This page provides an independent statistical analysis and educational interpretation of publicly reported results. ClinicalTrials.gov provides the official trial registry record. Numerical trial results on this page are restricted to the results posted in the ClinicalTrials.gov record; calculations added by Clinical Biostats are labelled as such.
1. Trial at a Glance
This page covers the registry results for Oral Omadacycline vs. Oral Nitrofurantoin for the Treatment of Cystitis (NCT03425396), a randomized phase 2 study. The primary outcome is Number of Participants With an Investigator Assessment of Clinical Response at the Post Therapy Evaluation (PTE) Visit (ITT Population).
| Feature | Registry value |
|---|---|
| ClinicalTrials.gov identifier | NCT03425396 |
| Phase | Phase 2 |
| Condition | Uncomplicated Urinary Tract Infection, Cystitis |
| Allocation | Randomized |
| Design model | Parallel |
| Masking | Triple |
| Enrollment | 225 |
| Arms in the primary outcome | n/a |
| Lead sponsor | Paratek Pharmaceuticals Inc |
| Results posted | Yes |
2. Clinical Question
Population
Female adults with cystitis were the population of interest. The registry record also lists uncomplicated urinary tract infection as a condition. The primary endpoint used the Intent-to-Treat (ITT) Population, defined as all randomized participants whether or not they received study drug.
Intervention
The study evaluated oral omadacycline in several dose schedules: 300/300 once every 24 hours, 450/300 once every 24 hours, 450/450 once every 24 hours, and 450/450 once every 12 hours. The arm descriptions specify dosing on Day 1 and Days 2 through 7, with food-state instructions; the description of the even-dose timing is incomplete in the registry record.
Comparator
The comparison treatment was oral nitrofurantoin 100/100 once every 12 hours. Its arm description also specifies dosing on Day 1 and Days 2 through 7. The study included multiple omadacycline schedules, so the clinical question is not limited to one omadacycline regimen versus nitrofurantoin.
Primary question
At the Post Therapy Evaluation (PTE) visit, how many participants in the ITT Population had an investigator assessment of clinical response? The registry defines clinical outcome categories, but the primary endpoint has several categories and is not reduced to a single comparison. Outcome values and a treatment-effect estimate are not reported in the registry record.
In statistical terms, this is a randomized, parallel-group treatment comparison with a categorical clinical outcome. Its central question concerns clinical status at the post-treatment assessment, not simply whether a participant completed treatment or had a particular laboratory result. Clinical Success, Clinical Failure, and Indeterminate are distinct outcomes under the registry definitions. The Indeterminate category includes a PTE visit that was not completed.
The registry identifies the study as triple-masked. It does not specify in the information available which particular groups or roles were masked, so the masking label should not be expanded into assumptions about who knew treatment assignment. Likewise, the registry record does not report the primary outcome counts or a statistical comparison. The question can therefore be described from the endpoint definition, but its answer cannot be inferred from the design description alone.
3. Trial Design
The registry identifies NCT03425396 as a randomized, triple-masked, parallel-group phase 2 study. Its official title describes an adaptive study of oral omadacycline and oral nitrofurantoin in female adults with cystitis. The record lists an enrollment of 225 and marks the study as completed. The study start is recorded as 2018-01-04 and primary completion as 2019-05-15.
The treatment groups comprised four omadacycline dose schedules and one nitrofurantoin schedule. The listed omadacycline schedules were 300/300 once every 24 hours, 450/300 once every 24 hours, 450/450 once every 24 hours, and 450/450 once every 12 hours. The comparator was nitrofurantoin 100/100 once every 12 hours. The descriptions state that treatment was given orally on Day 1 and Days 2 through 7, and include food-state instructions. The registry descriptions end before fully specifying the timing of even doses, so further administration details are not established by this record.
Random allocation and parallel groups mean that participants were assigned to a treatment group and the groups were followed as separate arms. These design features support a between-group comparison, but they do not by themselves establish how allocation was generated, concealed, or analyzed. Those details are not reported in the registry record. Although the official title calls the study adaptive, the registry information available does not describe the adaptation rules or how any adaptation affected treatment assignment or analysis.
