Rapid Evaluation of Acute Kidney Injury With NGAL in Acutely Ill Patients in the ICU: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Rapid Evaluation of Acute Kidney Injury With NGAL in Acutely Ill Patients in the ICU (NCT01294228), a registered phase not stated study. The primary outcome is The Efficacy of the Triage Neutraphil-Gelatinase Associated Lipocalin (NGAL) Test as an Aid in the Diagnosis of Acute Kidney Injury (AKI) in an All-comers ICU Setting..

2. Clinical Question

The clinical question is therefore diagnostic, not therapeutic. It concerns the relationship between test results obtained at study enrollment and an adjudicated diagnosis among eligible participants. The registry record does not report whether the test result was interpreted without knowledge of the diagnosis, how the committee adjudicated cases, or what diagnostic threshold or performance criterion was used. Those details would matter when judging how closely the test evaluation reflects a real diagnostic workflow.

3. Trial Design

NCT01294228 is recorded as a completed, multicenter, prospective, observational study of patients admitted to an intensive care unit. The registry lists an enrollment of 1001 and identifies acute kidney injury as the condition. The sponsor is Abbott RDx Cardiometabolic. The record lists a start of 2011-03 and primary completion of 2013-04.

The study summary states that no treatment or intervention was included and characterizes the study as nonsignificant risk. This is consistent with its observational design: the registry describes evaluation of a diagnostic test, not assignment to a treatment. It does not state an allocation procedure, and it should not be read as a randomized treatment comparison. There are no trial arms described as equivalent treatment and control groups.

The primary outcome concerns the efficacy of the Triage NGAL test as an aid in diagnosing acute kidney injury in an all-comers ICU setting. The outcome timeframe is prior to or within 72 hours. The endpoint population is defined by availability of both an adjudicated acute kidney injury diagnosis and an evaluable T=0, or study enrollment, blood collection and associated test results. Thus the enrolled population and the population eligible for the stated primary endpoint are not necessarily identical.

The registry lists one outcome measure but no analyses. The numerical primary outcome result is not reported in the registry record. Further design details, including the method of selecting participants, any diagnostic threshold, and procedures for handling incomplete test or diagnosis information, are also not reported in the registry record. The record does not state a protocol-based sample-size justification. Any hypothetical sample-size planning assumptions should be distinguished from the observational study design itself, particularly because a two-arm planning illustration does not establish that the study had two arms.

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

Analysis population for the primary outcome, as defined in the registry: Study participants who had both an adjudicated AKI diagnosis and an evaluable T=0 (study enrollment) blood collection and associated test results.

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 whom received an adjudicated diagnosis of either AKI or non-AKI.

6. Primary Endpoint

The registry lists the primary outcome as The Efficacy of the Triage Neutraphil-Gelatinase Associated Lipocalin (NGAL) Test as an Aid in the Diagnosis of Acute Kidney Injury (AKI) in an All-comers ICU Setting., measured over Prior to or within 72 hours..

The primary endpoint addresses the Triage NGAL test as an aid in diagnosing acute kidney injury among patients in an all-comers ICU setting. The registry states that final acute kidney injury diagnoses were established by an adjudication committee. It specifies the endpoint timeframe as prior to or within 72 hours and limits the endpoint population to participants with both an adjudicated diagnosis and an evaluable T=0 blood collection with associated test results.

A diagnostic endpoint is useful because it focuses on whether a test result can contribute information relevant to identifying a condition, rather than whether a treatment changes a clinical outcome. For interpretation, the definition of the reference diagnosis and the way test results are compared with that diagnosis are important. The registry identifies adjudication as the source of final diagnoses but does not report the adjudication procedures, a test threshold, or a specific measure such as sensitivity, specificity, or predictive value. Those metric definitions are not reported in the registry record.

The registry describes the outcome unit as probability, identifies the parameter as a number, and gives a 95% confidence interval as the dispersion measure. However, it does not report a numerical estimate or interval. Consequently, the endpoint's stated purpose can be described, but the magnitude and precision of the posted diagnostic result cannot be assessed from the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What does the observational design imply?

The registry describes a prospective, multicenter, observational study. Prospective collection means the study was organized to collect information as participants were followed through the study process, rather than relying solely on a retrospective reconstruction. Observational design means the record describes measurement and evaluation without assigning a treatment or intervention. In this case, the stated objective was to evaluate a diagnostic test in an ICU setting.

General statistical context: observational data can describe how a test result relates to a diagnosis, but the interpretation depends on how participants were selected, how measurements were obtained, and whether important information was missing. Observational design does not make a diagnostic evaluation invalid; it does mean that the study should not be interpreted as a randomized test of treatment effects. The registry does not report participant-selection procedures or whether the test result was assessed independently of adjudication.

How is the diagnosis used?

The primary outcome description says final acute kidney injury diagnoses were established by an adjudication committee. This supplies a reference diagnosis for the stated diagnostic question. The registry does not report the committee's composition, adjudication rules, or whether committee members were blinded to test results. Those details are relevant to assessing the possibility that diagnostic judgments could be influenced by information from the test under evaluation.

