Study of Ceftolozane/Tazobactam (MK-7625A) in Combination With Metronidazole in Japanese Participants With Complicated Intra-abdominal Infection (MK-7625A-013): Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Study of Ceftolozane/Tazobactam (MK-7625A) in Combination With Metronidazole in Japanese Participants With Complicated Intra-abdominal Infection (MK-7625A-013) (NCT02739997), a na phase 3 study. The primary outcome is Percentage of Participants With Clinical Response (Clinical Cure, Clinical Failure, or Indeterminate) at Test of Cure (TOC).

2. Clinical Question

The study addresses clinical response after combination treatment for complicated intra-abdominal infection. Cure was defined by complete resolution or significant improvement in signs and symptoms such that additional antibacterial therapy or a surgical or drainage procedure was not required. Failure included specified infection-related outcomes, including death related to intra-abdominal infection, persisting or recurrent infection requiring intervention, and additional treatment for ongoing symptoms. Indeterminate covered cases that could not be classified as cure or failure.

The primary assessment was scheduled at test of cure on Day 28, described as 28 days after initiating study therapy. The endpoint therefore concerns a clinical assessment at a defined follow-up point, not simply whether treatment was administered or whether an infection-related event occurred during treatment.

The registry record does not report the primary endpoint result. It therefore does not establish what percentage had cure, failure or an indeterminate outcome. With no control group, the study also cannot provide a like-for-like comparison with another treatment. Its registry description frames the question as an assessment of clinical response and safety in this study population, rather than a randomized estimate of comparative treatment effect.

3. Trial Design

This was a Phase III, multicenter, open-label, noncomparative study in Japanese participants with complicated intra-abdominal infection. The registry lists a single treatment group receiving MK-7625A, or ceftolozane/tazobactam, together with metronidazole. It lists enrollment of 100. The study is marked completed.

The intervention is described as MK-7625A 1.5 g, consisting of ceftolozane 1 g and tazobactam 0.5 g, plus metronidazole 500 mg. Both were administered by intravenous infusion every 8 hours for 4 to 14 days. For participants with creatinine clearance of 30-50 mL/min, the registry describes a reduced MK-7625A dose of 750 mg, consisting of ceftolozane 500 mg and tazobactam 250 mg. These are the regimen details in the record; they do not establish how often each regimen was used.

The study was open-label, so treatment masking was not used. Allocation is listed as not applicable, consistent with the single-group design. There is no randomized allocation between treatments and no concurrent control arm. Consequently, the posted study design does not support a direct comparison between the combination and another regimen.

The registry lists the study start as 2016-04-08 and primary completion as 2017-07-28. The primary endpoint was the percentage of clinically evaluable participants with a clinical response at test of cure on Day 28. Secondary outcomes included clinical response at end of therapy and late follow-up, and microbiological response at end of therapy and test of cure, including responses by pathogen.

The registry record does not report the rationale for the enrollment target, a detailed statistical analysis plan, or how the study’s noncomparative design informed its target. It also does not report an efficacy result for the primary endpoint. These absences limit what can be concluded about the observed clinical response from this record.

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

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Clinically evaluable participants were defined as those who received study therapy for ≥3 days, had 80-120% study therapy compliance, met criteria for cIAI, adhered to study procedures, and had a clinical response at the TOC visit within the specified visit window are included.

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 Percentage of Participants With Clinical Response (Clinical Cure, Clinical Failure, or Indeterminate) at Test of Cure (TOC), measured over Day 28 (28 days after initiating study therapy).

The primary endpoint is the percentage of clinically evaluable participants with a clinical response at test of cure. Response was classified as clinical cure, clinical failure or indeterminate. The assessment was scheduled for Day 28, described as 28 days after study therapy began.

Cure required complete resolution or significant improvement in the signs and symptoms of the index infection, with no further antibacterial therapy or surgical or drainage procedure required. Failure included specified infection-related outcomes, such as persisting or recurrent infection requiring intervention or additional antibiotics for ongoing symptoms. An outcome was indeterminate when study data were unavailable for evaluation or circumstances prevented classification as cure or failure.

