Efficacy of Dexlansoprazole MR on Heartburn Control in Participants Previously Receiving Twice Daily Proton Pump Inhibitor Therapy: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Efficacy of Dexlansoprazole MR on Heartburn Control in Participants Previously Receiving Twice Daily Proton Pump Inhibitor Therapy (NCT00847808), a non-randomized phase 3 study. The primary outcome is Proportion of Participants Who Remain Well Controlled After Switching From Their Current Twice-daily Proton Pump Inhibitor Therapy to Dexlansoprazole MR..

2. Clinical Question

The clinical question is about the proportion meeting a prespecified symptom-control definition after a treatment change, rather than a comparative difference between randomized groups. This distinction matters: a single-group proportion can describe the experience of participants in the study, but without a concurrent control it cannot isolate the effect of the switch from other explanations, such as changes over time or participant selection.

The registry's brief summary frames the study around whether participants with well-controlled symptoms on twice-daily therapy remain well controlled after stepping down to once-daily dexlansoprazole MR 30 mg. However, the registry record does not report the primary outcome proportion, its numerator, or an interval estimate. It therefore states the question and how control was classified, but not the numerical answer.

3. Trial Design

This was a Phase 3b multicenter, single-blind trial, with PHASE3 recorded as its phase. Allocation is recorded as non-randomized, and the model is single-group. The listed intervention was dexlansoprazole MR once daily; the official title specifies 30 mg. Enrollment was 178. The registry lists gastroesophageal reflux as the condition under study.

The study addressed participants who had been receiving twice-daily proton pump inhibitor therapy and were described as having well-controlled heartburn symptoms. Its stated aim was to assess control after switching to once-daily dexlansoprazole MR. The registry identifies the primary outcome timeframe as Week 3 through Week 6. It further defines the relevant diary period as Days 15 through 42, inclusive. These are two descriptions of the endpoint's assessment period in the record.

Because the design is single-group and non-randomized, the registry does not describe a randomized treatment allocation or a concurrent control arm. The record therefore supports a descriptive account of the proportion meeting the control definition in the study population, not a randomized comparative estimate. The single-blind designation is recorded, but the identity of the party or parties who were blinded is not reported in the registry record.

The registry lists the study as completed, with a start of 2009-02 and primary completion of 2010-04. It names Takeda as sponsor. The arm description is blank, and details about treatment adherence, visit schedule, procedures beyond the diary-based endpoint, and study conduct are not reported in the registry record. A detailed protocol or statistical analysis plan is also not reported in the registry record, so the trial's additional design decisions should not be inferred from the brief description.

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: Participants with a diagnosis of gastroesophageal reflux disease, whose symptoms were well controlled on twice daily proton pump inhibitors, were enrolled in the study and received a once-daily (QD) dexlansoprazole modified release (MR) capsule in the morning and a matched placebo capsule in the evening.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Values are from the 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 Proportion of Participants Who Remain Well Controlled After Switching From Their Current Twice-daily Proton Pump Inhibitor Therapy to Dexlansoprazole MR., measured over Week 3 through Week 6.

The primary endpoint is the proportion of participants who remain well controlled after switching from their current twice-daily proton pump inhibitor therapy to dexlansoprazole MR. The outcome is expressed as a percentage of participants. The registry defines a participant as well controlled if they completed the study, had at least 23 days of evaluable diary entries between Days 15 and 42, inclusive, and had no more than 4 heartburn occurrences during that interval. The timeframe is Week 3 through Week 6, and the stated analysis population is the Full Analysis Set.

This endpoint translates repeated symptom records into a participant-level classification: each participant either meets the stated criteria or does not. Such a measure can summarize how often a defined level of symptom control was achieved in the study group. The diary requirement also makes the definition dependent on having enough evaluable records, while the completion requirement means that completion is part of the endpoint itself.

The registry record does not report how many participants met the definition, the resulting percentage, or a confidence interval. It also does not report further details about how incomplete diary records were handled beyond the evaluability requirement included in the endpoint definition. The endpoint is therefore defined, but its estimated value and precision are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The primary outcome is a binary participant-level measure summarized as a percentage. Each participant is classified according to whether the study completion and diary-based criteria are met. In general, a percentage for a binary outcome is calculated from the number of participants classified as having the outcome relative to the relevant analysis denominator. The registry identifies the Full Analysis Set as the population for this endpoint, but it does not report the number meeting the definition or the denominator used in the result.

What does a single-group estimate represent?

In a single-group study, an outcome percentage describes the participants observed in that group under the study conditions. It does not automatically estimate what would have happened to those same participants under another treatment. A concurrent comparator can help distinguish treatment-related differences from background changes, differences in participant characteristics, or other influences. No comparator is listed for this study, so the record does not support a between-group treatment-effect estimate.

The outcome definition combines several requirements. The participant must complete the study, contribute at least 23 evaluable diary days within the specified interval, and have no more than 4 heartburn occurrences over that period. This makes the endpoint a measure of meeting the complete operational definition, rather than a direct summary of every diary entry. The evaluability threshold is part of the definition; the registry does not separately explain how diary entries that are missing or otherwise unevaluable were treated.

