This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Study to Evaluate the Pharmacokinetics and Pharmacodynamics of Dabigatran Etexilate in Patients With Stable Severe Renal Disease. (NCT01711853), a na phase 1 study. The primary outcome is Cmax,ss.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01711853 |
| Phase | Phase 1 |
| Condition | Renal Insufficiency, Chronic |
| Allocation | Not applicable (single group) |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 19 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Boehringer Ingelheim |
| Results posted | Yes |
2. Clinical Question
Population
Patients with stable severe renal disease were the study population described in the title. The condition listed in the registry record is chronic renal insufficiency. The primary endpoint population was the pharmacokinetic set: treated subjects with at least one observation for at least one primary pharmacokinetic endpoint, no important protocol violations affecting endpoint evaluation, and predose values not greater than 5% of Cmax. The record reports enrollment of 19 participants; the size of the pharmacokinetic set is not reported in the registry record.
Intervention
The study intervention was dabigatran etexilate. The arm description says participants were to receive a capsule containing 75 mg. The study is described as prospective and open label. The registry record does not report additional details about treatment duration or the dosing schedule.
Comparator
There was no comparator group. The record describes a single-group study and lists allocation as not applicable. It is therefore not a randomized, like-for-like comparison of dabigatran etexilate with another treatment or with a control group. Changes or measurements in this group cannot be interpreted as comparative treatment effects.
Primary question
The primary endpoint was Cmax,ss: the maximum plasma concentration of dabigatran etexilate at steady state, expressed as a geometric mean with a geometric coefficient of variation. The central question was how this pharmacokinetic measure was characterized in participants with stable severe renal disease. Although the endpoint definition and sampling timeframe are recorded, its numerical result is not reported in the registry record. The record therefore does not allow the reader to assess the estimated concentration or its variability.
3. Trial Design
The registry record describes NCT01711853 as a Phase 1, prospective, open-label, single-group study of dabigatran etexilate in patients with stable severe renal disease. The listed condition is chronic renal insufficiency. Boehringer Ingelheim is named as sponsor. The record gives a start date of 2012-10, a primary completion date of 2013-12, and a status of completed. Enrollment was 19.
Participants were to receive a capsule containing 75 mg of dabigatran etexilate. The study description says it was designed to evaluate pharmacokinetic and pharmacodynamic measures, coagulation parameters, and safety in patients with chronic kidney disease. These are the study aims described in the registry; they should not be taken as evidence that every measure or analysis has a numerical result available in the posted record.
The design is not a randomized comparison. Allocation is listed as not applicable, masking as none, and the model as single group. The study therefore provides no concurrent control group for separating changes associated with treatment from other influences. Open-label means participants and study personnel were not masked to the intervention, according to the recorded masking designation. The record does not report further details about blinding procedures.
Two outcome measures and six analyses are reported in the record. The primary outcome is Cmax,ss, the maximum plasma concentration at steady state. The record does not provide enough detail to reconstruct all six analyses or identify the estimates and inferential procedures used for each. Details such as a protocol-based sample-size justification, interim analyses, and a complete statistical analysis plan 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
| Stage | Dabigatran 75 mg |
|---|---|
| STARTED | 19 |
| COMPLETED | 16 |
| NOT COMPLETED | 3 |
Reasons for not completing this period:
| Reason | Dabigatran 75 mg |
|---|---|
| Not treated | 3 |
Analysis population for the primary outcome, as defined in the registry: Pharmacokinetic set (PKS) which included all treated subjects that provided at least 1 observation for at least 1 primary pharmacokinetic endpoint without important protocol violations with respect to the evaluation of the pharmacokinetic endpoints and with predose values not greater than 5% of Cmax.
