Fluticasone Propionate-salmeterol Combination Adherence in Patients With Chronic Obstructive Pulmonary Disease (COPD): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fluticasone Propionate-salmeterol Combination Adherence in Patients With Chronic Obstructive Pulmonary Disease (COPD) (NCT01381471), a registered phase not stated study. The primary outcome is Mean Number of Pharmacy Claims by Participants During the Post-Index Period.

2. Clinical Question

3. Trial Design

The registry record describes a completed study sponsored by GlaxoSmithKline. It lists a start date of 2009-08, a primary completion date of 2010-05, and enrollment of 11060. The condition is chronic obstructive pulmonary disease. The listed intervention is fluticasone propionate/salmeterol xinafoate combination, and the arm description identifies patients with a diagnosis code of COPD.

The brief summary describes several aims: to describe one-year Advair dispensing rates, examine the association between adherence and health-care utilization such as emergency room visits and inpatient admissions, and compare moderate or severe COPD exacerbation risk over a three-month follow-up between adherent and non-adherent patients. Those aims indicate questions about medication use and associations in a patient population; they do not establish that treatment assignment was randomized.

The registry explicitly states that allocation was not stated and that the arms are not a like-for-like control comparison. Accordingly, the adherent and non-adherent groups should not be treated as randomly assigned groups. Differences between such groups could reflect factors other than adherence, and the record does not provide information sufficient to assess or adjust for those factors.

The primary outcome is the mean number of pharmacy claims incurred during the one-year post-index period. The record gives a claims-based population description, but its final eligibility text is incomplete. It does not report the index-date definition, the operational definition of adherence, the method used to identify health-care utilization, or how follow-up was handled. The registry lists two outcome measures and zero analyses. Detailed analysis methods and numerical endpoint results 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.

Before assignment: Participants were not recruited or enrolled in this study. This study is a retrospective observational study. Data from medical records or insurance claims databases are anonymized and were used to develop a cohort. All diagnoses and treatments are recorded in the course of routine medical practice.

Overall Study

Analysis population for the primary outcome, as defined in the registry: Participants age 40 or older with at least one pharmacy claim for FSC, at least one medical claim with a primary or secondary diagnosis of COPD (ICD-9 codes 490.xx, 491.xx, 492.xx, or 496.xx), and at least one pharmacy claim for an anticholinergic medication but no diagnosis for cystic fibrosis (ICD-9 = 277.0x)

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 Mean Number of Pharmacy Claims by Participants During the Post-Index Period, measured over One Year.

The primary endpoint is the mean number of pharmacy claims by participants during the one-year post-index period, measured in pharmacy claims. The outcome description says that the mean number of claims incurred over that period was measured. The registry identifies the measure as continuous and names the standard deviation as its dispersion measure, but it does not report the observed mean or standard deviation.

A claims count can describe medication dispensing recorded in pharmacy data. It is not, by itself, a direct measure of whether medication was taken as prescribed. The study summary links dispensing and adherence to questions about health-care utilization, but the record does not explain how pharmacy claims were translated into adherence or how claims were attributed to particular medications beyond the stated outcome description.

As a general statistical matter, a mean gives the average outcome in a defined population, while a standard deviation describes the spread of individual measurements around that average. Both can help characterize a claims distribution. Counts may be unevenly distributed, with many participants having relatively few claims and some having more. If that pattern occurs, the mean and standard deviation alone may not convey all aspects of the distribution. Whether that pattern occurred in this study is not reported in the registry record.

The endpoint is relevant to the stated descriptive aim of documenting dispensing. It does not by itself answer whether adherence is associated with emergency visits, inpatient admissions, or exacerbations. Those are separate questions, and their results are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry lists a continuous primary outcome summarized as a mean with standard deviation. The following concepts are general statistical explanations; they do not establish which methods were used in this study. Specific analysis procedures are not reported in the registry record.

What does a mean describe?

A mean is the arithmetic average of measured values in a defined group. For a claims outcome, it offers a compact description of average recorded pharmacy use over the stated observation period. It is sensitive to the values of all observations, including unusually high counts. It should therefore be interpreted alongside information about the distribution and the number of participants contributing data. Those endpoint summaries are not reported in the registry record.

What does the standard deviation add?

