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 Comparison of the Effect of Eprosartan and Eprosartan Mesylate on Blood Pressure in Essential Hypertension (NCT01631227), a randomized phase 3 study. The primary outcome is Assess the Therapeutic Equivalence of Eprosartan (a New Formulation Containing Only the Active Moiety Eprosartan) With Eprosartan Mesylate (Currently Marketed Formulation) on Change of Sitting Diastolic Blood Pressure (DBP) From Baseline.
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT01631227 |
| Phase | Phase 3 |
| Condition | Essential Hypertension |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Quadruple |
| Enrollment | 665 |
| Arms in the primary outcome | 2 |
| Lead sponsor | Abbott |
| Results posted | Yes |
2. Clinical Question
Population
The trial enrolled subjects with mild to moderate essential hypertension. The primary outcome describes the full analysis subject sample. The registry record lists enrollment as 665, while the posted outcome and safety records use their own group denominators; the record does not explain how those denominators relate to enrollment.
Intervention
The intervention was eprosartan, described in the primary outcome as a new formulation containing only the active moiety eprosartan. The arm description pairs eprosartan with placebo eprosartan mesylate. This design detail indicates that the comparison used matched active and placebo components, but the registry record does not give further administration instructions.
Comparator
The comparator was eprosartan mesylate, identified as the currently marketed formulation. Its arm description pairs eprosartan mesylate with placebo eprosartan. The study aim was to compare blood-pressure lowering between formulations, with equivalent efficacy as the stated objective.
Primary question
Did the formulations differ in mean change from baseline in sitting diastolic blood pressure (DBP) after 8 weeks? The posted group means are −7.4 mmHg for eprosartan and −7.2 mmHg for eprosartan mesylate. The reported comparison is a mean difference of 0.2 mmHg, with an interval estimate that spans zero. The registry record does not report the prespecified equivalence margin needed to judge whether the formulations met a formal equivalence criterion.
The scientific question is about similarity between two formulations of the same named medicine, not a comparison of either formulation with no treatment. A small observed difference can be consistent with similarity, but a formal equivalence conclusion also depends on how much difference the study was designed to rule out. Without that margin and the full sponsor analysis details, the observed comparison alone cannot establish therapeutic equivalence.
3. Trial Design
This was a phase 3, randomized, quadruple-masked, parallel-group study sponsored by Abbott. The official title describes a prospective, randomized, double-blind parallel-group comparison in subjects with mild to moderate essential hypertension. The registry record reports enrollment of 665 and a completed status. The listed study period began in 2012-06, with primary completion in 2013-04.
Random allocation is intended to make treatment groups comparable, on average, with respect to both measured and unmeasured characteristics. In a parallel-group design, participants remain assigned to their group rather than crossing between formulations. These features support a direct between-group comparison. The record does not describe the randomization sequence, allocation concealment, stratification factors, or how masking was implemented. Although masking is classified as quadruple, the identities of the masked roles are not reported in the registry record.
The intervention descriptions show eprosartan with placebo eprosartan mesylate in one arm and eprosartan mesylate with placebo eprosartan in the other. This resembles a double-dummy arrangement, which can help maintain masking when formulations differ. The registry record does not provide dosing schedules or enough detail to characterize the treatment regimen further.
The primary outcome is change from baseline in sitting DBP, assessed at 8 weeks. The record identifies the reported measure as a least-squares mean and gives a standard deviation for each arm. It names the full analysis subject sample as the outcome population. However, the exact definition of that population, rules for handling missing measurements, and details of any covariate adjustment are not reported in the registry record. The registry record also does not report the trial's original sample-size assumptions or an equivalence margin.
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 | Eprosartan | Eprosartan Mesylate |
|---|---|---|
| STARTED | 333 | 332 |
| Safety Subject Sample | 332 | 332 |
| Full Analysis Set Population | 330 | 331 |
| COMPLETED | 303 | 310 |
| NOT COMPLETED | 30 | 22 |
Reasons for not completing this period:
| Reason | Eprosartan | Eprosartan Mesylate |
|---|---|---|
| withdrawn consent | 27 | 21 |
| Adverse Event | 1 | 0 |
| administrative | 2 | 1 |
Analysis population for the primary outcome, as defined in the registry: Full analysis subject sample
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: Full analysis set consists of 330 and 331 patients respectively.
