Estimating baseline kidney function in hospitalized patients with impaired kidney function

Area of Science:

• Nephrology
• Clinical Chemistry

Background:

• Accurate baseline kidney function is essential for diagnosing acute kidney injury (AKI) and studying its outcomes.
• Current methods for determining baseline kidney function, especially with multiple preadmission creatinine values, lack consensus.

Purpose of the Study:

• To compare the accuracy of common methods for estimating baseline serum creatinine against a nephrologist-adjudicated reference standard.
• To identify the optimal method for determining baseline kidney function in patients with or at risk for AKI.

Main Methods:

• A study involving 379 patients with AKI or CKD admitted to a tertiary referral center.
• Comparison of commonly used serum creatinine estimation methods against a reference standard determined by a panel of nephrologists.

Main Results:

• The highest agreement between estimating methods and the reference standard was achieved using creatinine values measured 7-365 days before admission.
• The mean outpatient serum creatinine level within this interval showed the highest intraclass correlation coefficient (ICC), indicating superior accuracy.
• Incorporating the final inpatient creatinine value improved the accuracy of the most recent outpatient creatinine method.

Conclusions:

• The mean outpatient serum creatinine measured within one year prior to hospitalization most accurately reflects nephrologist-adjudicated serum creatinine values.
• This finding provides a more reliable method for establishing baseline kidney function in clinical practice and research settings.