Omadacycline vs Moxifloxacin for the Treatment of CABP (EudraCT #2013-004071-13): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Omadacycline vs Moxifloxacin for the Treatment of CABP (EudraCT #2013-004071-13) (NCT02531438), a randomized phase 3 study. The primary outcome is Number of Participants With Early Clinical Response.

2. Clinical Question

3. Trial Design

NCT02531438 is a phase 3 randomized, double-blind, multicenter study of omadacycline versus moxifloxacin for adults with community-acquired bacterial pneumonia. The registry lists a parallel-group model and triple masking. The intervention descriptions specify intravenous treatment and tablets in both arms. The study status is completed, and the reported enrollment is 774.

The registry gives a study start of 2015-11 and a primary completion date of 2017-02-05. Paratek Pharmaceuticals Inc is listed as the sponsor. These record details describe the study’s organization and conduct; they do not, on their own, establish the size or direction of any treatment effect.

The primary outcome is a count of participants with early clinical response, assessed from screening through 72 to 120 hours after the first dose of test article. The record also lists investigator assessments of clinical response at the Post Therapy Evaluation visit in the ITT Population and in the Clinically Evaluable-Post Therapy Evaluation population. It reports 3 outcome measures and 3 analyses, but the primary outcome has several categories or time points and is not reduced to one comparison.

The posted record does not report the randomization procedure, the identity of the masked parties, details of treatment allocation concealment, or a full statistical analysis plan. Those features should not be inferred from the labels for randomization, masking, or study model.

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 who met inclusion criteria and did not meet exclusion criteria were randomly assigned to a treatment group, and received their first dose of test article within 4 hours after randomization. All participants were expected to present with CABP PORT Risk Class II, III, or IV to require a minimum of at least 3 days of IV treatment.

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Intent-to-Treat (ITT) Population: all randomized participants regardless of whether or not the participant received the test article

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 Participants With Early Clinical Response, measured over Screening; 72 to 120 hours after the first dose of test article.

Early clinical response is the primary endpoint. It is a participant-level classification based on survival and improvement in CABP symptoms. A participant is classified as a clinical success if they survive and improve by at least 1 level from baseline in at least 2 symptoms—cough, sputum production, pleuritic chest pain, and dyspnea—with no worsening in the remaining CABP symptoms. Symptom severity was assessed on a 4-point scale: absent, mild, moderate, or severe. The response was determined programmatically from the investigator’s symptom assessments.

The endpoint also defines clinical failure and indeterminate response. Failure includes no required symptom improvement, worsening of any CABP symptom, alternative antibacterial treatment for CABP, discontinuation due to an adverse event, or death. An indeterminate response is one that could not be adequately inferred because assessment did not occur following withdrawal of consent, loss to follow-up, or another specified reason.

As a general statistical point, a prespecified clinical endpoint makes the outcome being compared explicit. This endpoint combines symptom change with survival and other failure criteria, so its classification depends on all parts of that definition. The registry record does not report the primary response counts or a single comparison of the endpoint between arms.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the endpoint count?

The primary outcome is a count of participants classified as having early clinical response. The classification is based on investigator assessments of four CABP symptoms and on survival. The stated success rule requires survival, improvement by at least 1 level from baseline in at least 2 symptoms, and no worsening in the other symptoms. The severity scale ranges from absent to severe through mild and moderate. Clinical failure and indeterminate response are also defined in the record.

As a general statistical explanation, a binary outcome assigns each assessed participant to a category such as success or not success. A count communicates how many participants fall into a category, while a denominator identifies the population in which that count was observed. A count alone is not an arm-to-arm effect estimate. Interpretation also depends on the endpoint categories, the analysis population, and the method used to handle participants whose outcomes are indeterminate or missing. The registry record does not report primary response counts or a single primary comparison.

What does randomization contribute?

Randomization is recorded as the allocation method, and the study model is parallel. In general, random allocation is intended to make treatment groups comparable with respect to factors that could affect outcomes, on average. It does not guarantee that all observed features will be identical, and it does not replace a clearly reported analysis. The record does not report the randomization procedure or allocation-concealment details, so those should not be inferred.

The study is described as double-blind and as having triple masking. These labels indicate that masking was part of the design, but the record does not identify which groups of people were masked or describe how masking was maintained. The labels therefore cannot establish whether masking was successful throughout the study.

How should uncertainty be understood?

As a general statistical explanation, an estimate describes the observed contrast, while a confidence interval describes the range of values compatible with the data and the chosen method, subject to the method’s assumptions. A narrow interval indicates greater precision than a wide interval, but neither an interval nor a point estimate alone establishes clinical importance. The registry record does not report an estimate or confidence interval for the primary comparison, so its precision cannot be assessed from the record.