| Characteristic | Unit | Eprosartan | Eprosartan Mesylate | Total |
|---|---|---|---|---|
| Participants analysed | 333 | 332 | 665 | |
| Age, Continuous | years | 60 (SD 10) | 60 (SD 10) | 60 (SD 10) |
| Gender: Female | participants | 186 | 201 | 387 |
| Gender: Male | participants | 144 | 130 | 274 |
6. Primary Endpoint
The registry lists the primary outcome as Assess the Therapeutic Equivalence of Eprosartan (a New Formulation Containing Only the Active Moiety Eprosartan) With Eprosartan Mesylate (Currently Marketed Formulation) on Change of Sitting Diastolic Blood Pressure (DBP) From Baseline, measured over 8 weeks.
| Element | Registry entry |
|---|---|
| Result type | Least Squares Mean |
| Measure of spread | Standard Deviation |
| Unit | mmHg |
| Endpoint classification | Continuous Endpoint |
The primary endpoint is change from baseline in sitting diastolic blood pressure (DBP), measured in mmHg at 8 weeks. DBP is the lower pressure value recorded during a heartbeat cycle, and measuring change from baseline focuses the comparison on how measurements shifted during the study rather than on the final measurement alone. Sitting measurement specifies the posture used for the assessment.
For a continuous endpoint such as DBP change, the group result is expressed as a mean. The registry record labels the measure a least-squares mean, a model-based mean that can account for specified covariates. The precise model and its covariates are not reported in the registry record. The posted group values are −7.4 mmHg for eprosartan and −7.2 mmHg for eprosartan mesylate, each with a reported standard deviation.
Change in DBP is relevant to the stated comparison because the study sought to assess whether the formulations had equivalent blood-pressure lowering effects. A between-group difference summarizes how separated the group averages are, while an uncertainty interval indicates how imprecisely that difference is estimated. For equivalence, the difference must be evaluated against a prespecified range of clinically acceptable differences. That range is not reported in the registry record, so the endpoint results can describe the observed comparison but cannot by themselves demonstrate that a formal equivalence criterion was satisfied.
7. Results Posted in the Registry
- Eprosartan Mesylate: mean -7.20 versus -7.40 on control; difference 0.20 (95% CI -0.96 to 1.36), standardized effect d = 0.03; z-test p = 0.735.
Mean difference: Eprosartan Mesylate
95% CI: -0.96 to 1.36
Recalculated from the posted summary statistics
8. Statistical Interpretation
The posted outcome means show decreases from baseline in both groups: −7.4 mmHg with eprosartan and −7.2 mmHg with eprosartan mesylate. The reported mean difference is 0.2 mmHg, with the comparison expressed as eprosartan mesylate relative to eprosartan. This is a small point estimate in the units of the endpoint. It describes the observed separation between the group means; it does not establish that the formulations are equivalent.
The reported interval for the difference spans zero. In general, an interval that includes zero is compatible with no mean difference as well as with differences in either direction within the interval. The posted unadjusted p-value is 0.735. It does not provide evidence of a statistically detectable difference under the corresponding null-hypothesis test. A non-significant test is not proof that the groups are identical, and it is not an equivalence test.
Equivalence asks a different question from whether a conventional test detects a difference. It requires a prespecified equivalence margin: a range of differences considered acceptably small. The confidence interval must be sufficiently contained within that margin under the trial's planned method. The registry record does not report the margin or the sponsor's full analysis method, so the formal equivalence question cannot be resolved from the posted summary statistics alone. The trial's stated objective was to demonstrate equivalent efficacy, but an objective is not itself evidence that the criterion was met.
The standard deviations are 7.7 mmHg for eprosartan and 7.5 mmHg for eprosartan mesylate. These describe participant-level spread around each reported group mean, rather than the uncertainty in the difference itself. The standard errors listed for the group means are 0.424 and 0.412. A standard error characterizes sampling uncertainty in an estimated mean; it is not a measure of the range of individual responses. The posted uncertainty interval for the comparison is therefore more directly relevant to precision of the between-group estimate than either group standard deviation alone.
The outcome records list 330 participants in the eprosartan arm and 331 in the eprosartan mesylate arm. These are the denominators attached to the primary outcome results. The record does not explain how they relate to the overall enrollment, define the full analysis subject sample, or describe missing outcome handling. It is therefore not possible to infer from the summary whether all enrolled participants contributed to this endpoint or why any denominators differ across record components.
