

14. 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 of the registry record for statistical interpretation is that it does not report the primary outcome results or any analyses. The CAD categories are defined, but their participant counts, group-specific denominators, effect estimate, confidence interval, and p-value are not reported. The record therefore does not permit assessment of the primary comparison's direction, magnitude, or precision.

The primary endpoint population is described as subjects actively participating at the 28-week assessment, corresponding to participants marked completed in Participant Flow. The count analyzed by group, participant flow details, and reasons for missing outcomes are not reported in the registry record. Nor does the record explain whether analysis followed randomized assignment or how incomplete observations were handled.

Randomization is recorded, but the sequence-generation and allocation-concealment procedures are not described. Masking is listed as none, while the roles of outcome assessors and any safeguards against biased assessment are not reported. The record also does not provide a statistical analysis plan, multiplicity approach, or analysis details for the several outcome categories or time points.

For safety, at-risk and affected counts are listed, but the registry does not specify the serious-event counting method, provide death counts, or give the denominator behind the percentages attached to the event terms. Those entries cannot be converted into a clear comparative risk assessment from the information reported.

Finally, the intervention description does not establish how consistently it was delivered, what adherence measures were used, or how treatment varied across participants. These protocol and implementation details are not reported in the registry record. They limit interpretation of what the intervention contrast represented in practice.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Treatment of Depressed Chronic Obstructive Pulmonary Disease Patients — NCT00151372.
• Registry record last updated 2010-01-11; status last verified 2009-12.
• Results first posted 2010-01-11.
• 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.

18. Record Summary

NCT00151372 is a completed randomized, parallel-group study with no masking and an enrollment of 141. The registry lists chronic obstructive pulmonary disease and major depression as conditions. The sponsor was Weill Medical College of Cornell University; the recorded start was 2002-03 and primary completion was 2008-07.

The trial compared Treatment Adherence Intervention, in which a therapist regularly addressed treatment-adherence obstacles with participants, with Enhanced Care, in which aftercare physicians received written diagnosis information without clinical instructions from the research team. The primary endpoint was the Composite Antidepressant Score scale at 28 Weeks, a measure of antidepressant dosage adequacy. The Hamilton Depression Rating Scale is listed as a secondary outcome.

The registry does not report the primary endpoint results or statistical analyses. Safety entries list serious adverse events in both groups, while deaths are not reported in the registry record. The available record describes the trial question and design but does not support an estimate of the intervention's comparative effect.