Scenario* | Outcomes | TP | TS | TFS |
Complete case (n = 360) | Cost | 2848 | 2786 | 3800 |
QALY | 0.7016 | 0.7160 | 0.7301 | |
Adjusted QALY | 0 | 0.00312 | 0.01665 | |
Exacerbation | 1.52 | 1.60 | 1.24 | |
Cost/exacerbation avoided | Reference | 865 | 3332 | |
Cost/QALY | Dominant | 57 142 | ||
Non-COPD related | Costs | 3846 | 3528 | 5004 |
Hospitalisations included | Cost/exacerbation avoided | Reference | 2958 | 5463 |
Cost/QALY | 342 484 | 96 271 | ||
Zero exacerbations after death | Exacerbation | 1.52 | 1.64 | 1.28 |
Cost/exacerbation avoided | Reference | Dominated | 4123 | |
One exacerbation for each period after death† | Exacerbation | 1.65 | 1.84 | 1.64 |
Cost/exacerbation avoided | Reference | Dominated | 47 768 | |
Severe COPD (FEV1 ⩽50% predicted)‡ | Cost | 2790 | 2711 | 4121 |
QALY | 0.6924 | 0.6866 | 0.7021 | |
Adjusted QALY | 0 | −0.0031 | 0.0096 | |
Exacerbation | 1.82 | 1.82 | 1.51 | |
Cost/exacerbation avoided | Reference | Dominant | 4293 | |
Cost/QALY | 25 483 | 141 979 | ||
Moderate COPD (50% <FEV1 <65% predicted)‡ | Cost | 1402 | 2341 | 2701 |
QALY | 0.7241 | 0.7567 | 0.7600 | |
Adjusted QALY | 0 | 0.0032 | 0.0096 | |
Exacerbation | 1.01 | 1.34 | 0.94 | |
Cost/exacerbation avoided | Reference | Dominated | 18 591 | |
Cost/QALY | 289 509 | 139 218 | ||
Disutility during exacerbation | QALY | 0.7031 | 0.7064 | 0.7207 |
Adjusted QALY | 0 | −0.0094 | 0.0073 | |
Cost/QALY | Reference | Dominated | 139 459 |
*For each scenario, only the outcome(s) that might be affected by the new assumption are reported.
†The ICER in this scenario could be interpreted as cost per one exacerbation free period (28 days) achieved.
‡According to the GOLD criteria:4 severe COPD was defined as observed over predicted FEV1 of more, less than or equal to 50% of predicted.
COPD, chronic obstructive pulmonary disease; FEV1, forced expiratory volume in 1 s; ICER, incremental cost effectiveness ratio; TP, tiotropium+placebo; TS, tiotropium+salmeterol; TFS, tiotropium+fluticasone/salmeterol; QALY, quality adjusted life years.