title: Lupus anticoagulant: case-based external quality assessment.
abstract: OBJECTIVE
  A model for presenting case histories with quality assessment material is to be developed for the Dutch external quality assessment (EQA) scheme for blood coagulation testing. The purpose of the present study was to assess the performance of clinical laboratories in case-based EQA using the case history of a patient suffering from lupus erythematosus of the skin.
  
  
  METHODS
  Along with the case history, a freeze-dried plasma sample from the patient was distributed to the participants of the Dutch EQA scheme for blood coagulation testing. The participants were requested to report their coagulation test results, interpretation of the test results, and suggestions for further testing.
  
  
  RESULTS
  The response rate was 65%. Tests for lupus anticoagulant were performed by 27% of the respondents and mixing experiments by 32%. The interpretation of the test results was heterogeneous but the presence of lupus anticoagulant was suggested by 54% of the respondents. A substantial number of respondents (23%) did not provide any interpretation. Only few participants followed the sequential steps for lupus anticoagulant identification recommended by the Scientific and Standardization Committee of the International Society on Thrombosis and Haemostasis.
  
  
  CONCLUSIONS
  Case-based EQA is useful as an educational postanalytical tool. Several limitations were noted, and these included the limited volume of the sample, the different matrix of the freeze-dried sample compared with a fresh sample, and the time lag between the case history and the preparation of the freeze-dried sample.
authors.affiliation: Department of Thrombosis and Haemostasis, Leiden University Medical Centre, PO Box 9600, 2300 RC Leiden, The Netherlands. a.m.h.p.van_den_besselaar@lumc.nl
authors.forename: A M H P
authors.initials: AM
authors.lastname: van den Besselaar
authors.forename: K M J
authors.initials: KM
authors.lastname: Devreese
authors.forename: P G
authors.initials: PG
authors.lastname: de Groot
authors.forename: A
authors.initials: A
authors.lastname: Castel
mesh_terms: D000328:Adult; D001778:Blood Coagulation Disorders / Q000175:diagnosis* / Q000209:etiology; D001780:Blood Coagulation Tests / Q000379:methods / Q000592:standards; D005612:Freeze Drying; D019983:Guideline Adherence / Q000706:statistics & numerical data; D006801:Humans; D007753:Laboratories / Q000592:standards; D016682:Lupus Coagulation Inhibitor / Q000097:blood*; D008178:Lupus Erythematosus, Cutaneous / Q000097:blood / Q000150:complications; D008297:Male; D009426:Netherlands; D017410:Practice Guidelines as Topic; D011785:Quality Assurance, Health Care / Q000379:methods*
chemical_list: D016682:Lupus Coagulation Inhibitor