Intravenous antibiotic use and exacerbation events in an adult cystic fibrosis centre: A prospective observational study

Introduction: In CF, people with higher FEV₁ are less aggressively treated with intravenous (IV) antibiotics, with resultant negative impact on their health outcomes. This could be entirely clinician-driven, but patient choice may also influence IV use. In this prospective observational study, we explored IV recommendations by clinicians and IV acceptance by adults with CF to understand how clinical presentations consistent with exacerbations resulted in IV use.

Methods: Clinical presentations consistent with exacerbations, IV recommendation by clinicians and IV acceptance by patients were prospectively identified for every adult with CF in Sheffield throughout 2016, excluding those who had lung transplantation (n = 7) or on ivacaftor (n = 13). Relevant demographic data, e.g. %FEV₁, were extracted from medical records. Multi-level mixed-effects logistic regression models were used to compare IV recommendations vs non-recommendations for all clinical encounters, and IV acceptance vs non-acceptance for all IV recommendations.

Results: Among 186 adults (median age 27 years, median FEV₁ 78.5%), there were 434 exacerbation events and 318 IV use episodes following 1010 clinical encounters. Only 254 (58.5%) of exacerbations were IV treated. A diagnosis of exacerbation, higher number of symptoms and lower %FEV₁ were independent predictors for IV recommendation by clinicians. Higher number of symptoms and lower %FEV₁ were also independent predictors for IV acceptance by adults with CF.

Conclusions: Lower IV use among adults with higher %FEV₁ was influenced by both clinicians' and patients' decisions. Using IV antibiotics as an exacerbation surrogate could under-estimate exacerbation rates and conceal differential treatment decisions according to varying clinical characteristics.