The appropriate reading is narrow: the posted means are close, the estimated mean difference is 0.2 mmHg, and the uncertainty interval includes zero. The result does not establish the absence of a difference, nor does it demonstrate equivalence without the prespecified margin and analysis details. It also does not answer questions about outcomes other than the primary DBP measure or about effects beyond the 8-week timeframe.
9. Statistical Methods Explained
The primary measure is continuous: each participant has a change in sitting DBP expressed in mmHg, and the group result summarizes those changes with a mean. A mean is useful because it describes the average change across the analyzed group and permits a direct comparison of average changes. It does not describe every participant's experience. The standard deviation gives a sense of how dispersed individual changes are around the group average. In the posted results, the reported standard deviations are 7.7 mmHg for eprosartan and 7.5 mmHg for eprosartan mesylate.
What does a mean difference represent?
A mean difference subtracts one group mean from the other in a stated order. Here, the listed comparison is eprosartan mesylate relative to eprosartan, with a reported estimate of 0.2 mmHg. Its sign depends on that order. Since both group means are negative changes, the positive difference means the eprosartan mesylate mean change is less negative than the eprosartan mean change. The estimate is a contrast between group averages, not an estimate of the change for a typical individual and not a percentage change.
For randomized parallel-group trials, comparing group outcomes is generally a way to estimate the effect of assignment, subject to the analysis population and missing-data procedures. Randomization supports comparability at baseline in expectation, but it does not guarantee that every characteristic is balanced in the realized groups. The registry record does not give baseline outcome values, covariate adjustments, or the detailed model used to produce the least-squares means. The methods underlying those means therefore cannot be reconstructed from the posted summary alone.
What does an uncertainty interval add?
A confidence interval is a range of values compatible with the observed data and a specified statistical procedure. It conveys precision as well as direction: a narrower interval generally indicates more precise estimation, while a wider interval leaves more possible values consistent with the data. The posted interval for the mean difference crosses zero, so it does not rule out a zero difference at the interval's stated confidence level. The confidence level itself is not specified in the registry record, and the lower endpoint is not repeated because its displayed precision exceeds the permitted reporting precision.
Interval estimation is particularly important for equivalence questions. A conventional superiority test often asks whether the data are inconsistent with a zero difference. Equivalence instead asks whether the plausible differences are contained within boundaries judged acceptable in advance. A broad interval may include zero and still extend beyond an equivalence boundary; a narrow interval may support equivalence if it lies entirely within the prespecified boundaries. The registry record does not report those boundaries, so the posted interval cannot be interpreted as a formal equivalence result.
How should the p-value be read?
The posted unadjusted p-value is 0.735. In general, a p-value is calculated under a specified null model and describes how unusual the data, or data at least as incompatible with that model, would be if the null model held. It is not the probability that the null hypothesis is true, and it does not measure the size or clinical importance of a difference. The term unadjusted indicates that the displayed value is not adjusted for multiplicity. The registry record does not state the complete testing plan or whether this was the sponsor's prespecified primary analysis.
A large p-value is not evidence that two formulations are identical. It can arise when the estimated difference is small, when uncertainty is substantial, or both. The estimate, its interval, and the design's equivalence criterion are needed to interpret the result. For this trial, the observed mean difference is small, and the interval spans zero, but the required equivalence margin is not reported.
Why can variation affect precision?
General statistical explanation: variability among individual measurements influences how precisely a group mean and a between-group difference can be estimated. More spread tends to make estimates less precise if other design features remain unchanged. The standard deviations in the record reflect observed spread, while the standard errors reflect uncertainty in the group mean estimates. These statistics answer related but distinct questions. A group standard deviation is not an uncertainty interval for the treatment difference.
General statistical explanation: over-dispersion occurs when data vary more than a statistical model assumes. In such settings, a model that understates variability may produce confidence intervals that are too narrow and p-values that are too small. The primary endpoint is continuous and is summarized with means and standard deviations; the registry record does not report an over-dispersion assessment or enough model detail to evaluate that issue. It should not be assumed either to have occurred or to have been ruled out.
What is known about the analysis population?
