Efficacy and Safety of Azilsartan Medoxomil in African American Participants With Essential Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Azilsartan Medoxomil in African American Participants With Essential Hypertension (NCT00591253), a randomized phase 3 study. The primary outcome is Change From Baseline in the 24-hour Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring..

2. Clinical Question

The primary outcome is a continuous measurement in mmHg. The registry describes the outcome as the change from baseline in the 24-hour mean systolic blood pressure measured by ambulatory blood pressure monitoring. This monitoring records blood pressure at intervals during the day and night; the endpoint averages readings over the 24 hours after dosing.

The main comparisons are each dose group against placebo, rather than a direct comparison of the two doses. The posted results also include clinic blood-pressure measures and other ambulatory blood-pressure outcomes. Those secondary measures add context about different settings and time periods, but they do not replace the primary question.

This is a question about observed group-average changes in a defined trial population and timeframe. It does not, by itself, establish what an individual participant’s response would be, or how results might apply outside the population and conditions described in the registry record.

3. Trial Design

The registry record describes a Phase 3, randomized, double-blind, placebo-controlled, parallel-group study. The trial enrolled 413 participants and is marked completed. Its stated purpose was to evaluate the effectiveness and safety of once-daily azilsartan medoxomil compared with placebo in African-American participants with essential hypertension.

Participants were assigned to azilsartan medoxomil 40 mg once daily, azilsartan medoxomil 80 mg once daily, or placebo once daily. The parallel-group design means participants were assigned to a group and the groups were compared over the study period. The registry records quadruple masking; it does not describe which specific people or roles were masked.

The primary outcome was assessed from baseline to Week 6. The primary analysis population is identified as the Full Analysis Set. The posted arm results for this outcome include 94 participants in the 40 mg group, 101 in the 80 mg group, and 94 in the placebo group. The registry record does not explain why these analysis counts differ from overall enrollment.

The record includes additional blood-pressure outcomes, including clinic readings and ambulatory readings over 24 hours, daytime, nighttime, and 12-hour periods. It lists 15 outcome measures and 30 analyses. Details of the original sample-size justification, the intended statistical analysis plan, and any interim analyses are not reported in the registry record.

The study start is listed as 2007-10, and primary completion as 2009-04. These record dates describe the trial timeline; they do not provide detail about the duration of follow-up for every participant.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: Black participants with essential hypertension were enrolled in one of three, once-daily (QD) treatment groups.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Full Analysis Set.

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.

6. Primary Endpoint

The registry lists the primary outcome as Change From Baseline in the 24-hour Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring., measured over Baseline and Week 6..

The primary endpoint is the change from baseline to Week 6 in 24-hour mean systolic blood pressure measured by ambulatory blood pressure monitoring, expressed in mmHg. The registry defines the 24-hour mean as the average of measurements recorded throughout 24 hours after dosing. It reports least-squares means and standard errors for the groups.

Ambulatory monitoring collects readings during usual daytime and nighttime periods rather than relying only on a clinic measurement. Averaging across the 24-hour period gives a continuous summary of blood pressure across those recorded intervals. As a general statistical point, continuous outcomes retain information about the magnitude of measurements, rather than reducing them to categories.

Change from baseline expresses the follow-up measurement relative to each participant’s starting measurement. Comparing the group averages of these changes helps describe how the groups differed over the specified period. The comparison with placebo provides context for changes that occurred in the group without active study drug.

The endpoint is specific to the measurement method, population, and Week 6 timeframe in the registry record. It is not a direct measure of every aspect of blood pressure or of longer-term outcomes. Details of the monitoring schedule beyond the registry description, and details of how incomplete measurements were handled, are not reported in the registry record.

7. Results Posted in the Registry

• Azilsartan Medoxomil 40 mg QD: mean -7.70 versus -2.70 on control; difference -5.00 (95% CI -7.95 to -2.05), standardized effect d = -0.48; z-test p = <0.001.
• Azilsartan Medoxomil 80 mg QD: mean -10.48 versus -2.70 on control; difference -7.78 (95% CI -10.68 to -4.88), standardized effect d = -0.75; z-test p = <0.001.

