Location and duration of treatment of cystic fibrosis respiratory exacerbations do not affect outcomes

Abstract

Rationale: Individuals with cystic fibrosis (CF) are subject to recurrent respiratory infections (exacerbations) that often require intravenous antibiotic treatment and may result in permanent loss of lung function. The optimal means of delivering therapy remains unclear.

Objectives: To determine whether duration or venue of intravenous antibiotic administration affect lung function.

Methods: Data were retrospectively collected on 1,535 subjects recruited by the US CF Twin and Sibling Study from US CF care centers between 2000 and 2007.

Measurements and main results: Long-term decline in FEV₁ after exacerbation was observed regardless of whether antibiotics were administered in the hospital (mean, -3.3 percentage points [95% confidence interval, -3.9 to -2.6]; n = 602 courses of therapy) or at home (mean, -3.5 percentage points [95% confidence interval, -4.5 to -2.5]; n = 232 courses of therapy); this decline was not different by venue using t tests (P = 0.69) or regression (P = 0.91). No difference in intervals between courses of antibiotics was observed between hospital (median, 119 d [interquartile range, 166]; n = 602) and home (median, 98 d [interquartile range, 155]; n = 232) (P = 0.29). Patients with greater drops in FEV₁ with exacerbations had worse long-term decline even if lung function initially recovered with treatment (P < 0.001). Examination of FEV₁ measures obtained during treatment for exacerbations indicated that improvement in FEV₁ plateaus after 7-10 days of therapy.

Conclusions: Intravenous antibiotic therapy for CF respiratory exacerbations administered in the hospital and in the home was found to be equivalent in terms of long-term FEV₁ change and interval between courses of antibiotics. Optimal duration of therapy (7-10 d) may be shorter than current practice. Large prospective studies are needed to answer these essential questions for CF respiratory management.

Figures

Figure 1.

Lung function measures.

Figure 2.

Mean lung function over time (based on data from Table 1). This figure provides the mean values for each measure of lung function before and after a respiratory exacerbation by venue of treatment. As can be seen, all groups experience a substantial decline in lung function with an exacerbation, followed by recovery in some cases back to the original baseline, but long-term lung function is decreased compared with the original baseline lung function. The 95% confidence intervals for all lung function measures can be found in Table E2.

Figure 3.

Change in FEV1 by duration of therapy. This figure provides the mean values for each measure of lung function before and after a respiratory exacerbation by duration of treatment for the same population depicted in Figure 2. Subjects who receive longer courses of intravenous antibiotics tend to have worse lung function and do not recover all lost lung function immediately after a treatment course. In all groups long-term lung function is decreased compared with the original baseline lung function. The 95% confidence intervals for all lung function measures can be found in Table E2.

Figure 4.

Mean improvement in FEV1 by day of therapy. This figure demonstrates the SE improvement in lung function corrected and normalized (mean baseline FEV1, 68.8%) for baseline lung function by day of intravenous therapy using pulmonary function tests obtained during therapy. The numbers above each reflect the number of pulmonary function tests contributing to each datapoint. As can be seen, lung function demonstrates improvement until approximately 8–10 days of therapy, where it then plateaus. The analysis was limited to the first 22 days of therapy because the number of FEV1 measurements available for any particular day was fewer than 40 after Day 22 of therapy.