Characteristics of Pts Initiating Spiriva Respimat in Asthma: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Characteristics of Pts Initiating Spiriva Respimat in Asthma (NCT03692676), a registered phase not stated study. The primary outcome is Number of Participants With Cardiac Arrhythmias.

2. Clinical Question

The registered title identifies the study as an examination of characteristics of patients initiating Spiriva Respimat in asthma in the UK, using the Clinical Practice Research Datalink. Its cross-sectional, non-interventional design is consistent with describing patient characteristics from existing data rather than assigning a treatment. The registered enrollment is 116133, but group-specific counts and the number of people included in the primary outcome analysis are not reported in the registry record.

The primary outcome is a count of participants with cardiac arrhythmias, with a timeframe covering the index date or the year before it. A secondary outcome concerns the number of participants with cardiac failure. The registry record lists two outcome measures, but does not report their observed counts or other outcome estimates. Consequently, the registered question can be described, but the magnitude or distribution of the recorded conditions across treatment groups cannot be assessed from the available results.

3. Trial Design

This is a cross-sectional, non-interventional study based on existing data, described in the registry as NISed. Its official title identifies the Clinical Practice Research Datalink as the data source and the United Kingdom as the setting. The record lists the study as completed, with a start date of 2019-03-05 and a primary completion date of 2019-10-11. The registered enrollment is 116133.

The population description concerns asthma patients with prior ICS/LABA FDC prescribing who experienced one of several treatment changes: initiating Spiriva Respimat, initiating LTRA, receiving a higher ICS/LABA FDC dose, or switching to a new ICS/LABA FDC. These groups represent different treatment pathways rather than assigned study arms in a randomized comparison. The registry record explicitly notes that allocation is not stated and that the arms are not a like-for-like control comparison. How treatment changes were selected in clinical practice, and whether other factors influenced group membership, are not reported in the registry record.

The registered primary outcome is a count of participants with cardiac arrhythmias on the index date or in the year before that date. The secondary outcome is a count of participants with cardiac failure. The index-date definition, detailed observation rules, and outcome ascertainment procedures are not reported in the registry record. Although the study is listed as completed, no outcome estimates or analyses are listed: the registry record lists zero analyses. It therefore does not establish how many participants contributed to each outcome or how the outcomes differed, if at all, among the treatment groups.

Because this is an observational description of existing data, the treatment groups should not be interpreted as randomized alternatives. Their characteristics may differ for reasons that the registry record does not document. A comparison between them would therefore be descriptive unless supported by specified methods addressing those differences; such methods 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: All subjects were screened for eligibility to participate in trial. Subjects meeting the exclusion criteria were excluded.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Asthma patients who initiated Spiriva Respimat, who initiated leukotriene receptor antagonist (LTRA), who received a higher dose of ICS/LABA FDC, or who switched to a new ICS/LABA FDC in asthma, and who did not violate any of the exclusion criteria, in the United Kingdom during the studied period (Sep 2014 - Dec 2017).

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.

Population: Asthma patients who initiated Spiriva Respimat, who initiated leukotriene receptor antagonist (LTRA), who received a higher dose of ICS/LABA FDC, or who switched to a new ICS/LABA FDC in asthma, and who did not violate any of the exclusion criteria, in the United Kingdom during the study period (Sep 2014 - Dec 2017).

6. Primary Endpoint

The registry lists the primary outcome as Number of Participants With Cardiac Arrhythmias, measured over On the index date or in the year prior to the index date.

The primary endpoint is the number of participants with cardiac arrhythmias on the index date or during the year before the index date. The unit is participants, and the registered parameter is a count of participants. Thus, the endpoint concerns whether participants were recorded as having cardiac arrhythmia within that defined timeframe; it is not described as the number of arrhythmia episodes, the duration of arrhythmia, or a rate over person-time.

Counts can describe how many people in a defined group meet an outcome definition. To compare the frequency of an outcome across groups, counts generally need to be interpreted alongside the number of people assessed in each group. A count alone does not show the proportion affected or allow a meaningful comparison when group sizes differ. Group denominators and the observed primary-outcome counts are not reported in the registry record, so neither a group-specific proportion nor a comparative estimate can be stated.

