TABLE 2.
Results of the base‐case analysis
| Parameters | Warfarin * | Clopidogrel # | Irinotecan $ | |||
|---|---|---|---|---|---|---|
| Genotype‐guided dosing | Standard dosing | Genotype‐guided dosing | Standard dosing | Genotype‐guided dosing | Standard dosing | |
| Cost per patient per year (US$) | 466.8713 | 385.2739 | 892.9846 | 350.9054 | 19 680.8570 | 19 567.4206 |
| Incremental cost | 81.5974 | 542.0792 | 113.4364 | |||
| QALY gained per patient year | 0.7133 | 0.6978 | 0.6567 | 0.6383 | 0.7837 | 0.7656 |
| Incremental QALY | 0.0155 | 0.0184 | 0.0181 | |||
| Incremental cost per QALY gained (US$) | 5264.3484 | 29 460.8261 | 6267.2044 | |||
| Adverse events per patient year | 0.0116 | 0.0224 | 0.0927 | 0.1063 | 0.0402 | 0.0516 |
| Adverse events averted per patient year | 0.0108 | 0.0136 | 0.0114 | |||
| Incremental cost per adverse event averted (US$) | 7555.3148 | 39 858.7647 | 9 950.5614 | |||
For warfarin, the genotype‐guided dosing algorithms and standard dosing strategies were previously described. 9 , 10 Adverse events of major thromboembolism, severe intracerebral and extracerebral haemorrhage were the observation endpoints for both arms.
For clopidogrel, standard dosing patients took clopidogrel at the dose of 75 mg/day without PGx testing. PGx guided dosing patients adjusted medication according to CYP2C19 genotypes as following: wild‐type patients used standard dosing and mutation carriers took ticagrelor 90 mg twice daily.
For irinotecan, drugs used for standard dosing patients were irinotecan 500 mg/m2, calcium leucovorin 200 mg/m2 and 5‐FU 400 mg/m2. PGx guided dosing patients adjusted medication according to UGT1A1 genotypes. Patients with wild‐type or one‐mutated site of UGT1A1*6 and *28 treated with standard dose, while those with two‐mutated site variants were treated with a 50% dose reduction of irinotecan.
Abbreviation: QALY, quality‐adjusted life‐year.
Incremental outcome (cost, QALY) = Outcome of genotype‐guided dosing – Outcome of standard dosing.
Adverse events per patient‐year = Total adverse events per patient year.
Adverse events per patient‐year averted = Total adverse events of standard dosing – Total adverse events of genotype‐guided dosing.