Table 2 Parameters used in the model
Parameters | Distribution | Mean | SE | References |
|---|---|---|---|---|
Probability of recurrence in patients with no adjuvant imatinib treatment (per month) | ||||
 Probability of recurrence at year 1 | Beta | 0.0205 | 0.0041 | Chart reviewa |
 Probability of recurrence at year 3 | Beta | 0.0154 | 0.0031 | |
 Probability of recurrence at year 5 | Beta | 0.0056 | 0.0011 | |
Probability of death from GIST in patients with no adjuvant imatinib treatment (per month) | ||||
 Probability of death at year 1 | Beta | 0.0017 | 0.0003 | Chart reviewa |
 Probability of death at year 3 | Beta | 0.0031 | 0.0006 | |
 Probability of death at year 5 | Beta | 0.0028 | 0.0006 | |
 Probability of death at year 7 | Beta | 0.0020 | 0.0004 | |
 Probability of death at year 9 | Beta | 0.0038 | 0.0008 | |
Hazard ratio (HR) of recurrence in patients receiving adjuvant imatinib treatment (compared with no adjuvant imatinib treatment) | ||||
 Adjuvant imatinib treatment for 1 year | Log normal | 0.29 | 0.0995 | [6]b |
 Adjuvant imatinib treatment for 3 years | Log normal | 0.133 | 0.0543 | |
Probability of progression during treatment (per month) | ||||
 Imatinib treatment | Beta | 0.015 | 0.0038 | [12] |
 Sunitinib treatment | Beta | 0.012 | 0.0010 | |
Probability of death during treatment (per month) | ||||
 Imatinib treatment | Beta | 0.0056 | 0.0009 | [12] |
 Sunitinib treatment | Beta | 0.0289 | 0.0087 | |
 Best supportive care | Beta | 0.0680 | 0.0093 | |
Probability of discontinuation of adjuvant imatinib treatment (per month) | ||||
 Adjuvant imatinib treatment for 1 year (1–6 months) | Beta | 0.0136 | 0.0014 | [17] |
 Adjuvant imatinib treatment for 1 year (7–12 months) | Beta | 0.0009 | 0.0001 | |
 Adjuvant imatinib treatment for 3 years (1–6 months) | Beta | 0.0097 | 0.0001 | |
 Adjuvant imatinib treatment for 3 years (7 months onwards) | Beta | 0.0028 | 0.0003 | |
Direct medical costs (THB per month) | ||||
 Imatinib 400 mg/day | – | 111,306 | – | [14] |
 Sunitinib 50 mg/day (receive drug for 4 weeks, then stop for 2 weeks, and repeat a cycle) | – | 82,173 | – | |
 Costs for patients with no recurrence and no adjuvant imatinib treatment | Gamma | 2758 | 308 | Hospital database |
 Costs for patients with no recurrence and receiving adjuvant imatinib treatmentc | Gamma | 1477 | 573 | |
 Costs for patients during recurrence and receiving imatinib treatmentc | Gamma | 421 | 38 | [12] |
 Costs for patients during recurrence and receiving sunitinib treatmentc | Gamma | 714 | 150 | |
 Costs for patients during recurrence and receiving best supportive care | Gamma | 424 | 78 | |
 Costs for treating adverse events from adjuvant imatinib treatment | Gamma | 570 | 114 | Expert opinion |
Direct non-medical costs | ||||
 Travel costs (THB per visit) | Gamma | 296 | 24 | [15] |
 Food costs (THB per visit) | Gamma | 109 | 11 | |
 Opportunity cost of caregivers (THB per visit) | Gamma | 99 | 37 | |
 Number of visits for patients with no recurrence and no adjuvant imatinib treatment (visits per month) | Gamma | 0.3 | 0.1 | Hospital database |
 Number of visits for patients with no recurrence and receiving adjuvant imatinib treatment (visits per month) | Gamma | 0.6 | 0.2 | |
 Number of visits for patients during recurrence (visits per month) | – | 1 | – | [12] |
Utility | ||||
 No recurrence and no adjuvant imatinib treatment | Beta | 0.89 | 0.03 | Interviewing patients |
 No recurrence and receiving adjuvant imatinib treatment | Beta | 0.79 | 0.09 | |
 Recurrence and receiving imatinib treatment | Beta | 0.66 | 0.05 | [12] |
 Recurrence and receiving sunitinib treatment | Beta | 0.58 | 0.06 | |
 Recurrence and receiving best supportive care | Beta | 0.42 | 0.03 | |