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: Treated set (TS) which included all patients who had taken at least 1 dose of trial medication.
| Characteristic | Unit | Dabigatran 75 mg |
|---|---|---|
| Participants analysed | 16 | |
| Age, Continuous | years | 72.7 (SD 7.6) |
| Sex: Female, Male: Female | Participants | 3 |
| Sex: Female, Male: Male | Participants | 13 |
6. Primary Endpoint
The registry lists the primary outcome as Cmax,ss, measured over -0.5 hours (h), 0.5h, 1h, 2h, 3h, 4h, 6h, 8h, 12h, 23.5h, 47.5h, 71.5h, 95.5h, 119.5h, 155.5h, 167.5h, 168.5h, 169h, 170h, 171h, 172h, 174h, 176h, 179.5h, 180h, 192h, 216h, 240h.
| Element | Registry entry |
|---|---|
| Result type | Geometric Mean |
| Measure of spread | Geometric Coefficient of Variation |
| Unit | ng/mL |
| Endpoint classification | not reduced to a single comparison |
The primary endpoint, Cmax,ss, is the maximum concentration of dabigatran etexilate in plasma at steady state. It is reported in ng/mL and summarized using a geometric mean and geometric coefficient of variation. Pharmacokinetic measures describe drug concentration over time; maximum concentration is one way to characterize the upper concentration reached during the measured sampling period. In general, concentration measures can help describe exposure, but a value by itself does not establish a clinical benefit or harm.
The registry lists repeated sampling times, beginning at -0.5 hours and continuing through 240 hours. Its endpoint description says samples were to be collected from 30 minutes before drug administration up to 11 days after drug administration. Those details describe the intended observation window, not a numerical finding. The record does not report the primary endpoint estimate, its geometric coefficient of variation, a confidence interval, or a statistical test result.
The stated primary endpoint population is the pharmacokinetic set. It includes treated subjects with at least one observation for at least one primary pharmacokinetic endpoint, no important protocol violations relevant to endpoint evaluation, and predose values not greater than 5% of Cmax. The number meeting those criteria is not reported in the registry record. Without the numerical result and analysis-set size, the endpoint definition can be understood, but its observed magnitude and precision cannot be evaluated.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record establishes the study question and design, but it does not report a numerical result for the primary endpoint. Cmax,ss is defined as the maximum plasma concentration at steady state, summarized by a geometric mean and geometric coefficient of variation. The record supplies the measurement unit and sampling timeframe, but not the observed geometric mean, variability estimate, confidence interval, or a p-value. Consequently, the posted record does not show the size or precision of the primary pharmacokinetic estimate.
This absence matters for interpretation. An endpoint definition describes what investigators intended to measure; it is not itself a result. The sampling schedule likewise indicates when measurements were planned, not what concentrations were observed. No conclusion about the magnitude of dabigatran etexilate concentration in this population can be drawn from the endpoint label or timepoints alone.
The study is single group and open label, with no comparator group. Accordingly, even if a within-group concentration estimate were available, it would characterize participants in the study rather than establish a comparative effect against another intervention. The design is not a randomized treatment comparison, and the registry specifically notes that its arms are not a like-for-like control comparison. The data described cannot support a claim about comparative efficacy or safety.
Enrollment was 19, while the primary endpoint population is defined using pharmacokinetic evaluability criteria. The number in that analysis population is not reported in the registry record, so enrollment should not be assumed to equal the number contributing to the primary analysis. The record also gives no numerical results for pharmacodynamic measures or coagulation parameters, despite describing these as study aims.
The registry lists 16 participants at risk for serious adverse events, with zero affected, and 16 at risk for other adverse events, with 6 affected. These are distinct safety categories as recorded. The number of deaths is not reported in the registry record, and no serious-event terms are listed. These counts describe the posted safety summary; they do not supply comparative evidence, and the study's single-group design limits interpretation across treatments.
Overall, the available record allows a description of the intended pharmacokinetic endpoint, population criteria, study design, and some safety counts. It does not provide the primary numerical estimate needed to judge the measured concentration or its precision. Details of the full statistical plan, including any interim analyses or sample-size justification, are not reported in the registry record. Interpretation should therefore remain limited to what is explicitly recorded.
9. Statistical Methods Explained
What does a geometric mean represent?
