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. 2006 Jun;1(2):e11.
doi: 10.1371/journal.pctr.0010011. Epub 2006 Jun 30.

Secondary outcomes of a pilot randomized trial of azithromycin treatment for asthma

Affiliations

Secondary outcomes of a pilot randomized trial of azithromycin treatment for asthma

David L Hahn et al. PLoS Clin Trials. 2006 Jun.

Abstract

Objectives: The respiratory pathogen Chlamydia pneumoniae (C. pneumoniae) produces acute and chronic lung infections and is associated with asthma. Evidence for effectiveness of antichlamydial antibiotics in asthma is limited. The primary objective of this pilot study was to investigate the feasibility of performing an asthma clinical trial in practice settings where most asthma is encountered and managed. The secondary objectives were to investigate (1) whether azithromycin treatment would affect any asthma outcomes and (2) whether C. pneumoniae serology would be related to outcomes. This report presents the secondary results.

Design: Randomized, placebo-controlled, blinded (participants, physicians, study personnel, data analysts), allocation-concealed parallel group clinical trial.

Setting: Community-based health-care settings located in four states and one Canadian province.

Participants: Adults with stable, persistent asthma.

Interventions: Azithromycin (six weekly doses) or identical matching placebo, plus usual community care.

Outcome measures: Juniper Asthma Quality of Life Questionnaire (Juniper AQLQ), symptom, and medication changes from baseline (pretreatment) to 3 mo posttreatment (follow-up); C. pneumoniae IgG and IgA antibodies at baseline and follow-up.

Results: Juniper AQLQ improved by 0.25 (95% confidence interval; -0.3, 0.8) units, overall asthma symptoms improved by 0.68 (0.1, 1.3) units, and rescue inhaler use decreased by 0.59 (-0.5, 1.6) daily administrations in azithromycin-treated compared to placebo-treated participants. Baseline IgA antibodies were positively associated with worsening overall asthma symptoms at follow-up (p = 0.04), but IgG was not (p = 0.63). Overall asthma symptom improvement attributable to azithromycin was 28% in high IgA participants versus 12% in low IgA participants (p for interaction = 0.27).

Conclusions: Azithromycin did not improve Juniper AQLQ but appeared to improve overall asthma symptoms. Larger community-based trials of antichlamydial antibiotics for asthma are warranted.

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Conflict of interest statement

Competing Interests: DLH has received an unrestricted educational grant, study medication (azithromycin and placebo), and speaking honoraria from Pfizer, Inc. MBP owns stock in Pfizer.

Figures

Figure 1
Figure 1. Study Flowchart
Figure 2
Figure 2. Overall Asthma Symptoms in the Azithromycin and Placebo Groups
Months 1 and 2: Baseline and treatment period. Month 3: Completion of treatment. Months 4–6: Posttreatment. Numbers of participants included in each data point are indicated under the x-axis. Error bars represent 95% confidence intervals for individual data points. Linear regression analysis showed a significant (p = 0.04) overall difference between azithromycin and placebo group patterns.
Figure 3
Figure 3. Scatter Plot of Chlamydia pneumoniae–specific IgG and IgA Optical Density (OD) Values Obtained on Available Baseline Patient Sera (n = 42)
Y-axis: IgG OD; X-axis: IgA OD. High IgG was defined by inspection as an OD above the mean (1.18 OD units). High IgA was defined by inspection as an OD greater than 0.5.

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