How should precision be assessed?

For a percentage, precision is commonly conveyed with a confidence interval. In general, the interval reflects sampling uncertainty around the estimated percentage, given the statistical procedure and its assumptions. A narrower interval indicates greater precision, while a wider interval indicates greater uncertainty. The registry record does not report a confidence interval for the primary outcome or the outcome estimate itself, so precision cannot be evaluated from the record.

For binary outcomes, the amount of information depends on how many participants contribute usable outcome data and how the outcome is distributed. The registry reports enrollment of 178, but it does not report the analysis denominator or outcome count. It would therefore be inappropriate to infer the precision of the endpoint from enrollment alone. No interval method or variance estimation procedure for the primary outcome is reported in the registry record.

What do the planning assumptions describe?

The registry includes a planning illustration that uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. It describes the target effect in relation to a stated fraction of the observed effect. The notes distinguish planning counts for time-to-event outcomes from participant counts per arm for other outcomes. These are assumptions for a planning exercise, not evidence that this trial randomized participants or used a two-arm design. The recorded trial design is non-randomized and single-group.

The observed effect and numerical planning results are not reported in the registry record. Thus, the planning description cannot be used to reconstruct the primary estimate or to claim that a particular sample size was achieved for a specified power. Sample-size planning illustrations concern hypothetical study requirements under their stated assumptions; they are not observed power and do not replace an estimate with an uncertainty interval.

Why does over-dispersion matter in general?

Over-dispersion is a general concern when observed variability is greater than a statistical model assumes. If a model underestimates variability, standard errors can be too small and confidence intervals can be too narrow. Its relevance depends on the outcome structure and the model being used. The registry record does not report a model for repeated diary observations, an over-dispersion assessment, or a method for accounting for within-participant correlation. It is therefore not possible to say whether or how these issues were addressed in the analysis.

The registry also lists no analysis results for the primary outcome. The test used, any covariate adjustment, any sensitivity analysis, and the handling of deviations from the endpoint definition are not reported in the registry record. General methods can clarify what information would be useful for interpreting a binary endpoint, but cannot fill in those unreported analysis choices or results.

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("Dexlansoprazole MR QD")
n      <- c(142)
events <- c(125)
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  Dexlansoprazole MR QD  142  125  88.0  81.5  92.9  81.7  92.4  81.6  92.4

11. Multiplicity, Missing Data and Analysis Populations

The registry lists a primary endpoint and multiple secondary outcomes. The secondary measures include changes from baseline in PAGI-QOL subscales covering daily activities, clothing, diet and food habits, relationships, psychological well-being, and the total score. It also lists changes in PAGI-SYM nausea/vomiting and fullness/early satiety subscales, each described for participants who remain well controlled.

When several outcomes are tested, the chance of at least one apparently notable result can increase if each is evaluated separately without an adjustment. In general, a prespecified strategy can identify which outcome is primary, whether secondary analyses are confirmatory or exploratory, and whether statistical tests or confidence intervals are adjusted for multiple comparisons. The multiplicity strategy and any hierarchy among outcomes are not reported in the registry record. The record also does not report outcome-specific estimates or tests that would allow readers to assess how multiplicity was handled in practice.

The primary outcome is defined for the Full Analysis Set, but the membership rules for that set and its size are not reported in the registry record. The registry's endpoint definition requires at least 23 evaluable diary days and study completion; further procedures for incomplete diaries, withdrawal, or other missing data are not reported. Imputation methods, sensitivity analyses for missing outcomes, and the assumptions underlying any such methods are also not reported in the registry record.

These omissions matter because the outcome depends on both symptom entries and availability of evaluable diary data. The recorded endpoint definition indicates a minimum data requirement, but does not establish how participants who failed that requirement were represented in the analysis. Without the analysis population details and missing-data approach, the risk of bias associated with incomplete outcome information cannot be assessed from the registry record.

12. 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 2% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: diverticular perforation (0.6%), cellulitis (0.6%), animal bite (0.6%), intentional overdose (0.6%), breast cancer female (0.6%).

For the dexlansoprazole MR QD group, 178 participants were listed as at risk for serious adverse events, and 6 were listed as affected. For other adverse events, 178 were listed as at risk and 34 as affected. These figures describe participants recorded in the registry's safety summaries; they do not provide a comparison with another group.

The listed serious adverse event terms are diverticular perforation, cellulitis, animal bite, intentional overdose, breast cancer female, and dizziness, each reported as 0.6%. These terms should be read as event listings in the registry, not as evidence that the intervention caused each event. The record does not provide further information about the timing, clinical course, relatedness assessment, or individual participants behind each term. Deaths are not reported in the registry record.

Safety counts and efficacy outcomes answer different questions. The serious adverse event figures do not indicate how many participants met the primary heartburn-control definition, and they do not establish a treatment effect. The record does not describe the method for collecting or adjudicating adverse events, or provide a control group against which to compare these counts.

