Quality assurance ; Laboratory proficiency testing ; Therapeutic drug monitoring ; Drug of abuse
Abstract
Korean Association of External Quality Assessment Service offered to conduct
a proficiency test program for therapeutic drug monitoring (TDM) and testing
drugs of abuse (DOA), which was named as the TDM and Toxicology program.
This report summarizes the results of the proficiency tests performed
between 2015–2019. In the proficiency test program, low- and high-level
control materials for TDM, and positive and negative control materials for
testing DOA were examined in the participating laboratories. The number
of participating laboratories for TDM increased from 105 in 2015 (1st trial)
to 114 in 2019 (2nd trial). Valproic acid was the most commonly tested
substance. The most widely used TDM analyzer was the Architect i System
(Abbott Laboratories, USA). The TDM proficiency test coefficients of variation
for each test substance exhibit a broad range (0%–300%), which is mainly
attributed to the test substance, concentration, or number of participating
laboratories. The number of participating laboratories for DOA testing
markedly increased from 35 in 2015 (1st trial) to 123 in 2019 (2nd trial). The
proportion of the acceptable results ranged between 84%–100%. In 2019, five
laboratories reported false negative results in the first trial, but later, they
reported correct results in the second trial. In the proficiency test program
for TDM and testing DOA during 2015–2019, the performance of participating
laboratories was generally decent. However, continuous efforts to monitor
and improve the quality of testing are required, which can happen only with
increased participation in the proficiency test program.