External quality assessment for biochemical markers of myocardial damage: an Italian experience

In 1999 the Centre of Biomedical Research (CRB) in co-operation with the Italian interdisciplinary and intersociety Working Group on Markers of Myocardial Damage proposed a national external quality assurance scheme that was granted in accordance with the UK Clinical Pathology Accreditation Standards in 2001. The scheme, which stresses the importance of educational aspects in quality assurance, was scientifically designed to ensure that it would provide an objective assessment of participants' performance and promote quality improvements to meet the needs of participants. The present paper reports on the data collected in EQA cycles conducted to evaluate improvements in the performance of participants and in related methods. The findings obtained demonstrate that during the 4-year experience the scheme provided opportunities to improve the performance of laboratories and promoted an efficient, more satisfactory approach to analytical aspects. The number of unacceptable performances decreased from 11.6% to 5.6% for troponin I, from 19.5% to 9.0% for myoglobin and from 13.2% to 4.3% for creatine kinase myocardial isoenzyme (CK-MB). During cycles in 2001 and 2002, inter-variability (coefficient of variation, CV%) data for all markers appeared satisfactory and showed a significant improvement (lower than 10%), in particular for procedures automated on Dade Behring Dimension and Beckman Access systems. However, reference values/decisional limits declared by laboratories and those suggested by the manufacturers are not comparable, even within the same diagnostic system. The findings demonstrate that participation in EQA schemes provided an opportunity for participating laboratories to continuously improve the quality of their services.