183 - Variability of coagulation testing between two separate laboratories: implications for diagnosis and therapeutic monitoring

G. Lippi, D. Giavarina, M.R. Carta, G. Poli, M. Montagnana, G.L. Salvagno, G. Soffiati, G.C. Guidi Despite introduction of some measures to achieve a more effective standardization in routine coagulation testing, there are evidences that harmonization among different clinical laboratories has not been fully achieved as yet. To evaluate whether differences in instruments and reagents between two separate laboratories might influence the clinical management of patients with hemostatic disturbances, we analyzed prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen and d-dimer in 84 consecutive outpatients on oral or heparin anticoagulant therapy. Despite statistically significant differences could be observed for all the parameters tested, Passing & Bablok analysis yielded acceptable results. The extent of measurement deviation always exceeded the current analytical quality specifications for desirable bias, when available. The percentage of patients in the therapeutic range or outside the respective reference range was significantly different between laboratories for APTT and fibrinogen, but not for PT and d-dimer. In conclusion, results of our investigation testify that some further efforts are needed to achieve harmonization of routine coagulation testing among laboratories.