8. Secondary Efficacy Endpoints

The registry also posts results for secondary outcomes. For each outcome below, the endpoint type, the test applied to the posted summary statistics, the result and its interpretation are given in turn. Secondary endpoints are usually not adjusted for multiple testing, so they support rather than confirm the primary finding.

Change From Baseline in Mean Trough Clinic Sitting Systolic Blood Pressure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Azilsartan Medoxomil 40 mg QD: mean -9.51 versus -3.04 on control; difference -6.47 (95% CI -10.16 to -2.78), standardized effect d = -0.42; z-test p = <0.001.
  • Azilsartan Medoxomil 80 mg QD: mean -9.58 versus -3.04 on control; difference -6.54 (95% CI -10.26 to -2.82), standardized effect d = -0.43; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 40 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 80 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline in the 24-hour Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Azilsartan Medoxomil 40 mg QD: mean -4.93 versus -1.49 on control; difference -3.44 (95% CI -5.47 to -1.41), standardized effect d = -0.49; z-test p = <0.001.
  • Azilsartan Medoxomil 80 mg QD: mean -7.27 versus -1.49 on control; difference -5.78 (95% CI -7.77 to -3.79), standardized effect d = -0.82; z-test p = <0.001.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 40 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 80 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

Change From Baseline in Mean Trough Clinic Sitting Diastolic Blood Pressure

• Endpoint type: Continuous: a mean value per participant, compared as a difference in means.
• Test: Unadjusted two-sample z-test for the difference in means, using the posted standard errors.
• Result:
  • Azilsartan Medoxomil 40 mg QD: mean -5.48 versus -2.36 on control; difference -3.12 (95% CI -5.22 to -1.02), standardized effect d = -0.36; z-test p = 0.004.
  • Azilsartan Medoxomil 80 mg QD: mean -5.32 versus -2.36 on control; difference -2.96 (95% CI -5.07 to -0.85), standardized effect d = -0.34; z-test p = 0.006.
• Interpretation:
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 40 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.
  • The 95% confidence interval excludes no difference, so the mean is statistically lower for Azilsartan Medoxomil 80 mg QD than for the control. This is an unadjusted, secondary comparison, so it is suggestive rather than confirmatory.

The posted secondary outcomes cover clinic sitting blood pressure and ambulatory blood pressure measures over 24-hour, daytime, nighttime, and 12-hour periods. Across the secondary results available in the registry, both azilsartan medoxomil groups generally have more negative mean changes than placebo. The posted sponsor comparisons for the reported secondary outcomes also indicate differences from placebo in the same overall direction.

This broad pattern is related to the primary result because it spans more than one measurement setting and time period. It may help readers understand whether the primary result sits alongside other blood-pressure summaries in the record. It does not turn the secondary outcomes into independent confirmation: the measures are related, and the registry does not report a complete strategy for controlling the interpretation of multiple tests.

The registry lists 15 outcome measures, 14 secondary outcomes posted, and 30 analyses. As a general statistical point, examining many endpoints and comparisons without a stated multiplicity approach can increase the chance that some results appear notable by chance alone. The registry’s testing hierarchy, family of outcomes for adjustment, and any multiplicity correction are not reported in the registry record.

For that reason, the secondary findings carry less weight than the prespecified primary question when interpreting the trial. Their consistency in direction is descriptive context, not proof that every endpoint independently supports the same conclusion. The registry record does not report enough information to determine which secondary comparisons were confirmatory and which were exploratory.