General explanation: A geometric mean is a way to summarize measurements that are positive and may vary multiplicatively. Rather than averaging the original measurements directly, the method works on a logarithmic scale and then expresses the summary back on the original scale. It can be useful for concentration data when values are unevenly distributed. The registry specifies a geometric mean for Cmax,ss, but does not report the estimate or describe the calculation in further detail.
How should the geometric coefficient of variation be read?
General explanation: A coefficient of variation describes variability relative to a measure of central tendency. A geometric coefficient of variation is designed for data summarized on a geometric scale. It provides information about how dispersed the measurements are, rather than an additional measure of the average concentration. The registry names this dispersion measure for the primary endpoint, but its numerical value is not reported in the registry record. Without that value, the degree of observed variability cannot be assessed.
Why does sampling over time matter?
General explanation: Pharmacokinetic measurements are taken at specified times because concentration can change over time after drug administration. A schedule with observations at multiple times can describe the concentration profile and help identify the maximum observed concentration in the sampling window. The registry lists sampling from -0.5 hours through 240 hours and describes collection from 30 minutes before drug administration up to 11 days after drug administration. Those details explain the planned measurement window, but do not reveal the actual values or whether every planned sample was collected.
The primary endpoint is a summary of maximum concentration at steady state, rather than a clinical outcome. A pharmacokinetic endpoint can characterize exposure, but it does not alone establish an effect on symptoms, disease outcomes, or safety. The record does not provide a numerical concentration estimate or a comparison that would permit a treatment-effect interpretation.
What can a confidence interval tell a reader?
General explanation: A confidence interval expresses uncertainty around an estimated quantity under the assumptions of the analysis. A narrower interval indicates greater precision in the estimate, while a wider interval indicates more uncertainty. An interval does not correct limitations in study design, measurement, or population selection. No confidence interval for Cmax,ss is reported in the registry record, so the precision of the primary estimate cannot be evaluated from this record.
What does the single-group design allow?
General explanation: A single-group study can describe observations made among participants receiving the study intervention. Without a concurrent comparator, it cannot directly estimate how those observations differ from what would have occurred under another treatment or control condition. Open-label status also means masking was not used, as reflected in the registry. This design information is essential context, but the record does not provide enough outcome results to assess even the primary descriptive estimate.
The study record lists one group receiving dabigatran etexilate and does not identify a control arm. Allocation is listed as not applicable, and the trial is not a randomized comparison. The sample-size planning assumptions associated with the posted planning illustrations are not the trial's own design: they use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation, with the effect to detect expressed as a stated fraction of the observed effect. Because the actual study is single group, the equal-allocation assumption does not describe its design. Such illustrations are planning exercises, not observed power, and do not replace a protocol-based sample-size justification. That justification is not reported in the registry record.
Why can over-dispersion matter?
General explanation: In count outcomes, over-dispersion means the observed variation is greater than a chosen statistical model expects. If a model does not account for that extra variation, uncertainty estimates can be too small and inferential conclusions can be misleading. This concept is relevant to some count-data analyses, but the primary endpoint in this study is a concentration summarized by a geometric mean and geometric coefficient of variation. The registry does not report that an over-dispersion model was used, and the specific methods for the six analyses are not reported in the registry record.
Similarly, general methods such as adjustment for covariates, transformations, or alternative distributions should not be attributed to this study without documentation. The endpoint's geometric summary indicates the type of descriptive statistic named in the record; it does not establish which additional modeling choices were made.
What is known about the analysis plan?
The registry identifies two outcome measures and six analyses, but does not provide sufficient details in the listed information to reconstruct all analysis methods or results. The analysis population for Cmax,ss is described through inclusion criteria, including treated status, at least one relevant observation, no important protocol violations affecting pharmacokinetic evaluation, and predose values not greater than 5% of Cmax. The size of that population is not reported in the registry record.
