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Predicting Health Care Use Resulting From Terrorism

Public Health Emergency Preparedness

This resource was part of AHRQ's Public Health Emergency Preparedness program, which was discontinued on June 30, 2011, in a realignment of Federal efforts.

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Tools To Aid State Planning


To examine health care utilization following the 9/11 terrorism attacks, Emory University researchers studied enrollees in Aetna health plans. Emory is a partner of the Integrated Delivery System Research Network (IDSRN) of the Agency for Healthcare Research and Quality (AHRQ).

Although the researchers could not conclusively examine outcomes that would be common to all terrorist events, they did make conclusions and recommendations that may be useful to individuals and groups responsible for public health preparedness.

To purchase the full report, call the National Technical Information Service (NTIS) at (703) 605-6000; local calls 800-553-6847. Refer to the title of the publication and its NTIS accession No. (PB2005-100666).


Terrorism can have an immediate and widespread impact on mental and physical health. Because stress is a risk factor for many illnesses, terrorism may have somatic consequences. Terrorism-induced after-effects have the potential to overburden health care delivery systems. While the direct morbidity resulting from terrorism during the fall of 2001 has been described, the magnitude of the potential secondary effects of the psychological stress experienced in the United States has not been fully characterized.

To study health care utilization following the 9/11 terrorism attacks in the New York and Washington, DC, areas and anthrax events in south Florida, Emory University researchers studied enrollees in Aetna health plans. Emory is a partner of the Integrated Delivery System Research Network (IDSRN) of AHRQ.


This ecological study was undertaken to examine patterns of health care utilization in an insured population before and after September 11, 2001, in the New York City Consolidated Metropolitan Statistical Area (CMSA) and in other regions throughout the country. The study assesses utilization for a range of mental, behavioral, and medical health outcomes in various settings of care and subpopulations for persons enrolled in Aetna health plans.

Health care visits per 10,000 Aetna enrollees per month as the basic utilization measure were examined. Outcomes of interest were identified primarily using ICD-9-CM diagnostic codes and Current Procedural Terminology (CPT) codes. To account for seasonal and year-to-year changes in health care use, the researchers developed measures of absolute and relative change in utilization that compare observed utilization post-9/11 with utilization expected in the absence of the 9/11 events.


In the New York City CMSA and Washington, DC, the areas most directly affected by 9/11, there was a transient decline in health care utilization in virtually all settings of care from September 11 to 30, 2001. The decline was followed by an increase from the expected level in office visits for adults during fourth quarter of 2001, again most significant in directly affected areas.

Overall, mental health utilization fell post-9/11 in New York City, but generally remained at expected levels in other areas of the country through the end of 2001. An exception to the pattern in New York City was noted for the mental health subset of stress-related disorders (stress disorders, interpersonal violence, sleep disorders, and prescriptions for sleep medications), where there was an excess of visits over the expected level. Other exceptions included more visits than expected for sleep disorders and conduct disorders among young children, and for adjustment and depressive disorders among older adults. Most stress-related disorders were also above expected levels in Washington, DC, south Florida, the Northeast, and the Midwest.

We subdivided the study population from the New York CMSA into concentric mileage bands centered at the World Trade Center (WTC), based on the residential ZIP Code of each enrollee.

During the fourth quarter of 2001, visits for physical diagnoses or symptoms that may be precipitated or aggravated by stress (e.g., syncope, palpitations, chest pain) increased more (compared with the expected number of visits) in areas closest to Ground Zero than in other geographic areas. Visits for dermatitis and rash increased across the country in the last quarter of 2001, as did prescriptions for doxycycline and ciprofloxacin. The highest increase above expected levels for doxycycline and ciprofloxacin occurred in the directly affected areas (New York CMSA, Washington, DC, and south Florida). There was no major increase in visits for asthma or bronchitis in New York City compared with expected levels. Visits for cough rose in the area closest to Ground Zero in the last quarter of 2001 but the increase above expected levels was not sustained into 2002.

In summary, terrorism may have resulted in an increase in office visits for somatic symptoms related to stress following a transient decline after 9/11, most apparent in areas directly affected by 9/11 and anthrax events. Direct concern with the potential for anthrax exposure was evidenced by an increase in prescriptions filled for doxycycline and ciprofloxacin, and an increase in visits for rashes across the country. Overall, mental health utilization fell following 9/11 in New York City, and the fall from the expected level of visits was sustained for many months; people may either have not recognized or not attended to their mental health needs. There was evidence of stress-related effects not only in New York City and the other affected areas, but also elsewhere in the Nation.

Bioterrorism Research Portfolio

The Emory Center on Health Outcomes and Quality of Emory University, one of AHRQ's IDSRN partners, produced these tools under Contract No. 290-00-0011-2. This project was funded under the Agency's bioterrorism research portfolio.

AHRQ sponsors research that provides the evidence base for tools and resources needed in bioterrorism planning and response. For more information, go to:

Current as of January 2005


The information on this page is archived and provided for reference purposes only.


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