Probability of IV antibiotic retreatment within thirty days is associated with duration and location of IV antibiotic treatment for pulmonary exacerbation in cystic fibrosis

Background: There are few objective data to guide management of cystic fibrosis (CF) pulmonary exacerbations. We studied intravenous (IV) antibiotic treatment failure as defined by a need to retreat patients with IV antibiotics within 30 days of completion of a prior IV antibiotic treatment for pulmonary exacerbation. Methods: The first IV-treated exacerbation on or after Jan. 1, 2010 among US CF Foundation Patient Registry patients was studied, combining treatments separated by <7 days into single treatments. IV treatment duration categories were: 1-4, 5-8, 9-12, 13-16, 17-22, and >= 23 days (inclusive). Logistic regressions for IV retreatment in <= 30 days were adjusted with 12 categorical covariates, including age, sex, lung function, prior-year exacerbations, CF complications, CF Care Program, and ever/never treated in hospital. Results: 777 of 13,579 patients (5.7%) were retreated within 30 days, with incidence varying by treatment duration: 1-4 days, 8.7%; 5-8 days; 6.6%; 9-12 days, 3.2%; 13-16 days, 4.5%; 17-22 days, 6.2%; >= 23 days, 10.3% and hospitalization: ever, 5.0%; never 8.5%. Adjusted odds ratios (OR) for retreatment (compared to 13-16 days treatment) were: 1-4 days, 1.94 [95%CI 1.49, 2.54] P<.001; 5-8 days, 1.55 [1.18, 2.04] P=.002; 9-12 days, 0.78 [0.58, 1.04] P=.09; 17-22 days, 1.12 [0.88, 1.42] P=.37; >= 23 days, 1.46 [1.12, 1.91] P=.005. Adjusted retreatment OR for never/ever hospitalized was 1.57 [1.29, 1.90] P<.001. Prior-year exacerbation number, oxygen therapy, non-invasive ventilation, and female sex were significantly associated with retreatment. Modeling hazard rate time-dependence showed that treatment duration and location-associated hazard rates attenuated within a few months after treatment. Conclusion: After adjustment for covariates known to be associated with increased risk of IV treatment for exacerbation, IV antibiotic treatments of <9 and >= 23 days and those without hospitalization were significant risk factors for IV retreatment within 30 days of completion of an exacerbation treatment. (C) 2016 The Authors. Published by Elsevier B.V. on behalf of European Cystic Fibrosis Society. This is an open access article under the CC BY NC -ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).