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 Effectiveness and Patient Self-assessed Compliance of Blood Pressure Treatment With Tarka® Fixed Combination in Patients With Essential Hypertension (NCT01127139), a registered phase not stated study. The primary outcome is Compliance With Tarka Treatment, All Participants and by Gender..
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01127139 |
| Phase | Phase not stated |
| Condition | Essential Hypertension |
| Allocation | Not Stated |
| Design model | Not Stated |
| Masking | Not Stated |
| Enrollment | 3828 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Abbott |
| Results posted | Yes |
2. Clinical Question
Population
Czech women and men with essential hypertension were eligible if their systolic blood pressure was at least 140 mmHg or their diastolic blood pressure was at least 90 mmHg and they could be treated with fixed-combination Tarka®. The primary-outcome population is described as participants with evaluable case report forms.
Intervention
The treatment of interest was fixed-combination verapamil SR/trandolapril, marketed as Tarka®. It was prescribed in routine clinical practice according to local authorization and guidelines, rather than assigned by the study as part of a randomized treatment comparison.
Comparator
There was no comparator arm. This single-arm study therefore describes experience among participants receiving Tarka®; it cannot directly estimate how their outcomes would compare with outcomes under another treatment or no treatment.
Primary question
The primary outcome title concerns compliance with Tarka® treatment, for all participants and by gender. Its description asks how many doses participants had missed after three months of treatment. The brief summary instead describes an endpoint based on the number or percentage continuing fixed-combination Tarka® after six months. The registry record does not resolve this difference or report a numerical primary-outcome result.
Other listed outcomes concern change in systolic and diastolic blood pressure, reaching the stated blood-pressure goal, additional antihypertensive drugs, and adverse events leading to discontinuation. The record describes these as study outcomes but does not provide numerical results for them in the information available. The clinical question is consequently about treatment continuation or missed doses in routine practice, rather than a causal comparison of Tarka® with another approach.
3. Trial Design
The registry describes a prospective, single-arm, single-country, multicenter post-marketing observational study. Its stated setting was routine clinical practice, with cardiologists, internal-medicine doctors, and general practitioners among the participating investigators. Tarka® was to be prescribed in the usual manner, consistent with local market authorization concerning dose, population, and indication, as well as local guidelines. The design therefore records experience under clinical practice rather than assigning treatment through a randomized trial protocol.
The recorded enrollment is 3828, and the status is COMPLETED. The recorded study start is 2010-04, and primary completion is recorded as 2011-03. These dates and the completion status describe the registry record; they do not, by themselves, establish when every participant began or finished follow-up.
The primary outcome is titled as compliance with Tarka® treatment, all participants and by gender. The outcome description says participants were asked how many doses they had missed after three months of treatment. Separately, the brief summary defines the endpoint as the number or percentage of patients continuing fixed-combination Tarka® after six months. Those descriptions refer to different follow-up points and different ways of expressing compliance. The registry record does not explain whether both measures were collected, which definition governed the primary analysis, or how the discrepancy was resolved.
The record identifies participants with evaluable case report forms as the primary-outcome population. It does not define evaluability or describe the number of participants contributing to that outcome. The listed design does not include a like-for-like control group, and the record does not state an allocation method. Results from this design can describe observed outcomes among the treated participants, but without a comparator they cannot isolate treatment effects from other influences, such as changes in care or participant characteristics.
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 | Czech Patients With Essential Hypertension |
|---|---|
| STARTED | 3828 |
| Number of Participants Analyzed | 3828 |
| COMPLETED | 3771 |
| NOT COMPLETED | 57 |
Reasons for not completing this period:
| Reason | Czech Patients With Essential Hypertension |
|---|---|
| Adverse Event | 40 |
| Incompliance | 12 |
| Lack of Efficacy | 4 |
| Reason not specified | 1 |
Analysis population for the primary outcome, as defined in the registry: All participants with evaluable case report forms were analyzed.