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

The registry record establishes that the study asked whether participants with controlled heartburn on twice-daily proton pump inhibitor therapy remained controlled after switching to once-daily dexlansoprazole MR 30 mg. It also gives an operational definition based on study completion and diary entries during Week 3 through Week 6. Those details make the intended endpoint understandable.

What the record does not establish is the proportion who met that definition. The primary result, its uncertainty, and any associated analysis are not reported in the registry record. Consequently, it is not possible from this record to describe the observed frequency of continued control, the precision of that frequency, or whether it differed from a particular benchmark.

Even if the primary percentage were available, the single-group, non-randomized design would limit what it could mean. It could describe the outcome among the analyzed participants following the treatment switch, but it would not provide a randomized comparison with continued twice-daily therapy. A before-and-after causal interpretation is not supported by the information in the registry record, which does not report a comparator or a comparative analysis.

The endpoint also represents a specific classification, not every dimension of symptoms or quality of life. The registry lists additional PAGI-QOL and PAGI-SYM outcomes, but does not report their results. The registry record therefore does not establish changes in those measures either.

The safety summaries give counts of participants affected and list serious adverse event terms, but the record does not provide a comparator or enough detail to determine causality. Overall, the record conveys the study question, design, endpoint definition, and selected safety counts. It does not contain the numerical efficacy findings needed to draw conclusions about the frequency of the defined outcome, or comparative evidence about treatment effects.

14. Why This Trial Matters Statistically

This study is statistically informative as an example of the distinction between a clearly defined outcome and a reported result. The registry specifies a participant-level definition of heartburn control that includes both symptom frequency and diary completeness. Such operational rules matter because they determine precisely what the percentage is intended to summarize.

The design also illustrates why an outcome proportion and a comparative treatment effect are not interchangeable. A single-group estimate can describe the frequency of an outcome in the study population. Without a concurrent comparison group, it does not show how that frequency would differ under another treatment or under no treatment change. The non-randomized, single-group structure is therefore central to interpreting the clinical question.

Precision is another essential part of statistical interpretation. A point estimate alone would not show how uncertain the result is, and the registry record does not report either the primary estimate or its confidence interval. The enrollment figure cannot substitute for the analyzed denominator, outcome count, or interval estimate. The registry's planning assumptions also describe a hypothetical two-arm framework, while the listed study design is single-group; the planning illustration should not be mistaken for the trial's design or an observed result.

Finally, the endpoint's reliance on diary completeness makes missing-data procedures important. The registry states a minimum evaluability criterion but does not report further missing-data handling. Together, the design, endpoint definition, absence of reported efficacy estimates, and missing analytic details show why statistical interpretation requires more than a stated study aim: readers need the actual estimate, its precision, and enough methods detail to understand the population and data contributing to it.

15. 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 most consequential limitation of the registry record for interpretation is that it does not report the primary outcome value. There is no reported percentage of participants who remained well controlled, no outcome numerator or analysis denominator, and no confidence interval. The record therefore cannot support a quantitative assessment of the primary endpoint or its precision.

The design is recorded as non-randomized and single-group, with no comparator listed. This means the registry record does not provide a like-for-like control comparison. The outcome, even if reported, would be descriptive of the study group and would not by itself separate the effect of switching treatment from other possible influences.

Several analytic details are not reported in the registry record: the statistical method for the primary endpoint, the membership rules and size of the Full Analysis Set, the approach to missing diary data beyond the endpoint's minimum evaluability requirement, and any sensitivity analyses. The record also does not identify who was blinded under the single-blind design, or describe adherence and treatment implementation. These omissions limit assessment of the analysis and its potential sources of bias.

The registry lists multiple secondary outcomes but does not report their results or a multiplicity strategy. The safety summary includes participant counts and event terms, but does not report event timing, relatedness, or a comparator. These limitations are specific to the information recorded for this study and should be distinguished from the endpoint definition and design features that are explicitly described.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Efficacy of Dexlansoprazole MR on Heartburn Control in Participants Previously Receiving Twice Daily Proton Pump Inhibitor Therapy — NCT00847808.
• Registry record last updated 2012-02-03; status last verified 2012-02.
• Results first posted 2011-04-29.
• 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.

19. Record Summary

The registry describes a completed Phase 3b multicenter, single-blind, non-randomized, single-group study of dexlansoprazole MR once daily in participants previously receiving twice-daily proton pump inhibitor therapy. Enrollment was 178. The primary endpoint was the percentage who remained well controlled during Week 3 through Week 6, using a definition based on study completion, diary evaluability, and heartburn occurrences.

The primary endpoint estimate and its precision are not reported in the registry record. The record lists secondary PAGI-QOL and PAGI-SYM outcomes, but does not report their results or the multiplicity and missing-data procedures. It also lists serious and other adverse event counts for the study group, without a comparative safety group. The design supports descriptive interpretation of the study population, not a randomized treatment comparison.