The endpoint is labeled as using the full analysis subject sample, and the posted groups list 330 and 331 participants. Those labels alone do not define inclusion rules. The registry record does not explain whether the population follows an intention-to-treat principle, how protocol deviations were handled, or whether missing measurements were imputed, excluded, or modeled. Missing-data choices can affect estimated means and uncertainty, especially when missingness is related to outcomes or treatment assignment. Without those details, the summary estimates should be understood as the posted results for the named analysis population, not as a complete account of all enrolled participants.
The registry lists no posted secondary outcomes and no analysis entries, although it does post a primary outcome summary and a comparison. This limits the amount of analysis detail available for interpreting model assumptions, multiplicity, and sensitivity analyses. The statistical interpretation should consequently remain focused on the summary endpoint and its reported comparison rather than inferring unreported methods.
10. Confidence Intervals and Precision
The comparison estimate is a mean difference of 0.2 mmHg. Its reported interval extends on both sides of zero, which means that the summary does not pin down the direction of the underlying difference with high certainty. The interval is relevant to precision because it shows a range of values compatible with the data under the method used. The record does not state the confidence level or provide the detailed calculation method.
The group means, −7.4 mmHg and −7.2 mmHg, are close, but closeness of point estimates is not the same as precision. The group standard deviations, 7.7 mmHg and 7.5 mmHg, describe variation in participant changes, while the standard errors of the group means are 0.424 and 0.412. The uncertainty interval for the difference is the pertinent measure for judging how precisely the between-group contrast is estimated.
For a formal equivalence claim, precision must be evaluated against the prespecified equivalence margin. If the interval lies entirely within acceptable boundaries, that can support equivalence under the planned procedure. If it crosses a boundary, the evidence may be inconclusive even when the point estimate is near zero. The registry record does not report the margin, so it is not possible to determine whether the interval is narrow enough for the trial's intended equivalence assessment.
The posted unadjusted p-value of 0.735 and an interval spanning zero are consistent with the absence of a statistically detectable difference in a conventional test. Neither establishes that the difference is exactly zero. The estimate's practical interpretation also depends on what differences in DBP were considered acceptable, which is not reported in the registry record.
11. Planning a Similar Trial: Sample Size
This is a planning illustration, not a re-evaluation of the original trial. It asks: if a new study wanted to detect a difference like the one observed, or a smaller one, how large would it need to be? It is deliberately not “observed power” of the finished trial, which is not a meaningful quantity.
| Effect to detect | Participants per arm, 80% power | Participants per arm, 90% power |
|---|---|---|
| 100% of the observed effect | 22,671 | 30,350 |
| 75% of the observed effect | 40,304 | 53,955 |
| 50% of the observed effect | 90,683 | 121,398 |
The planning figures are participants per arm, not total events. They are illustrations based on the observed effect, rather than the trial's original design calculation. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation. The effect targeted in each row is the stated fraction of the observed effect.
The 80% power column gives the planned participants per arm for a hypothetical study to have an 80% chance of detecting the specified effect under those assumptions, if the assumed effect and model are appropriate. The 90% power column uses the same interpretation with a higher target probability. These are design probabilities under assumptions, not probabilities that the trial's result is true. They do not describe the power actually achieved in this completed study; the figures are not observed power.
For 100% of the observed effect, the illustration gives 22,671 participants per arm for 80% power and 30,350 participants per arm for 90% power. For 75% of the observed effect, it gives 40,304 participants per arm for 80% power and 53,955 participants per arm for 90% power. For 50% of the observed effect, it gives 90,683 participants per arm for 80% power and 121,398 participants per arm for 90% power.
The sequence illustrates why smaller effects require more participants: when the target difference is reduced, it is harder to distinguish it from random variation, so a larger group is needed to reach the same target power under the specified assumptions. These figures should not be read as a recommendation or as the original trial's intended enrollment. The registry record does not report the original sample-size justification, and the planning values depend on the observed effect, which may not be a stable estimate of the effect in a future study.
12. How the Sample Size Is Derived
Power is the probability that a study of a given size rejects the null hypothesis when a specific true effect exists. It depends on four things: the effect to detect, the variability of the outcome, the significance level (here a two-sided α of 0.05, so z1−α/2 = 1.960) and the desired power (z1−β = 0.842 for 80% and 1.282 for 90%).
Formula
n is the number of participants in each arm, Δ is the difference in means to detect and σ is the common standard deviation.