Secondary outcomes registered for this trial, for reference (only those above were recalculated):

• Change From Baseline in Mean Trough Clinic Sitting Systolic Blood Pressure
• Change From Baseline in the 24-hour Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.
• Change From Baseline in Mean Trough Clinic Sitting Diastolic Blood Pressure
• Change From Baseline in Daytime (6am to 10 pm) Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.
• Change From Baseline in Daytime (6am to 10 pm) Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.
• Change From Baseline in the Nighttime (12 am to 6 am) Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.
• Change From Baseline in the Nighttime (12 am to 6 am) Mean Diastolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.
• Change From Baseline in the 12-hr Mean Systolic Blood Pressure Measured by Ambulatory Blood Pressure Monitoring.

9. Statistical Interpretation

10. Statistical Methods Explained

The primary endpoint is continuous: change in 24-hour mean systolic blood pressure, measured in mmHg. The registry reports least-squares means and standard errors for the study groups. A least-squares mean is an adjusted group estimate from a statistical model; it can differ from a simple arithmetic average when the model accounts for other terms. The registry identifies ANCOVA for the sponsor’s reported pairwise analyses, but the full model specification and covariates are not reported in the registry record.

The sponsor’s reported analyses compare each dose group with placebo. For the 40 mg comparison, the reported mean difference is -5.00, with a 95% confidence interval from -7.97 to -2.04 and p = 0.001. For the 80 mg comparison, the reported mean difference is -7.78, with a 95% confidence interval from -10.69 to -4.86 and p < 0.001. The direction of the contrast depends on the registry’s group ordering; here, negative estimates correspond to a more negative change in the active-treatment group than in placebo.

The recalculated comparisons use the posted group summaries and are described as simple, unadjusted recalculations. The recalculation uses an approximate pooled standard deviation inferred from the posted standard errors and analysis counts. This is an approximation: standard errors describe uncertainty in estimated group means, while a standard deviation describes variation among observations. The conversions rely on assumptions about how those quantities relate to the analysis data and do not reproduce the sponsor’s ANCOVA model.

The recalculated estimates are -5.0 for 40 mg versus placebo and -7.78 for 80 mg versus placebo. The posted recalculated confidence intervals are -7.949 to -2.051 and -10.68 to -4.882, respectively. Their unadjusted p-values are both <0.001. Small differences between these intervals and the sponsor’s reported intervals are consistent with using different calculation approaches and rounding. The registry’s reported ANCOVA results remain the trial’s own analysis.

What a confidence interval conveys

As a general statistical explanation, a confidence interval describes the uncertainty around an estimated effect under the method’s assumptions. A narrower interval indicates greater precision for that estimate, while a wider interval indicates more uncertainty. An interval that does not include zero is consistent with a nonzero group difference under the corresponding analysis, but it does not measure the probability that the result is true or important.

What a p-value conveys

As a general explanation, a p-value describes how incompatible the observed data are with a specified null hypothesis, assuming the statistical model and its assumptions. It is not the probability that the null hypothesis is true, and it does not measure the size or practical importance of an effect. The p-values posted for the recalculations are unadjusted; the registry does not report whether the sponsor’s interpretation accounted for multiple testing.

Why multiplicity matters

As a general statistical concept, when many outcomes or comparisons are assessed, the chance of at least one apparently notable result can increase if each is judged separately without adjustment. The registry lists 15 outcome measures and 30 analyses, but a planned testing order, family definition, or multiplicity correction is not reported in the registry record. This leaves uncertainty about how the complete set of tests was intended to support formal conclusions.

Model assumptions and dispersion

As a general explanation, many methods for continuous outcomes rely on assumptions about the distribution of errors, the relationship between observations and model terms, and the adequacy of the chosen model. When data are more variable than a model assumes, standard errors and intervals may be too small unless the analysis accounts for that extra variation; this is commonly described as over-dispersion in settings where it applies. The registry record does not provide enough model diagnostics to assess these assumptions for this trial. The recalculation’s approximate pooled standard deviations should therefore be read as planning and comparison aids, not as a replacement for the sponsor’s adjusted analysis.

11. Confidence Intervals and Precision

The sponsor-reported primary comparisons have 95% confidence intervals from -7.97 to -2.04 for azilsartan medoxomil 40 mg versus placebo, and from -10.69 to -4.86 for 80 mg versus placebo. Both intervals lie below zero. Their widths show that the reported estimates still allow a range of plausible group differences, rather than identifying a single exact effect.