Interim analyses, a statistical analysis plan, and a sample-size justification are not reported in the registry record. Therefore, no claim can be made about whether analyses were prespecified, how missing observations were handled, or whether adjustments for multiple testing were applied. The distinction between a named endpoint and a fully documented analysis matters: the former is available, but the latter cannot be reconstructed from the recorded information.
10. Multiplicity, Missing Data and Analysis Populations
The registry reports two outcome measures and six analyses. It does not describe the full set of analyses, how they relate to the outcome measures, or whether any were primary, secondary, exploratory, or repeated assessments of the same quantity. A multiplicity-adjustment method is not reported in the registry record. Without those details, it is not possible to determine how the chance of false-positive findings across multiple statistical tests was handled.
The primary endpoint is defined, but its numerical result is not reported. The record also does not provide a confidence interval or p-value for that endpoint. No inference about statistical significance or precision can therefore be drawn from the listed endpoint definition.
The pharmacokinetic set has stated eligibility criteria, but its size is not reported in the registry record. Enrollment of 19 does not establish how many participants met those criteria or contributed data to the primary endpoint. The record does not explain how incomplete sampling, missing endpoint measurements, or protocol deviations were handled beyond defining which participants qualified for the pharmacokinetic set.
Interim analyses and a complete statistical analysis plan are not reported in the registry record. Nor is a protocol-based sample-size justification reported. The separate planning assumptions use a two-sided significance level of 0.05, equal allocation, and a normal approximation, but they are planning illustrations based on the observed effect, not the study's design or observed power. Since the trial is single group, equal allocation between two arms is not a description of its actual allocation.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Dabigatran 75 mg | 0 | 16 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 5% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Dabigatran 75 mg | 6 of 16 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Dabigatran 75 mg |
|---|---|---|
| Diarrhoea | Gastrointestinal disorders | 2 of 16 |
| Gastrooesophageal reflux disease | Gastrointestinal disorders | 1 of 16 |
| Nausea | Gastrointestinal disorders | 1 of 16 |
| Vomiting | Gastrointestinal disorders | 1 of 16 |
| Nail injury | Injury, poisoning and procedural complications | 1 of 16 |
| Wound | Injury, poisoning and procedural complications | 1 of 16 |
| Thrombophlebitis | Vascular disorders | 1 of 16 |
The safety summary lists 16 participants at risk for serious adverse events; zero were affected. It separately lists 16 participants at risk for other adverse events; 6 were affected. These categories should be read as distinct registry summaries, not combined into a single count. The record does not list any serious adverse-event terms. The number of deaths is not reported in the registry record.
The at-risk counts are the denominators recorded for these safety categories. The registry reports enrollment of 19, but the safety denominators are 16; the reason for this difference is not reported in the registry record. The safety population should therefore not be assumed to include all enrolled participants.
These figures describe events recorded in a single-group study. With no comparator group, the counts do not establish whether events were more or less frequent than under another treatment or control condition. The registry summary also does not provide further event-level details, such as timing or relatedness, so interpretation should remain confined to the reported counts and categories.
12. What the Result Does, and Does Not, Mean
This study provides a recorded design for evaluating pharmacokinetic and pharmacodynamic measures, coagulation parameters, and safety of dabigatran etexilate in patients with chronic kidney disease. Its primary endpoint is the maximum plasma concentration at steady state, summarized as a geometric mean with a geometric coefficient of variation. The registry also describes the sampling window and the criteria for inclusion in the pharmacokinetic set.
Those details do not amount to a reported primary result. The numerical Cmax,ss estimate and its variability are not reported in the registry record, nor are a confidence interval or p-value. Therefore, the record does not establish what concentration was observed or how precise that estimate was. It also does not provide numerical results for the pharmacodynamic or coagulation measures described among the study aims.
The study was open label and single group, with no randomized comparator. It can be described as an investigation in the enrolled population, but its design does not support a direct treatment comparison. The posted safety summary records zero serious adverse events among 16 at risk and 6 participants with other adverse events among 16 at risk. These counts are not comparative estimates, and the record does not report the number of deaths.
