Annual Report on External Quality Assessment in Therapeutic Drug Monitoring in Korea (2004)

Two trials of external quality assessment for Therapeutic Drug Monitoring (TDM) Subcommittee of Korean Association of Quality Assurance for Clinical Pathology (KAQACP) were performed in 2004. Number of participating laboratories were increased to 89, by 11.3% increase comparing with the previous year Response rates were 100.0% for both trials just like the previous year. Two kinds of control materials were requested to be tested in each trial so that each institution could know the possible systematic error. In both trials, 20 test Items were responded at least from one laboratory. The average drug item was 6.8 per institution, which was elevated slightly from 65 in recent 5 years. The most common test items were valproic acid, digoxin, phenytoin, carbamazepine, theophylline, and phenobarbital which were peformed in more than 71% of participating laboratories, followed by cyclosporine, Iithium, tacrolimus, vancomycin, methotrexate, amikacin, gentamycln, salicylate, tobramycin, acetaminophen, primidone, free phenytoin, and amitryptyline. The most widely used TDM analyzer was Abbott TDxiTDxFLx (41.6%), followed by Roche Cobas lntegra (21 3%), and Abbott AxSym (20.2%). The inter-laboratory coefficients of variations were not greatly improved comparing with previous years. We also determined cyclosporine and tacrolimus with reference method using liquid chromatography-tandem mass spectrometry. In conclusion, the TDM external quality assessment of 2004 showed grossly similar pattern comparlng with those of previous year, except the 11.3% increase of participating laboratories.ope