Worked calculation for this trial
- Observed difference Δ = 0.200; pooled standard deviation σ = 7.601.
- n = 2 × (1.96 + 0.842)2 × 7.6012 / 0.2002 = 22,670.6, rounded up to 22,671 participants per arm for 80% power.
The smaller-effect rows in the table above repeat the same calculation with the effect multiplied by 0.75 and 0.5 (for ratios, applied to the logarithm of the ratio).
R code
alpha <- 0.05
z_a <- qnorm(1 - alpha / 2) # two-sided
delta <- 0.2 # observed difference in means
sigma <- 7.60050613281524 # pooled standard deviation
n_per_arm <- function(power, frac = 1) {
ceiling(round(2 * (z_a + qnorm(power))^2 * sigma^2 / (delta * frac)^2, 6))
}
for (f in c(1, 0.75, 0.5))
cat(sprintf("%3.0f%% of observed effect: n per arm = %s (80%% power), %s (90%% power)\n", 100 * f,
format(n_per_arm(0.80, f), big.mark = ","), format(n_per_arm(0.90, f), big.mark = ",")))
# Check against R's built-in function (t-based, so very slightly larger)
cat("power.t.test:", round(power.t.test(delta = delta, sd = sigma, power = 0.80)$n, 1), "\n")
# Simulation: exact two-sample t-test using simulated means and variances
set.seed(1631227)
n <- n_per_arm(0.80)
reps <- 20000
m_diff <- rnorm(reps, delta, sigma * sqrt(2 / n)) # difference in sample means
s2 <- sigma^2 * rchisq(reps, 2 * (n - 1)) / (2 * (n - 1)) # pooled sample variance
tstat <- m_diff / sqrt(s2 * 2 / n)
cat(sprintf("Simulated power at n = %s per arm: %.3f (%d replicates)\n", format(n, big.mark = ","), mean(abs(tstat) > qt(0.975, 2 * (n - 1))), reps))
Output from running the code
100% of observed effect: n per arm = 22,671 (80% power), 30,350 (90% power)
75% of observed effect: n per arm = 40,304 (80% power), 53,955 (90% power)
50% of observed effect: n per arm = 90,683 (80% power), 121,398 (90% power)
power.t.test: 22671.5
Simulated power at n = 22,671 per arm: 0.800 (20000 replicates)The simulation draws many sets of group means and variances at the planned sample size and counts how often the two-sample t-test rejects the null. It should land close to the target power; at very small required sample sizes it can fall below it, because the normal approximation is rough there.
13. Multiplicity, Missing Data and Analysis Populations
Multiplicity arises when a study evaluates multiple outcomes, time points, treatment comparisons, or statistical tests. If many tests are conducted, the chance of at least one apparently notable result can increase unless the testing strategy accounts for that. The primary endpoint listed in the registry record is change from baseline in sitting DBP at 8 weeks. The record lists one outcome measure, no posted secondary outcomes, and no analysis entries. It does not provide a full statistical analysis plan or explain whether any additional outcomes or comparisons were assessed outside the posted record.
The displayed p-value is identified as unadjusted. That means it should not be interpreted as having a multiplicity correction. The registry record does not describe a testing hierarchy, family of hypotheses, or adjustment procedure. Since the primary analysis strategy is not reported in detail, the role of this p-value within the complete sponsor analysis cannot be established from the record alone.
Missing-data handling is also not reported. The endpoint population is named as the full analysis subject sample, but the record does not define inclusion criteria or state how participants without an 8-week measurement were handled. It does not report imputation, a missing-at-random assumption, sensitivity analyses, or reasons for missingness. These details matter because methods make assumptions about the unobserved measurements, and different assumptions can lead to different estimates or uncertainty intervals.
The primary outcome denominators are 330 for eprosartan and 331 for eprosartan mesylate. The safety record lists 332 at risk in each group. These are outcome-specific denominators in separate record components; the registry record does not reconcile them. They should not be combined or treated as proof of a particular missing-data pattern.
The record's stated analysis population should therefore be reported as named, without relabeling it as a specific intention-to-treat or per-protocol population. The sponsor's complete analysis plan, missing-data procedures, multiplicity strategy, and any sensitivity analyses are not reported in the registry record. These omissions constrain evaluation of the robustness of the result and its formal equivalence interpretation.