General statistical context: a reference diagnosis provides the basis for comparing a diagnostic test with a condition status. Interpretation depends on the quality and independence of that reference. If the reference process differs from the intended clinical setting, or if it incorporates the test being evaluated, estimates of diagnostic performance may be difficult to interpret. No such procedures can be inferred from the registry record.

What does the confidence interval indicate?

The registry specifies a 95% confidence interval as the dispersion measure for the primary outcome. It does not post a numerical interval or point estimate. Accordingly, the confidence interval cannot be used to assess the reported precision of the endpoint because no numerical result is reported.

General statistical context: a confidence interval is a range calculated from data using a stated statistical method. Under the method's assumptions, it represents uncertainty in the estimated quantity. Its width is affected by such factors as the amount of information available and the variability in the observations. A confidence interval is not a guarantee that the true value lies within a particular interval, and it does not replace consideration of the estimate itself. The exact method used to calculate the registry's intended interval is not reported in the registry record.

What can be learned from the outcome description?

The registry lists one outcome measure, but its description does not define a particular diagnostic performance statistic or test threshold. It identifies the purpose of evaluating NGAL as a diagnostic aid, the adjudication committee's role in establishing final diagnoses, the endpoint timeframe, and the eligibility requirements for the endpoint population. These details clarify the intended question but do not supply the numerical result or a complete analysis specification.

General statistical context: diagnostic performance can be represented by different measures, each answering a distinct question. A measure of how often a test identifies people with a condition is not interchangeable with a measure of how often a positive result corresponds to the condition. The test threshold, reference definition, and participant spectrum affect interpretation. Since the registry does not identify the metric or threshold, no particular diagnostic statistic should be assumed.

How should planning illustrations be read?

The registry's planning assumptions describe an illustration based on an observed effect, using a two-sided significance level of 0.05, equal allocation between two hypothetical arms, and a normal approximation. The stated effect to detect is a fraction of the observed effect. For time-to-event planning, the assumptions refer to total events using the Schoenfeld approach; other illustrations refer to participants per arm. These assumptions describe planning calculations, not the actual design of this observational study. The registry does not state that participants were allocated to two arms.

General statistical context: a planning calculation estimates the sample size or event count needed under specified assumptions. Such an illustration depends on the effect size chosen and the statistical model. It is not observed power, does not establish the study's actual sample-size rationale, and cannot substitute for a reported endpoint estimate and uncertainty interval. The registry record does not report a protocol-based sample-size justification, and no particular planning result should be inferred from the assumptions alone.

The registry reports zero analyses. It therefore does not provide an analysis method for a posted primary result, such as adjustment variables, a detailed estimator, or a method for the confidence interval. These analysis details are not reported in the registry record. General statistical context: reproducible interpretation requires a clear definition of the target quantity and a description of how the estimate and its uncertainty were obtained. The outcome description is not a substitute for those analysis specifications.

10. Multiplicity, Missing Data and Analysis Populations

The registry lists one outcome measure and zero analyses. A single listed outcome reduces the immediate concern about choosing among multiple registered outcomes, but it does not establish that the study had no additional analyses or that no multiplicity issue arose. The registry does not report a multiplicity adjustment plan, a hierarchy of outcomes, or a prespecified analysis strategy. These details are not reported in the registry record.

The primary endpoint population is defined as participants with both an adjudicated acute kidney injury diagnosis and an evaluable T=0 blood collection with associated test results. The overall enrollment is 1001, but the number meeting that endpoint definition is not reported in the registry record. The record does not describe how missing blood samples, unevaluable test results, or unavailable adjudicated diagnoses were handled. It also does not report whether any participants were excluded from the endpoint analysis or why.

General statistical context: missingness can affect an estimate when the availability of data is related to participant characteristics, test results, or diagnosis. An analysis restricted to evaluable participants may not represent all enrolled participants if the reasons for missing information are systematic. The registry's endpoint eligibility criteria make the distinction between enrollment and endpoint population important, but there is not enough information to assess the extent or consequences of missing data.

The registry does not define additional analysis populations, such as a broader enrolled population or a restricted per-protocol population. It does not report sensitivity analyses for missing data or alternative endpoint definitions. These analysis populations and procedures are not reported in the registry record. As a result, the robustness of any endpoint estimate cannot be assessed from the posted record.

11. Safety Results

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

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 0% reporting threshold.

The registry lists a clinical study population with 1001 participants at risk for serious adverse events and zero affected by serious adverse events. It also lists 1001 at risk for other adverse events and zero affected. No top serious adverse event terms are listed. The death count is not reported in the registry record.

These entries describe the posted safety counts for the study population. They should not be read as a comparison between a treatment group and a control group: the study summary says there was no treatment or intervention, and the registry does not identify randomized arms. The entries also do not establish that all possible events were captured or that the test was causally responsible for any event.

General statistical context: a count of zero recorded events is a description of the registry's reported observations, not proof that an event is impossible or that risk is absent. Interpreting safety counts depends on how events were defined, collected, reviewed, and followed over time. Those procedures are not reported in the registry record. Because the death value is not reported, it should not be treated as a zero count.