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.
| Characteristic | Unit | Czech Patients With Essential Hypertension |
|---|---|---|
| Participants analysed | 3828 | |
| Age, Customized: Age not reported | Participants | 3828 |
| Sex: Female, Male: Female | Participants | 1943 |
| Sex: Female, Male: Male | Participants | 1885 |
6. Primary Endpoint
The registry lists the primary outcome as Compliance With Tarka Treatment, All Participants and by Gender., measured over Month 3 Visit.
| Element | Registry entry |
|---|---|
| Result type | Number |
| Measure of spread | not applicable |
| Unit | participants |
| Endpoint classification | Binary Endpoint |
The primary outcome is titled as compliance with Tarka® treatment, for all participants and by gender. Its description says participants were asked how many doses of Tarka® they had missed after three months of treatment. A missed-dose count is a measure of self-reported medication-taking behavior at the time of assessment. It is not the same as an objective measurement of medication use, and a count alone does not describe the reasons doses were missed.
The brief summary uses a different endpoint description: the number or percentage of patients continuing fixed-combination Tarka® after six months. Continued treatment captures whether participants remained on the fixed combination at that later point; it does not by itself establish how consistently they took each dose while continuing. The registry record does not state how these two descriptions were reconciled or which was used to produce the primary result.
Compliance and treatment continuation are relevant descriptive outcomes in an observational study of routine practice because they characterize whether participants report missed doses or remain on the prescribed combination. They do not establish that treatment caused any observed behavior, nor do they measure blood-pressure response directly. The record does not report a numerical result for the primary outcome, its distribution, or its uncertainty. As a result, the outcome definition can be described, but the amount of reported missed dosing or continuation cannot be interpreted from this record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record describes a completed observational study of Tarka® treatment in Czech patients with essential hypertension. It records enrollment of 3828 and gives a primary outcome concerning treatment compliance. However, the record does not report a numerical result for that outcome. It therefore does not establish how many doses participants reported missing, what proportion continued treatment, or how either measure varied by gender.
There is also an unresolved difference in the outcome descriptions. The primary-outcome entry asks about doses missed after three months, while the brief summary describes continuation after six months. These measures are related to treatment-taking behavior but are not interchangeable. A participant may continue treatment while missing doses, and the record does not state whether the study measured both, how continuation was defined, or which follow-up point was used for the primary analysis. Without a stated resolution, a reader should not treat either description as a reported numerical finding.
The single-arm observational design is important for interpretation. It can describe outcomes among people treated in routine practice, but it has no untreated or alternative-treatment comparison group. As a general statistical point, outcomes observed in a single group can reflect more than the treatment itself: patient characteristics, clinical decisions, other care, and measurement practices may also contribute. The design therefore does not estimate a comparative treatment effect.
The listed secondary outcomes include blood-pressure changes and goal attainment, additional antihypertensive drugs, and adverse events leading to discontinuation. The registry information does not report numerical results for those outcomes. It is not possible to assess the size or precision of a blood-pressure change, the frequency of goal attainment, or the use of additional drugs from the listed outcome descriptions alone.
For serious adverse events, the record lists 0 affected in the study group, with 3828 at risk. It also lists 0 affected for other adverse events, with 3828 at risk. These registry counts are descriptive entries, not estimates of comparative safety. The record does not provide serious adverse-event terms, and deaths are not reported in the registry record. The zero counts should be read within the limits of what the record reports; they do not establish that no events occurred outside the recorded categories or reporting process.
No analysis entries are reported. A confidence interval would ordinarily convey the precision of an estimate, but the record does not provide a primary-outcome estimate or interval to interpret. Planning illustrations based on an observed effect should not be mistaken for observed power or evidence about the treatment; the underlying numerical result needed to interpret such an illustration is not reported in the registry record.
9. Statistical Methods Explained
Statistical methods explain how outcomes are turned into estimates and how much uncertainty surrounds them. The registry record identifies a single-arm observational study and describes a primary outcome involving treatment compliance. It does not report a numerical primary-outcome analysis, a statistical analysis plan, or an analysis entry. Consequently, the methods discussion can distinguish the kinds of analysis that might apply in general from methods that are actually documented for this study.
