This systematic review sought to identify the best available evidence regarding strategies for allocating scarce resources during mass casualty events (MCEs). Specifically, the review addresses the following questions: (1) What strategies are available to policymakers to optimize the allocation of scarce resources during MCEs? (2) What strategies are available to providers to optimize the allocation of scarce resources during MCEs? (3) What are the public's key perceptions and concerns regarding the implementation of strategies to allocate scarce resources during MCEs? (4) What methods are available to engage providers in discussions regarding the development and implementation of strategies to allocate scarce resources during MCEs?

We searched Medline, Scopus, Embase, CINAHL (Cumulative Index to Nursing and Allied Health Literature), Global Health, Web of Science®, and the Cochrane Database of Systematic Reviews from 1990 through 2011. To identify relevant non-peer-reviewed reports, we searched the New York Academy of Medicine's Grey Literature Report. We also reviewed relevant State and Federal plans, peer-reviewed reports and papers by nongovernmental organizations, and consensus statements published by professional societies. We included both English- and foreign-language studies.

Our review included studies that evaluated tested strategies in real-world MCEs as well as strategies tested in drills, exercises, or computer simulations, all of which included a comparison group. We reviewed separately studies that lacked a comparison group but nonetheless evaluated promising strategies. We also identified consensus recommendations developed by professional societies or government panels. We reviewed existing State plans to examine the current state of planning for scarce resource allocation during MCEs. Two investigators independently reviewed each article, abstracted data, and assessed study quality.

We considered 5,716 reports for this comparative effectiveness review (CER); we ultimately included 170 in the review. Twenty-seven studies focus on strategies for policymakers. Among this group were studies that examined various ways to distribute biological countermeasures more efficiently during a bioterror attack or influenza pandemic. They provided modest evidence that the way these systems are organized influences the speed of distribution. The review includes 119 studies that address strategies for providers. A number of these studies provided evidence suggesting that commonly used triage systems do not perform consistently in actual MCEs. The number of high-quality studies addressing other specific strategies was insufficient to support firm conclusions about their effectiveness. Only 10 studies included strategies that consider the public's perspective. However, these studies were consistent in their findings. In particular, the public believes that resource allocation guidelines should be simple and consistent across health care facilities but should allow facilities some flexibility to make allocation decisions based on the specific demand and supply situation. The public also believes that a successful allocation system should balance the goals of ensuring the functioning of society, saving the greatest number of people, protecting the most vulnerable people, reducing deaths and hospitalizations, and treating people fairly and equitably. The remaining 14 studies provided strategies for engaging providers in discussions about allocating and managing scarce medical resources. These studies did not identify one engagement approach as clearly superior; however, they consistently noted the importance of a broad, inclusive, and systematic engagement process.

Scientific research to identify the most effective adaptive strategies to implement during MCEs is an emerging area. While it remains unclear which of the many options available to policymakers and providers will be most effective, ongoing efforts to develop a focused, well-organized program of applied research should help to identify the optimal methods, techniques, and technologies to strengthen our nation's capacity to respond to MCEs.