Fast Antibiotic Susceptibility Testing for Gram Negative Bacteremia Trial: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Fast Antibiotic Susceptibility Testing for Gram Negative Bacteremia Trial (NCT06174649), a randomized na study. The primary outcome is Participant Clinical Outcomes, as Measured by Desirability of Outcome Ranking (DOOR).

2. Clinical Question

The question is about a diagnostic testing strategy and its relationship to clinical outcomes, rather than a direct comparison of antibiotic treatments. The record describes random allocation to the testing strategies and defines the primary outcome using survival, clinical response, discharge, and undesirable events. It does not report the comparative DOOR result, so the registry record does not establish which arm had a more favorable outcome or how precisely any difference was estimated.

3. Trial Design

The Fast Antibiotic Susceptibility Testing for Gram Negative Bacteremia Trial is described as a prospective, randomized, controlled, parallel-group study. It is a 2-arm, multicenter, multinational trial sponsored by Duke University. The registry record lists the study as completed, with enrollment of 899. The recorded start date is 2023-12-22 and the primary completion date is 2025-06-18. Phase is listed as NA.

Hospitalized subjects with blood cultures growing Gram-negative bacilli were to be randomized 1:1. In the Reveal arm, positive blood cultures were characterized using Reveal, a rapid antimicrobial susceptibility test, as well as standard-of-care testing. In the Standard of Care arm, positive cultures were characterized using standard testing. The record describes the study as double-masked but does not report who was masked or how masking was implemented.

The primary outcome is participant clinical outcomes measured by DOOR, assessed up to 30 days after the Gram stain result. Secondary outcomes listed include all-cause mortality, hospital stay length, ICU admissions, and new acquisition of multidrug-resistant organisms and/or C. difficile. The record also lists outcomes for new multidrug-resistant organisms, C. difficile, MRSA, and VRE. It records 19 outcome measures and 19 analyses, but does not report enough detail to reconstruct the outcome-by-outcome analysis plan or the populations included in each analysis.

The registry record does not report the rationale for the enrollment target, how allocation was generated or concealed, or the operational details of masking. Those design details should not be inferred from the randomized and double-masked labels alone.

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:

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: Participants who completed the study.

6. Primary Endpoint

The registry lists the primary outcome as Participant Clinical Outcomes, as Measured by Desirability of Outcome Ranking (DOOR), measured over Up to 30 days after Gram stain result.

The primary endpoint is participant clinical outcomes measured using Desirability of Outcome Ranking (DOOR), up to 30 days after the Gram stain result. It is a composite with three ordered levels: alive without deleterious events; alive with at least one deleterious event; and death. The deleterious events named in the record are unsuccessful discharge, lack of clinical response, and undesirable events.

This endpoint combines survival with other aspects of the clinical course. In general, an ordered composite can preserve distinctions between outcome states rather than reducing all events to a simple event-versus-no-event indicator. Its interpretation depends on the ordering chosen: the record defines survival without deleterious events as best, survival with at least one deleterious event next, and death as worst. The outcome therefore represents a ranking across clinically different states, not a count of a single event type.

The record identifies the primary measure as a count of participants, but does not report a primary comparison or a statistical summary of the distribution across DOOR levels. It also does not report how the composite was analyzed or how any missing component information was handled. Without those details and the comparative results, the endpoint definition alone cannot establish whether the testing strategies had different outcome distributions.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

Randomization and comparison. Randomization assigns participants to study groups by chance, which is intended to make the groups comparable on average with respect to measured and unmeasured characteristics. The record says participants were randomized 1:1 to Reveal plus standard testing or standard testing alone. That allocation description does not by itself establish whether allocation was concealed before assignment, and concealment procedures are not reported in the registry record. The study is also described as double-masked, but the masked parties and procedures are not reported.

What an ordered composite represents. DOOR places outcome states in a defined order, from alive without deleterious events to death. In general, an ordered outcome can retain information about whether a participant experienced a less or more favorable state, rather than treating every state as equivalent. But interpretation depends on the definitions and ordering of categories, and the record’s stated ordering should not be mistaken for a numerical effect estimate. The record identifies the measure as a count of participants but does not report the statistical procedure used to compare the ordered outcome.

Effect estimates and uncertainty. A comparative analysis would ordinarily need a clearly defined contrast between the randomized groups and an estimate of that contrast. A confidence interval describes uncertainty around an estimate; it helps readers judge how compatible the data are with different effect sizes, given the model and assumptions used. A p-value, when reported, summarizes how unusual the observed data would be under a specified null model. Neither can replace an effect estimate, and neither is reported for the primary endpoint in the available registry information. The exact analysis method, null hypothesis, and confidence-interval procedure are not reported in the registry record.

