Table 1 Transition probabilities, utilities and costs

Probabilities

 Annual probability of recurrence post abdominoperineal resection

0.0871

0.0435–0.130^a

Beta

Rutkowski et al. [8]

 Annual conditional probability of local recurrence post abdominoperineal resection^a

0.135

0.0675–0.203^a

Uniform

Rutkowski et al. [8]

 Annual probability of 1st progression in metastatic GIST

0.370

 0.296–0.444^b

Beta

Blanke et al. [4]

 Annual probability of 2nd progression in metastatic GIST

0.811

 0.649–0.973^b

Beta

Blanke et al. [4]

 Annual probability of 3rd progression in metastatic GIST

0.708

 0.566–0.850^b

Beta

Demetri et al. [13]

 Annual probability of death in metastatic GIST post-regorafenib

0.405

0.270–0.410^b

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

0.750–1^b

Beta

Wilson et al. [17]

 GIST recurrence

0.748

0.598–0.898^b

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

7 408–44 448^c

Gamma

NCCS data

 Annual cost of sunitinib 50 mg once daily 4 weeks on, 2 weeks off

64 063

51 250–76 876^b

Gamma

NCCS data

 Annual cost of regorafenib 160 mg once daily 3 weeks on, 1 week off

72 001

57 601–86 401^b

Gamma

NCCS data

 Abdominoperineal resection

38 000

30 400 –45 600^b

Gamma

NCCS data

 Salvage surgery (following 1st local recurrence post abdominoperineal resection)

38 000

30 400–45 600^b

Gamma

NCCS data

 Annual cost of follow-up (consultation, blood tests, computer tomography scans every 3 months)

3 000

2 400–3 600^b

Gamma

NCCS data