Patients with cystic fibrosis (CF) have recurrent exacerbations of respiratory infections requiring antibiotic treatment. Results of a study published in the American Journal of Respiratory and Critical Care Medicinesuggest that there is little difference in lung function improvement between inpatient and outpatient treatment settings.
“We undertook the research because there is a paucity of information to guide clinicians in best practices when treating cystic fibrosis exacerbations,” said J. Michael Collaco, MD, from the Eudowood Division of Pediatric Respiratory Sciences at Johns Hopkins University in Baltimore. “Two of the key issues, the best site for delivery of intravenous antibiotics and optimal duration of therapy, were able to be studied by examining outcomes in a large registry.”
Using the US Cystic Fibrosis Twin-Sibling Study, the researchers recruited 1535 individuals from 755 families. All met the diagnostic criteria for CF. Additional information was pulled from the Cystic Fibrosis Association Patient Registry. Analysis was limited to courses of intravenous antibiotics lasting 42 days or less.
Long-term decline in forced expiratory volume (FEV1) following exacerbation was seen regardless of where the antibiotics were administered (hospital mean, -3.3% [95% confidence interval (CI), -3.9 to -2.6]; n = 602 courses of therapy; home mean, -3.5% [95% CI, -4.5 to -2.5]; n = 232). The decline was no different by venue using t tests (P = .69) or regression (P = .91).
Another indicator is interval between courses of antibiotics. Again, no differences were observed between the hospital (median time, 119 days [interquartile range (IQR), 166]; n = 602) and the home (median time, 98 days [IQR, 155]; n = 232; P = .29).
“By examining FEV1 measurement we obtained during courses of antibiotic therapy, we observed that the majority of improvement in lung function may occur during the first week,” he said. “There was a plateau of improvement within 8 days of starting the therapy. This suggests that courses of 14 to 21 days may not provide additional benefits for many patients.”
Importantly, shorter courses of antibiotics were not associated with a shorter interval between courses. Using 2417 exacerbations involving 524 subjects, duration of therapy did not predict time until next exacerbation (P = .11) using linear regression with adjustment for baseline FEV1.
“We found no differences in terms of long-term respiratory outcomes regardless of whether therapy was administered in the home or in the hospital,” said Dr Collaco. “Furthermore, optimal duration of treatment may be shorter than is common practice, at least based on lung function. Ultimately, controlled studies are needed to establish best practice guidelines of cystic fibrosis management.”
Author Disclosures:The research was supported by a grant from the National Heart, Lung, and Blood Institute and through Cystic Fibrosis Foundation funding. The authors reported no conflicts of interest.
Source:Collaco JM, Green DM, Cutting GR, Naughton KM, Mogayzel PJ Jr. Location and duration of treatment of cystic fibrosis respiratory exacerbations do not affect outcomes. Am J Respir Crit Care Med. 2010; Epub ahead of print.