Counts, denominators, and outcome meaning. Counts alone can be difficult to interpret if the relevant denominators, eligibility rules, follow-up, or analysis population are unclear. In general, a group count is not a risk or rate unless its denominator and the relevant observation period are defined. For DOOR, category-specific counts and a method for comparing the ordered distribution would be needed to understand the primary result. Those results are not reported in the registry record. The separate death counts in the adverse-event listing cannot fill that gap because the record does not connect them to a primary DOOR analysis or give the associated analyzed denominators.

Over-dispersion and outcome structure. General statistical context: over-dispersion occurs when observed variability is greater than a model assumes. It can make model-based uncertainty too small if the model does not account for the extra variability. Whether over-dispersion is relevant depends on the outcome and analysis model. The primary outcome is described as a participant count across ordered categories, but the analysis model and any assessment of model fit or over-dispersion are not reported in the registry record. It would not be appropriate to assume that a particular model was used or that this issue was tested.

Planning illustrations. The stated sample-size assumptions describe planning illustrations based on the observed effect, using a two-sided significance level of 0.05, equal allocation, and a normal approximation; the effect to detect is described as a stated fraction of the observed effect. For time-to-event tables, the stated quantity is total events; for other outcomes, it is participants per arm. Such illustrations describe what sample sizes would be under those assumptions. They are not observed power and do not establish that the trial had a particular probability of detecting an effect. The record does not report a design justification or enough primary-outcome results to assess the planning illustration against the trial’s observed primary comparison.

Multiplicity and secondary outcomes. When a study evaluates multiple outcomes or analyses, the chance of at least one apparently noteworthy result can increase if no multiplicity strategy is used. General approaches may adjust inference or designate a hierarchy of outcomes, but the appropriate approach depends on the prespecified analysis plan. The record lists 19 outcome measures and 19 analyses, yet the multiplicity strategy, outcome hierarchy, and any adjustment are not reported. No particular method should be attributed to the trial.

Missingness and analysis populations. Missing outcome data can affect interpretation if availability differs between groups or is related to participants’ outcomes. In general, researchers may describe missingness, define analysis populations, and conduct sensitivity analyses to examine assumptions. The registry record does not report missing-data counts or methods, analysis-population definitions, exclusions, or sensitivity analyses. Consequently, the available information is insufficient to determine how incomplete follow-up or unavailable DOOR components were treated.

10. Multiplicity, Missing Data and Analysis Populations

The registry record lists 19 outcome measures and 19 analyses. Evaluating multiple outcomes raises a general multiplicity issue: without an appropriate prespecified strategy, the chance of finding at least one result that appears statistically notable can increase. Studies may address this through a hierarchy of outcomes, adjusted testing, or another planned approach. The multiplicity strategy, any hierarchy beyond identifying the primary outcome, and any adjustment are not reported in the registry record. The reported number of measures and analyses does not reveal whether they were prespecified, independent, or subject to a common adjustment.

The record defines the primary DOOR outcome and lists secondary outcomes, but does not report the analysis populations for these measures. It does not report how many participants had primary outcome information available, whether any participants were excluded from particular analyses, or whether the analyses followed randomized assignment. These details are necessary for understanding how the randomized comparison was carried into the reported results.

Missing-data methods are also not reported in the registry record. For a composite that includes survival, discharge, clinical response, and undesirable events, missing information on a component could affect how an outcome category is assigned. General statistical practice is to describe the amount and pattern of missingness, explain the method used to handle it, and assess whether conclusions depend on assumptions about unavailable data. The record does not report those details or sensitivity analyses. No assumptions about complete follow-up, imputation, or exclusion should therefore be made.

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

The registry record describes a randomized comparison of Reveal plus standard-of-care testing against standard-of-care testing alone in hospitalized subjects with blood cultures growing Gram-negative bacilli. It also defines a primary outcome that ranks participant states using survival and deleterious events up to 30 days after the Gram stain result. These details explain what the trial was designed to compare and what its primary clinical outcome represents.

They do not establish whether either testing strategy produced a more favorable outcome. The comparative primary DOOR result, its effect estimate, and its precision are not reported in the registry record. The study’s completed status and recorded enrollment do not substitute for those results. Likewise, the adverse-event listing’s death counts are not a reported primary comparison, and cannot be interpreted as group-specific rates or as the effect of one strategy relative to the other without relevant denominators and analysis details.

