Decision theoretic analysis of improving epidemic detection

Abstract

The potentially catastrophic impact of an epidemic specially these due to bioterrorist attack, makes developing effective detection methods essential for public health. Current detection methods trade off reliability of alarms for early detection of outbreaks. The performance of these methods can be improved by disease-specific modeling techniques that take into account the potential costs and effects of an attack to provide optimal warnings and the cost and effectiveness of interventions. We study this optimization problem in the framework of sequential decision making under uncertainty. Our approach relies on estimating the future benefit of true alarms and the costs of false alarms. Using these quantities it identifies optimal decisions regarding the credibility of outputs from a traditional detection method at each point in time. The key contribution of this paper is to apply Partially Observable Markov Decision Processes (POMDPs) on outbreak detection methods for improving alarm function in the case of anthrax. We present empirical evidence illustrating that at a fixed specificity, the performance of detection methods with respect to sensitivity and timeliness is improved significantly by utilizing POMDPs in detection of anthrax attacks.

Figure 1

The POMDP model for anthrax outbreak detection.

Figure 2

The estimate of accumulative preventable loss for detection of anthrax per day after a release.

Figure 3

The timeliness of anthrax outbreak detection method with and without using POMDPs: sensitivities during different days of the outbreak for attacks that resulted in 10 additional visits.

Figure 4

The timeliness of anthrax outbreak detection method with and without using POMDPs: sensitivities during different days of the outbreak for attacks that resulted in 20 additional visits.