In general, a cardiac-arrhythmia measure may be useful for characterizing health conditions recorded around a treatment change. The record does not state why this endpoint was selected, how the condition was identified in the data, or whether a particular clinical definition was applied. The timeframe combines the index date with the preceding year, so the endpoint does not by itself establish when an arrhythmia began relative to treatment initiation. It is not a measure of an effect caused by Spiriva Respimat or any comparator treatment.

The secondary outcome is the number of participants with cardiac failure. Its detailed timeframe and operational definition are not reported in the registry record. Neither primary nor secondary outcome results are reported, limiting interpretation to the outcome definitions that were registered.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry describes a cross-sectional, non-interventional study using existing data. That description is important for interpreting both the estimand and the limits of comparisons. The record does not report a statistical analysis plan, an adjustment strategy, or a detailed description of how the listed outcomes were analyzed. It lists zero analyses, so there are no registered estimates to evaluate for model choice, uncertainty, or robustness.

What does a count measure?

The primary outcome is a count of participants with cardiac arrhythmias within the stated timeframe. A participant count is a descriptive measure: it records how many people meet an outcome definition. It is distinct from an event count, which could include repeated episodes for one person, and from an incidence rate, which requires a person-time denominator. The registry specifies participants as the unit, not episodes or person-time.

In general, counts depend on the number of people observed. A larger group can have more participants with an outcome even when the underlying frequency is similar. For comparisons, analysts commonly need the number assessed in each group as well as the number with the outcome. A proportion expresses the count relative to a group denominator; an uncertainty interval can then convey how imprecisely that proportion is estimated. Neither denominators nor outcome counts are reported for these groups, so those quantities cannot be described.

What can a cross-sectional design establish?

In general, a cross-sectional analysis describes characteristics or outcomes in a defined dataset or period. It can show how recorded conditions occur among the people included, but by itself it does not establish that an exposure preceded an outcome or caused it. In this study, the primary timeframe includes the index date and the year before it. That timing allows a description of arrhythmias recorded around the index date, but does not show when a condition began in relation to a treatment change.

The study is non-interventional and the registry states that allocation is not stated. The listed groups reflect different treatment changes. They are not identified as randomized groups, and the record cautions that they are not like-for-like controls. In general, patient characteristics and clinical circumstances can differ across such groups. An unadjusted comparison could therefore mix a treatment-group association with differences in the people receiving each treatment. No covariate adjustment or other method to address group differences is reported in the registry record.

How should uncertainty be assessed?

In general, a point estimate gives a single summary of an outcome, while a confidence interval describes the statistical uncertainty around that estimate under a model’s assumptions. A narrow interval indicates greater statistical precision than a wide interval, but neither width nor coverage addresses every source of error. Selection, measurement, and confounding can remain concerns even when an interval is narrow. The registry record reports no point estimates or confidence intervals for either outcome, so the statistical precision of any group-level frequency or difference is unknown.

A p-value, when used, is a measure calculated under a specified statistical model and null hypothesis. It does not measure the probability that a treatment works, nor does it quantify clinical importance. No p-values or inferential analyses are reported in the registry record. Consequently, there is no basis to label a difference statistically significant or not significant.

What do the planning assumptions mean?

The record describes planning illustrations based on an observed effect, with a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It states that the effect to detect is a specified fraction of the observed effect. These are planning assumptions, not evidence that the study used that design or that an analysis was conducted. The record does not report the study’s own sample-size justification or analysis plan. Such illustrations are hypothetical sample-size calculations, not observed power and not outcome results.

In general, a sample-size calculation estimates how many participants would be needed under chosen assumptions about the outcome, effect size, allocation, and error rates. Its answer is conditional on those assumptions. It cannot confirm that an analysis was adequately powered after the fact, and it does not replace reporting the observed estimates and their uncertainty. The registry record does not report the numerical planning outputs or the assumptions underlying any observed effect beyond the general description.

Why does the data source matter?

Existing clinical data are collected for purposes beyond a particular research analysis. In general, the variables available, how completely they are recorded, and the rules used to identify conditions can affect the analysis. The registry names the Clinical Practice Research Datalink but does not report the detailed arrhythmia or cardiac-failure definitions, missing-data procedures, or validation methods. Those details are needed to assess how recorded diagnoses map to the registered endpoints. Their absence leaves measurement and data completeness uncertain.

