TABLE 1.
Model inputs (three-month cycle)
| Inputs | Stage 1 | Stage 2 | Stage 3 | References |
|---|---|---|---|---|
| Baseline distribution of patients, % | 93 | 4 | 3 | 12 |
| Progression to next disease stage, % | 2.97 (2.87–3.07) | 9.94 (9.84–10.04) | n/a | 25 |
| Exacerbations per year (LABA), % | 0.17 (0.153–0.187) | 0.59 (0.531–0.649) | 0.83 (0.747–0.913) | 14 |
| Mild | 93.7 | 26.0 | 0 | 16,23,36,37 |
| Moderate | 3.8 | 61.9 | 69.8 | 16,23,36,37 |
| Severe | 2.5 | 12.0 | 30.2 | 16,23,36,37 |
| Relative risk (CT versus LABA) | 0.86 (0.77–0.97) | 0.86 (0.77–0.97) | 0.86 (0.77–0.97) | 17–20 |
| All-cause mortality rates (events/100 person-years) | 3.92 (3.72–4.12) | 6.16 (5.85–6.47) | 9.24 (8.78–9.71) | 38 |
| QALY | 0.897 (0.807–0.987) | 0.750 (0.675–0.825) | 0.549 (0.494–0.604) | 24,39 |
| Reduction in QALY due to: | ||||
| Mild exacerbation | −0.17 (0.15–0.19 | −0.17 (0.15–0.19) | −0.17 (0.15–0.19) | 40 |
| Moderate exacerbation | −0.47 (0.42–0.52) | −0.47 (0.42–0.52) | −0.47 (0.42–0.52) | 41 |
| Severe exacerbation | −0.47 (0.42–0.52) | −0.47 (0.42–0.52) | −0.47 (0.42–0.52) | 41 |
| Cost of COPD per year, $ | 687 (618–756) | 658 (752–724) | 1,752 (1,576–1,927) | 25 |
| Cost of mild exacerbation, $ | 60 (54–66) | 60 (54–66) | 60 (54–66) | 25 |
| Cost of moderate exacerbation, $ | 270 (243–297) | 270 (243–297) | 270 (243–297) | 25 |
| Cost of severe exacerbation, $ | 4,827 (4,344–5,309) | 4,827 (4,344–5,309) | 4,827 (4,344–5,309) | 25 |
| Average daily cost of LABA, $ | 1.61 (1.47–1.75) | 1.61 (1.47–1.75) | 1.61 (1.47–1.75) | 42 |
| Average daily cost of CT, $ | 2.77 (2.60–4.18) | 2.77 (2.60–4.18) | 2.77 (2.60–4.18) | 42 |
Values for sensitivity analysis are in parenthesis. Doses: Oxeze (AstraZeneca Canada): 12 μg formoterol per dose twice daily; Serevent (GlaxoSmithKline Canada): 50 μg salmeterol twice daily; Advair (GlaxoSmithKline Canada) (usual dose): 50 μg salmeterol/250 μg fluticasone propionate per dose twice daily; Advair (GlaxoSmithKline Canada) (high dose): 50 μg salmeterol/500 μg fluticasone propionate per dose twice daily; Symbicort (AstraZeneca Canada): 200 μg budesonide/6 μg formoterol per dose twice daily. COPD Chronic obstructive pulmonary disease; CT Combination therapy; LABA Long-acting beta2-agonist; n/a Not available; QALY Quality-adjusted life years