Table 3 Results of one way sensitivity analyses
Complete case (n = 360)Cost284827863800
Adjusted QALY00.003120.01665
Cost/exacerbation avoidedReference8653332
Cost/QALYDominant57 142
Non-COPD relatedCosts384635285004
Hospitalisations includedCost/exacerbation avoidedReference29585463
Cost/QALY342 48496 271
Zero exacerbations after deathExacerbation1.521.641.28
Cost/exacerbation avoidedReferenceDominated4123
One exacerbation for each period after death†Exacerbation1.651.841.64
Cost/exacerbation avoidedReferenceDominated47 768
Severe COPD (FEV1 ⩽50% predicted)‡Cost279027114121
Adjusted QALY0−0.00310.0096
Cost/exacerbation avoidedReferenceDominant4293
Cost/QALY25 483141 979
Moderate COPD (50% <FEV1 <65% predicted)‡Cost140223412701
Adjusted QALY00.00320.0096
Cost/exacerbation avoidedReferenceDominated18 591
Cost/QALY289 509139 218
Disutility during exacerbationQALY0.70310.70640.7207
Adjusted QALY0−0.00940.0073
Cost/QALYReferenceDominated139 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.