Table 83, Description of the health states included in the model - Cystic Fibrosis

Health state	Description
FEV₁% >70	Patients in this health state are on-treatment and incur a treatment cost. Patients can experience a TRAE, where the transition probability is informed by the literature. Patients in this health state have the highest quality of life in the model. A proportion of patients in this health state experience an exacerbation for 2 weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA. Patients can remain in this health state for more than 1 cycle. The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the NMA.
FEV₁% 40–70	Patients in this health state are on-treatment and incur a treatment cost. Patients can experience a TRAE, where the transition probability is informed by the literature. Patients in this health state have a lower quality of life than patients in the FEV₁% >70 health state and a higher quality of life than patients in the FEV₁% <40 health state. A proportion of patients in this health state experience an exacerbation for two weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA. Patients can remain in this health state for more than 1 cycle. Patients can enter this health state from FEV₁% >70%. The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the NMA.
FEV₁% <40%	Patients in this health state are on-treatment and incur a treatment cost. Patients can experience a TRAE, where the transition probability is informed by the literature. Patients in this health state have the lowest quality of life out of the 3 FEV₁% health states in the model. A proportion of patients in this health state experience an exacerbation for 2 weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA. Patients enter this health state from FEV₁% 40–70%. Patients can remain in this health state for more than 1 cycle. The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the clinical evidence review. A proportion of patients in this health state are eligible for a lung transplant, where the transition probability is informed by the literature.
Post lung transplant	Patients enter this health state from the FEV₁% <40% health state. Patients remain in this health state for 5 years until death. Patients in this health state incur a one-off cost associated with the procedure plus the ongoing cost of care for 5 years. Patients are off-treatment in this health state and will not experience exacerbations.
Treatment related adverse event (TRAE)	Patients enter a TRAE health state from 1 of the 3 FEV₁% health states, where the transition probability is informed by the literature. Macrolides (azithromycin) are associated with hearing impairments. Patients who experience a hearing impairment will go off-treatment and follow the placebo effect. Oral corticosteroids (prednisolone) are associated with reduced BMD, cataracts and diabetes. These are concurrent health states as patients who experience any of one of these adverse events will remain on oral corticosteroid treatment. NSAIDs (ibuprofen) are associated with abdominal pain, abdominal bleeds and renal impairments. Patients who experience any one of these adverse events will go on to receive a macrolide (azithromycin) treatment and continue to follow the ibuprofen treatment effect on the assumption that azithromycin would have been chosen first line if it was more effective.
Death	Terminal state where the risk is based on CF mortality. Treatment related adverse events including diabetes and renal impairments increase the risk of mortality. No utility or costs are incurred during death.

Health state

Description

FEV₁% >70

Patients in this health state are on-treatment and incur a treatment cost.
Patients can experience a TRAE, where the transition probability is informed by the literature.
Patients in this health state have the highest quality of life in the model.
A proportion of patients in this health state experience an exacerbation for 2 weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA.
Patients can remain in this health state for more than 1 cycle.
The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the NMA.

FEV₁% 40–70

Patients in this health state are on-treatment and incur a treatment cost.
Patients can experience a TRAE, where the transition probability is informed by the literature.
Patients in this health state have a lower quality of life than patients in the FEV₁% >70 health state and a higher quality of life than patients in the FEV₁% <40 health state.
A proportion of patients in this health state experience an exacerbation for two weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA.
Patients can remain in this health state for more than 1 cycle.
Patients can enter this health state from FEV₁% >70%.
The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the NMA.

FEV₁% <40%

Patients in this health state are on-treatment and incur a treatment cost.
Patients can experience a TRAE, where the transition probability is informed by the literature.
Patients in this health state have the lowest quality of life out of the 3 FEV₁% health states in the model.
A proportion of patients in this health state experience an exacerbation for 2 weeks that incurs a treatment cost and disutility. The number of exacerbations a patient experiences is treatment specific and informed by the NMA.
Patients enter this health state from FEV₁% 40–70%.
Patients can remain in this health state for more than 1 cycle.
The proportion of patients in this cycle is influenced by the natural history of FEV₁%, where FEV₁% declines with age (Konstan 2012) and the treatment effect taken from the clinical evidence review.
A proportion of patients in this health state are eligible for a lung transplant, where the transition probability is informed by the literature.

Post lung transplant

Patients enter this health state from the FEV₁% <40% health state.
Patients remain in this health state for 5 years until death.
Patients in this health state incur a one-off cost associated with the procedure plus the ongoing cost of care for 5 years.
Patients are off-treatment in this health state and will not experience exacerbations.

Treatment related adverse event (TRAE)

Patients enter a TRAE health state from 1 of the 3 FEV₁% health states, where the transition probability is informed by the literature.
Macrolides (azithromycin) are associated with hearing impairments. Patients who experience a hearing impairment will go off-treatment and follow the placebo effect.
Oral corticosteroids (prednisolone) are associated with reduced BMD, cataracts and diabetes. These are concurrent health states as patients who experience any of one of these adverse events will remain on oral corticosteroid treatment.
NSAIDs (ibuprofen) are associated with abdominal pain, abdominal bleeds and renal impairments. Patients who experience any one of these adverse events will go on to receive a macrolide (azithromycin) treatment and continue to follow the ibuprofen treatment effect on the assumption that azithromycin would have been chosen first line if it was more effective.

Death

Terminal state where the risk is based on CF mortality.
Treatment related adverse events including diabetes and renal impairments increase the risk of mortality.
No utility or costs are incurred during death.

From: Appendix K, Health Economics

Cystic Fibrosis: Diagnosis and management.

NICE Guideline, No. 78.

National Guideline Alliance (UK).

London: National Institute for Health and Care Excellence (NICE); 2017 Oct 25.

NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.

Table 83Description of the health states included in the model