Table. 3.

Proficiency test CV% for therapeutic drug monitoring based on the level of control materials during 2015–2019

Test substances No. of labs at 2019 (2nd) Proficiency test CV for low-level control materials Proficiency test CV for high-level control materials


2015 (1st) 2015 (2nd) 2016 (1st) 2016 (2nd) 2017 (1st) 2017 (2nd) 2018 (1st) 2018 (2nd) 2019 (1st) 2019 (2nd) 2015 (1st) 2015 (2nd) 2016 (1st) 2016 (2nd) 2017 (1st) 2017 (2nd) 2018 (1st) 2018 (2nd) 2019 (1st) 2019 (2nd)
Acetaminophen 6 5.0 0.0 5.5 0.0 3.4 0.9 3.5 6.0 7.6 5.2 1.5 3.8 3.7 3.1 2.7 2.2 2.7 4.9 1.7 2.2
Amikacin 6 3.9 1.8 3.0 6.1 4.2 1.5 8.1 9.2 5.8 7.8 5.6 4.3 3.3 0.8 3.2 3.6 3.5 3.3 5.8 2.8
Carbamazepine 38 8.2 7.6 7.8 2.3 5.2 3.6 7.5 5.5 8.7 6.4 6.0 4.6 4.1 3.5 4.2 7.0 4.3 4.9 4.9 3.1
Digoxin 59 17.9 19.9 15.9 17.3 11.5 14.1 15.2 20.0 17.8 21.7 6.7 7.0 4.8 9.5 8.3 6.9 5.1 9.2 9.1 11.9
Gentamicin 5 4.4 5.5 4.0 0.0 0.0 0.0 4.1 3.8 10.9 3.8 8.8 9.5 10.3 4.4 4.1 11.9 10.4 8.4 2.2 3.0
Lithium 33 7.7 7.5 5.9 6.7 7.3 7.4 6.7 7.8 4.8 9.4 12.2 11.5 11.8 10.8 8.1 15.4 9.8 8.0 9.3 11.8
Methotrexate 18 7.9 1.5 4.8 3.7 3.0 4.6 3.7 3.3 1.8 3.9 6.6 4.2 4.2 7.8 2.9 9.5 3.8 5.1 4.2 5.0
Phenobarbital 22 5.7 4.8 3.3 6.8 5.4 7.0 3.8 4.6 4.6 3.6 5.8 4.0 4.3 8.8 7.4 7.6 3.5 4.0 4.0 2.6
Phenytoin 37 4.8 4.5 4.6 4.9 4.4 5.3 4.6 3.1 4.8 2.6 4.2 3.6 4.7 4.8 5.4 4.7 4.1 3.9 3.5 2.3
Phenytoin, free 1 - - - - - - - - - - - - - - - - - - - -
Salicylate 3 2.9 7.9 2.9 131.5 4.1 0.5 2.4 6.0 75.6 74.6 0.8 3.6 0.3 131.2 2.3 0.9 1.1 4.5 75.0 74.2
Theophylline 24 4.3 4.1 5.0 4.2 4.5 2.9 3.4 5.2 2.8 3.9 5.9 5.6 4.9 5.0 2.9 4.4 4.2 4.2 2.1 3.8
Tobramycin 3 16.7 8.7 7.9 6.9 17.8 27.0 27.7 23.9 23.6 24.4 10.0 5.3 8.6 9.4 7.5 12.0 11.6 12.1 9.2 10.4
Valproic acid 84 5.3 4.9 9.7 6.0 4.1 6.3 7.6 4.3 4.8 6.1 4.5 3.6 6.7 3.3 5.8 4.7 4.7 3.9 3.8 4.7
Valproic acid, free 2 - - 95.2 56.6 68.3 58.2 71.0 75.2 109.5 112.2 - - 36.7 38.7 42.3 14.7 51.5 55.0 69.8 75.8
Vancomycin 74 6.0 5.3 7.3 8.8 5.1 4.9 7.4 5.6 6.6 3.9 5.9 5.8 7.4 8.6 6.7 2.8 8.4 8.9 7.1 7.2
Cyclosporine 52 11.5 13.6 9.4 11.5 13.0 11.9 13.1 10.9 13.1 15.3 8.7 8.5 6.9 7.8 9.7 5.7 8.5 6.8 8.5 11.3
Everolimus 12 - - 138.4 105.5 114.1 144.2 - - 300.0 184.8 - - 1.9 9.4 15.8 6.4 13.7 10.2 9.7 6.0
Sirolimus 15 9.3 14.1 10.2 7.1 7.0 11.4 10.1 5.3 10.4 10.4 8.2 15.4 18.7 25.9 17.9 23.4 11.9 24.4 21.8 17.6
Tacrolimus (FK506) 73 6.4 6.6 5.0 4.8 5.6 5.8 5.8 3.8 8.7 9.5 5.0 4.3 4.3 3.4 3.6 5.1 5.4 5.4 6.9 7.1
Total mean of CVs 7.5 7.0 18.2 20.6 13.2 14.7 11.9 11.6 28.4 23.8 6.3 6.1 7.8 15.6 7.9 6.9 9.4 9.9 13.2 12.7

Abbreviation: CV, coefficients of variation.

J Lab Med Qual Assur 2020;42:183~193 https://doi.org/10.15263/jlmqa.2020.42.4.183
© Lab Med Qual Assur