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 A Study of Safety and Efficacy in MK-0954A Combination in Participants With Hypertension (MK-0954A-373 AM3) (NCT01431508), a non-randomized phase 4 study. The primary outcome is Mean Change From Baseline in Trough Sitting Diastolic Blood Pressure (SiDBP) at Week 12.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01431508 |
| Phase | Phase 4 |
| Condition | Hypertension |
| Allocation | Non-Randomized |
| Design model | Single Group |
| Masking | None (open label) |
| Enrollment | 15 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Organon and Co |
| Results posted | Yes |
2. Clinical Question
Population
Participants with mild to moderate essential hypertension. The primary outcome description focuses on participants whose trough sitting diastolic blood pressure (SiDBP) was 95-115 mm Hg at the end of baseline. The registry record identifies the intention-to-treat population for the primary outcome.
Intervention
Losartan 50 mg / hydrochlorothiazide (HCTZ) 12.5 mg, taken once a day for 12 weeks.
Comparator
There was no separate comparator group: the design is single-group and non-randomized. The study therefore does not provide a randomized, like-for-like comparison with another treatment or with a control condition.
Primary question
What was the mean change from baseline in trough sitting diastolic blood pressure at Week 12 among the stated analysis population? The registry record names this endpoint but does not report its numerical estimate or standard deviation.
The clinical question is framed around change in a continuous blood-pressure measure during treatment. It is not a between-group question, because the study has a single treatment group. The record also identifies safety as a study aim, but the primary endpoint described is the change in SiDBP, not an adverse-event outcome.
The population description is important when interpreting the endpoint. The outcome description refers to participants meeting the baseline SiDBP range at the end of baseline, while the listed analysis population is intention-to-treat. The registry record does not further explain how those statements were implemented together, or how missing baseline or Week 12 measurements were handled. Those details are not reported in the registry record.
3. Trial Design
This is a Phase 4, prospective, open-label, single-group study. The allocation is non-randomized, and no masking is listed. The registry record describes treatment with losartan 50 mg / HCTZ 12.5 mg once a day for 12 weeks in participants with mild to moderate essential hypertension. Enrollment is listed as 15. The study status is completed; the listed start date is 2007-08-01 and the listed primary completion date is 2009-06-01.
Because there is no separate control group, the design can describe outcomes observed during treatment but cannot directly estimate a treatment-versus-control difference. Changes from baseline may reflect treatment, but they may also be influenced by other factors over time. General statistical point: without a concurrent comparison group, it is difficult to distinguish a treatment-associated change from changes that might have occurred for other reasons. This is a design limitation, not evidence for or against an effect.
The study is described as open-label, so masking is not part of the recorded design. The registry record does not report additional procedural details about outcome measurement, adherence, treatment changes, or follow-up beyond the stated 12-week treatment period and the primary endpoint timeframe. Those details are not reported in the registry record.
The registry lists one outcome measure and one analysis. It does not report a sample-size justification, a formal statistical analysis plan, interim analyses, or details of any prespecified procedures beyond the information attached to the primary endpoint. Those details are not reported in the registry record. A planning illustration based on an observed effect is not evidence that the original study was designed around that effect, and it is not a measure of the study's observed power.
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 | Losartan 50 mg / HCTZ 12.5 mg |
|---|---|
| STARTED | 15 |
| COMPLETED | 13 |
| NOT COMPLETED | 2 |
Reasons for not completing this period:
| Reason | Losartan 50 mg / HCTZ 12.5 mg |
|---|---|
| Lack of Efficacy | 1 |
| Unable to Follow Protocol Procedures | 1 |
Analysis population for the primary outcome, as defined in the registry: Intention-to-Treat
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 | Losartan 50 mg / HCTZ 12.5 mg |
|---|---|---|
| Participants analysed | 15 | |
| Age, Continuous | years | 50.5 (SD 6.7) |
| Sex: Female, Male: Female | Participants | 6 |
| Sex: Female, Male: Male | Participants | 9 |
6. Primary Endpoint
The registry lists the primary outcome as Mean Change From Baseline in Trough Sitting Diastolic Blood Pressure (SiDBP) at Week 12, measured over At Baseline and Week 12.