The recalculated intervals are -7.949 to -2.051 for the 40 mg comparison and -10.68 to -4.882 for the 80 mg comparison. They are based on an unadjusted calculation from posted summary statistics, so the sponsor’s ANCOVA intervals are the more direct account of the trial’s reported analysis. The estimates are close, but the methods are not identical.

As a general statistical explanation, a confidence interval reflects both the estimated effect and its uncertainty under the analysis method. It does not mean that a stated percentage of individual outcomes fall inside the interval, nor does it provide a guarantee about the true effect. The standard errors attached to the posted group means also describe uncertainty in those estimates, not the spread of individual blood-pressure measurements.

Precision depends on the amount and variability of information available, as well as the analysis method. The registry record does not report all details needed to evaluate how missing observations, model choices, or the trial’s original planning assumptions affected precision. The intervals should therefore be interpreted alongside the study design and the limitations of the reported information.

12. 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.

The sample-size figures are planning illustrations based on the observed effect, not the trial’s original design justification. For these continuous outcomes, the figures refer to participants per arm. The listed assumptions are a two-sided significance level of 0.05, equal allocation between the two arms, and a normal approximation; each planning scenario considers an effect equal to the stated fraction of the observed effect.

The 80% power column gives the illustrative number of participants per arm for a design with an 80% chance of detecting the assumed effect at the stated significance level, if that effect and the planning assumptions were correct. The 90% column uses a higher target chance of detection. These are prospective planning quantities, not estimates of the chance that this completed trial produced a correct result.

The rows for 100%, 75%, and 50% of the observed effect show how the planning requirements change when the assumed effect is smaller. A smaller effect is harder to distinguish from random variation, so the illustration requires more participants per arm. The values are conditional on the posted effect estimate and the stated simplifying assumptions; they do not establish what the trial’s original sample-size calculation used.

The curve should be read as a visual counterpart to those planning scenarios: it relates the assumed effect size to the illustrative participant requirement under the stated approach. It is not a record of actual enrollment or a measure of the trial’s achieved probability of finding a result. This is not observed power.

The registry record’s own sample-size assumptions and justification are not reported in the registry record. The planning figures therefore help explain how design requirements can vary with the target effect, but do not show that the completed trial was adequately or inadequately sized for its original objectives.

13. 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 z_1−α/2 = 1.960) and the desired power (z_1−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

1. Observed difference Δ = -5.000; pooled standard deviation σ = 10.316.
2. n = 2 × (1.96 + 0.842)² × 10.316² / -5.000² = 66.8, rounded up to 67 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 <- -5                      # observed difference in means
sigma <- 10.315867292671                     # 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(591253)
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 = 67 (80% power), 90 (90% power)
 75% of observed effect: n per arm = 119 (80% power), 160 (90% power)
 50% of observed effect: n per arm = 268 (80% power), 358 (90% power)
power.t.test: 67.8 
Simulated power at n = 67 per arm: 0.794 (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.

14. Analyses Reported by the Sponsor

The registry reports sponsor analyses using ANCOVA for both primary comparisons. For 40 mg versus placebo, the sponsor reports a mean difference of -5.00, a 95% confidence interval from -7.97 to -2.04, and p = 0.001. For 80 mg versus placebo, the sponsor reports -7.78, a 95% confidence interval from -10.69 to -4.86, and p < 0.001.

The posted recalculations use the group summary statistics and are unadjusted. They produce estimates of -5.0 and -7.78 for the respective comparisons, with intervals that are close to the sponsor’s intervals. They provide a transparent comparison based on the posted summaries, but they do not replicate the covariate-adjusted ANCOVA.

The registry record marks no discrepancy between the recalculations and the reported analyses. Even so, the small differences in interval limits reflect the distinct calculation methods and rounding. The sponsor’s own ANCOVA results are the appropriate results to cite as the trial’s reported analyses; the recalculations are supplementary context, not a substitute for them.

