False-Positive Rate of AKI Using Consensus Creatinine-Based Criteria

Area of Science:

• Nephrology
• Clinical Chemistry
• Biostatistics

Background:

• Diagnosing acute kidney injury (AKI) using small serum creatinine (SCr) changes enables early detection.
• However, inherent laboratory and biologic variabilities in SCr measurements can increase false-positive rates.

Purpose of the Study:

• To model and quantify the false-positive rates of AKI diagnosis based on SCr variability.
• To assess the impact of baseline SCr levels on AKI diagnostic accuracy.

Main Methods:

• Utilized a prospective observational clinical cohort of 2267 adult patients with AKI.
• Developed a simulation model incorporating laboratory and biologic SCr variability to assess false-positive AKI diagnoses.
• Simulated up to seven successive SCr measurements on hypothetical patients with stable true SCr values.

Main Results:

• An overall AKI false-positive rate of 8.0% was observed after four simulated SCr measurements, accounting for variability.
• Patients with true SCr ≥1.5 mg/dl exhibited a significantly higher false-positive AKI diagnosis rate (30.5%) compared to those with SCr <1.5 mg/dl (2.0%).
• 75% of the clinical cohort had at least four SCr draws within a 48-hour period.

Conclusions:

• The use of small SCr changes for AKI diagnosis is limited by substantial false-positive rates, particularly at higher baseline SCr levels.
• Inherent SCr variability can lead to misclassification of patients, especially those with chronic kidney disease (CKD).
• Clinical interpretation of SCr trends for AKI diagnosis requires careful consideration of measurement variability and baseline values.