Is it influenza or anthrax? A decision analytic approach to the treatment of patients with influenza-like illnesses☆
Received 14 May 2003; received in revised form 11 September 2003; accepted 17 September 2003.
Refers to article:
Chinese curses, anthrax, and the risk of bioterrorism
Carl H Schultz
Annals of Emergency Medicine
March 2004 (Vol. 43, Issue 3, Pages 329-332) Full Text |
Full-Text PDF (67 KB)
Abstract
Study objective
We analyze the risks and benefits of alternative treatment strategies for non–septic-appearing febrile patients with influenza-like illnesses and possible exposure to anthrax.
Methods
We used a decision analytic model to evaluate 6 testing and treatment strategies in an emergency department. Patients were non–septic-appearing and had influenza-like illnesses but low likelihood of exposure to anthrax. The following interventions were used: (1) no empiric antibiotics; (2) blood culture and treatment only if the result was positive; (3) rapid testing for influenza and, for those who tested negative, treatment with 60 days of ciprofloxacin; (4) a two-test strategy in which all patients were first tested for influenza; those who tested negative had a blood culture test and were treated empirically with ciprofloxacin for 3 days while waiting for blood culture results; (5) culture test for all patients and treatment with ciprofloxacin for up to 3 days while waiting for blood culture results; and (6) treatment of all patients with ciprofloxacin empirically for 60 days. Main outcome measures were deaths, complications from anthrax, adverse events from ciprofloxacin, and ciprofloxacin patient-days.
Results
For nonzero probabilities of anthrax, patient mortality was always lowest in the strategies in which all patients were treated empirically for anthrax either for 60 days or for 3 days pending blood culture results. These strategies, however, were associated with more morbidity (more ciprofloxacin patient-days and more antibiotic adverse events) than were strategies without empiric treatment. The numbers of adverse events and antibiotic patient-days were reduced substantially with the two-test strategy, in which patients with influenza were identified early and not treated. In general, for probabilities of anthrax equaling or exceeding 2%, treating all patients empirically for 60 days was best, but for probabilities between 0.1% and 2%, the sensitivity of blood culture for anthrax determined the optimal strategy: when the sensitivity exceeded 95%, a short course of empiric ciprofloxacin until blood culture results became available was best, but for sensitivities below 95%, more aggressive empiric antibiotics use was warranted. The proportion of patients with influenza in the community affected the choice of strategy, so that seasonal variation exists.
Conclusion
During influenza season, our findings support rapid testing for influenza, followed by empiric treatment for anthrax pending blood culture results for those who test negative for influenza. Our results help to highlight the importance of developing rapid and sensitive tests for anthrax and of developing improved surveillance and methods to calculate the previous probability of attacks.
aDivision of Emergency Medicine, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
bInformatics Program, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
cDivision of Clinical Decision Making, Tufts–New England Medical Center, Boston, MA, USA
Address for correspondence: Andrew M. Fine, MD, MPH, Division of Emergency Medicine, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA, 02115; 617-355-6624, fax 617-731-3279
☆ Author contributions: AMF, HSFF, and KDM conceived the study. AMF, JBW, HSFF, GRF, and KDM designed the methods. JBW provided statistical advice and expertise on modeling outcomes in the decision analysis. GRF provided expert infectious disease advice. AMF drafted the manuscript, and all authors contributed substantially to its revision. AMF takes responsibility for the paper as a whole.
Presented in part at the Society for Pediatric Research, Baltimore, MD, May 2002.
Supported in part by National Research Service Award grant T32 HD40128-01 (Research Training in Pediatric Emergency Medicine); by the National Institutes of Health through grants R01LM07677-01 and LM07092-10 from the National Library of Medicine, Bethesda, MD; and by contract 290-00-0020 from the Agency for Healthcare Research and Quality, Rockville, MD.
ABSTRACT