The registry record does not provide the full ANCOVA specification or enough detail to reproduce the sponsor’s model independently. It also does not report whether the sponsor adjusted its interpretation for the full set of outcomes and analyses.

15. Multiplicity, Missing Data and Analysis Populations

The registry identifies the primary endpoint and lists numerous additional outcomes and analyses. It does not report a complete statistical analysis plan, a hierarchy for testing endpoints, or a multiplicity adjustment. These details are important because interpreting many tests separately can make nominal p-values harder to interpret as evidence across the full set of questions.

As a general statistical explanation, multiplicity refers to the challenge created when several hypotheses are tested. Adjustments or a prespecified testing sequence can help control the chance of false-positive findings across a defined family of tests. Without a reported plan, it is not possible to determine from the registry record whether or how multiplicity was addressed. The posted p-values should therefore be understood as reported for their individual comparisons, not as evidence that the family of outcomes was controlled at a particular error rate.

The primary analysis population is identified as the Full Analysis Set. The record does not define that population further or describe how participants with missing endpoint measurements were treated. Missing-data assumptions, imputation methods, sensitivity analyses, and participant-level exclusions are not reported in the registry record.

These omissions limit assessment of potential bias if the availability of Week 6 measurements differed between groups or was related to outcome. As a general concept, methods for incomplete data rely on assumptions about why values are missing; different assumptions can lead to different estimates. The record does not provide enough information to evaluate those assumptions or their consequences for the reported estimates.

The registry also does not report the original sample-size justification, any interim analyses, or full model details for the ANCOVA. These gaps do not invalidate the posted results, but they prevent a complete assessment of how the analyses were planned and whether all intended decisions were followed.

16. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: vomiting (0.7%), diabetic ketoacidosis (0.7%), cerebral haemorrhage (0.7%), asthma (0.7%).

The registry reports serious adverse events affecting 3 participants in the 40 mg group, 1 participant in the 80 mg group, and 0 participants in the placebo group. The corresponding groups at risk are 137, 137, and 138. These are event summaries for the groups and should be read as reported counts, not as estimates that establish comparative safety.

The registry lists vomiting, diabetic ketoacidosis, cerebral haemorrhage, and asthma among the serious adverse event terms, each reported as 0.7%. These entries describe terms and percentages in the record; they do not establish that every event was caused by study treatment. The registry record does not report death counts.

Serious adverse event counts are distinct from counts for other adverse events, which are also listed in the record. Small numbers of events provide limited information for comparing groups, and the record does not give enough detail to assess timing, severity beyond the serious classification, or causal attribution for each event. These summaries should be interpreted as a report of observed events during the recorded study, not as a complete measure of safety in other settings or over longer periods.

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

The posted primary results show that the mean change in 24-hour systolic blood pressure was more negative in each azilsartan medoxomil group than in placebo by Week 6. The sponsor-reported ANCOVA estimates and confidence intervals quantify those between-group differences, while also showing uncertainty around their magnitude. The record therefore supports a description of the observed group comparisons in this trial, not a precise prediction for any individual.

The result does not establish what would happen over a longer period, in populations not represented by the trial description, or under different measurement and treatment conditions. The registry’s primary endpoint is a specific ambulatory blood-pressure summary assessed at Week 6. It is not a direct measure of every possible clinical outcome.

A p-value is not the probability that a treatment effect is real, and a confidence interval is not a guarantee that the true effect lies inside it. As general statistical concepts, these quantities describe the data in relation to an analysis and its assumptions. They do not determine whether an estimated difference is important in practical or clinical terms.

The registry reports secondary outcomes and serious adverse events, but the multiplicity approach, missing-data methods, and full statistical analysis plan are not reported. Those gaps constrain how completely the full set of findings can be evaluated. Safety counts are also limited summaries and do not establish causation or characterize longer-term risk.