The registry defines the primary analysis population as clinically evaluable participants. Eligibility for that group required receiving study therapy for at least 3 days, 80-120% study therapy compliance, meeting the criteria for complicated intra-abdominal infection, adhering to study procedures, and having a clinical response assessment at the test-of-cure visit within its specified window. The endpoint therefore does not describe every person listed under study enrollment unless they also met these analysis-population criteria.

As general statistical context, a percentage summarizes how often a specified outcome occurs in a defined group. Its interpretation depends on both the outcome classification and the denominator used. Here, the registry record describes the endpoint and population but does not report the observed percentage or the category counts. The endpoint can therefore be explained, but its observed result and precision cannot be assessed from the registry information presented.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

The registry identifies the primary outcome as a percentage of participants with an event classification. In this study, the classification is clinical response at test of cure, with clinical cure, clinical failure and indeterminate as the stated categories. The endpoint is binary in the broad sense that each participant is classified for the assessment, although the registry describes three possible outcome categories. It does not report the counts or percentage for those categories.

What does a percentage describe?

As general statistical context, a percentage is a proportion expressed on a percent scale. It is meaningful only alongside a clear definition of who is included in the denominator and how outcomes are classified. Here, the primary population is clinically evaluable participants, with inclusion criteria based on treatment exposure, compliance, infection criteria, adherence to study procedures and an assessment within the test-of-cure visit window. The registry record does not state how many participants met that definition or report the number in each outcome category.

A percentage from a clinically evaluable population answers a question about that defined group. It is not automatically a percentage of everyone enrolled. Participants who do not meet the analysis-population criteria may not contribute to that endpoint summary, depending on the stated analysis. The record gives the population definition but does not report a full accounting of exclusions, missing assessments or analysis denominators.

Why is precision relevant?

As general statistical context, a confidence interval describes a range of values compatible with the data under a particular statistical method. A narrower interval generally indicates greater precision, while a wider interval indicates more uncertainty about the estimated proportion. An interval does not correct for limitations such as selection into an analysis population or the absence of a comparison group. The registry record does not report a confidence interval for the primary outcome, so the precision of the endpoint estimate cannot be evaluated from this record.

The registry’s endpoint definition also makes the classification rules important. Cure is a clinical judgment based on resolution or significant improvement and the absence of a need for additional treatment or a procedure. Failure includes several defined clinical events. Indeterminate is not the same as cure or failure: it includes cases that cannot be evaluated or classified. Combining or excluding indeterminate outcomes would change the question being answered, so the handling of this category needs to be explicit. The registry record lists the category but does not report the analysis rule for it or the results.

What does the single-group design allow?

As general statistical context, a single-group study can describe outcomes in its treated participants. It does not provide a concurrent estimate of what would have happened to a comparable group under another treatment. Without random allocation and a control group, differences between treatment and outcome cannot be separated from other influences using a direct randomized contrast. This study is described as noncomparative, with allocation listed as not applicable and masking listed as none. Therefore, no between-group treatment effect is reported.

The design does not make the descriptive endpoint meaningless; it defines the type of question the study can address. It can report clinical response within the study population if outcome results are available. But the registry record does not report those primary results, so even that descriptive estimate cannot be.

How should planning illustrations be read?

As general statistical context, sample-size calculations can illustrate how many participants per arm might be needed under specified assumptions to detect a chosen effect with a chosen level of statistical power. The registry-associated assumptions describe a two-sided significance level of 0.05, equal allocation between two arms and a normal approximation, with the effect to detect expressed as a fraction of the observed effect. These are planning assumptions for an illustration, not evidence about the study’s actual design rationale.

The study itself is single-group and noncomparative, whereas the planning assumptions refer to equal allocation between two arms. Such an illustration should not be read as a description of the trial’s allocation, nor as observed power. Sample-size planning values are hypothetical quantities under assumptions; they do not show whether the trial achieved a particular level of power or whether the endpoint result was precise. The registry record does not report the trial’s own sample-size justification. No numerical planning output is stated in the registry entries.

What can the safety counts tell us?

As general statistical context, adverse-event counts describe events or participants meeting specified safety definitions; interpretation depends on whether the count represents participants or events and on the exposure period and coding rules. The registry lists participants affected in serious and other adverse event categories, along with serious-event terms and percentages. It does not report detailed event-level timing, causal attribution, or participant-level overlap between the categories. Those safety figures should not be treated as a comparative estimate of risk, because there is no concurrent control group.

