Determination of Agreement Between Laboratory Instruments

Area of Science:

• Clinical Laboratory Science
• Biomedical Engineering
• Statistical Methods in Medicine

Background:

• Evaluating agreement between laboratory instruments is crucial for reliable clinical decision-making.
• Traditional methods like regression analysis may not be optimal for assessing instrument agreement.
• Non-statisticians require accessible methods for data interpretation.

Purpose of the Study:

• To demonstrate the utility of Bland-Altman plots for assessing agreement between two laboratory instruments.
• To provide a practical tool for laboratory staff and non-statisticians.
• To evaluate the agreement between the ABL 500 Radiometer and i-STAT Portable Chemistry Analyzer.

Main Methods:

• Literature review on agreement assessment methods.
• Application of Bland-Altman plots to compare measurements from two instruments.
• Evaluation of pH, partial pressure of carbon dioxide (PCO2), and total carbon dioxide (TCO2) values.
• Comparison with regression analysis limitations.

Main Results:

• Bland-Altman plots are simple to generate and interpret graphically.
• The ABL 500 Radiometer and i-STAT Portable Chemistry Analyzer demonstrated good agreement for the evaluated parameters.
• This agreement suggests acceptable interchangeability of the equipment for clinical use.

Conclusions:

• Bland-Altman plots are a valuable, user-friendly tool for assessing instrument agreement in clinical laboratories.
• The study confirms the interchangeability of the ABL 500 and i-STAT analyzers for pH, PCO2, and TCO2.
• Accessible statistical methods enhance laboratory quality control and clinical decision support.