Table 2

Model parameters related to disease progression and outcomes (per annum)

Transitions (probability)*24
 GOLD 10.90470.08760.00000.00000.0077
 GOLD 20.05100.90010.03620.00000.0128
 GOLD 30.00000.10440.83680.03240.0265
 GOLD 40.00000.00000.09360.81870.0877
Transition for symptomatic patients*
 Symptoms, no COPD48 49 0.00400.00150.00000.00000.0026†
Exacerbation (probability)
 Severe exacerbation‡15 0.02700.07600.27200.3480
 Mortality after severe exacerbation33 0.07030.07030.07030.0703
Treatment effect (OR)
 All-cause mortality29 0.98000.98000.98000.9800
 Severe exacerbation29 0.85000.85000.85000.8500
 Progression to the next GOLD stage§0.85000.85000.85000.8500
Costs (£)¶
 Scheduled GP and hospital visits19 164.56267.06394.01541.06
 Inhaled medication33 485.16567.84735.96824.52
 Inpatient stay due to exacerbation33 2263.002263.002263.002263.00
Health outcomes
 Utility‡15 0.71970.70130.67980.5855
 Disutility from severe exacerbation‡15 −0.2398−0.2337−0.2265−0.1951
 Utility gained from treatment50 0.03670.03670.03670.0367
  • *Age -dependent parameters. Values presented are for individuals aged 50- years-old.

  • †Value represents mortality risk in the general population.

  • ‡Birmingham COPD cohort: data from the Birmingham Lung Improvement StudieS: an ongoing series of studies aimed at evaluating better strategies for identifying and managing COPD in primary care.15 Disutility data shows utility loss over 1 year: 50% utility loss in the first month and 25% utility loss for the second and third month per cycle. The impact of exacerbations on quality of life is greater in patients with less severe disease who also tend to be younger.51

  • §Expert panel comprised consultant pulmonologists, epidemiologists and senior health economist. The panel was presented with results of prior scoping reviews on the effect of treatment on exacerbation, mortality and lung function, but there was no review transition between GOLD stages. Given that the OR in reviews were around 0.85, the panel agreed then that the odds of treatment slowing disease progression to the next worse GOLD stage should be 0.85 for the base case.

  • ¶Cost method was adapted and unit costs were updated to 2015 price year.