Crisis in drug testing. Results of CDC blind study

In response to questions about the reliability of the results of screening urine for drugs, we evaluated the performance of 13 laboratories, which serve a total of 262 methadone treatment facilities, by submitting prereferenced samples through the treatment facilities as patient samples (blind testing). Error rates for the 13 laboratories on samples containing barbiturates, amphetamines, methadone, cocaine, codeine, and morphine ranged from 11% to 94%, 19% to 100%, 0% to 33%, 0% to 100%, 0% to 100%, and 5% to 100%, respectively. Similarly, error rates on samples not containing these drugs (false-positives) ranged from 0% to 6%, 0% to 37%, 0% to 66%, 0% to 6%, 0% to 7%, and 0% to 10%, respectively. These blind tests indicate that greater care is taken with known evaluation samples than with routine samples, laboratories are often unable to detect drugs at concentrations called for by their contracts, and the observed underreporting of drugs may threaten the treatment process. Drug treatment facilities should monitor the performance of their contract laboratories with quality-control samples, preferably through blind testing.