The standard deviation describes variation among participant-level measurements around the mean. It is a measure of dispersion, not a measure of uncertainty in the mean. A confidence interval for a mean or for a difference addresses uncertainty in an estimated quantity, whereas the standard deviation describes how spread out individual outcomes are. The registry names a standard deviation but does not report its value or a confidence interval.

Why might count data need careful modeling?

General statistical methods for counts often begin with assumptions about how counts vary across observations. Real-world claims counts may be more variable than a simple model assumes, a pattern called over-dispersion. When over-dispersion is present, methods that fail to account for it can give uncertainty estimates that are too small. Other features, such as many participants having no claims or differences in observation time, can also affect model choice. These are general considerations, not findings about this study. The registry record does not report a count-data model, distributional checks, or methods addressing over-dispersion.

How should a group comparison be read?

For a comparison between adherent and non-adherent groups, an estimate would describe the observed contrast in an outcome, while a confidence interval would indicate the range of values reasonably compatible with the data under the model. A p-value addresses compatibility with a specified null hypothesis under assumptions; it does not measure clinical importance or the probability that the null hypothesis is true. The registry record provides no comparison estimate, confidence interval, or p-value. It does not report whether the comparison was adjusted for other characteristics.

What does the design imply for interpretation?

General causal reasoning requires attention to how groups arise. When patients are not randomly assigned, differences in health status, medication access, health-care seeking, or other measured and unmeasured characteristics may contribute to group differences. Adjustment can address measured factors under appropriate assumptions, but it cannot automatically remove bias from unmeasured factors. The registry says allocation was not stated and warns that the arms are not a like-for-like control comparison. It does not report an adjustment strategy, so the degree to which confounding was addressed cannot be evaluated.

What do the planning assumptions mean?

The record describes sample-size planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation, and a normal approximation. In general, a planning calculation estimates the sample size needed to detect a specified effect under chosen assumptions. A calculation based on a fraction of an observed effect is a scenario, not evidence that the study achieved that power. It is not observed power. The planning assumptions do not demonstrate that the actual groups were equally allocated, and the registry states that allocation was not stated. The underlying observed effect is not reported in the registry record, so the planning calculations cannot be tied to a reported primary result.

What methods are not documented?

The registry does not report the analysis population, missing-data approach, covariates, model specification, multiplicity procedure, or interim-analysis plan. It also does not describe how adherence was defined, how index dates were assigned, or how the follow-up windows were applied. These details affect the interpretation of estimates, their uncertainty, and the risk of bias. Without them and without numerical results, the appropriate conclusion is that the statistical methods and endpoint findings are not reported in the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The brief summary describes more than one study aim: dispensing rates, the association between adherence and health-care utilization, and the comparison of COPD exacerbation risk. The registry lists two outcome measures but does not provide their full results or analysis details. It does not report which analyses were designated primary beyond naming the mean number of pharmacy claims as the primary outcome, or whether any secondary analyses were planned.

When several outcomes or comparisons are tested, the chance of at least one apparently unusual result can increase. General methods for addressing multiplicity include prespecifying a hierarchy of outcomes or adjusting inference across a family of tests. Which approach, if any, was used is not reported in the registry record. There are no analysis records listed, so multiplicity handling cannot be evaluated from reported tests.

The record does not report participant flow, outcome-specific denominators, missing outcome data, exclusions after enrollment, or a missing-data method. It also does not identify an intention-to-treat or other analysis population. The listed claims-based outcome has an eligibility description, but the full criteria are truncated and the method for selecting records with incomplete follow-up is not reported. These gaps prevent assessment of whether the analyzed population matches the intended population or whether missingness could affect the findings.

The registry does not report interim analyses, stopping rules, or a statistical analysis plan. These items are not assumed to have been absent; they are simply not reported in the registry record.

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

The registry establishes that the study concerned COPD, fluticasone propionate/salmeterol combination use, pharmacy claims, adherence, and health-care utilization. It records a primary endpoint of mean pharmacy claims over a one-year post-index period and describes additional aims involving utilization and exacerbations. It does not report numerical endpoint results or analysis estimates.

Consequently, the record does not show how many claims participants had on average, how variable the claims were, whether adherence groups differed, or how precisely any estimated association was measured. It also does not report results for emergency room visits, inpatient admissions, or moderate or severe exacerbations. The lack of reported findings is not evidence that an outcome was unchanged or that there was no association.