| Element | Registry entry |
|---|---|
| Result type | Mean |
| Measure of spread | Standard Deviation |
| Unit | mm Hg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is the mean change from baseline in trough sitting diastolic blood pressure (SiDBP) at Week 12, measured in mm Hg. The record describes measurements at baseline and Week 12 and specifies that the endpoint description concerns participants whose SiDBP was 95-115 mm Hg at the end of baseline. The analysis population is listed as intention-to-treat.
As a continuous endpoint, the measure records the amount of change for each participant and summarizes those changes with a mean. The standard deviation is the stated measure of dispersion; it describes how spread out individual changes are around the mean. General statistical point: a mean can summarize the direction and average size of change, while the standard deviation provides context about variation among participants. Neither summary alone establishes why a change occurred.
Blood pressure is used as an outcome because it gives a measurable clinical quantity that can be assessed at baseline and after treatment. The registry record does not report the mean change, its standard deviation, a confidence interval, or a p-value. Without those result values, the magnitude and precision of the observed endpoint cannot be assessed from the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The registry record identifies the primary outcome and its timing, but it does not provide the numerical mean change in SiDBP or the stated standard deviation. As a result, the direction, magnitude, and variability of the primary outcome cannot be described from the record. A numerical confidence interval or p-value is also not reported in the registry record, so the precision of an estimated change and its compatibility with different values cannot be evaluated.
The single-group design shapes what any observed change could mean. A before-and-after comparison can describe how measurements changed over time among participants in the treatment group. It cannot, by itself, establish that treatment caused the change. General statistical point: without a concurrent control group, time-related changes, measurement variation, regression to the mean, or other influences cannot be separated reliably from a treatment-associated change. These are general possibilities inherent to the design, not findings reported for this study.
The listed population is intention-to-treat, but the registry record does not provide a detailed definition of that population or the numbers contributing measurements at each time point. Enrollment is listed as 15, but that figure does not establish how many participants had an evaluable Week 12 measurement or were included in the primary analysis. Such analysis counts are not reported in the registry record.
For a continuous outcome, the mean and standard deviation would help characterize the observed change, while a confidence interval would communicate uncertainty around the estimate. General statistical point: a confidence interval reflects the range of estimates reasonably compatible with the data under the statistical model and its assumptions. It is not a guarantee that the true value lies in a particular range. Because those numerical summaries are not reported, readers cannot judge whether the estimated change was precise or highly uncertain.
The registry lists one outcome measure and one analysis, but it does not state whether any multiplicity adjustment was planned or applied. It also does not report whether the analysis was adjusted for baseline values or other covariates, or whether assumptions were checked. These details are not reported in the registry record. No inference about statistical significance should be made without the result estimate and its analysis details.
Safety results are reported separately from the primary efficacy endpoint. The record lists zero participants with serious adverse events among 15 at risk and 8 with other adverse events among 15 at risk. These counts describe what is recorded for this group; they do not provide a randomized comparison or establish the likelihood of events in other populations. The record does not report serious adverse-event terms or a death count. The absence of those details should not be interpreted as evidence that no such events occurred.
Overall, the registry record supports a description of the design, treatment regimen, endpoint definition, and some adverse-event counts. It does not include the numerical primary outcome results needed to quantify the average blood-pressure change or its precision. Any interpretation of efficacy based on this record alone must therefore remain limited to the stated study question and design rather than a claim about an observed treatment effect.
9. Statistical Methods Explained
The main statistical task for the primary endpoint is to summarize change in a continuous measurement. The record specifies a mean and standard deviation for trough sitting diastolic blood pressure change from baseline to Week 12. The numerical result is not reported in the registry record, so the endpoint can be explained but not quantified.
What does a mean change describe?
