Evaluation of automatic and semiautomatic coagulation assay instruments

Area of Science:

• Clinical Chemistry
• Hematology
• Medical Laboratory Science

Background:

• Activated partial thromboplastin time (PTT) and prothrombin time (PT) are crucial diagnostic assays.
• Instrument and reagent variability can impact the accuracy and reliability of coagulation test results.
• Standardization of coagulation testing is essential for consistent patient care.

Purpose of the Study:

• To compare the precision of five different hemostasis instruments in performing PTT assays.
• To evaluate the impact of three distinct coagulation reagent systems on PTT assay performance.
• To assess the correlation and agreement between instruments for both PT and PTT assays.

Main Methods:

• Five instruments (Coag-A-Mate, Auto-Fi, Coagulyzer, Electra 600, Fibrometer) were evaluated.
• Three reagent systems (Ortho, Dade, General Diagnostics) were used with normal and abnormal controls.
• PT and PTT assays were performed on healthy donors and patient samples.

Main Results:

• Significant variations in mean PTT values and coefficients of variation (CV) were observed across instruments and reagents.
• The Coagulyzer (Dade), Coag-A-Mate (Dade, General Diagnostics), and Auto-Fi (General Diagnostics) demonstrated the lowest CVs for PTT.
• Poor correlation was found for PT results, while PTT results between Coag-A-Mate and Auto-Fi showed a correlation of 0.84.
• Coincidence rates for classifying patient samples as normal/abnormal were 91.2% for PTT and 85.1% for PT.

Conclusions:

• Instrument and reagent choice significantly affects PTT assay precision.
• The Coagulyzer, Coag-A-Mate, and Auto-Fi offer superior precision for PTT testing under specific reagent conditions.
• Discrepancies in PT and PTT classifications highlight the need for careful instrument selection and method validation.