The primary outcome was investigator-assessed clinical response at the PTE visit, identified as Day 14, with the visit window stated as ± 2 days after the first dose. Other listed outcomes concern investigator-assessed clinical response at the End of Treatment, PTE, and Final Follow-up visits in different analysis populations. The record lists 15 outcome measures and 52 analyses, but their full analysis procedures are not reported in the registry record. In particular, the record does not give a statistical analysis plan or explain how the multiple outcome assessments were prioritized beyond identifying the primary endpoint.
4. Participant Flow and Accounting
The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.
Overall Study
| Stage | Omadacycline 300/300 Once Every 24 Hours | Omadacycline 450/300 Once Every 24 Hours | Omadacycline 450/450 Once Every 24 Hours | Omadacycline 450/450 Once Every 12 Hours | Nitrofurantoin 100/100 Once Every 12 Hours |
|---|---|---|---|---|---|
| STARTED | 55 | 54 | 54 | 8 | 54 |
| Completed End of Treatment Visit | 53 | 52 | 51 | 7 | 53 |
| Completed Post-therapy Evaluation Visit | 53 | 49 | 51 | 7 | 54 |
| Completed Final Follow-up Visit | 53 | 47 | 51 | 7 | 53 |
| COMPLETED | 53 | 47 | 51 | 7 | 53 |
| NOT COMPLETED | 2 | 7 | 3 | 1 | 1 |
Reasons for not completing this period:
| Reason | Omadacycline 300/300 Once Every 24 Hours | Omadacycline 450/300 Once Every 24 Hours | Omadacycline 450/450 Once Every 24 Hours | Omadacycline 450/450 Once Every 12 Hours | Nitrofurantoin 100/100 Once Every 12 Hours |
|---|---|---|---|---|---|
| Lost to Follow-up | 2 | 5 | 2 | 0 | 0 |
| Withdrawal by Subject | 0 | 1 | 0 | 1 | 0 |
| Other | 0 | 1 | 1 | 0 | 1 |
Analysis population for the primary outcome, as defined in the registry: The Intent-to-Treat (ITT) Population consisted of all randomized participants regardless of whether or not the participant received study drug.
5. Baseline Characteristics
The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.
Population: The Intent-to-Treat (ITT) Population consisted of all randomized participants regardless of whether or not the participant received study drug.
| Characteristic | Unit | Omadacycline 300/300 Once Every 24 Hours | Omadacycline 450/300 Once Every 24 Hours | Omadacycline 450/450 Once Every 24 Hours | Omadacycline 450/450 Once Every 12 Hours | Nitrofurantoin 100/100 Once Every 12 Hours | Total |
|---|---|---|---|---|---|---|---|
| Participants analysed | 55 | 54 | 54 | 8 | 54 | 225 | |
| Age, Continuous | years | 45.3 (SD 17.05) | 47.4 (SD 15.70) | 45.0 (SD 15.49) | 37.5 (SD 13.60) | 45.5 (SD 17.82) | 45.5 (SD 16.41) |
| Sex: Female, Male: Female | Participants | 55 | 54 | 54 | 8 | 54 | 225 |
| Sex: Female, Male: Male | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Ethnicity (NIH/OMB): Hispanic or Latino | Participants | 47 | 47 | 43 | 7 | 47 | 191 |
| Ethnicity (NIH/OMB): Not Hispanic or Latino | Participants | 8 | 7 | 11 | 1 | 7 | 34 |
| Ethnicity (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): American Indian or Alaska Native | Participants | 0 | 0 | 0 | 0 | 1 | 1 |
| Race (NIH/OMB): Asian | Participants | 0 | 1 | 1 | 0 | 1 | 3 |
| Race (NIH/OMB): Native Hawaiian or Other Pacific Islander | Participants | 1 | 0 | 0 | 0 | 1 | 2 |
| Race (NIH/OMB): Black or African American | Participants | 2 | 1 | 4 | 2 | 4 | 13 |
| Race (NIH/OMB): White | Participants | 52 | 52 | 48 | 6 | 47 | 205 |
| Race (NIH/OMB): More than one race | Participants | 0 | 0 | 0 | 0 | 0 | 0 |
| Race (NIH/OMB): Unknown or Not Reported | Participants | 0 | 0 | 1 | 0 | 0 | 1 |
6. Primary Endpoint
The registry lists the primary outcome as Number of Participants With an Investigator Assessment of Clinical Response at the Post Therapy Evaluation (PTE) Visit (ITT Population), measured over Day 14 (A PTE occurred on Day 14 ± 2 days after the participant's first dose of study drug).
