Macrolides for chronic asthma

Asthma is a chronic disease of the airways in which inflammation of the respiratory mucosa plays a crucial role. The mechanisms responsible for the maintaining of this inflammatory response are only partially known and there is evidence that a role could be paid by chronic infection by intracellular pathogens (such as Chlamydia pneumoniae). Macrolides are antibiotics with both antimicrobial and anti-inflammatory activities and thus their use in asthmatic patients could lead to reduction of the airways inflammation and therefore improvement of symptoms and pulmonary function.

To determine whether macrolides are effective in the management of patients with chronic asthma.

We searched MEDLINE, EMBASE and CINAHL up to May 2001. This was also supplemented by manually searching bibliographies of previously published reviews, conference proceedings, and contacting study authors. All languages were included in the initial search.

Randomised, controlled clinical trials involving both children and adult patients with chronic asthma treated with macrolides for more than 4 weeks, versus placebo.

Two reviewers independently examined all identified articles. Two reviewers reviewed the full text of any potentially relevant article independently.

The initial search retrieved 95 studies. Preliminary evaluation identified 20 studies that were potentially eligible. Five (357 patients) met the entry criteria. The entry criteria for the primary trials differed, but all recruited a specific subgroup of patients (eg severe oral steroid dependent, aspirin intolerant or evidence of Chlamydia pnuemoniae infection). There was a positive effect on symptoms (Standardised Mean Difference -1.25, 95% Confidence Intervals (CI) -1.80, -0.70) and markers of eosinophilic inflammation; eg sputum eosinophils Weighted Mean difference -78.5, 95%CI -90.8, -66.1). Tests of oral corticosteroid-sparing effects have not yet been performed on the newer agents such as roxithromycin and clarithromycin.

Considering the small number of patients studied, there is insufficient evidence to support or to refute the use of macrolides in patients with chronic asthma. Further studies are needed in particular to clarify the potential role of macrolides in some subgroups of asthmatics such as those with evidence of chronic bacterial infection.