14. 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 |
|---|---|---|---|
| Eprosartan | 3 | 332 | 0.9% |
| Eprosartan Mesylate | 7 | 332 | 2.1% |
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 |
|---|---|
| Eprosartan | 15 of 332 |
| Eprosartan Mesylate | 18 of 332 |
Most frequent serious adverse event terms
| Event term | Organ system | Eprosartan | Eprosartan Mesylate |
|---|---|---|---|
| GASTRITIS HAEMORRHAGIC | Gastrointestinal disorders | 0 of 332 | 1 of 332 |
| GASTROOESOPHAGEAL REFLUX DISEASE | Gastrointestinal disorders | 0 of 332 | 1 of 332 |
| TIBIA FRACTURE | Injury, poisoning and procedural complications | 1 of 332 | 0 of 332 |
| FOREARM FRACTURE | Injury, poisoning and procedural complications | 0 of 332 | 1 of 332 |
| HEADACHE | Nervous system disorders | 0 of 332 | 1 of 332 |
| MIGRAINE | Nervous system disorders | 1 of 332 | 0 of 332 |
| DIZZINESS | Nervous system disorders | 0 of 332 | 1 of 332 |
| THYROID CYST | Endocrine disorders | 0 of 332 | 1 of 332 |
| CYSTIC RUPTURE | General disorders | 0 of 332 | 1 of 332 |
| VIRAL UPPER RESPIRATORY TRACT INFECTION | Infections and infestations | 1 of 332 | 0 of 332 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Eprosartan | Eprosartan Mesylate |
|---|---|---|---|
| NASOPHARYNGITIS | Infections and infestations | 15 of 332 | 18 of 332 |
Serious events with the highest arm-level rate: gastritis haemorrhagic (0.3%), gastrooesophageal reflux disease (0.3%), tibia fracture (0.3%), forearm fracture (0.3%), headache (0.3%).
The adverse-event record lists serious adverse events for groups with 332 participants at risk in each arm. It reports 3 serious events as affecting participants in the eprosartan group and 7 in the eprosartan mesylate group. The record lists other adverse events affecting 15 participants in the eprosartan group and 18 in the eprosartan mesylate group, with 332 at risk in each group for that category.
These are counts, not rates adjusted for exposure time. The registry record does not give event-specific time at risk, the duration of follow-up for safety, or a statistical comparison of the groups. It also does not report deaths in the posted safety summary. The term serious adverse event is not interchangeable with every adverse event; seriousness generally refers to regulatory criteria such as outcomes involving significant medical consequences, rather than simply the intensity of a symptom. The record does not define its classification procedures.
The listed serious-event terms each have a reported frequency of 0.3%: gastritis haemorrhagic, gastrooesophageal reflux disease, tibia fracture, forearm fracture, headache, and migraine. The summary does not establish that these terms occurred only once or describe overlap among terms and participants. These counts and terms are descriptive safety information, not evidence of a causal difference between formulations. A full safety assessment would require more detail than this registry summary reports.
15. What the Result Does, and Does Not, Mean
The posted results describe a close comparison of average change in sitting DBP at 8 weeks. The mean change was −7.4 mmHg for eprosartan and −7.2 mmHg for eprosartan mesylate, with a reported mean difference of 0.2 mmHg. The interval for the comparison spans zero, and the unadjusted p-value is 0.735. Together, these statistics indicate that the posted summary does not show a statistically detectable difference in the conventional null-hypothesis sense.
That finding is not proof that the formulations have exactly the same effect. A failure to detect a difference can reflect a genuinely small difference, uncertainty in the estimate, or both. Equivalence is a separate claim requiring a prespecified acceptable range and an analysis showing that the uncertainty interval falls within it. The registry record does not report that margin or the complete analysis method. Therefore, the stated objective of demonstrating equivalent efficacy cannot be confirmed from these summary statistics alone.
The result is specific to the endpoint, analysis population, and timeframe described in the record: change from baseline in sitting DBP in the full analysis subject sample at 8 weeks. It does not establish comparative effects on other blood-pressure measures, other clinical outcomes, or longer-term outcomes. The registry record lists no secondary outcomes. It also does not provide the detailed missing-data procedures or the sponsor's complete analysis plan.
The adverse-event summary provides descriptive counts for serious and other events, but it does not include a comparative statistical analysis or enough detail to assess event timing and exposure. Those counts should not be interpreted as proof that one formulation is safer than the other. More broadly, the posted efficacy and safety summaries support a focused reading of the recorded outcomes, not a general conclusion about all potential benefits and harms.
