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

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.

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.

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.

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.