Experience with external quality assessment of drugs of abuse testing in the Lombardy Region in Italy.

Following up previous experience with External Quality Assessment (EQA) and Proficiency Testing Programs (PTP) on drugs of abuse (DoA) testing in Italy and in other European countries, the government of the Lombardy Region, first among Italian regions, established in 1995 a compulsory EQA scheme for laboratories authorized to perform these tests. The purpose of the present work is the description of the program and the overall evaluation of the results obtained in the first three annual cycles (1995-1998). During each annual cycle laboratories received 22 urine samples; some samples were collected from patients ("real samples") and some were "spiked" urine samples.