What does a missed-dose count represent?
The primary-outcome description asks participants how many doses they missed after three months of treatment. In general, a count records the number of occurrences for each participant over a defined period. Counts may be summarized by their distribution, rather than by a single average alone, because a few participants with relatively high counts can affect the average. The record does not report individual or aggregate counts, the range of possible responses, or how the question was administered. It also does not report whether participants who could not answer were excluded, treated as missing, or handled another way.
The study information characterizes the primary outcome as a participant count, while the outcome title also refers to compliance by gender. A count of participants and a count of missed doses answer different questions: the first concerns how many participants meet a specified category, while the second concerns reported dose-taking events. The registry record does not give a categorization rule for compliance or explain how gender-specific results would be calculated. No gender-specific estimate or uncertainty measure is reported.
How should continuation be distinguished from missed doses?
In general, treatment continuation is a status measure at a follow-up point, whereas missed doses describe behavior during treatment. Continuation can be summarized as a number or percentage only after defining who is considered to have continued, the follow-up point, and how participants without follow-up information are treated. The brief summary refers to continuation after six months, but the primary outcome description refers to missed doses after three months. The registry record does not specify a common definition, establish which time point is primary, or report a numerical analysis for either description.
What can a single-arm analysis estimate?
For a single group, an analysis can describe observed counts, proportions, or changes over time, if those results and the relevant denominators are reported. Such estimates characterize the participants included in the analysis. They do not provide a direct comparison with what would have occurred under a different treatment. In general, a randomized comparison can help balance measured and unmeasured characteristics between groups, while an observational single-arm description has no such comparison built into its design. That general distinction does not imply a particular bias or outcome in this study; it limits the causal question that can be answered from the design.
The record says that all participants with evaluable case report forms were analyzed for the primary outcome. This identifies a stated analysis population, but it does not define evaluability, report how many participants had evaluable forms, or describe whether participants with missing responses differed from those included. A result based only on evaluable forms could be difficult to interpret if missingness is related to treatment-taking behavior. That is a general concern, not evidence that such a pattern occurred in this study.
What do uncertainty measures add?
In general, a confidence interval gives a range of values compatible with an estimate under the analysis assumptions. A narrow interval indicates greater statistical precision than a wide interval, but neither interval width nor statistical significance establishes clinical importance or causation. The registry information does not provide a primary-outcome estimate, confidence interval, or p-value. Thus, neither the magnitude nor the precision of the primary finding can be evaluated.
For a binary outcome, an analysis might report the number meeting a definition and the corresponding proportion, with uncertainty around that proportion. For a count outcome, an analysis might report a count distribution or a summary suitable for the data. These are general options, not methods documented for this record. The registry does not state a model, estimation procedure, adjustment variables, or handling of repeated measurements. It would be inappropriate to infer those choices from the outcome descriptions alone.
Why can over-dispersion matter?
As a general statistical concept, a count model may assume a particular relationship between the average count and its variability. Over-dispersion occurs when the observed variability is greater than that assumption allows. If a model does not account for this, standard errors can be too small and uncertainty can appear understated. This matters especially when counts vary substantially across participants. The record does not report a count model, count results, or a dispersion assessment, so over-dispersion cannot be evaluated as a feature of this study's analysis.
The sample-size material is described as a planning illustration based on the observed effect, with two-sided significance level 0.05, equal allocation between two arms, and a normal approximation; it says the effect to detect is a stated fraction of the observed effect. For time-to-event tables, the stated convention is a total number of events; otherwise it is participants per arm. These are planning assumptions, not evidence that the observational study had two randomized arms or an observed-power calculation. The registry design is single-arm, and the numerical observed effect needed to interpret the planning illustration is not reported in the registry record. The assumptions therefore cannot supply evidence about the study's outcome or precision.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists multiple outcomes, including compliance, changes in systolic and diastolic blood pressure, blood-pressure goal attainment, additional antihypertensive drugs, and adverse events leading to discontinuation. When many outcomes or subgroup analyses are examined, the chance of finding an apparently notable result by chance can increase. As a general statistical approach, a study may prespecify a primary outcome and use methods to address multiple testing. The registry record does not report a multiplicity adjustment, a hierarchy among the secondary outcomes, or a statistical analysis plan. No conclusion about whether adjustment was intended or performed can be drawn from that absence.
