Factors associated with a shorter time until the next pulmonary exacerbation in adult patients with cystic fibrosis

Time until the subsequent exacerbation (PEx) in cystic fibrosis (CF) is a significant health outcome and one of the significant end points in clinical trials. Risk factors associated with shorter time until the next exacerbation (TUNE) have not been reported. This is a prospective study. TUNE was the number of days from the end of intravenous (IV) antibiotic treatment of a PEx until the day of start of IV antibiotics for the following PEx. Factors assessed were age, gender, site of treatment, CF-related diabetes (CFRD), allergic bronchopulmonary aspergillosis (ABPA) and infection with Pseudomonas aeruginosa (PA). In addition, we examined parameters obtained at day 14 of treatment including forced expiratory volume in the first second (FEV1), body mass index, CF respiratory symptom score, C-reactive protein (CRP) and serum cytokines. A total of 170 exacerbations in 58 adult CF patients (27 female), mean (SD) age 25.8 (6.7) years were analysed. When analysing individual variables, patients with lower FEV1, greater symptom score and higher CRP at the end of exacerbation were associated with shorter TUNE. Patients with ABPA and CFRD had a shorter TUNE than those without. When applying multiple regression analysis, factors associated with shorter TUNE were older age and lower day-14 FEV1 values. Shorter periods until the following PEx are expected in older CF patients and those with lower FEV1 at the end of course of treatment. When these risk factors are present, there may be a justification to take therapeutic steps to increase the time until the following PEx.