The effect of oral and intravenous antimicrobials on pulmonary exacerbation recovery in cystic fibrosis.

Background: Retrospective studies indicate that more cystic fibrosis (CF) pulmonary exacerbations (PEx) are treated with oral (PO) than with intravenous (IV) antimicrobials despite little knowledge of the relative effects of PO treatment on lung function recovery or long-term impacts on lung disease progression. Previous studies have suggested that PO treatment may be associated with slower lung function recovery compared with IV treatment. We used longitudinal home spirometry data from the eICE study (NCT01104402) to compare PO versus IV antimicrobial treatment responses for PEx diagnosed by home spirometry and symptom assessment.

Methods: Adolescent and adult eICE participants performed home spirometry twice weekly for one year. PEx were diagnosed by a protocol-defined algorithm of change in percent predicted forced expiratory volume in 1 second (ppFEV) and/or respiratory signs and symptoms. PO- and IV-treated PEx were grouped by initial ppFEV drop magnitude. Group ppFEV treatment responses were modeled with multivariate, repeat-measure linear regression.

Results: Of 87 qualifying PEx from 56 participants, 62 were PO-treated and 25 were IV-treated. The average drop from best ppFEV to PEx start was 11.0 [95%CI: 8.5, 13.5] with similar treatment group means (p=0.72). Participants with IV-treated PEx averaged 0.72 [0.24, 1.20] ppFEV/day greater response than those treated with PO, who experienced minimal ppFEV1 recovery. Many PO-treated participants who had <10 ppFEV drop from baseline tended to worsen or show no ppFEV improvement.

Discussion: These results suggest that, in this cohort, PO antimicrobial treatment of CF PEx were less effective than IVs at improving ppFEV during treatment.