Historical Data Analysis of Hospital Discharges Related to the Amerithrax Attack in Florida.

Interrupted time-series analysis (ITSA) can be used to identify, quantify, and evaluate the magnitude and direction of an event on the basis of time-series data. This study evaluates the impact of the bioterrorist anthrax attacks ("Amerithrax") on hospital inpatient discharges in the metropolitan statistical area of Palm Beach, Broward, and Miami-Dade counties in the fourth quarter of 2001. Three statistical methods-standardized incidence ratio (SIR), segmented regression, and an autoregressive integrated moving average (ARIMA)-were used to determine whether Amerithrax influenced inpatient utilization.