(492) The effect of antibiotic changes during treatment of cystic fibrosis pulmonary exacerbations

Background: Cystic fibrosis (CF) pulmonary exacerbations are associated with significant negative impact on patient morbidity and mortality. Antibiotics are often changed during treatment of a pulmonary exacerbation in cystic fibrosis (CF) patients who have a poor clinical response. We aimed to characterize the reasons for antibiotic changes and examined the effects of these changes on lung function recovery.

Methods: This was a retrospective cohort study using the Toronto CF Database from 2009 to 2015 of adults and pediatric patients with CF pulmonary exacerbations treated with intravenous antibiotics. The primary outcome measure was absolute and relative change in forced expiratory lung volume in 1 second (FEV₁) at end of treatment and follow-up. Secondary outcome assessed the proportion of patients returning to > 90% or > 100% previous baseline FEV₁.

Results: A total of 399 exacerbations were included of which 105 exacerbations had an antibiotic change. Reasons for antibiotic changes included change in antibiotic route prior to discharge (26%), drug reactions (20%), poor FEV₁ response (25%) and lack of symptom improvement (13%). In our multivariable analysis, among non-responders (< 90% FEV₁ recovery to baseline or lack of symptom improvement at the interim time point), a change in antibiotics was not associated with any significant difference in absolute or relative FEV₁ at end of treatment or at follow-up. Antibiotic change in non-responders was not associated with improved return to 90% or 100% baseline FEV₁ at end of treatment or follow-up.

Conclusions: In this retrospective study using adult and paediatric pulmonary exacerbation data from the Toronto CF database, we described the reasons for antibiotic changes and assessed the effects of changing antibiotics in patients with poor clinical response. Changing antibiotics during pulmonary exacerbation treatment in CF patients with poor clinical response was not associated with any improved FEV₁ response or return to baseline lung function.

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