General statistical interpretation also distinguishes absence of reported evidence from evidence of no difference. Without a reported estimate and its uncertainty, the record does not establish that the strategies had the same outcomes, nor does it establish that they differed. It is not possible to judge the size or clinical importance of any difference from the endpoint definition alone.

The trial question concerns a testing method used alongside standard testing. The registry description does not report whether the rapid method changed antibiotic decisions, how quickly results were acted upon, or whether these processes mediated clinical outcomes. Such details should not be inferred from the intervention label. The registry entries support describing the intended comparison, but not claiming that a strategy works, does not work, or should be used in any particular setting.

12. Why This Trial Matters Statistically

This trial addresses a statistical challenge common to diagnostic-strategy studies: the test itself is not the final clinical outcome. The comparison is between strategies for characterizing positive blood cultures, while the primary endpoint combines survival with other aspects of the clinical course. That distinction matters because an improvement in test speed or test information would not, by itself, establish a difference in patient outcomes. The registry’s primary DOOR definition focuses attention on an ordered clinical outcome rather than a laboratory measure alone.

The endpoint also illustrates a tradeoff in composite outcomes. A composite can represent several clinically relevant dimensions in a single framework, but its interpretation depends on the components, their definitions, and their ordering. Here, the record ranks being alive without deleterious events above being alive with at least one deleterious event, and places death as the least favorable state. To understand a comparative result, readers would need the distribution across those states and the analysis used to compare them; these are not reported in the registry record.

The study’s randomized design is relevant because random allocation can support a more credible comparison than an uncontrolled observational contrast, subject to the conduct and analysis of the trial. However, design labels alone do not show how well the comparison was implemented or how missing outcomes and multiple analyses were handled. The record’s listing of 19 outcome measures and 19 analyses makes transparent reporting of the analysis plan and outcome-specific results particularly important.

Finally, the record demonstrates why completion status and enrollment are not enough to interpret efficacy. A clinical question may be clearly framed while the comparative result remains unavailable in the reported information. Without the outcome estimates and their uncertainty, statistical importance and practical meaning cannot be assessed.

13. 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.

A major limitation of the information available for this trial is that it defines the primary DOOR endpoint without reporting the comparative primary result. The registry record does not provide category-specific DOOR counts, an effect estimate, a confidence interval, or a test result. Consequently, neither the direction nor the precision of the primary comparison can be assessed.

The record does not describe the statistical method used for the ordered composite, the prespecified analysis population, or how missing outcome components were handled. It also does not report the multiplicity strategy despite listing 19 outcome measures and 19 analyses. These omissions limit assessment of whether the reported analysis, if available elsewhere in the registry, followed a prespecified plan and how uncertainty should be interpreted.

The adverse-event listing includes death counts for both arms, but the registry entries do not provide corresponding analyzed denominators or connect those entries to the primary DOOR outcome. Those counts cannot be treated as a comparative risk, a primary endpoint result, or a substitute for an all-cause mortality analysis. The record lists all-cause mortality as a secondary outcome but does not report its comparative result in the information.

Other trial-specific details not reported in the registry record include allocation concealment procedures, which parties were masked, the rationale for the enrollment target, and how the testing results affected clinical decisions. The record describes a multicenter, multinational study, but does not provide site-level results or information on variation in setting. These gaps constrain assessment of the trial’s conduct, the precision of its comparisons, and how broadly its findings might apply.

14. Related Tutorials

15. Related Statistical Calculators

16. Sources

• ClinicalTrials.gov: Fast Antibiotic Susceptibility Testing for Gram Negative Bacteremia Trial — NCT06174649.
• Registry record last updated 2026-07-28; status last verified 2026-06.
• Results first posted 2026-07-28.
• 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.

17. Record Summary

The FAST trial is a completed, prospective, randomized, controlled, parallel-group study sponsored by Duke University. It is described as a 2-arm, multicenter, multinational trial with double masking and enrollment of 899. The recorded start date is 2023-12-22 and the primary completion date is 2025-06-18.

Hospitalized subjects with blood cultures growing Gram-negative bacilli were assigned 1:1 to Reveal rapid antimicrobial susceptibility testing plus standard-of-care testing or standard testing alone. The primary endpoint is participant clinical outcomes measured by the ordered DOOR composite up to 30 days after the Gram stain result. Listed secondary outcomes include mortality, hospital stay length, ICU admissions, and several infection-related outcomes.

The available registry information defines the trial question and endpoint but does not report the comparative primary DOOR result, its uncertainty, or key analysis details. It therefore does not support a conclusion about the relative clinical outcomes of the testing strategies.