Leukocyte Function in Chronic Obstructive Pulmonary Disease (COPD): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Leukocyte Function in Chronic Obstructive Pulmonary Disease (COPD) (NCT00147082), a registered phase not stated study. The primary outcome is Effective Concentration (EC 50) of GRO Alpha.

2. Clinical Question

The research objective is mechanistic rather than a test of a treatment. The study description asks how leukocytes are recruited to the lung in COPD and whether their behavior differs from that of cells from healthy smokers and non-smokers. It also describes examining cell-surface receptors involved in trafficking and comparing cell differentiation in vitro, including expression of enzymes associated with tissue destruction.

The registered primary endpoint focuses on a laboratory migration response to GRO Alpha. It is an effective concentration, expressed in ng/ml, with a stated timeframe of 2 hours. The registry description defines EC 50 as the concentration required for 50% inhibition in vitro. The record does not report the measured EC 50 values, group contrasts, or uncertainty estimates, so the primary question cannot be answered from the registered numerical results available in this record.

3. Trial Design

This completed study is titled “Leukocyte Function in Chronic Obstructive Pulmonary Disease (COPD).” Its official title describes leukocyte migration and differentiation in COPD patients compared with healthy smokers and healthy non-smoking subjects. Imperial College London is listed as the sponsor. The record gives a start date of 2001-02 and a primary completion date of 2004-12. Enrollment is listed as 100.

Three groups are described: patients with COPD, smokers without COPD, and non-smokers with no history of respiratory disease. Each arm description states that there was no intervention. The record does not state how participants were allocated. It specifically cautions that this is not a randomized comparison and that the arms are not a like-for-like control comparison. Consequently, the group structure should be read as a comparison of participant categories, not as a randomized treatment contrast.

The study description emphasizes laboratory work on leukocytes isolated from blood. The planned scientific questions included movement toward chemoattractants, cell-surface receptors involved in cell trafficking, and in-vitro differentiation. It also refers to examining enzymes associated with tissue destruction. These objectives describe the broader research program; they do not establish that numerical results for each objective are available in the registry record.

The primary endpoint is the effective concentration (EC 50) of GRO Alpha, measured in ng/ml, for a PBMC migration response. The stated timeframe is 2 hours. The record lists 3 outcome measures and 3 analyses, but does not report a detailed protocol, allocation procedure, or analysis plan. No sample-size justification is reported in the registry record. The study status is completed, but completion status alone does not establish that all intended results were posted.

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 Effective Concentration (EC 50) of GRO Alpha, measured over 2 hours.

The primary endpoint is titled “Effective Concentration (EC 50) of GRO Alpha.” It concerns the migration response of peripheral blood mononuclear cells (PBMC) to a chemokine and is recorded in ng/ml. The stated timeframe is 2 hours. The registry description says EC 50 represents the concentration of a drug required for 50% inhibition in vitro. That definition describes the endpoint’s intended interpretation; the numerical concentration and any group-level estimates are not reported in the registry record.

An effective concentration can express the concentration associated with a specified response level. In this study’s description, that response level is 50% inhibition. Such a measure can characterize a laboratory response on a concentration scale, rather than simply recording whether migration occurred. Comparing the measure across participant groups could address whether the in-vitro response differs among the groups, provided the underlying estimates and comparison methods are available.

The endpoint is relevant to the stated mechanistic aim because the study investigates leukocyte movement toward chemoattractants. It is a laboratory measure, however, and does not by itself measure lung tissue damage, clinical symptoms, or the effect of a therapy. The record gives the endpoint name, unit, and timeframe, but does not report its mean, standard error, group differences, confidence intervals, or a statistical test. Therefore, the direction, size, and precision of any group contrast cannot be assessed from the registered result information.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The endpoint is a continuous laboratory measure, and the registry identifies the mean as its summary parameter and the standard error as its dispersion measure. These summaries answer different questions. A mean describes the center of the observed measurements in a group. A standard error describes how precisely the group mean is estimated; it is not a direct summary of how widely individual participants’ measurements vary. A measure of participant-to-participant variability, such as a standard deviation, is not reported in the registry record.

What does an EC 50 measure?

In general, an EC 50 is a concentration associated with a specified response level. The registry description states that this endpoint represents the concentration required for 50% inhibition in vitro. Here, the registered measure concerns the PBMC migration response to GRO Alpha and is expressed in ng/ml. The stated timeframe is 2 hours. The registry record does not give the concentration-response data, the fitted method used to identify the EC 50, or the resulting estimates. Those details matter for evaluating how the measure was derived and how uncertain it is.

How should a mean and standard error be read?

