Efficacy and Safety of Olmesartan Medoxomil in Stage 1 and 2 Essential Hypertension: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy and Safety of Olmesartan Medoxomil in Stage 1 and 2 Essential Hypertension (NCT00890591), a na phase 4 study. The primary outcome is Number of Patients That Achieved a Blood Pressure Goal of Less Than 130/85 (Olmesartan 20 mg Monotherapy).

2. Clinical Question

The clinical question is about goal attainment during the initial monotherapy level, rather than a direct comparison between treatment strategies. The registry reports that 144 participants started in this dosage group and 38 met the stated goal. It also reports that 106 started the first titration regimen, with no dropouts. These are counts described in the registry record; they do not establish how the algorithm would compare with another treatment or with no treatment.

The broader study assessed a staged treatment scheme, with medication additions possible when blood pressure remained at or above the stated escalation threshold. The registry description places the primary outcome specifically at the olmesartan 20 mg monotherapy level. Thus, the primary question is narrower than whether the full sequence of monotherapy and possible additions achieved control across the study. Results for that broader question are not reported in the registry record.

3. Trial Design

The registry describes a Phase 4, national, multicenter, open-label, prospective study with a single-group model. Enrollment was 144, and the study status is completed. The recorded study dates are 2006-08 for start and 2007-06 for primary completion. The allocation field is recorded as NA, and masking is recorded as none.

The treatment was an algorithm based on olmesartan medoxomil, with hydrochlorothiazide and amlodipine besylate added if necessary. The brief description states that participants were new to treatment or had an ineffective previous treatment after a 2-week washout. The scheme included monotherapy, two phases involving addition of hydrochlorothiazide, and addition of amlodipine. The primary outcome pertains to olmesartan 20 mg monotherapy over 4 - 9 wks.

The registry describes escalation when blood pressure was at or above 140/90 at 4,8, or 9 wks. It says participants meeting that condition moved to the next medication level for an additional 4-9 weeks. The primary outcome description also states that 144 started the first dosage group, 38 met the blood pressure goal, and 106 started the first titration regimen. It reports no dropouts.

Because this is a single-group, open-label study and no randomized comparison is recorded, the design does not provide a concurrent control for estimating a treatment contrast. The registry record does not report details such as the country, eligibility criteria beyond the brief treatment-history description, visit procedures, or the precise rules used to determine which participants were eligible for each escalation step.

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: A wash out period was needed in case of a previous inefficient antihypertensive medication, so it was interrupted from 2 to 3 wks before the enrollment. The patient could be excluded considering the exclusion criteria.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: In this first dosage group 144 started and 38 patients met their blood pressure goal; therefore, 106 started the first titration regimen. There were no dropouts.

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 Number of Patients That Achieved a Blood Pressure Goal of Less Than 130/85 (Olmesartan 20 mg Monotherapy), measured over 4 - 9 wks of olmesartan monotherapy.

The primary endpoint is the number of participants who achieved a blood pressure goal of less than 130/85 during olmesartan 20 mg monotherapy. The registry gives the timeframe as 4 - 9 wks of monotherapy and identifies the outcome unit as participants. It reports that 38 participants met the goal among the 144 who started in this dosage group.

A count records how many people met the defined outcome. It is not itself a comparison between treatments, and it does not express how much an individual participant’s blood pressure changed. The registry’s wording describes a threshold-based outcome: participants either met the specified goal or did not, according to the assessment used for this endpoint. The record does not report additional details about measurement procedures or how readings across the stated timeframe were combined.

Threshold outcomes can be useful because they express attainment of a prespecified clinical target in an interpretable form. They also simplify a potentially continuous measurement into a count. That simplification loses information about the actual blood pressure values and how close participants were to the threshold. Since the record reports the count but not an uncertainty interval or a comparative estimate, the precision of the count as an estimate for a wider population is not described there.

The registry’s escalation description refers to a separate threshold of 140/90 for moving to the next treatment level at specified assessments. This escalation condition should not be confused with the primary goal of less than 130/85.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does a count outcome say?

The primary outcome is recorded as a number of participants who met a blood pressure threshold. In general, a count answers how many people had the defined event in the group being described. It differs from a continuous outcome, such as a change in a measured blood pressure value, because a threshold count does not show the distance between a participant’s measurement and the target. The registry reports the count of 38 participants meeting the goal and the count of 144 who started the first dosage group.