Accordingly, the most precise reading is that the posted analyses estimate group-average differences in the specified population and timeframe, with confidence intervals indicating statistical uncertainty. Broader claims about durability, generalizability, or overall benefit and risk are not established by these registry results alone.

18. Why This Trial Matters Statistically

This trial offers a useful statistical example of how to read a continuous primary endpoint alongside adjusted sponsor analyses and simple recalculations from posted summaries. The outcome is a change in a measured quantity, so interpretation depends on both the estimated group difference and its uncertainty, not on a binary label alone.

The record also illustrates why the analysis method matters. The sponsor reports ANCOVA comparisons, whereas the supplementary recalculations are unadjusted and rely on approximate variability derived from summary information. Similar estimates can reassure readers that the broad numerical pattern is not sensitive to that simple recalculation, but the two approaches answer the question using different assumptions and should not be treated as interchangeable.

There are multiple related endpoints and analyses. Considering those results together requires attention to multiplicity, analysis populations, and missing-data handling. The absence of a reported testing hierarchy and detailed missing-data methods makes those aspects difficult to assess from the registry record alone.

The planning illustrations further demonstrate, as a general design principle, that the participant requirement depends on the effect a study aims to detect and the desired power. Their role is to aid understanding of design trade-offs, not to describe the original plan or the completed trial’s observed power.

Overall, the record provides estimates, intervals, and trial characteristics that support a careful statistical reading. It also shows why a result should be interpreted in light of the outcome definition, method, uncertainty, and limits of reporting.

19. 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 registry record has important reporting gaps for statistical interpretation. It does not provide the original sample-size justification, the full analysis plan, details of any interim analyses, or the complete ANCOVA specification. The analysis population is named as the Full Analysis Set but is not defined in further detail.

Missing-data methods and sensitivity analyses are not reported in the registry record. The primary outcome counts differ across the three posted analysis groups, while the overall enrollment is 413; the reason for the analysis counts is not reported in the registry record. Without participant flow and missingness details, it is difficult to assess how the analysis population relates to enrollment.

The registry lists many outcomes and analyses but does not report a testing hierarchy or multiplicity strategy. This limits interpretation of secondary findings and of the collection of nominal p-values. The secondary endpoints are related blood-pressure measures, so they should not be treated as wholly independent evidence.

The recalculated comparisons are unadjusted and use approximate pooled standard deviations inferred from posted standard errors and analysis counts. They are useful as supplementary calculations but cannot reproduce the sponsor’s adjusted ANCOVA. The registry record does not include the data or full model details needed for independent reproduction.

Safety reporting is also limited in the available summary: event counts are small, death counts are not reported, and the record does not describe event timing or causal assessment in detail. The Week 6 endpoint provides a short-term assessment as recorded, and longer-term outcomes are not established by these results.

20. Related Tutorials

21. Related Statistical Calculators

22. Sources

• ClinicalTrials.gov: Efficacy and Safety of Azilsartan Medoxomil in African American Participants With Essential Hypertension — NCT00591253.
• Registry record last updated 2011-04-19; status last verified 2011-03.
• Results first posted 2011-04-19.
• 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.

23. Record Summary

The registry record describes a completed, randomized, double-blind, placebo-controlled, parallel-group Phase 3 trial of azilsartan medoxomil in African-American participants with essential hypertension. Overall enrollment was 413, and the study compared once-daily 40 mg and 80 mg groups with once-daily placebo.

The primary endpoint was change from baseline to Week 6 in 24-hour mean systolic blood pressure measured by ambulatory monitoring. The sponsor reported ANCOVA comparisons against placebo, with negative mean differences and 95% confidence intervals that did not include zero. The posted recalculations are close but use a different, unadjusted approach.

The record includes secondary blood-pressure outcomes and serious adverse event counts. It does not report the original sample-size justification, a full statistical analysis plan, multiplicity procedures, or missing-data methods. These reporting limits matter when assessing the breadth and certainty of conclusions from the posted results.