In general, a mean can be useful for comparing the central response across groups, while a standard error indicates the precision of each estimated mean. A smaller standard error, considered in context, indicates a more precise estimate of the mean; it does not mean that individual observations are necessarily less variable. To assess a difference between groups, readers also need a contrast or a suitable comparison procedure. Separate group summaries alone do not necessarily convey the uncertainty in the difference. No group means, standard errors, contrast estimates, or comparison results are reported in the registry record.

What would a confidence interval add?

In general, a confidence interval expresses uncertainty around an estimate and helps show which effect sizes remain compatible with the data under the analysis assumptions. It complements a point estimate: the point estimate conveys the estimated direction and magnitude, while the interval conveys precision. A confidence interval is not reported for the primary endpoint in the registry record. Without an estimate and its uncertainty, it is not possible to distinguish a small, precise difference from a large but imprecise one.

What does the design imply for comparisons?

The three groups are COPD, smokers without COPD, and non-smokers. No intervention is listed, allocation is not stated, and the record cautions that the arms are not a like-for-like control comparison. In general, a non-randomized group comparison can describe an association but does not by itself isolate the effect of one characteristic from other differences between groups. The record does not report adjusted estimates or the covariates, if any, considered in an analysis. No adjustment strategy should therefore be inferred.

The record gives a planning illustration framework based on the observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It specifies that the effect to detect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not evidence that the original study was designed around those assumptions. The sample-size justification for the trial itself is not reported in the registry record. Numerical planning results and their specific effect fractions are not reported in the registry record.

More generally, a test result depends on the estimate, its uncertainty, and the analysis assumptions. A p-value, if available, would quantify how incompatible the data are with a specified null model under those assumptions; it would not measure the probability that a hypothesis is true or the clinical importance of an effect. No p-value or test specification for the primary endpoint is reported in the registry record. No particular statistical test, model, or distributional assumption can be attributed to the study from the information recorded.

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("COPD", "Smokers Without COPD", "Non-smokers")
n   <- c(37, 33, 30)
m   <- c(1.5, 0.9, 0.6)
sp  <- c(0.9, 0.2, 0.3)
sd  <- sp * sqrt(n)      # standard errors converted to SDs
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  COPD  37  1.500  5.474  -0.325  3.325
CARM  Smokers Without COPD  33  0.900  1.149  0.493  1.307
CARM  Non-smokers  30  0.600  1.643  -0.014  1.214

11. Multiplicity, Missing Data and Analysis Populations

The registry lists 3 outcome measures and 3 analyses. It does not report which outcomes were designated primary beyond the named GRO Alpha EC 50 endpoint, how the analyses map to outcomes, or whether additional comparisons were made. A multiplicity adjustment, such as a method controlling the chance of false-positive findings across several tests, is not reported in the registry record. It is therefore not possible to determine whether or how the analysis addressed multiple outcomes or comparisons.

The outcome description identifies the primary measure as continuous and reports the mean and standard error as its summary and dispersion. The number of participants or samples contributing to each endpoint analysis is not reported. The record also does not describe whether measurements were excluded, how incomplete measurements were handled, or whether any imputation was used. Missing-data methods are not reported in the registry record.

The analysis population is likewise not specified. The record does not state which participants were included in each analysis, whether all enrolled participants were assessed for the endpoint, or whether exclusions were applied. Although overall enrollment is listed, that total should not be taken as the endpoint-specific analysis size. No participant flow or endpoint-specific denominator is reported in the registry record.

These gaps limit interpretation even if a point estimate is available elsewhere. The analysis population and missing-data approach can affect both the estimated group means and their uncertainty, while the handling of multiple outcomes affects how individual statistical findings should be read. Neither issue can be resolved from the registry entries recorded for this trial.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The adverse-event figures list zero serious adverse events and zero other adverse events for each of the three groups. The numbers at risk for the serious and other adverse-event summaries are 37 in the COPD group, 33 in the Smokers Without COPD group, and 30 in the Non-smokers group. The deaths field is also zero for each group. No serious adverse-event terms are listed.

These are the registry’s recorded counts, not a demonstration that no events could have occurred outside the captured reporting or observation process. The timeframe and method for collecting adverse events are not reported in the registry record. The record also does not explain how the adverse-event groups relate to overall enrollment or to the population assessed for the primary endpoint. The safety counts should therefore be read as the posted summaries, without assuming a particular follow-up duration or completeness of ascertainment.

Because no intervention is listed in any group, these figures are not a comparison of adverse effects between randomized treatments. They describe the recorded safety counts by participant group. They do not establish that a treatment is safe or unsafe, and they do not inform the size or precision of the primary laboratory outcome.

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

This trial record matters as a description of a laboratory study focused on leukocyte behavior in COPD. It identifies a primary measure, the GRO Alpha EC 50 for a PBMC migration response, and describes broader interests in chemoattractant movement, cell-surface receptors, cell differentiation, and enzymes associated with tissue destruction. Those aims provide the scientific context for the registered endpoint.

