Methodological issues in therapeutic trials of COPD

Area of Science:

• Respiratory Medicine
• Clinical Trial Methodology
• Pharmacotherapy

Background:

• The Towards a Revolution in COPD Health (TORCH) trial confirmed inhaled corticosteroids (ICS) reduce exacerbations but not mortality in chronic obstructive pulmonary disease (COPD).
• Previous trials also suggested ICS effectiveness for exacerbations, but methodological issues warrant re-evaluation.

Purpose of the Study:

• To review methodological shortcomings in COPD randomized trials, including the TORCH trial.
• To re-evaluate the effectiveness of inhaled corticosteroids (ICS) in COPD management by addressing patient selection and follow-up biases.

Main Methods:

• Analysis of data from the Canadian Optimal Therapy of COPD Trial and the TORCH trial.
• Examination of exacerbation rates in patients with and without prior ICS use.
• Assessment of exacerbation rates before and after study drug discontinuation.
• 2x2 factorial analysis of TORCH data for mortality components (salmeterol and fluticasone).

Main Results:

• Prior ICS use in the Canadian trial was associated with a reduced hazard ratio for exacerbations (0.71), while new users showed no benefit (1.11).
• Exacerbation rates with ICS were lower during treatment (0.78) but higher after discontinuation (1.23).
• TORCH trial data indicated salmeterol reduced mortality (0.83 ratio), but fluticasone (ICS) did not (1.00 ratio).

Conclusions:

• Methodological limitations in COPD trials cast doubt on the effectiveness of inhaled corticosteroids (ICS) for treating COPD.
• Observed benefits of combination therapy in COPD may be attributable solely to the long-acting bronchodilator component.