| Element | Registry entry |
|---|---|
| Result type | Count Of Participants |
| Measure of spread | not applicable |
| Unit | Participants |
| Endpoint classification | Binary Endpoint |
The primary endpoint counts participants in the ITT Population according to the investigator’s clinical-response assessment at the PTE visit. The assessment was scheduled for Day 14, within ± 2 days after the first study-drug dose. The ITT Population includes all randomized participants whether or not they received study drug, as defined in the registry record.
The endpoint distinguishes Clinical Success, Clinical Failure, and Indeterminate. Success means that cystitis signs and symptoms had resolved sufficiently that no additional systemic antimicrobial therapy was required for the current infection. Failure means there was no apparent response, symptoms persisted, or symptoms reappeared by the PTE visit such that additional systemic antimicrobial therapy was required. The outcome is Indeterminate when the PTE visit was not completed.
This kind of clinical endpoint is used to assess a participant’s overall clinical status at a defined follow-up point, rather than relying only on an isolated symptom or laboratory measure. Its interpretation depends on both the category definitions and how missing visits are handled. Here, a missed PTE visit has an explicit endpoint category, but the registry record does not explain the broader missing-data analysis or provide category counts. Because the endpoint has several categories and time points, it is not appropriate to present it as a single binary comparison without further analysis choices. The primary outcome values and their statistical comparison are not reported in the registry record.
7. Why No Re-analysis Is Shown
8. Statistical Interpretation
The record establishes the design and the definition of the primary endpoint, but does not report primary clinical-response counts, group-level response estimates, confidence intervals, or a treatment comparison. The posted information therefore does not quantify how the omadacycline groups compared with the nitrofurantoin group on clinical response. No conclusion about the direction, size, or precision of an efficacy difference can be drawn from the endpoint definition or the study’s completed status.
The primary endpoint is categorical. Clinical Success, Clinical Failure, and Indeterminate represent different clinical states under the registry definitions; a count for one category alone would not describe the full outcome distribution. The Indeterminate category is specifically assigned when the PTE visit was not completed. Without the category counts and the analysis approach, it is not possible to tell how many participants fell into each outcome or how any missing assessments affected the reported result.
There are multiple treatment schedules, with four omadacycline regimens and one nitrofurantoin regimen. A comparison involving one omadacycline schedule may answer a different question from a pooled or overall comparison across the omadacycline schedules. The registry record does not report which treatment contrasts were planned or how those contrasts were handled. It also does not report the analysis population or adjustment method for the primary outcome beyond defining the ITT Population in the endpoint description.
The adverse-event information is separate from the efficacy endpoint. It reports serious adverse events in one omadacycline group and other adverse events in each group, along with deaths. These safety counts describe observed events in the listed groups; they do not provide a substitute for the missing clinical-response results. Group sizes and event counts should be read as reported, without inferring a causal explanation or a treatment effect from the counts alone.
Precision cannot be assessed for the primary endpoint because its estimates and uncertainty measures are not reported in the registry record. A confidence interval, in general, describes the range of effect estimates compatible with the data under the method used; its width reflects statistical uncertainty as well as the analysis and data. No primary-outcome interval is available to interpret. The study’s enrollment figure does not by itself establish the precision of any particular comparison, especially when the outcome counts, group-specific denominators, and analysis details are absent.
The study is marked completed, but completion is a status, not a result. The registry record does not report whether the trial met a predefined efficacy objective, whether any analysis was interim or final, or how the adaptive feature operated. Consequently, interpretation should remain limited to the design, endpoint definitions, and adverse-event counts that are recorded.
