Table 2.

Model parameters to inform long-term decision analytic model

Transition probability	Sources	Specific details of the fields in source
Remaining in IT	NTP NCRF	Time of withdrawal from IT Time of withdrawal from IT
LTOT to IT	The trial	Proportion of people engaged in IT
IT to LTOT	NTP NCRF	Time of withdrawal from IT Time of withdrawal from IT
IT to SOLMP	NTP NCRF	Time of completely stopping the use of opioids Time of completely stopping the use of opioids
IT to dead state	PL	All-cause mortality data from ONS
Remaining in LTOT	The trial	Number of people who do not engage in IT and remain in LTOT
SOLMP to LTOT	PtQ GPRs	Medication data Prescription data
LTOT to PT	PtQ GPRs	Medication data Prescription data
LTOT to dead state	PL	All-cause mortality data from ONS
Remaining in PT	The trial PtQ GPRs	Number of people who remain in PT over time Medication data Prescription data
PT to LTOT	PtQ GPRs	Medication data Prescription data
PT to SOLMP	PtQ GPRs	Medication data Prescription data
PT to dead state	PL	All-cause mortality data from ONS
Remaining in SOLMP	PtQ GPRs	Medication data Prescription data
SOLMP to dead state		All-cause mortality rates from ONS
Utility scores	Source	Specific details of the source
LTOT	PL PtQ	Utility of opioid therapy45 Regression analysis of patient self-reported EQ-5D
PT	PtQ	Regression analysis of patient self-reported EQ-5D
IT	PtQ	Regression analysis of patient self-reported EQ-5D
SOLMP	PtQ	Regression analysis of patient self-reported EQ-5D
Costs	Source	Specific details of the source
LTOT	PL PtQ GPRs	Cost of opioid therapy per cycle46 Costs associated with self-reported resource use Costs associated with resource use collected
PT	The trial PtQ GPRs	Cost associated with usual care Costs associated with self-reported resource use Costs associated with resource use collected
IT	The trial	Cost associated with intervention
SOLMP	PL	Assumption—1× contact with GP28

‘The trial’ means the I-WOTCH trial.

GP, general practitioner; GPRs, GP records; IT, I-WOTCH tapering; I-WOTCH, Improving the Well-being of people with Opioid Treated CHronic pain; LTOT, long-term opioid therapy; NCRF, nurse clinical record form; NTP, nurse tapering plan; ONS, Office of National Statistics; PL, published literature; PT, patient-driven tapering; PtD, patient diary; PtQ, patient questionnaire; SOLMP, successful opioid-less management of pain.