[Long-term trials assessing pharmacological treatments in COPD: lessons and limitations]

Abstract

Introduction: Several long-term studies designed to assess pharmacological treatments for Chronic Obstructive Pulmonary Disease (COPD) have been published recently. Only such long-term studies allow an accurate analysis of the effect of treatments on criteria of effectiveness such as survival or decline in pulmonary function. A review of these studies is opportune.

Background: The high drop out rate, which is not a random event, leads to serious methodological problems that are of importance in the interpretation of these studies. Post hoc analysis of both the TORCH and UPLIFT trials suggest a positive effect of long-acting bronchodilators on survival. Up to now, no treatment has convincingly demonstrated an effect on the rate of decline of FEV(1). The treatments evaluated lead to a decrease in exacerbation rates and an improvement in quality of life although the effects of inhaled corticosteroids are subject to methodological concerns. The treatments are all well tolerated.

Viewpoint: The design of future studies should avoid the withdrawal of treatments at enrolment into a study in order to limit the number of drop outs.

Conclusion: Long-term studies have made important progress in the knowledge, not only of the effects of the treatments assessed but also of the methodological issues which need to be addressed.