A count alone is not a full description of uncertainty. Statistical estimates often pair a result with an interval that conveys how imprecisely the underlying quantity may be estimated. The registry record does not report an interval for this endpoint. It also does not report a test of a prespecified hypothesis or a comparison with a control group. General statistical interpretation therefore needs to remain distinct from the recorded descriptive result.

Why does the study design matter?

In a randomized comparison, random allocation is used to create treatment groups intended to be comparable in expectation. This record describes a single group and lists allocation as NA, so it does not provide that kind of concurrent randomized contrast. In general, changes observed within a single group can reflect treatment, but they may also reflect other influences over time, including the natural course of measurements, co-interventions, or differences in who remains at a particular treatment level. The registry does not report analyses that separate such influences.

The study is also open label. In general, lack of masking can matter when treatment knowledge affects decisions or outcome assessment. The direction and extent of any such influence cannot be determined from the registry information alone. No claim that bias occurred follows merely from the open-label designation.

How should a threshold endpoint be read?

The endpoint uses a goal of less than 130/85. A threshold makes the outcome easy to state as attainment or non-attainment, but it discards differences in the underlying measurements. Two participants on opposite sides of a threshold may have quite similar measurements, while two participants on the same side may differ substantially. The registry does not give individual measurements or a continuous summary for this primary outcome.

The escalation description uses a separate criterion: blood pressure at or above 140/90 at 4,8, or 9 wks led to the next medication level. That operational rule describes movement through the treatment algorithm; it is not the primary endpoint’s goal. The record does not give enough detail to determine how readings at different assessments were handled when applying either threshold.

What does over-dispersion mean in general?

For count data, some statistical models assume that variability follows a particular relationship to the average count. Over-dispersion means observed variation is greater than that assumed by the model. When it is present and ignored, standard errors can be too small and intervals or tests can appear more certain than warranted. This is a general consideration for analyses of counts, not a finding about this study. The registry record does not report a count model, a dispersion assessment, or an inferential analysis for the primary outcome.

What do the planning illustrations represent?

The accompanying sample-size calculations are planning illustrations based on an 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 described as a stated fraction of the observed effect. For time-to-event calculations, the stated quantity is a total number of events; for other calculations, it is participants per arm. These are prospective planning quantities, not observed trial results and not observed power.

In general, a planning calculation estimates the size of a future comparison that might be needed under chosen assumptions. It does not establish that the original study was designed around those assumptions. The registry record does not report its own sample-size justification or a two-arm comparison, and the single-group design does not match the equal-allocation comparison assumed by the planning illustration. A planning result should therefore not be read as a feature of the trial’s actual design.

What analysis details are absent?

The registry records 0 analyses. It does not report a model for the primary outcome, an adjustment strategy, a confidence interval, a hypothesis test, or an analysis population definition. It also does not report a statistical plan for handling repeated blood pressure measurements. These omissions limit what can be inferred about statistical precision and analysis choices; they do not change the descriptive details recorded for the outcome.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Olmesartan Monotherapy")
n      <- c(144)
events <- c(38)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Olmesartan Monotherapy  144  38  26.4  19.4  34.4  19.9  34.1  19.9  34.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists four outcome measures, but it does not report a multiplicity strategy. In general, when investigators test multiple outcomes or conduct multiple comparisons, the chance of at least one apparently notable result can increase if no adjustment or other prespecified approach is used. Whether that issue affects a particular conclusion depends on the planned analyses and the claims being made. The registry record reports 0 analyses, so it does not provide inferential results for which an adjustment can be evaluated.

The record reports no dropouts in the first dosage group. It does not describe missing blood pressure readings, the handling of assessments that were unavailable or out of range, or an imputation method. The absence of reported dropouts does not by itself establish that every scheduled measurement was available or that missing-data concerns were assessed.

An analysis population definition is not reported in the registry record. The primary outcome description says that 144 started in the first dosage group, 38 met the goal, and 106 started the first titration regimen. Those reported flow statements do not specify an intention-to-treat, per-protocol, or other analysis population, and no such label should be inferred.

The registry also does not report how participants were included in analyses after escalation or how outcomes across treatment levels were handled. Consequently, the primary count can be interpreted descriptively as recorded, while missing-data procedures, multiplicity control, and population definitions remain unreported.