For a participant count, uncertainty depends on the number of participants observed in the relevant categories and on the denominator used. Comparisons can also depend on whether results are analyzed according to randomized assignment, receipt of treatment, or a restricted evaluable population. The primary endpoint names the ITT Population, defined as all randomized participants regardless of whether they received the test article. The other listed clinical-response outcome includes a Clinically Evaluable-Post Therapy Evaluation population, but the registry record does not report its detailed eligibility rules.

What do the planning assumptions mean?

The registry’s planning description concerns illustrations computed from an observed effect, not the trial’s own design justification. It specifies a two-sided significance level of 0.05, equal allocation between arms, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. As a general explanation, such a calculation asks what sample size would be needed under the chosen assumptions to detect a specified effect with a chosen power. It is conditional on those assumptions and is not a measure of the power actually achieved in a completed trial.

The description distinguishes participant counts per arm from total event counts for time-to-event outcomes. No time-to-event primary endpoint is identified in the registry record for this study. The registry record does not report the trial’s own sample-size justification, its planned power, or whether the planning assumptions above were used in designing the study. Planning illustrations should therefore not be presented as observed power or as evidence that the study was adequately or inadequately sized.

What remains unspecified?

The record does not report the statistical model, estimation method, covariate adjustment, hypothesis-testing procedure, or missing-data method for the primary outcome. It does not report whether interim analyses were planned or conducted. These omissions limit reconstruction of how the primary comparison would have been calculated. They also make it important to distinguish the endpoint definition, which is reported, from the statistical procedure used to compare treatment groups, which is not reported in the registry record.

As a general principle, methods should be matched to outcome structure. A binary participant classification, a count, and a time-to-event outcome can call for different models and assumptions. Over-dispersion is a general concern when count data vary more than a chosen count model allows; it is not identified as a reported issue for this study. No model-specific conclusion about over-dispersion or other distributional assumptions can be made from the registry record.

10. Multiplicity, Missing Data and Analysis Populations

The record lists a primary outcome with several categories or time points and notes that it was not reduced to one comparison. It also lists secondary investigator assessments at the Post Therapy Evaluation visit in the ITT and Clinically Evaluable-Post Therapy Evaluation populations. The registry reports 3 outcome measures and 3 analyses, but does not report a multiplicity strategy or a hierarchy for interpreting these outcomes. It is therefore not possible to determine from the registry record how the overall chance of false-positive findings across multiple outcomes, categories, time points, or populations was addressed.

The primary outcome definition includes an indeterminate response when assessment could not be adequately inferred because of withdrawal of consent, loss to follow-up, or another specified reason. The record does not report how indeterminate responses were handled in the analysis, or how other missing outcome assessments were handled. It also does not report an imputation method, sensitivity analyses, or the amount of missing primary outcome data.

The ITT population is defined as all randomized participants regardless of whether they received the test article. A separate secondary outcome is listed for a clinically evaluable population at the post-therapy visit, but the registry record does not report its detailed definition. The analysis population can affect interpretation because restricting an analysis to participants meeting evaluability criteria may answer a different question from analyzing all randomized participants.

These are reporting gaps, not evidence that a particular method was or was not used. The multiplicity procedure, missing-data strategy, and full analysis-population rules are not reported in the registry record.

11. Safety Results

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

Deaths

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: pneumonia (1.5%), influenza (0.8%), pleural effusion (0.8%), acute respiratory failure (0.8%), acute myocardial infarction (0.5%).

The registry lists serious adverse events and other adverse events separately. In the omadacycline group, 382 participants were recorded as at risk for each category; 23 were affected by serious adverse events and 63 by other adverse events. In the moxifloxacin group, 388 participants were recorded as at risk; 26 were affected by serious adverse events and 94 by other adverse events. The reported death counts are 8 for omadacycline and 4 for moxifloxacin.

The record’s most frequent listed serious-event terms include Pneumonia at 1.5%, Influenza at 0.8%, Pleural Effusion at 0.8%, Acute Respiratory Failure at 0.8%, Acute Myocardial Infarction at 0.5%, and Cardiogenic Shock at 0.5%. These are listed event terms and percentages; they do not establish that an event was caused by treatment.

As a general statistical point, adverse-event counts are descriptive unless accompanied by a defined comparison and appropriate uncertainty estimates. The registry record does not report a statistical comparison of these safety counts, event timing, exposure-adjusted rates, or attribution of deaths. The counts should not be read as proof of a treatment effect or as evidence about the cause of any individual event.

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

The record establishes that a completed phase 3 randomized study compared intravenous and oral omadacycline with intravenous and oral moxifloxacin in adults with community-acquired bacterial pneumonia. It also defines early clinical response and lists secondary clinical-response assessments and safety counts. These details describe the study question and some reported observations.

