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.