For each participant with the relevant measurements, change is defined by comparing the Week 12 value with the baseline value. The mean summarizes those individual changes across the analysis population. Its interpretation depends on the direction convention used for change; the registry record does not state that convention explicitly. The reported outcome title gives the comparison time points but does not provide an outcome value.
A mean is useful because it condenses a set of measurements into a single measure of average change. It can, however, conceal variation between participants. The standard deviation describes the spread of individual changes around the mean. A smaller spread indicates observations are more clustered around the mean, whereas a larger spread indicates more variation. General statistical point: the standard deviation is a description of the observed data, not a measure of uncertainty in the estimated mean. A confidence interval is typically used to express uncertainty about an estimate, but no confidence interval is reported in the registry record.
Why does the design matter?
This study is non-randomized and single-group, with no separate comparator. A within-group change can show whether measured SiDBP differed between baseline and Week 12 among the participants analyzed. It does not provide a randomized contrast that controls for changes over time unrelated to treatment. General statistical point: a control group can help distinguish treatment-associated differences from background time trends and other influences, while random allocation helps make groups comparable on average. Those protections are not present in this design.
The study is open-label and no masking is listed. General statistical point: masking can reduce the influence of knowledge of treatment assignment on some aspects of measurement or reporting. The registry record does not provide enough procedural detail to assess how outcome measurement was conducted, so no more specific claim about measurement bias is warranted.
How should uncertainty be assessed?
A confidence interval around a mean change would indicate the statistical uncertainty in the estimated average, subject to the analysis assumptions. Its width is influenced by the observed variability and the information available for analysis. A p-value, if reported, would address compatibility between the data and a specified null hypothesis under a statistical model; it would not describe the size or clinical importance of a change. Neither a confidence interval nor a p-value is reported in the registry record for the primary outcome. The mean and standard deviation are also not reported, so these quantities cannot be reconstructed from the posted record.
General statistical point: small studies often have limited precision, but the actual precision depends on the outcome variability and the number of observations analyzed. Enrollment is listed as 15, but the number contributing to the primary analysis is not reported in the registry record. Therefore, the analysis precision cannot be inferred from enrollment alone.
What do the planning illustrations represent?
The sample-size assumptions describe a planning illustration computed from the observed effect, not the trial's own design. The stated assumptions are a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such calculations illustrate the number of participants per arm for 80% power under the specified assumptions. They are planning illustrations, never observed power. They do not show that the original study was planned with those assumptions or that it had a particular probability of detecting an effect.
The record also states that time-to-event planning calculations use the total number of events, while other calculations use participants per arm. The primary endpoint in this study is continuous, so the relevant planning interpretation is participants per arm, not a total event count. No numerical planning results are reported in the registry record. A planning calculation based on an observed effect should also be interpreted cautiously: an observed effect can be imprecise, particularly when the study is small, and the illustration depends on its stated assumptions.
What cannot be assessed from the recorded methods?
The registry record does not report a detailed statistical analysis plan, model specification, baseline adjustment, handling of missing outcome measurements, or a method for checking distributional assumptions. It does not report any interim analyses or a sample-size justification. These details are not reported in the registry record. General statistical point: the choice of model and assumptions can affect estimates and uncertainty, so transparent reporting is needed to evaluate whether an analysis is appropriate for the data.
In a continuous outcome analysis, possible concerns include skewed changes, influential observations, and unequal variability. General statistical point: over-dispersion is a term more commonly used for count data when the observed variation exceeds what a model assumes; when that occurs, standard errors from a model that ignores the extra variation can be too small. The registry record does not identify a count-outcome model for the primary endpoint, and this general issue should not be mistaken for a reported problem in this study.
10. Multiplicity, Missing Data and Analysis Populations
The registry record lists one outcome measure and one analysis. It does not report whether the study had additional endpoints outside the registry record, whether any subgroup analyses were planned, or whether any multiplicity procedure was used. Those details are not reported in the registry record.