In short, the observed mean changes are similar in magnitude and the estimated contrast is small, but the available record leaves the central formal equivalence criterion unspecified. A reader can describe the observed comparison and its uncertainty, while distinguishing that description from a definitive equivalence conclusion.
16. Why This Trial Matters Statistically
This trial raises an important statistical distinction between finding no detectable difference and demonstrating equivalence. Those conclusions require different questions and usually different decision criteria. A conventional test evaluates whether the data provide evidence against a zero-difference hypothesis. An equivalence analysis asks whether the plausible difference is small enough to fall within boundaries specified in advance. A small point estimate and a non-significant p-value do not replace those boundaries.
The posted mean difference is 0.2 mmHg, and its interval spans zero. These registry entries characterize the observed estimate and its uncertainty, but the registry record does not report the equivalence margin. That omission prevents a reader from assessing whether the uncertainty interval was sufficiently narrow relative to the study's intended equivalence criterion. The record's stated objective can therefore be distinguished from evidence that the objective was achieved.
The trial also illustrates why a p-value should not be read in isolation. The unadjusted value of 0.735 does not quantify the size of the difference, establish identity, or indicate the probability that the formulations are equivalent. The effect estimate and interval provide more direct information about the possible size and direction of the contrast. In equivalence research, the relationship between that interval and the prespecified margin is central.
Finally, registry summaries can convey useful outcome estimates while leaving analysis details unresolved. Here, the primary endpoint and group summaries are posted, but the model, missing-data procedures, original sample-size justification, and equivalence margin are not reported in the registry record. Recognizing the boundary between observed results and unavailable design details is part of sound statistical interpretation.
17. 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 main limitation for interpreting the study's stated objective is that the registry record does not report the equivalence margin. Without it, the mean difference and its uncertainty cannot be judged against the trial's intended acceptable range. The record also does not provide the sponsor's full statistical analysis plan or enough detail to determine exactly how the least-squares means and comparison were estimated.
The outcome population is labeled as the full analysis subject sample, but its definition is not reported. The record does not explain missing measurements, exclusions, protocol deviations, or sensitivity analyses. The primary outcome group denominators differ from the safety denominators, and the record does not reconcile those counts. This prevents a detailed assessment of analysis-set construction and completeness.
The posted results focus on change in sitting DBP at 8 weeks. The registry record lists no secondary outcomes, so it does not support a broad interpretation across other outcomes or timeframes. The safety summary is also limited: it provides adverse-event counts and selected serious-event terms, but not event timing, exposure-adjusted rates, detailed ascertainment methods, or a comparative safety analysis. Deaths are not reported in the registry record.
The trial is randomized and parallel-group, but the record does not describe sequence generation, allocation concealment, the roles masked under quadruple masking, or the detailed treatment regimen. These details may be important for a complete appraisal, but their absence does not justify guessing how the study was conducted. The record also does not report the trial's original sample-size assumptions or justification; the displayed planning illustrations are based on the observed effect and should not be confused with the original design.
18. Related Tutorials
19. Related Statistical Calculators
20. Sources
- ClinicalTrials.gov: Comparison of the Effect of Eprosartan and Eprosartan Mesylate on Blood Pressure in Essential Hypertension — NCT01631227.
- Registry record last updated 2014-07-25; status last verified 2014-07.
- Results first posted 2014-05-26.
- 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.
Continue through the Clinical Biostats statistical pathway
Use this trial's endpoint as a starting point for deeper study of effect measures, confidence intervals, and sample-size planning.
21. Record Summary
NCT01631227 is a completed phase 3 randomized, quadruple-masked parallel-group study sponsored by Abbott. It compared eprosartan with eprosartan mesylate in subjects with mild to moderate essential hypertension. The primary endpoint was change from baseline in sitting DBP at 8 weeks, in the full analysis subject sample.
The posted mean changes were −7.4 mmHg for eprosartan and −7.2 mmHg for eprosartan mesylate. The reported mean difference was 0.2 mmHg, the interval spans zero, and the unadjusted p-value was 0.735. The record does not report an equivalence margin, the full analysis plan, or missing-data procedures, so the posted comparison alone cannot establish formal equivalence.