Characteristics of the external quality assessment (EQA) scheme for haematology in Spain.

Ensuring reliable results of the tests which are performed in large haematology laboratories is essential because of the problems resulting from the use of complex automated instruments and the ever increasing workload. The Spanish Haematology EQA Scheme started in 1984 with 56 laboratories, a number which rose to 332 in 1989. The general scheme follows the guidelines established by the International Committee for Standardization in Haematology (ICSH) with participants from Public Health (57.9%) and Private (42.1%) laboratories. Surveys are performed monthly and on each occasion the following samples are prepared and sent by the Organizing Center (Haematology Laboratory Department, Hospital Clinic i Provincial of the University of Barcelona): whole blood for full blood counts (FBC), platelet suspensions (or equine total blood) and lyophilized plasma for prothrombin time (PT), partial thromboplastin time (PTT) and fibrinogen (F). After preparation, control materials are sent to participant laboratories where the requested tests are performed and the results reported back to the Organizing Center for statistical analysis. For result evaluation, laboratories are divided into four to eight groups depending on the methodologies used. Individuals results are assessed against a consensus value (mean) deviation index (DI) from the mean, coefficient of variation (CV) and Youden diagram for all results and groups of each parameter. Between 58.3 and 74.5% of laboratories responded. For WBC, the CV improved from 17 to 7%, for platelets from 34.4 to 24.3%. For coagulation tests CV was 18.1% for PT, 16% for PTT, and 26% for fibrinogen.(ABSTRACT TRUNCATED AT 250 WORDS)