9. Statistical Methods Explained
The study is described as randomized and parallel-group. In a randomized trial, assignment is intended to make treatment groups comparable on average with respect to both measured and unmeasured characteristics. This is a general property of random allocation, not proof that any particular comparison was unbiased. The registry record does not report the sequence-generation method, allocation concealment, or the procedures used to maintain masking. The triple-masked label indicates masking was used, but the masked roles are not specified in the record.
What does a categorical endpoint represent?
The primary endpoint is a count of participants classified by investigator-assessed clinical outcome at the PTE visit. The categories are Clinical Success, Clinical Failure, and Indeterminate. For a categorical outcome, analysis may describe the number or proportion in each category, or compare distributions between groups. These approaches answer related but not identical questions. A binary analysis would require a decision about which categories to combine or exclude, and the record does not specify such a reduction. The registry explicitly identifies the primary outcome as having several categories or time points and does not reduce it to one comparison.
In general, a count describes how many observations fall in a category, while a proportion relates that count to a denominator. The denominator and analysis population matter: a proportion among all randomized participants need not equal one calculated only among participants with an observed visit. The endpoint description defines the ITT Population, but outcome-specific denominators and response counts are not reported in the registry record. Thus, no primary-outcome proportion or group contrast should be reconstructed from the information recorded.
Why does the analysis population matter?
The ITT Population includes all randomized participants regardless of whether they received study drug. This preserves the randomized assignment as the basis for analysis and can reflect the consequence of assigning a treatment strategy. Other populations listed for secondary outcomes include Micro-ITT, CE-EOT, CE-PTE, and CE-FFU. The registry record does not provide definitions for all of these population labels in the information available, nor does it explain their inclusion rules. Results from different populations can differ because eligibility and evaluability criteria differ, so they should not be treated as interchangeable.
The record lists investigator assessments at End of Treatment, PTE, and Final Follow-up for multiple populations. Repeated assessments describe outcomes at different times; they do not automatically represent independent evidence. In general, the time point chosen affects the clinical question, and examining multiple outcomes or time points raises questions about which comparisons were prespecified and how multiplicity was handled. Those analysis details are not reported in the registry record.
How should uncertainty be understood?
In general, an effect estimate summarizes the observed difference or relationship, and a confidence interval communicates its statistical uncertainty under the chosen model and assumptions. A narrow interval indicates greater precision than a wide interval, but an interval does not by itself resolve issues such as bias, endpoint definition, missing data, or clinical relevance. The registry record does not report an effect estimate or confidence interval for the primary endpoint. Statistical significance, if reported elsewhere, would also not convey the size or practical importance of an effect on its own.
The record gives no primary outcome analysis model, test, adjustment strategy, or method for constructing uncertainty intervals. It does not report whether the primary comparison was adjusted for baseline characteristics or other factors. Any account of such methods would therefore go beyond the registry record.
What does over-dispersion mean in general?
Over-dispersion occurs when observed variability is greater than a statistical model expects. It matters because a model that assumes too little variability can understate uncertainty and make results appear more precise than they are. The primary endpoint is a categorical count outcome, but the registry record does not report a model or identify over-dispersion as an issue. This general concept should not be interpreted as a claim about this trial’s data.
The registry describes the trial as adaptive, but provides no adaptation rules, decision thresholds, interim analysis procedures, or explanation of any adjustment to statistical inference. Adaptive designs can, in general, allow prespecified changes in response to accumulating data, but valid inference depends on the design and analysis procedures. No such procedures can be inferred from the title alone.
A separate sample-size illustration is based on the observed effect and uses a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation; the effect to detect is a stated fraction of the observed effect. Such calculations are planning illustrations, not observed power and not the trial’s original design justification. The primary outcome values needed to interpret an observed-effect-based illustration are not reported in the registry record. The original sample-size justification is also not reported in the registry record.