The statistical reading is therefore constrained by what the record reports. The design and endpoint definitions are available, as are selected safety counts. The primary outcome counts, percentage, denominator and precision are not reported in the registry record. General statistical concepts can clarify what those measures would mean, but cannot fill in the missing results.

10. Multiplicity, Missing Data and Analysis Populations

The study lists a primary clinical-response outcome at test of cure and secondary outcomes covering clinical response at end of therapy and late follow-up, as well as microbiological response at end of therapy and test of cure. Some microbiological outcomes are also described by pathogen. Multiple outcomes create a general multiplicity issue: when many hypotheses are tested, the chance of at least one apparently notable result can increase unless the analysis plan accounts for the family of tests. This is general statistical context, not a statement that such adjustment was or was not performed in the trial.

The registry record does not report a multiplicity strategy, a hierarchy for testing secondary outcomes, or an inferential statistical plan. It lists 9 outcome measures and 0 analyses. The primary endpoint is defined, but its result is not reported. The record therefore does not permit evaluation of how multiple outcomes were interpreted or whether any adjustment was planned.

Missing data also matter because the primary analysis population requires a test-of-cure response within the specified visit window. The endpoint definition includes an indeterminate category for data that are unavailable for evaluation or circumstances that prevent classification. However, the registry record does not report how many outcomes were indeterminate, how many assessments were missing, or whether any imputation or sensitivity analysis was used.

The clinically evaluable population has specified entry criteria, including treatment exposure and compliance. The record does not report how many participants failed to meet those criteria or how those participants were handled in other analyses. It also does not report whether the primary outcome was analyzed in an additional population. These omissions limit assessment of how exclusions and missing assessments may affect the endpoint estimate.

As general context, analysis-population definitions and missing-data methods should be considered together: restricting a summary to assessable participants can change which participants contribute to the result, while assumptions about missing outcomes can affect an estimate. No particular missing-data method or analysis population beyond the stated clinically evaluable definition is 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 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: ileus (2.0%), gastrooesophageal reflux disease (1.0%), cholecystitis (1.0%), pneumonia (1.0%), sepsis (1.0%).

The registry lists safety information for the MK-7625A plus metronidazole group. It records 10 participants affected in the serious adverse event category, 32 affected in the other adverse event category, and 1 death. The record lists serious adverse event terms with percentages: ileus, 2.0%; gastrooesophageal reflux disease, 1.0%; cholecystitis, 1.0%; pneumonia, 1.0%; sepsis, 1.0%; and adenocarcinoma of colon, 1.0%.

These figures are descriptive. The serious-event terms identify categories recorded in the registry; they do not establish that the study treatment caused those events. The registry record does not report the causal assessment for each event, the timing of events, or whether participants with one listed term also had another. It also does not state whether the death was related to the infection, treatment or another cause.

The safety counts should not be combined into a total because the record does not clarify whether participants could appear in more than one category. Nor do these single-group figures provide a direct comparison of safety with another treatment. As general statistical context, interpreting event frequency requires attention to event definitions, observation time, participant overlap and comparison groups. The available registry information does not provide all of those details.

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

This study’s registry record describes a Phase III, open-label, noncomparative assessment of ceftolozane/tazobactam plus metronidazole in Japanese participants with complicated intra-abdominal infection. It specifies a clinical-response endpoint at test of cure, defines cure, failure and indeterminate status, and describes the clinically evaluable population. These details clarify the intended clinical question and the rules used to define the primary outcome.

The record does not report the primary endpoint result. It therefore does not show the observed percentage with clinical response, the number classified as cure or failure, or the endpoint’s precision. The endpoint definition alone cannot establish how participants fared. The enrollment field and treatment-group safety counts do not supply the missing efficacy result.

The single-group design also means that the study does not provide a randomized, concurrent comparison with another treatment. Even if a response percentage were reported, a descriptive outcome in one group would not by itself estimate a comparative treatment effect. The registry record does not report a comparator or a treatment-effect estimate.

The safety entries provide descriptive information about serious and other adverse events and a death in the treatment group. They should not be interpreted as proof that treatment caused the events, and they cannot establish comparative safety without a control group. The record does not report enough detail to determine event-level overlap or attribution.

