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Table 1 Transition probabilities, utilities and costs

From: Treatment of gastrointestinal tumor (GIST) of the rectum requiring abdominoperineal resection following neoadjuvant imatinib: a cost-effectiveness analysis

Variable Base case Range for sensitivity analysis Distribution for probabilistic sensitivity analysis Reference
Probabilities     
 Annual probability of recurrence post abdominoperineal resection 0.0871 0.0435–0.130a Beta Rutkowski et al. [8]
 Annual conditional probability of local recurrence post abdominoperineal resectiona 0.135 0.0675–0.203a Uniform Rutkowski et al. [8]
 Annual probability of 1st progression in metastatic GIST 0.370  0.296–0.444b Beta Blanke et al. [4]
 Annual probability of 2nd progression in metastatic GIST 0.811  0.649–0.973b Beta Blanke et al. [4]
 Annual probability of 3rd progression in metastatic GIST 0.708  0.566–0.850b Beta Demetri et al. [13]
 Annual probability of death in metastatic GIST post-regorafenib 0.405 0.270–0.410b Beta Demetri et al. [14]
Utilities     
 Recurrence-free health state post abdominoperineal resection 0.830 0.650–1 Beta Miller et al. [7]
 Recurrence-free health state on continued imatinib until progression 0.935 0.750–1b Beta Wilson et al. [17]
 GIST recurrence 0.748 0.598–0.898b Beta Majer et al. [10]
 GIST 1st progression in metastatic disease 0.712 0.685–0.739 Beta Chabot et al. [18]
 GIST 2nd progression in metastatic disease 0.712 0.685–0.739 Beta Assumption
 GIST 3rd progression in metastatic disease 0.712 0.685–0.739 Beta Assumption
COSTS (SGD)
 Annual cost of imatinib 400 mg once daily 37 040 7 408–44 448c Gamma NCCS data
 Annual cost of sunitinib 50 mg once daily 4 weeks on, 2 weeks off 64 063 51 250–76 876b Gamma NCCS data
 Annual cost of regorafenib 160 mg once daily 3 weeks on, 1 week off 72 001 57 601–86 401b Gamma NCCS data
 Abdominoperineal resection 38 000 30 400 –45 600b Gamma NCCS data
 Salvage surgery (following 1st local recurrence post abdominoperineal resection) 38 000 30 400–45 600b Gamma NCCS data
 Annual cost of follow-up (consultation, blood tests, computer tomography scans every 3 months) 3 000 2 400–3 600b Gamma NCCS data
  1. mg milligrams, GIST gastrointestinal stromal tumor, NCCS National Cancer Centre Singapore, SGD Singapore dollars
  2. a ± 50% (wider intervals used in estimation due to paucity of systematic data for recurrences specifically in rectal GIST post neoadjuvant imatinib)
  3. b ± 20%
  4. c + 20% and −80% (lower bound for imatinib extended to −80% to account for possible significant decrease in imatinib cost with advent of generic imatinib)