10. Multiplicity, Missing Data and Analysis Populations
The registry lists multiple outcomes, assessments, populations, and analyses. In general, testing multiple hypotheses can increase the chance of finding an apparently notable result by chance if no multiplicity strategy is used. A prespecified hierarchy, adjustment, or clearly limited set of primary comparisons can help interpret a family of tests. The registry record does not report a multiplicity plan, the planned primary contrasts, or whether any adjustment was used. The number of analyses listed does not, on its own, reveal how those analyses were selected or interpreted.
Missing data are relevant to the primary endpoint because the registry defines an uncompleted PTE visit as Indeterminate. This makes lack of a visit part of the endpoint classification, but does not explain how the primary analysis treated that category, whether sensitivity analyses were performed, or whether other missing information occurred. The missing-data approach is not reported in the registry record. The potential effect of missing assessments on the outcome comparison therefore cannot be evaluated from the recorded information.
The primary population is the ITT Population, defined as all randomized participants regardless of study-drug receipt. Several secondary outcomes refer to other populations, including Micro-ITT and clinically evaluable populations at different visits. Their full definitions and their role in the statistical analysis are not reported in the registry record. Since population choice can change the denominator and the participants contributing to an estimate, results across populations would require explicit interpretation rather than direct substitution for an ITT analysis.
The record does not report a statistical analysis plan, analysis-set rules beyond the stated ITT definition, or procedures for handling multiplicity and missing outcomes. Those omissions limit the ability to assess whether the reported analyses, if any, followed prespecified methods.
11. Safety Results
The registry reports serious adverse events as affected participants divided by participants at risk.
| Arm | Participants with serious adverse events | Participants at risk | Percentage |
|---|---|---|---|
| Omadacycline 300/300 Once Every 24 Hours | 0 | 55 | 0.0% |
| Omadacycline 450/300 Once Every 24 Hours | 0 | 54 | 0.0% |
| Omadacycline 450/450 Once Every 24 Hours | 1 | 54 | 1.9% |
| Omadacycline 450/450 Once Every 12 Hours | 0 | 8 | 0.0% |
| Nitrofurantoin 100/100 Once Every 12 Hours | 0 | 54 | 0.0% |
Deaths
| Arm | Deaths (participants affected of at risk) |
|---|---|
| Omadacycline 300/300 Once Every 24 Hours | 0 of 55 |
| Omadacycline 450/300 Once Every 24 Hours | 0 of 54 |
| Omadacycline 450/450 Once Every 24 Hours | 0 of 54 |
| Omadacycline 450/450 Once Every 12 Hours | 0 of 8 |
| Nitrofurantoin 100/100 Once Every 12 Hours | 0 of 54 |
Other (non-serious) adverse events
Participants with at least one non-serious event at or above the registry's 2% reporting threshold.
| Arm | Participants affected of at risk |
|---|---|
| Omadacycline 300/300 Once Every 24 Hours | 16 of 55 |
| Omadacycline 450/300 Once Every 24 Hours | 13 of 54 |
| Omadacycline 450/450 Once Every 24 Hours | 15 of 54 |
| Omadacycline 450/450 Once Every 12 Hours | 4 of 8 |
| Nitrofurantoin 100/100 Once Every 12 Hours | 9 of 54 |
Most frequent serious adverse event terms
| Event term | Organ system | Omadacycline 300/300 Once Every 24 Hours | Omadacycline 450/300 Once Every 24 Hours | Omadacycline 450/450 Once Every 24 Hours | Omadacycline 450/450 Once Every 12 Hours | Nitrofurantoin 100/100 Once Every 12 Hours |
|---|---|---|---|---|---|---|
| Pyelonephritis Acute | Infections and infestations | 0 of 55 | 0 of 54 | 1 of 54 | 0 of 8 | 0 of 54 |
Most frequent non-serious adverse event terms
| Event term | Organ system | Omadacycline 300/300 Once Every 24 Hours | Omadacycline 450/300 Once Every 24 Hours | Omadacycline 450/450 Once Every 24 Hours | Omadacycline 450/450 Once Every 12 Hours | Nitrofurantoin 100/100 Once Every 12 Hours |
|---|---|---|---|---|---|---|
| Nausea | Gastrointestinal disorders | 12 of 55 | 8 of 54 | 10 of 54 | 4 of 8 | 5 of 54 |
| Headache | Nervous system disorders | 3 of 55 | 2 of 54 | 4 of 54 | 2 of 8 | 1 of 54 |