As general statistical context, the strength of a conclusion depends on the study design, endpoint definition, analysis population, result and its precision. Here, the design and definitions are available, but the primary result and its precision are not reported in the registry record. The most defensible reading is therefore limited: the record documents the intended assessment and selected safety figures, but it does not support a conclusion about the observed primary clinical response or a comparative treatment effect.

13. Why This Trial Matters Statistically

The study illustrates why endpoint definitions and analysis populations matter when interpreting a clinical-trial record. The primary endpoint is not simply “improvement”: it distinguishes clinical cure, failure and indeterminate status, and ties that assessment to test of cure on Day 28. The clinically evaluable population also has stated requirements for treatment exposure, compliance, infection criteria, study procedures and assessment timing. Those rules determine what the primary measure is intended to represent.

It also illustrates the limits of a noncomparative design. A single-group study can describe outcomes in its treated population, but it does not include a concurrent randomized comparator. That design feature must shape interpretation independently of the clinical importance of the condition or the detail of the endpoint definition.

The registry record further shows the difference between having an endpoint specification and having an endpoint result. It describes what would count as cure, failure or indeterminate, but does not report the primary percentage or category counts. Without those results, readers cannot judge the observed response or its precision. Detailed definitions cannot substitute for outcome data.

The safety information illustrates a related distinction. The record lists serious and other adverse-event counts, selected serious-event terms and a death, but does not establish causation or provide a comparative safety estimate. Descriptive counts are useful only when read within the limits of the available definitions and design.

Finally, planning calculations should not be confused with evidence about the study’s realized results. The stated planning assumptions concern an illustrative two-arm calculation, while this trial is described as single-group and noncomparative. A planning illustration is not observed power and does not replace the missing outcome estimate. These distinctions help separate the trial’s design, its planned measurements, its reported safety entries and the efficacy conclusions the registry record can support.

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 main limitation for interpreting efficacy is that the registry record does not report the primary endpoint result. It provides no clinical-response percentage, category counts, endpoint denominator or confidence interval. The primary question can be described, but the observed answer and its precision cannot be assessed from the record.

The noncomparative, single-group design is another important limitation. There is no randomized control arm, so the study does not provide a direct estimate comparing the combination with another treatment. Open-label treatment also means masking was not used; the record does not describe additional procedures intended to address potential influences on clinical assessment.

The primary outcome is defined for a clinically evaluable population with several requirements. The registry does not report how many participants met those requirements, how many were excluded from that population, or how missing test-of-cure assessments were handled. It also does not report a missing-data method or sensitivity analysis. This prevents assessment of how population selection or unavailable assessments may affect the endpoint.

The registry does not report the detailed statistical plan, the study’s sample-size justification, an interim-analysis plan, or a multiplicity strategy. The planning assumptions associated with illustrative calculations do not establish the trial’s own design rationale. Secondary outcome results are not reported in the registry record by the registry record.

Safety information is limited to selected counts and serious-event terms. Causal attribution, event timing and participant-level overlap are not reported. The record’s stated information also does not permit a comparative safety assessment. These limitations apply to interpretation of the registry record and should not be filled by assumptions about unreported methods or results.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Study of Ceftolozane/Tazobactam (MK-7625A) in Combination With Metronidazole in Japanese Participants With Complicated Intra-abdominal Infection (MK-7625A-013) — NCT02739997.
• Registry record last updated 2018-08-09; status last verified 2018-07.
• Results first posted 2018-07-12.
• 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

The registry describes NCT02739997 as a completed, multicenter, open-label, noncomparative Phase III study in Japanese participants with complicated intra-abdominal infection. The single treatment group received ceftolozane/tazobactam, listed as MK-7625A, in combination with metronidazole. The enrollment field is 100.

The primary outcome was the percentage of clinically evaluable participants with clinical response at test of cure on Day 28. Response categories were clinical cure, clinical failure and indeterminate. The record defines these categories and the clinically evaluable population, but does not report the primary endpoint result.

The safety record lists 10 participants affected in the serious adverse event category, 32 in the other adverse event category and 1 death. It also lists serious adverse event terms with percentages. These figures are descriptive and do not establish causation or comparative safety. The record does not report a control-group comparison or a detailed statistical analysis plan.