Nothing in the available information establishes a clinical benefit or harm. A concentration endpoint is a pharmacokinetic measure, not by itself a clinical outcome, and the absence of a numerical result prevents assessment of even its observed magnitude. The registry record supports a limited account of the study question, design, endpoint definition, and safety counts; broader conclusions would require information that is not reported in the registry record.
13. Why This Trial Matters Statistically
Statistically, this study illustrates the importance of distinguishing an endpoint definition from an endpoint result. The record specifies Cmax,ss, its measurement unit, its geometric summary, dispersion measure, sampling times, and an analysis-population definition. Yet the numerical estimate and its uncertainty are not reported. A carefully defined measure is useful for understanding what was intended to be assessed, but it cannot substitute for the observed estimate.
The design also sets clear limits on inference. A single-group, open-label study can describe measurements among participants receiving the intervention, but it has no concurrent comparator for estimating a relative effect. The registry explicitly identifies the study as not being a randomized comparison. This distinction is important when readers encounter safety counts or pharmacokinetic aims: descriptive observations should not be mistaken for controlled evidence.
Population definitions matter as well. Enrollment was 19, while the primary endpoint applies to a pharmacokinetic set determined by treatment, availability of observations, protocol compliance, and predose values. The size of that set is not reported. This means that the number enrolled cannot stand in for the number analyzed without further information.
Finally, the record reports multiple outcome measures and analyses without documenting the full analysis plan, handling of missing observations, multiplicity procedures, interim analyses, or the protocol's sample-size justification. These omissions do not establish that appropriate methods were or were not used; they limit what can be verified from the registry. The case underscores why transparent reporting of estimates, uncertainty, analysis populations, and analytic decisions is needed for statistical interpretation.
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 of the available record is that it does not report the numerical result for the primary endpoint. Although Cmax,ss is defined and its geometric summary and dispersion measure are named, the observed estimate, variability, confidence interval, and p-value are not reported in the registry record. The primary pharmacokinetic set is described, but its size is also not reported.
The study has no comparator group and is not randomized. This prevents a like-for-like comparison with another treatment or control condition. Its open-label designation also means masking was absent. These features do not invalidate descriptive measurements, but they restrict the kinds of conclusions the design can support.
The registry describes pharmacokinetic and pharmacodynamic measures, coagulation parameters, and safety as study aims. It lists two outcome measures and six analyses, but the details and numerical results for the other measures and analyses are not reported in the registry record. The record does not explain how incomplete measurements or missing data were handled, nor does it give a full analysis plan or multiplicity procedure.
Enrollment was 19, while the safety summaries list 16 participants at risk in each category. The reason for this difference is not reported in the registry record. The number of deaths is also not reported. These omissions limit interpretation of the safety summary, particularly because no comparator is available.
A protocol-based sample-size justification and interim analyses are not reported in the registry record. The planning assumptions associated with the separate illustrations are not a description of the trial's original design. Taken together, these limitations mean that the record is informative about study structure and endpoint intent, but incomplete for judging the observed primary estimate, its precision, or comparative effects.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Study to Evaluate the Pharmacokinetics and Pharmacodynamics of Dabigatran Etexilate in Patients With Stable Severe Renal Disease. — NCT01711853.
- Registry record last updated 2015-01-13; status last verified 2015-01.
- Results first posted 2015-01-13.
- 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.
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18. Record Summary
NCT01711853 is a completed Phase 1, prospective, open-label, single-group study sponsored by Boehringer Ingelheim. It enrolled 19 participants and evaluated dabigatran etexilate, with an arm description specifying a capsule containing 75 mg, in patients with stable severe renal disease. The listed condition is chronic renal insufficiency.
The primary endpoint is Cmax,ss, the maximum plasma concentration at steady state, summarized as a geometric mean with a geometric coefficient of variation. The registry record describes sampling from 30 minutes before drug administration up to 11 days after drug administration, but does not report the numerical endpoint result. Safety summaries list zero serious adverse events among 16 at risk and 6 participants with other adverse events among 16 at risk. No comparator group is recorded.