| Vomiting | Gastrointestinal disorders | 3 of 55 | 3 of 54 | 3 of 54 | 1 of 8 | 0 of 54 |
| Diarrhoea | Gastrointestinal disorders | 2 of 55 | 1 of 54 | 3 of 54 | 0 of 8 | 2 of 54 |
| Asymptomatic bacteriuria | Infections and infestations | 1 of 55 | 2 of 54 | 1 of 54 | 0 of 8 | 0 of 54 |
| Urinary tract infection | Infections and infestations | 1 of 55 | 1 of 54 | 2 of 54 | 0 of 8 | 0 of 54 |
| Dysuria | Renal and urinary disorders | 2 of 55 | 0 of 54 | 1 of 54 | 0 of 8 | 0 of 54 |
| Bronchitis | Infections and infestations | 0 of 55 | 0 of 54 | 0 of 54 | 0 of 8 | 2 of 54 |
| Abdominal discomfort | Gastrointestinal disorders | 0 of 55 | 0 of 54 | 0 of 54 | 1 of 8 | 0 of 54 |
| Hordeolum | Infections and infestations | 0 of 55 | 0 of 54 | 0 of 54 | 1 of 8 | 0 of 54 |
Serious events with the highest arm-level rate: pyelonephritis acute (1.9%).
The registry reports serious adverse-event counts by treatment group. The listed at-risk group sizes are 55 for omadacycline 300/300 once every 24 hours, 54 for omadacycline 450/300 once every 24 hours, 54 for omadacycline 450/450 once every 24 hours, 8 for omadacycline 450/450 once every 12 hours, and 54 for nitrofurantoin 100/100 once every 12 hours. Serious adverse events affected 0, 0, 1, 0, and 0 participants, respectively. Deaths are recorded as 0 in every group.
The registry identifies Pyelonephritis Acute as a top serious-event term, with 1.9% reported. The record does not provide additional detail connecting that term to a specific clinical course, nor does it establish causation. The term and percentage should therefore be read as a registry safety entry rather than as proof that treatment caused the event.
Other adverse events affected 16, 13, 15, 4, and 9 participants in the respective groups. These are counts of participants affected, not a measure of event severity or a comparison adjusted for group size. The counts alone do not establish whether one regimen is safer than another. They also do not convey event duration, seriousness, or the number of events per affected participant. Safety interpretation is limited to the registry’s reported figures and categories.
12. What the Result Does, and Does Not, Mean
The record describes a randomized, triple-masked, parallel-group phase 2 trial comparing several oral omadacycline schedules with oral nitrofurantoin in female adults with cystitis. It defines an investigator-assessed clinical-response endpoint at the PTE visit and records adverse-event counts. These details establish what the study was designed to examine and how the primary clinical outcome was classified.
The record does not report primary clinical-response counts, group estimates, confidence intervals, or a statistical comparison. It therefore does not show the magnitude or precision of any difference in the primary endpoint. It cannot establish from the recorded efficacy information whether response outcomes differed among treatment groups, and it cannot support a claim that a regimen works or does not work.
The endpoint definition does not replace the missing results. Clinical Success, Clinical Failure, and Indeterminate have distinct meanings, and the PTE visit window is stated as Day 14 ± 2 days after the first dose. The classification of a missed PTE visit as Indeterminate is explicit, but the broader missing-data strategy is not. Without the outcome distribution and analysis method, the clinical meaning of the primary comparison remains unresolved.
The safety entries document the serious and other adverse-event counts recorded for the groups and report no deaths. They do not, by themselves, show that treatment caused an event or permit a definitive safety comparison. Interpretation would require the complete safety context and appropriate comparisons, neither of which is established by event counts alone.
Finally, the study’s completed status and enrollment figure are design and the registry entries, not evidence of an efficacy result. The record does not report the original sample-size justification, adaptive rules, or a complete statistical analysis plan. The appropriate conclusion is consequently descriptive: the study design and endpoints are specified, while the principal efficacy results and several key analysis details are not reported in the registry record.