The registry information does not report numerical results for the primary endpoint. It therefore does not show whether the measure was higher or lower in the COPD group, how large any difference was, or how precisely a difference was estimated. No conclusion about the observed direction, magnitude, or statistical significance of the primary comparison can be drawn from the registry record.

The study is not described as a randomized intervention trial. The groups have no intervention, allocation is not stated, and the record cautions that the groups are not a like-for-like control comparison. In general, comparisons among such groups can identify patterns that motivate further investigation, but they cannot alone establish that COPD or smoking caused a measured difference. The registry does not report adjusted comparisons or enough participant characteristics to assess alternative explanations.

The laboratory endpoint is also not a direct measure of clinical benefit, symptoms, or change in lung function. It concerns an in-vitro migration response and should be interpreted within that scope. The stated mechanistic rationale does not itself establish a clinical effect or a therapeutic target. The study’s stated objective of identifying possible targets is an aim, not a posted finding.

Accordingly, the strongest interpretation supported by the record is that a completed, non-interventional group study was registered to investigate leukocyte function, with a specified primary laboratory endpoint and no posted numerical endpoint result in the registry record. The zero adverse-event counts are separate descriptive safety summaries and do not fill that outcome-reporting gap.

14. Why This Trial Matters Statistically

This study illustrates an important distinction between a research question and an answer supported by reported data. The record articulates a mechanistic question about leukocyte recruitment and behavior in COPD and specifies a laboratory endpoint intended to characterize a migration response. Yet the endpoint’s numerical estimates and comparisons are not reported in the registry record. A clearly named outcome is not enough to judge a result without its estimate and uncertainty.

It also highlights why the comparison structure matters. COPD patients, smokers without COPD, and non-smokers are different participant groups, not randomized intervention arms. The record explicitly cautions that they are not a like-for-like control comparison. Statistical descriptions should preserve that distinction: an observed group association, if reported, would not by itself establish a causal effect.

The endpoint’s summary measure raises another useful statistical point. A mean and standard error communicate the estimated group center and its precision, but they do not provide all the information needed to understand individual variation or the reliability of a group contrast. Readers need the analysis population, comparison estimate, and uncertainty interval, as well as a clear account of the analysis method. Those details are not reported in the registry record.

Finally, the record lists multiple outcomes and analyses without describing how multiplicity was addressed. That omission makes it difficult to evaluate the evidential status of any individual finding, even if results are available elsewhere. Taken together, these features show why registry interpretation depends not only on the scientific aim but also on transparent reporting of estimates, uncertainty, analysis choices, and participant inclusion.

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 most immediate limitation for statistical interpretation is the absence of numerical primary outcome results in the registry record. The record names the endpoint, unit, summary parameter, dispersion measure, and timeframe, but does not report group estimates, contrasts, confidence intervals, or p-values. Direction, magnitude, and precision therefore cannot be assessed.

The design also limits causal interpretation. The study has three participant groups with no intervention, and allocation is not stated. The registry cautions that the groups are not a like-for-like control comparison. Participant characteristics and adjusted analyses that might help contextualize group differences are not reported in the registry record.

Further details needed to evaluate the analysis are absent: endpoint-specific sample sizes, analysis populations, missing-data handling, statistical tests or models, and the relationship between the listed outcomes and analyses. The registry also does not report a trial-specific sample-size justification or a multiplicity strategy. The planning assumptions described in the record are illustrations and should not be treated as the original design rationale or as observed power.

The primary endpoint is an in-vitro measure. The record does not establish how it relates to clinical outcomes, nor does it report results for the broader mechanistic objectives in sufficient numerical detail to evaluate them. The safety summaries give zero recorded events in each group, but their observation timeframe and ascertainment methods are not reported. These limitations constrain what can be concluded from the registry information, independently of the study’s completed status.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Leukocyte Function in Chronic Obstructive Pulmonary Disease (COPD) — NCT00147082.
• Registry record last updated 2019-12-05; status last verified 2019-12.
• Results first posted 2019-12-05.
• 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

NCT00147082 is a completed study sponsored by Imperial College London, with enrollment listed as 100. The record gives a start date of 2001-02 and a primary completion date of 2004-12. Its three non-intervention groups are people with COPD, smokers without COPD, and non-smokers with no history of respiratory disease; the record cautions that this is not a randomized, like-for-like comparison.

The primary endpoint is GRO Alpha EC 50 for a PBMC migration response, measured in ng/ml with a stated timeframe of 2 hours. The record lists 3 outcome measures and 3 analyses, but numerical primary endpoint results and details of the statistical analysis are not reported in the registry record. The adverse-event summaries list zero serious events, zero other events, and zero deaths in each group.