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

The registry record identifies a prospective observational evaluation of the Triage NGAL test as an aid to diagnosing acute kidney injury in an all-comers ICU setting. It specifies that final diagnoses were established by an adjudication committee and that the primary endpoint applied to participants with an evaluable enrollment blood collection and associated test results. These details define the intended diagnostic question and clarify that the study was not a treatment trial.

The record does not report a numerical primary outcome, a confidence interval, or the specific diagnostic performance metric. It therefore does not permit a quantitative judgment about the degree of diagnostic performance or the precision of an estimate. The endpoint is described, but the result itself is not reported in the registry record. Zero analyses are listed; that does not establish what analyses may have been conducted elsewhere.

The study also does not establish whether test-guided care changes patient outcomes. Diagnostic accuracy and clinical impact are different questions. A test may be evaluated against an adjudicated diagnosis without assessing whether decisions based on that test improve outcomes. No such treatment or clinical-impact comparison is described in the registry.

General statistical context: results are most interpretable when the target measure, analysis population, handling of missing information, and uncertainty are reported together. The registry's description supplies some design and endpoint context but not these numerical and methodological details. Conclusions should therefore remain limited to the study's stated aim, population definition, design, and posted safety counts, without extending to claims about benefit, harm, or effectiveness.

13. Why This Trial Matters Statistically

This study is statistically relevant because it illustrates the difference between registering a diagnostic question and reporting an interpretable diagnostic result. The record identifies an ICU population, a prospective observational design, the NGAL test under evaluation, an adjudication committee for final diagnoses, and a defined endpoint population. Those elements help readers understand what the study intended to examine.

At the same time, the primary outcome result and its stated confidence interval are not reported. The metric used to characterize diagnostic performance is not specified in the record. Without a point estimate, uncertainty interval, and metric definition, the central statistical question cannot be evaluated quantitatively. A registry entry can describe an endpoint without furnishing the information needed to judge its magnitude or precision.

The endpoint eligibility definition also highlights a common issue in diagnostic studies: the enrolled population may differ from the population with complete information for the primary analysis. The record reports enrollment of 1001 but does not report how many participants had both an adjudicated diagnosis and evaluable enrollment test results. That distinction matters because conclusions about the endpoint apply most directly to the analyzed population, which is not quantified in the record.

General statistical context: transparent reporting of diagnostic definitions, analysis populations, missing data, and uncertainty allows readers to assess how closely an estimate answers the intended question. This record provides some useful design details but leaves those result and analysis elements unavailable. The statistical lesson is not a conclusion about the test; it is the importance of pairing a clearly stated diagnostic aim with a complete, interpretable report of the corresponding estimate.

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 interpretation is that the registry record does not report a numerical primary outcome or a 95% confidence interval, despite naming that interval as the dispersion measure. It also does not specify the diagnostic performance metric or any threshold used to interpret test results. As a result, the magnitude and precision of the intended endpoint cannot be assessed.

The primary endpoint population requires both an adjudicated diagnosis and an evaluable T=0 blood collection with associated test results, but the number of participants satisfying those requirements is not reported in the registry record. The record does not describe missing-data handling, exclusions from endpoint analysis, or the characteristics of participants without evaluable information. This limits assessment of whether the endpoint population represents the full enrolled population.

The registry does not report the adjudication procedures, the committee's blinding status, or whether test results were available to those establishing diagnoses. It also does not describe test thresholds, the detailed statistical method, or an analysis plan. These details are not reported in the registry record and should not be inferred.

The observational design and absence of a treatment intervention mean the study is not a randomized comparison of clinical strategies. The record does not state allocation and offers no like-for-like control comparison. Although the registry gives a total enrollment, it does not report the analyzed endpoint sample size. The planning assumptions described for hypothetical sample-size illustrations do not establish the study's own design rationale or actual allocation.

Finally, the death count is not reported, and the available adverse-event entries do not describe event ascertainment procedures. These limitations concern what can be concluded from the registry record; they do not establish that additional information or analyses do not exist elsewhere.

15. Related Tutorials

16. Related Statistical Calculators

17. Sources

• ClinicalTrials.gov: Rapid Evaluation of Acute Kidney Injury With NGAL in Acutely Ill Patients in the ICU — NCT01294228.
• Registry record last updated 2017-02-02; status last verified 2016-12.
• Results first posted 2017-02-02.
• 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

NCT01294228 is listed as completed and enrolled 1001 participants. It was a multicenter, prospective, observational study of patients admitted to an ICU, with no treatment or intervention. The listed condition is acute kidney injury, and the sponsor is Abbott RDx Cardiometabolic.

The primary outcome evaluated the Triage NGAL test as an aid in diagnosing acute kidney injury. Final diagnoses were established by an adjudication committee. The outcome timeframe was prior to or within 72 hours, and the specified endpoint population required an adjudicated diagnosis plus an evaluable T=0 blood collection and associated test results.

The registry lists one outcome measure and zero analyses. A numerical endpoint result and its stated 95% confidence interval are not reported in the registry record. The safety entries report zero serious adverse events and zero other adverse events among 1001 participants at risk; the death count is not reported.