Background: Mortality from inhalational anthrax during the 2001 U.S. attack was substantially lower than that reported historically.
Purpose: To systematically review all published inhalational anthrax case reports to evaluate the predictors of disease progression and mortality.
Data sources: MEDLINE (1966-2005), 14 selected journal indexes (1900-1966), and bibliographies of all retrieved articles.
Study selection: Case reports (in any language) between 1900 and 2005 that met predefined criteria.
Data extraction: Two authors (1 author for non-English-language reports) independently abstracted patient data.
Data synthesis: The authors found 106 reports of 82 cases of inhalational anthrax. Mortality was statistically significantly lower for patients receiving antibiotics or anthrax antiserum during the prodromal phase of disease, multidrug antibiotic regimens, or pleural fluid drainage. Patients in the 2001 U.S. attack were less likely to die than historical anthrax case-patients (45% vs. 92%; P < 0.001) and were more likely to receive antibiotics during the prodromal phase (64% vs. 13%; P < 0.001), multidrug regimens (91% vs. 50%; P = 0.027), or pleural fluid drainage (73% vs. 11%; P < 0.001). Patients who progressed to the fulminant phase had a mortality rate of 97% (regardless of the treatment they received), and all patients with anthrax meningoencephalitis died.
Limitations: This was a retrospective case review of previously published heterogeneous reports.
Conclusions: Despite advances in supportive care, fulminant-phase inhalational anthrax is usually fatal. Initiation of antibiotic or anthrax antiserum therapy during the prodromal phase is associated with markedly improved survival, although other aspects of care, differences in clinical circumstances, or unreported factors may contribute to this observed reduction in mortality. Efforts to improve early diagnosis and timely initiation of appropriate antibiotics are critical to reducing mortality.