General statistical point: when researchers test multiple outcomes, time points, or subgroups, the chance of at least one apparently unusual result can increase if each test is interpreted without accounting for the full set of comparisons. Multiplicity procedures can address that issue, but their appropriateness depends on the questions and analysis plan. The record does not state that an adjustment was made, so readers should not assume either that multiplicity was controlled or that it was ignored.
The primary outcome population is listed as intention-to-treat, and the endpoint description specifies participants with baseline SiDBP of 95-115 mm Hg at the end of baseline. The registry record does not explain how these criteria were applied together, how the analysis population was defined in practice, or how participants without a Week 12 measurement were handled. Missing-data methods and analysis counts are not reported in the registry record.
General statistical point: missing outcomes can affect both the number of observations contributing to an estimate and the interpretation of that estimate, especially if missingness is related to participants' health or outcomes. Different assumptions about missing data can lead to different results. Without reporting the extent and handling of missing data, the robustness of the primary analysis cannot be evaluated.
The listed enrollment is 15; enrollment should not be treated as proof that every participant contributed to every analysis. The registry record does not report the number included in the primary analysis or the number measured at each time point. It also does not report a detailed protocol or statistical analysis plan that would clarify prespecification. Those details are not reported in the registry record.
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 |
|---|---|---|---|
| Losartan 50 mg/HCTZ 12.5 mg | 0 | 15 | 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 |
|---|---|
| Losartan 50 mg/HCTZ 12.5 mg | 8 of 15 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Losartan 50 mg/HCTZ 12.5 mg |
|---|---|---|
| BLOOD URIC ACID INCREASED | Investigations | 3 of 15 |
| BLOOD GLUCOSE ABNORMAL | Investigations | 2 of 15 |
| BLOOD TRIGLYCERIDES INCREASED | Investigations | 2 of 15 |
| ARRHYTHMIA | Cardiac disorders | 1 of 15 |
| PALPITATIONS | Cardiac disorders | 1 of 15 |
| ABDOMINAL DISTENSION | Gastrointestinal disorders | 1 of 15 |
| GASTRITIS | Gastrointestinal disorders | 1 of 15 |
| ASPARTATE AMINOTRANSFERASE INCREASED | Investigations | 1 of 15 |
| BLOOD CHOLESTEROL INCREASED | Investigations | 1 of 15 |
| BLOOD POTASSIUM DECREASED | Investigations | 1 of 15 |
The registry record lists 15 participants at risk for serious adverse events, with 0 affected. It also lists 15 at risk for other adverse events, with 8 affected. These are counts for the single treatment group, not comparisons with a control group. The number of participants at risk is not a measure of follow-up time, and the counts do not describe the rate of events over time.
The record does not list serious adverse-event terms; those terms are not reported in the registry record. The death count is also not reported in the registry record. A zero count for serious adverse events is not interchangeable with a reported zero for deaths, and an unreported death count should not be interpreted as no deaths.
General statistical point: safety counts from a small single-group study can describe events recorded among its participants, but they cannot establish how event frequency compares with another treatment or with no treatment. The record does not provide event-level detail, timing, severity categories for the other events, or a causal assessment for each event. Those details are not reported in the registry record. The counts should therefore be read as descriptive registry results rather than comparative evidence.
12. What the Result Does, and Does Not, Mean
The record establishes that a completed, open-label, single-group study evaluated losartan 50 mg / HCTZ 12.5 mg in participants with mild to moderate essential hypertension, with treatment described as once a day for 12 weeks. It specifies a primary endpoint of mean change from baseline in trough sitting diastolic blood pressure at Week 12. It also reports adverse-event counts for the study group.
The record does not report the numerical mean change, standard deviation, confidence interval, or p-value for the primary endpoint. It therefore does not show how much SiDBP changed on average, how variable participant changes were, or how precise an estimate might be. Without these results, the magnitude and uncertainty of the primary outcome cannot be assessed.