The record should also not be read as a randomized comparison. It states that allocation was not stated and that the arms are not a like-for-like control comparison. Even if a difference between adherence groups were reported elsewhere, a non-randomized comparison could reflect differences between patients as well as any relationship with adherence. The registry record does not provide the methods or results needed to examine that possibility.

In general, a claims-based dispensing measure captures recorded transactions, not necessarily medication use as prescribed. Its meaning depends on how claims were selected and how adherence was operationalized. Those details are not reported in the registry record. The primary endpoint therefore describes the intended measurement, while the available record does not permit a substantive estimate of dispensing or its association with clinical outcomes.

No treatment recommendation or causal conclusion can be drawn from the registry information alone. The appropriate statistical reading is limited: the study aims and endpoint are described, but the findings and their precision are not reported in the registry record.

12. Why This Trial Matters Statistically

This study raises a common statistical challenge in clinical research: translating administrative claims into measures of medication use and relating those measures to health outcomes. Claims can support descriptions of dispensing, but the operational definition of adherence and the observation period determine what the resulting measure represents. In this record, those methods are not reported, making the endpoint difficult to interpret beyond its stated description.

The design also illustrates why an adherence comparison is not automatically a treatment comparison. Patients who differ in adherence may differ in other characteristics that influence health-care use or exacerbation risk. A statistical association can be useful for describing patterns, but its interpretation depends on design, measurement, and adjustment. The registry explicitly cautions that the arms are not a like-for-like control comparison and does not report adjustment methods.

Another important issue is the distinction between a planned endpoint and an analyzable result. A mean and standard deviation are named, but neither is reported, and the registry lists zero analyses. Without estimates and uncertainty measures, readers cannot judge the magnitude or precision of the primary outcome. The broader aims likewise have no reported estimates in the registry record.

Finally, the record describes planning illustrations based on an observed effect. Such illustrations can clarify how assumptions influence a hypothetical sample-size requirement, but they do not show that a study achieved a particular power or establish an observed result. Keeping descriptive endpoints, causal questions, and planning calculations distinct is essential to sound interpretation.

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 registry record is incomplete for evaluating the study's statistical evidence. Although it describes the primary outcome, it does not report the mean number of claims, its standard deviation, a confidence interval, or an analysis estimate. It lists zero analyses. The registry therefore does not provide enough results to assess the size or precision of the primary endpoint.

The available design description is limited. Allocation is not stated, and the record warns that arms are not a like-for-like control comparison. The method for defining adherence, the index date, the full follow-up procedures, and any statistical adjustment are not reported in the registry record. These omissions limit assessment of group comparability, confounding, and the interpretation of associations.

The eligibility description for the primary outcome is truncated. The registry identifies age and claims-based criteria, but the complete population definition cannot be recovered from the record. Participant flow, analysis populations, missing data, and outcome-specific denominators are also not reported. It is therefore not possible to determine how the enrolled population relates to the population contributing to each endpoint.

The summary mentions health-care utilization and exacerbations, but numerical results and analysis methods for these aims are not reported. The record also does not report multiplicity handling, model assumptions, or sensitivity analyses. These limitations concern what the registry documents; they do not establish whether additional information exists outside the registry record.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Fluticasone Propionate-salmeterol Combination Adherence in Patients With Chronic Obstructive Pulmonary Disease (COPD) — NCT01381471.
• Registry record last updated 2012-03-29; status last verified 2012-02.
• Results first posted 2012-03-07.
• 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

NCT01381471 is a completed registry study sponsored by GlaxoSmithKline, with a recorded start date of 2009-08 and primary completion date of 2010-05. The condition is chronic obstructive pulmonary disease, and the listed intervention is fluticasone propionate/salmeterol xinafoate combination. Enrollment is recorded as 11060.

The primary outcome is the mean number of pharmacy claims during the one-year post-index period. The study summary also describes aims concerning Advair dispensing, adherence and health-care utilization, and COPD exacerbations during a three-month follow-up. The record says allocation was not stated and that the arms are not a like-for-like control comparison.

Although the endpoint and study aims are described, numerical outcome results, analysis estimates, and detailed statistical methods are not reported in the registry record. The registry lists zero analyses.