FRENCH NATIONAL QUALITY-CONTROL SURVEY - BIOLOGICAL DETECTION OF LUPUS ANTICOAGULANTS

In 1994, the French national quality control group in hematology, Etal onorme-Association Claude Bernard, conducted a large scale interlabora tory survey concerning lupus anticoagulants (LA) detection involving a ll the 4800 French laboratories. Each biologist received the same batc h of a lyophilized plasma (94B3) prepared from a patient with a LA con firmed by all the technics used in the intralaboratory study. All the participants were invited to follow the same procedure, to choose test s among a proposed List and to perform them with their own reagents an d their normal plasma. Results were obtained from 4029 labs; mean APTT was prolonged 45.2/31.2 sec (clotting ratio R = 1.44) with high coeff icients of variation (18.8%). Mixing studies were performed by only 26 98 laboratories; no correction of APTT was obtained (R = 1.36, Rosner index = 24) and a wide variation was observed according to the APTT-re agents used (17 < Rosner index < 39). 15% of the participants performe d confirmatory tests, principally TTI, Staclot LA and Staclot PNP (res pectively 509, 116 and 72 laboratories); Staclot LA gave 88% positive results, TTI 75% and Staclot PNP 61%. dRVVT was not performed in Franc e (5 labs). Among the biologists who performed APTT of the mixture 94B 3+ normal plasma, 70% interpreted the non correction of APTT as a LA; 20% found a correction of APTT and answered ''normal APTT or factor de ficiency''; the great majority of these laboratories used a APTT-reage nt containing kaolin. This survey allowed Etalonorme to inform and to make an educational program for the french biologists concerning the b iological detection and the mechanism of action of LA.