The registry lists adverse-event counts as zero for each group and gives no serious-event terms. Without an explanation of how those entries were generated, they cannot be interpreted as proof of no events. More broadly, a complete statistical interpretation would require group denominators, outcome counts, methods, and uncertainty measures; these are not reported in the registry record.

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("Spiriva Respimat", "Leukotriene Receptor Antagonist (LTRA)", "ICS/LABA Fixed Dose Combination (Switchers)", "ICS Dose Increase of ICS/LABA Fixed Dose Combinati")
n      <- c(940, 3704, 11135, 1561)
events <- c(11, 17, 102, 16)
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  Spiriva Respimat  940  11  1.2  0.6  2.1  0.7  2.1  0.7  2.1
ARM  Leukotriene Receptor Antagonist (LTRA)  3704  17  0.5  0.3  0.7  0.3  0.7  0.3  0.7
ARM  ICS/LABA Fixed Dose Combination (Switchers)  11135  102  0.9  0.7  1.1  0.8  1.1  0.8  1.1
ARM  ICS Dose Increase of ICS/LABA Fixed Dose Combinati  1561  16  1.0  0.6  1.7  0.6  1.7  0.6  1.7

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures: cardiac arrhythmias as the primary outcome and cardiac failure as a secondary outcome. It does not report a multiplicity strategy, such as whether analyses of multiple outcomes or treatment-group comparisons were planned to be interpreted jointly or separately. In general, examining multiple outcomes or contrasts can increase the chance of finding an apparently unusual result by chance. The appropriate interpretation depends on the analysis plan and the intended role of each outcome; that plan is not reported in the registry record. No outcome analyses are listed.

Missing-data handling is not reported in the registry record. It does not state how unavailable or incomplete clinical records, missing outcome information, or gaps in observation were handled. In general, missingness can affect who contributes to an analysis and whether the analyzed participants represent the intended population. Without the amount and pattern of missing information, and without the analysis approach, the direction or size of any possible effect on estimates cannot be assessed.

The record also does not define an analysis population or provide participant counts by treatment group and outcome. The overall enrollment of 116133 does not reveal how many people met the outcome-specific criteria or had sufficient records for analysis. The eligible population is described as patients with asthma in the United Kingdom who underwent one of the listed treatment changes and did not violate exclusion criteria, but the exclusion criteria and their application are not reported in full.

In general, analysis-population definitions clarify which participants contribute to each estimate. For a non-interventional study, those definitions are also relevant to understanding selection into treatment groups and the available data. Since no analysis populations, missing-data procedures, or inferential analyses are reported, readers cannot determine whether the outcome summaries would use the same participants across groups or across outcomes.

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

The record establishes that a completed, cross-sectional, non-interventional study was registered to describe patients with asthma undergoing specified treatment changes in the UK. It identifies cardiac arrhythmias as the primary outcome and cardiac failure as a secondary outcome. The primary endpoint covers the index date or the year before it. These details define the intended descriptive question, but they do not provide its answer.

No observed outcome counts, group denominators, effect estimates, confidence intervals, or p-values are reported in the registry record. The listed enrollment of 116133 cannot be used as a substitute for outcome-specific denominators. Accordingly, the record does not show how common either condition was in the study groups, how precisely any frequency was estimated, or whether groups differed.

Even a reported difference between these groups would need to be interpreted as an observational association unless the analysis addressed the factors that distinguish patients receiving different treatment changes. The registry says the arms are not a like-for-like control comparison and does not state an allocation method. It also does not report adjustment methods. The treatment groups therefore should not be interpreted as randomized alternatives, and the registered design alone cannot support a causal claim about treatment.

The adverse-event entries are zero across the listed groups, but the registry does not explain the meaning or completeness of those entries. They should not be read as a definitive statement that no adverse events occurred. Likewise, the absence of posted outcome analyses is not evidence that outcomes were absent or that there was no difference between groups.

In general, statistical evidence describes estimates and their uncertainty within the limits of the data and methods. It does not on its own resolve measurement error, missingness, or confounding. Because the record lacks outcome results and key analytic details, no conclusion about the frequency, precision, or comparative meaning of the registered outcomes can be drawn from it.