The record identifies participants with evaluable case report forms as the primary-outcome population, but it does not define evaluability or report how missing outcome data were handled. It does not state whether missing values were excluded, imputed, or included through another method. The number of participants contributing data to the primary outcome is not reported in the registry record. Missing-data handling matters because an analysis restricted to people with observed responses may not represent all enrolled participants if the likelihood of missingness is related to the outcome or participant characteristics. This is a general limitation, not evidence of a particular missingness pattern in this study.
The primary outcome title specifies all participants and by gender, but the record does not describe subgroup methods, interaction tests, or gender-specific estimates. It also gives two different timing and measurement descriptions for the primary endpoint: missed doses after three months and continued treatment after six months. The registry does not explain how those descriptions were reconciled. No analysis entries are reported, so the record does not permit assessment of which outcomes or populations were analyzed, whether analyses followed a prespecified plan, or how missing data and multiple outcomes affected the reported results.
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 |
|---|---|---|---|
| Czech Patients With Essential Hypertension | 0 | 3828 | 0.0% |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 1% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Czech Patients With Essential Hypertension | 0 of 3828 |
The registry lists 3828 participants at risk for serious adverse events and 0 affected. For other adverse events, it also lists 3828 at risk and 0 affected. These are the recorded counts for the Czech patients with essential hypertension group. The record does not list serious adverse-event terms, and deaths are not reported in the registry record.
These figures should be read as registry entries, not as evidence from a comparison with another treatment. A single-arm record cannot show whether the reported counts differ from what would have occurred under another approach. The entries also do not describe the observation period for these safety counts, how events were collected or classified, or how complete reporting was assessed. Those details are not reported in the registry record.
A zero count in a registry entry does not establish that no adverse events occurred in every sense; it means that 0 affected is listed for the category as recorded. Nor does it establish that the treatment is free of risk. Without event descriptions, follow-up detail, and comparative data, the figures support only a narrow description of what the registry lists. The secondary-outcome list includes adverse events leading to study discontinuation, but no numerical result for that outcome is reported in the registry record.
12. What the Result Does, and Does Not, Mean
The record establishes the broad design and question: a completed, prospective, single-arm observational study of fixed-combination Tarka® in routine practice among Czech patients with essential hypertension. The recorded enrollment is 3828. Compliance is identified as the primary outcome, with the outcome description referring to doses missed after three months. The brief summary instead describes continuation after six months. These registry entries characterize the study, but they do not supply a numerical estimate of compliance or continuation.
As a result, the record does not show how often participants missed doses, how many remained on treatment, or whether those outcomes differed by gender. It also does not provide numerical results for the listed blood-pressure outcomes, goal attainment, additional drugs, or discontinuations. There is no basis in the record for describing the size, direction, or precision of those outcomes. The serious and other adverse-event entries list 0 affected in the study group, but limited safety entries cannot establish comparative safety or rule out events not captured in those entries.
The observational design is suited to describing experience in the recorded clinical setting, but the absence of a comparator prevents a direct treatment contrast. In general, an outcome observed during treatment may reflect treatment, participant characteristics, other care, and measurement processes. The registry record does not separate those influences. It therefore cannot establish that Tarka® caused a particular compliance pattern or blood-pressure outcome.
These limits do not make the study question irrelevant. Compliance and continuation are practical features of treatment in routine care, and the listed outcomes show what the study intended to examine. But intended outcomes should not be confused with reported findings. The registry record does not provide the numerical results or analysis details needed to judge the observed pattern, its uncertainty, or its robustness. The appropriate interpretation is descriptive and limited to the information the record actually reports.
