An evaluation of four automated coagulation instruments.

Four automated coagulation instruments were evaluated for performance of prothrombin time and activated partial thromboplastin time (APTT): the Dade Auto-Fi, General Diagnostics Dual Channel Coag-a-Mate, MLA Electra 600D, and Sherwood Lancer Coagulyzer. Statistical comparisons showed only minor differences among values determined with these instruments. Reproducibilities of duplicate prothrombin times and APTTs were equivalent on all machines except the Coag-a-Mate; the problem here was in the alignment of the two channels, and should be correctable. Differences exist in the costs, technician acceptance, computer interfacing, and normal values on these instruments. The MLA instrument has the lowest purchase price, followed by the Sherwood and then the General Diagnostics instruments. These three instruments have comparable costs for disposable supplies. The Dade has a substantially higher purchase price and higher costs of disposable supplies. The Sherwood and MLA had the best technician acceptance. All instruments except the Coag-a-Mate can be easily interfaced to a computer. The Dade instrument gave longer coagulation times than the other three instruments when General Diagnostics reagents were used.