The record does not provide the primary response results in a form that supports a single comparison. It explicitly notes that the primary outcome has several categories or time points and was not reduced to one comparison. The primary response counts, treatment-effect estimate, confidence interval, and p-value are not reported in the registry record. Without those results, the direction, magnitude, and precision of the primary treatment contrast cannot be described from this record.

The safety counts are also descriptive. They do not by themselves show whether differences arose by chance, reflect different exposure or observation patterns, or are attributable to treatment. The registry record does not report the statistical analysis or event attribution needed to resolve those questions.

As a general interpretation principle, a trial’s design and outcome definitions are not substitutes for its results. Likewise, a planning calculation is conditional on its assumptions and is not observed power. Any illustration based on a fraction of an observed effect should be understood as a planning exercise, not as an additional finding from the trial.

Accordingly, the record supports an account of the study design, endpoint definitions, and reported safety counts, but not a conclusion that either treatment was superior, equivalent, or different on the primary endpoint. Such conclusions would require results and analyses not reported in the registry record.

13. Why This Trial Matters Statistically

This study illustrates why a clearly named primary endpoint is only part of the evidence needed for statistical interpretation. The registry defines early clinical response in operational terms, including symptom improvement, absence of worsening, survival, and rules for failure and indeterminate response. Those criteria make the intended clinical classification more explicit, but a treatment comparison still requires reported results and an analysis method.

The study also names more than one analysis population: the ITT Population for the primary endpoint and a Clinically Evaluable-Post Therapy Evaluation population for a secondary outcome. As a general statistical matter, results from different populations may address different estimands—the treatment questions defined by the population, outcome, and handling of events. The registry record does not provide enough detail to compare those estimands or explain the clinically evaluable population’s rules.

Safety reporting offers a related lesson. Counts are interpretable only alongside their at-risk populations and event definitions, and even then they remain descriptive without a reported comparison and uncertainty. A count should not be mistaken for a rate or causal effect, and deaths should not be attributed to treatment without supporting information.

Finally, the record’s note that the primary outcome was not reduced to one comparison highlights the importance of transparent reporting when outcomes involve multiple categories or time points. Without a reported multiplicity approach and complete primary results, readers cannot determine how the different pieces of evidence were combined or how uncertainty was controlled. These limitations affect what can be concluded from the registry record, not the underlying quality or value of the trial itself.

14. Limitations

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

The principal limitation for interpreting efficacy is that the registry record does not provide the primary response results as a single treatment comparison. Although the endpoint definition is detailed, response counts, an effect estimate, a confidence interval, and a p-value are not reported in the registry record. The note that the primary outcome has several categories or time points and was not reduced to one comparison further limits a direct arm-to-arm interpretation.

The record does not report the full statistical analysis plan, primary comparison method, multiplicity strategy, missing-data approach, or interim-analysis details. It also does not report the detailed rules for the Clinically Evaluable-Post Therapy Evaluation population. These gaps prevent a complete assessment of how the endpoint was analyzed and how results across populations or assessments should be weighed.

Safety information is presented as affected-participant counts, at-risk counts, selected serious-event terms, and deaths. The record does not report event timing, treatment attribution, exposure-adjusted rates, or a statistical comparison for these data. The counts therefore cannot establish the cause of events or quantify a comparative safety effect.

The record describes the study as randomized, double-blind, multicenter, and triple-masked, but does not report the randomization procedure, which parties were masked, or details of how masking was maintained. It also does not report the trial’s sample-size justification. These details are not reported in the registry record and should not be inferred from the design labels.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Omadacycline vs Moxifloxacin for the Treatment of CABP (EudraCT #2013-004071-13) — NCT02531438.
• Registry record last updated 2019-01-16; status last verified 2019-01.
• Results first posted 2018-11-29.
• 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.

18. Record Summary

NCT02531438 is a completed phase 3 randomized, double-blind, multicenter parallel study of omadacycline versus moxifloxacin in adults with community-acquired bacterial pneumonia. Both treatments are described as intravenous and oral. The registry lists triple masking, enrollment of 774, and Paratek Pharmaceuticals Inc as sponsor.

The primary outcome is the number of participants with early clinical response, assessed from screening through 72 to 120 hours after the first dose. Its definition includes survival and specified symptom improvement, as well as failure and indeterminate categories. Secondary outcomes concern investigator assessments at the Post Therapy Evaluation visit.

The record reports safety counts and selected serious-event terms, but does not report a single primary treatment comparison or its numerical results. The multiplicity plan, missing-data method, and full statistical analysis plan are not reported in the registry record.