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

The primary result means that the registry records 38 participants as having achieved a blood pressure goal of less than 130/85 during olmesartan 20 mg monotherapy. The registry also records that 144 participants started in that group and that 106 started the first titration regimen. It reports no dropouts. These statements describe what the record reports for the initial treatment level.

The result does not establish a causal effect relative to an untreated group or another treatment. No randomized comparator is recorded, and the study model is single group. It also does not establish whether the reported count is statistically precise, because the registry record does not provide an interval estimate or other uncertainty measure for the primary endpoint.

The primary result does not describe the outcomes of the complete treatment algorithm. Participants could move to additional medication levels, but the primary endpoint concerns monotherapy. The registry record does not report a summary of goal attainment after the possible additions or a comparative analysis of the stages.

In general, a threshold result gives a compact account of whether a target was met, but it does not describe the distribution of underlying measurements or changes from baseline. The registry does not report those details for the primary outcome. The result should therefore be understood as a descriptive count, not as a complete account of blood pressure response.

Nor does the result establish how the treatment algorithm would perform in populations or settings beyond those described in the record. The registry identifies essential hypertension and stage 1 and 2 disease but gives limited details about participant characteristics and setting. Interpretation should stay within the study description and the outcomes actually recorded.

13. Why This Trial Matters Statistically

This study is statistically instructive because its primary outcome is a readily interpretable count while its design does not support a randomized treatment contrast. The distinction between describing how many participants met a target and estimating a comparative treatment effect is central to reading clinical trial results. A clear outcome count can be useful without answering whether one strategy is better than another.

The study also illustrates why the endpoint and the treatment algorithm should be kept separate. The registry describes a staged regimen with possible additions, but the primary endpoint is tied to olmesartan 20 mg monotherapy. A result at that stage cannot automatically be treated as a summary of the full sequence. The escalation rule and the goal used for the primary endpoint are also different thresholds and serve different purposes in the record.

Finally, the record shows the limits of interpretation when statistical analysis details are absent. It reports the count and participant flow, but not an uncertainty interval, inferential analysis, multiplicity approach, missing-data method, or analysis population. The planning illustrations use stated assumptions for a prospective two-arm comparison; they do not change the single-group design or describe observed power. Keeping descriptive findings, design limitations, and planning calculations distinct helps prevent stronger conclusions than the registry record supports.

14. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The primary limitation is the absence of a randomized control group. With a single-group design, the reported number meeting the goal cannot by itself isolate the contribution of the treatment algorithm from other influences. Open-label conduct may also affect participant behavior, clinical decisions, or assessment in general, although the record does not establish that such effects occurred.

The primary endpoint is limited to goal attainment during olmesartan 20 mg monotherapy. The treatment scheme allowed escalation, but the registry does not report a corresponding primary result across the full sequence. The binary threshold also omits detail about actual blood pressure values, their changes, and proximity to the target.

Statistical precision cannot be assessed from the registry entry because it does not report an interval estimate or inferential analysis for the primary endpoint. The statistical analysis plan, sample-size justification, multiplicity approach, missing-data procedures, and analysis population are not reported in the registry record. Although no dropouts are reported for the first group, the record does not describe completeness of measurements at each assessment.

The registry provides limited information about participant characteristics, measurement procedures, and how readings were combined across the 4 - 9 wks timeframe. It also does not report detailed outcomes for the later medication levels. These omissions constrain assessment of generalizability and of how the algorithm performed beyond the initial monotherapy endpoint.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Efficacy and Safety of Olmesartan Medoxomil in Stage 1 and 2 Essential Hypertension — NCT00890591.
• Registry record last updated 2009-06-03; status last verified 2009-05.
• Results first posted 2009-04-30.
• 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.

18. Record Summary

NCT00890591 is a completed Phase 4, national, multicenter, open-label, prospective, single-group study of an olmesartan medoxomil-based treatment algorithm for stage 1 and 2 essential hypertension. The algorithm could add hydrochlorothiazide and amlodipine besylate if necessary. Enrollment was 144; the recorded start was 2006-08 and primary completion was 2007-06.

The primary outcome was the number of participants reaching a blood pressure goal of less than 130/85 during olmesartan 20 mg monotherapy over 4 - 9 wks. The registry reports 38 participants meeting the goal, 144 starting in the first dosage group, 106 starting the first titration regimen, and no dropouts. No randomized comparator or statistical analysis is reported. The registry record does not report uncertainty estimates, an analysis population, missing-data procedures, or a multiplicity strategy.