13. Why This Trial Matters Statistically

This study raises a useful statistical distinction between describing patient characteristics and estimating treatment effects. A cross-sectional study of existing clinical data can characterize a population around a treatment change. However, describing different treatment groups is not equivalent to comparing randomized groups. The registry itself notes that the groups are not like-for-like controls and that allocation is not stated. That warning matters because differences between groups may reflect who received each treatment change, not an effect of the treatment.

The primary outcome also illustrates why outcome definition and denominator must be considered together. The registered measure is a count of participants with cardiac arrhythmias on the index date or in the prior year. Without the number assessed in each group, a count cannot be translated into a group frequency or used to compare groups fairly. The timeframe also makes event ordering important: an arrhythmia recorded during the year before the index date may precede the treatment change.

Existing data can support research questions that would be difficult to address through intervention, but interpretation depends on how conditions and observation periods are defined and how incomplete records are handled. Those details are not reported in the registry record. The absence of analyses, estimates, and uncertainty measures further means the registered question cannot be evaluated statistically from the posted results.

For biostatisticians and clinical researchers, this record is a reminder to distinguish study registration from evidentiary results. A completed status and a large enrollment figure do not supply outcome estimates, establish precision, or overcome design limitations. Transparent reporting of group sizes, outcome counts, analytical methods, missing-data handling, and uncertainty would be needed to interpret the planned descriptive question and any comparisons between groups.

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 principal limitation for interpreting this particular record is that outcome results are not reported. The primary and secondary outcomes are named, but observed counts, group denominators, estimates, and uncertainty measures are absent. The registry lists zero analyses. As a result, the frequency of cardiac arrhythmias or cardiac failure and any difference between treatment groups cannot be assessed.

The registered enrollment of 116133 does not resolve this limitation because group-specific and outcome-specific participant counts are not reported. The record also does not provide enough detail to determine how many participants met the final eligibility criteria, how exclusions were applied, or how many had data available for each outcome.

The design is observational and cross-sectional, and the registry explicitly cautions that the groups are not like-for-like controls. It does not report how patients came to receive each treatment change, whether group differences were addressed analytically, or whether any adjustment was made. Thus, even if a descriptive difference were reported, the record would not establish that it was caused by treatment.

The primary timeframe combines the index date with the preceding year. The registry does not specify event dates or the method used to identify arrhythmia, so timing relative to treatment initiation and outcome ascertainment cannot be examined. Detailed definitions for cardiac arrhythmias and cardiac failure are not reported. Missing-data procedures, analysis populations, and the multiplicity approach are also not reported in the registry record.

Finally, the adverse-event listings contain zeros in all recorded categories, but the record does not explain whether those entries represent observed counts or reporting conventions. They cannot be interpreted as conclusive evidence that no events occurred. These limitations constrain both clinical interpretation and statistical assessment of the registered questions.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Characteristics of Pts Initiating Spiriva Respimat in Asthma — NCT03692676.
• Registry record last updated 2025-04-17; status last verified 2025-04.
• Results first posted 2020-12-21.
• 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

The registry describes NCT03692676, “Characteristics of Patients Initiating Spiriva Respimat in Asthma in the UK: a Cross-sectional Study Based on the Clinical Practice Research Datalink.” It is listed as a completed, cross-sectional, non-interventional study based on existing data, sponsored by Boehringer Ingelheim. The registered enrollment is 116133; the study start date is 2019-03-05, and the primary completion date is 2019-10-11.

The population description covers asthma patients undergoing one of several treatment changes: Spiriva Respimat initiation, LTRA initiation, an ICS/LABA FDC dose increase, or a switch to a new ICS/LABA FDC. The primary outcome is the number of participants with cardiac arrhythmias on the index date or in the year before it. Cardiac failure is listed as a secondary outcome.

The registry reports no analyses or outcome estimates. Group-specific counts, outcome denominators, statistical methods, missing-data procedures, and uncertainty measures are not reported in the registry record. It also cautions that the treatment groups are not like-for-like controls and that allocation is not stated. The record therefore defines a descriptive research question but does not report results that would answer it.