13. Why This Trial Matters Statistically
This study raises a useful statistical distinction between measuring treatment-taking behavior and measuring whether treatment continues. A missed-dose count records reported behavior over a period, while continuation records treatment status at a follow-up point. The registry describes both concepts, but at different time points: missed doses after three months and continuation after six months. Because the record does not explain their relationship, readers cannot treat them as equivalent measures or assume that one is a substitute for the other.
The single-arm, routine-practice design also illustrates the value and limits of observational evidence. Such a design can describe how outcomes are recorded among treated participants in clinical practice. It does not create a concurrent control group, so the observed outcomes cannot by themselves answer what would have happened under an alternative treatment. This is a design constraint, not a judgment about whether the study has descriptive value.
The distinction between an outcome being named and an outcome being reported is especially important. The registry lists compliance, blood-pressure measures, additional medications, and discontinuation due to adverse events, but numerical results for these outcomes are not reported in the record. Without estimates and uncertainty measures, readers cannot assess the size or precision of an observed association or outcome. Likewise, the safety entries are narrow recorded counts and do not provide a comparative safety analysis.
Finally, the record identifies an evaluable-case-report-form population without defining evaluability or describing missing-data handling. Those details matter because analysis populations and missing responses can shape the interpretation of observed outcomes. The record therefore offers a clear study setting and broad outcome aims, while leaving important questions about endpoint definition, analysis, and results unanswered.
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 primary endpoint is described inconsistently across the registry record. Its title concerns compliance for all participants and by gender, and its detailed description asks about doses missed after three months. The brief summary instead defines the endpoint as the number or percentage continuing treatment after six months. The record does not reconcile the timing or clarify whether these are separate measures. This makes the intended primary estimand—the precise quantity the analysis was meant to estimate—unclear.
The record does not report numerical results for the primary outcome or the listed secondary outcomes. It also does not provide an analysis plan, estimates of uncertainty, or analysis entries. Consequently, the magnitude and precision of outcomes cannot be assessed from the registry information. Although the primary analysis population is described as participants with evaluable case report forms, evaluability, the number contributing to the outcome, and missing-data methods are not reported.
The single-arm observational design has no like-for-like control group. Observed outcomes therefore cannot be interpreted as comparative effects or attributed to treatment alone. Treatment was prescribed in usual practice under local authorization and guidelines, but the registry does not report details of prescribing patterns, changes in treatment, or how these factors were incorporated into any analysis.
Safety information is also limited. The record lists 0 affected for serious and other adverse events, but does not give serious-event terms or describe the collection and follow-up procedures for safety data. Deaths are not reported in the registry record. The listed secondary outcome concerning adverse events leading to discontinuation has no numerical result in the record. These limitations restrict interpretation to the narrow registry entries rather than a complete assessment of safety or comparative outcomes.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Effectiveness and Patient Self-assessed Compliance of Blood Pressure Treatment With Tarka® Fixed Combination in Patients With Essential Hypertension — NCT01127139.
- Registry record last updated 2012-05-01; status last verified 2012-03.
- Results first posted 2012-05-01.
- 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
This completed registry record concerns a prospective, single-arm, single-country, multicenter observational study of fixed-combination verapamil SR/trandolapril (Tarka®) in Czech patients with essential hypertension. The recorded enrollment is 3828; the study start is 2010-04 and primary completion is 2011-03.
The primary outcome concerns treatment compliance, but its detailed description refers to missed doses after three months while the brief summary describes continued treatment after six months. The registry record does not explain this difference or report a numerical primary-outcome result. Listed secondary outcomes concern blood pressure, additional antihypertensive drugs, and adverse events leading to discontinuation; numerical results are not reported in the registry record.
The safety entries list 0 affected for serious and other adverse events, with 3828 at risk in each category. Serious-event terms are not listed, and deaths are not reported in the registry record. The single-arm design provides no concurrent comparator, so the record describes the study setting and outcomes of interest without establishing comparative treatment effects.