Antibacterial treatment in exacerbations of chronic obstructive pulmonary disease. Pitfalls in study design and evaluation.

In studies aimed at assessing the efficacy and safety of antibacterial agents used in treating infections of the respiratory tract, patients with exacerbations of a chronic obstructive pulmonary disease frequently are included. Both the indication for the prescription of an antibiotic and the evaluation of its effect can be difficult. As a general rule, treatment with steroids, bronchodilators and oxygen supply is indicated in cases of exacerbated pulmonary disease. These interventions will influence the clinical and bacteriological parameters usually used to evaluate the antibacterial effect. In a number of cases, non-antibacterial treatment will restore the bronchopulmonary defence sufficiently so that infection control is reached. In order to design meaningful efficacy studies, it is obligatory to understand the pathophysiological mechanisms in chronic obstructive pulmonary disease, to be aware of the pitfalls in making the diagnosis 'bacterial bronchitis' and to take into account the influence of co-medications on the clinical and bacteriological parameters. Some objections to comparative efficacy trials are raised.