13. Why This Trial Matters Statistically
This trial raises several statistical questions that matter in clinical research. The primary endpoint is a categorical investigator assessment rather than a single continuous measure, and it includes an Indeterminate category for an uncompleted PTE visit. Category definitions and missing-visit handling are therefore central to understanding any eventual comparison. The record defines the categories but does not report their observed counts or the analysis used to compare them.
The treatment structure also matters. The study lists four omadacycline schedules and one nitrofurantoin schedule. A comparison among individual schedules is not equivalent to an overall comparison that combines omadacycline arms. The registry information does not state which contrasts were planned, so the intended inferential focus cannot be reconstructed from the treatment list alone.
Repeated assessments at End of Treatment, PTE, and Final Follow-up, alongside different analysis populations, create further interpretive choices. In general, examining multiple endpoints and populations can complicate the distinction between primary evidence and exploratory findings. A transparent analysis plan helps readers understand that distinction; the plan and multiplicity approach are not reported in the registry record.
The adaptive designation is another reason that analysis methods matter. An adaptive design can be valid, but interpretation depends on prespecified rules and appropriate methods for the decisions made during the study. Those details are not reported, so the designation cannot be used to infer a particular adaptation or statistical correction.
Finally, statistical precision cannot be judged without endpoint estimates and uncertainty measures. The posted safety counts offer limited descriptive information, while the primary clinical-response results are absent from the registry record. This makes clear why trial design, outcome definitions, analysis transparency, and complete reporting are all needed to move from a study’s stated question to a well-supported interpretation.
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 registry record does not report the primary endpoint’s category counts or a between-group estimate. As a result, the efficacy outcome cannot be quantitatively interpreted from the record. It also does not report confidence intervals or another measure of uncertainty for the primary comparison.
The primary endpoint has multiple categories, and the outcome listing includes several assessment times and populations. The registry does not explain the planned contrasts, any pooling of treatment groups, or how multiple analyses were handled. The adaptation procedures are also not described, despite the adaptive designation in the official title.
The endpoint assigns Indeterminate when the PTE visit was not completed, but the record does not provide a broader missing-data strategy or sensitivity analyses. Definitions for all secondary analysis populations are not available in the registry information described. These gaps make it difficult to assess how population selection and incomplete follow-up may affect interpretation.
The arm descriptions include food-state instructions, but their wording ends before fully specifying the timing of even doses. The registry record also does not provide the full statistical analysis plan, the original sample-size justification, or the roles covered by triple masking. The sample-size illustration is based on the observed effect and should not be mistaken for the trial’s original design rationale.
Safety interpretation is limited to the reported affected-participant counts, at-risk group sizes, the listed serious-event term, and deaths. The record does not provide enough detail to infer causality or make a comprehensive comparative safety assessment.
15. Related Tutorials
16. Related Statistical Calculators
17. Sources
- ClinicalTrials.gov: Oral Omadacycline vs. Oral Nitrofurantoin for the Treatment of Cystitis — NCT03425396.
- Registry record last updated 2020-06-09; status last verified 2020-06.
- Results first posted 2020-06-04.
- 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.
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18. Record Summary
NCT03425396 is a completed, randomized, triple-masked, parallel-group phase 2 study of oral omadacycline and oral nitrofurantoin for female adults with cystitis. The registry records enrollment of 225, a study start of 2018-01-04, and primary completion on 2019-05-15.
Four omadacycline schedules were compared with nitrofurantoin 100/100 once every 12 hours. The primary endpoint was investigator-assessed clinical response at the PTE visit, defined as Day 14 ± 2 days after the first dose, in the ITT Population. Clinical outcomes were Success, Failure, or Indeterminate.
Primary endpoint outcome values and the statistical comparison are not reported in the registry record. The record lists safety counts by group, including no deaths, but these figures do not replace the missing efficacy results. The analysis plan, multiplicity approach, missing-data methods, and adaptive procedures are not reported in the registry record.