Even if a before-and-after estimate were available, the single-group design would limit causal interpretation. General statistical point: an observed change over time does not by itself distinguish a treatment effect from other influences that can affect measurements. The absence of a comparator also means there is no direct treatment-versus-control estimate in this study.
The adverse-event counts describe events recorded in the study group, but they do not establish comparative safety. There is no control group against which to compare the counts, and the record does not report serious-event terms or a death count. The reported counts should not be interpreted as a complete account of all possible risks or as evidence about other populations.
The study can be understood as a small, descriptive evaluation with a defined blood-pressure endpoint and a stated treatment period. Its registry record offers design and safety-count information, but the missing numerical primary outcome and analysis details prevent a fuller statistical assessment. It does not support a conclusion about whether treatment works or does not work.
13. Why This Trial Matters Statistically
This trial illustrates why a clearly named endpoint is not enough to evaluate a study's statistical result. The registry record defines the primary measure, its time point, and its dispersion statistic, but does not report the numerical mean change or standard deviation. Without those estimates, readers cannot assess the observed magnitude, variability, or precision.
The design also highlights the distinction between describing change and attributing change. A single-group before-and-after endpoint can describe measurements over time, but it lacks a concurrent comparison for separating treatment-associated changes from other influences. General statistical point: causal interpretation depends not only on the outcome measurement but also on how the study design supports a counterfactual comparison.
Enrollment is listed as 15. That figure makes it especially important to know how many observations contributed to the endpoint, how much variability was present, and how missing data were handled. Those analysis details are not reported in the registry record. A planning illustration based on an observed effect cannot substitute for an original design justification or for precision information from the actual analysis.
The adverse-event counts provide a further lesson in scope. Counts in one treatment group are descriptive; without a comparison group and sufficient event detail, they do not quantify relative safety. Overall, the record is useful for identifying the study question and design limitations, while its missing outcome and analysis details constrain what can be learned statistically.
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 interpretation is that the registry record does not report the numerical primary outcome results. The mean change and standard deviation are not reported in the registry record, and no confidence interval or p-value is listed. This prevents assessment of the observed endpoint's direction, magnitude, variability, and precision.
The study has no randomized comparator: it is non-randomized and single-group. Any change from baseline would therefore be descriptive and could not, on its own, isolate a treatment effect from other time-related influences. The open-label design also means no masking is listed.
The record lists enrollment as 15 but does not report the number included in the primary analysis, the number with baseline and Week 12 measurements, or the extent of missing data. It identifies intention-to-treat as the primary population, while the endpoint description gives a baseline SiDBP range; the practical relationship between those statements is not reported in the registry record.
Other details needed to assess the analysis are also not reported in the registry record. These include missing-data methods, model specification, baseline adjustment, assumption checks, multiplicity handling, a formal statistical analysis plan, interim analyses, and a sample-size justification. The registry record also does not report serious adverse-event terms or a death count. These limitations restrict both the efficacy interpretation and the detail available for reading the safety results.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: A Study of Safety and Efficacy in MK-0954A Combination in Participants With Hypertension (MK-0954A-373 AM3) — NCT01431508.
- Registry record last updated 2024-05-22; status last verified 2022-02.
- Results first posted 2011-11-22.
- 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
The registry record describes a completed Phase 4, prospective, open-label, non-randomized, single-group study in mild to moderate essential hypertension. Enrollment is listed as 15. Participants are described as receiving losartan 50 mg / HCTZ 12.5 mg once a day for 12 weeks.
The primary endpoint is mean change from baseline in trough sitting diastolic blood pressure at Week 12, with standard deviation as the dispersion measure and intention-to-treat as the listed population. Its numerical result is not reported in the registry record. The record lists 0 serious adverse events among 15 at risk and 8 other adverse events among 15 at risk; serious-event terms and a death count are not reported in the registry record.
The single-group design does not provide a randomized control comparison, and several analysis details, including missing-data handling and the statistical analysis plan, are not reported in the registry record.