The Challenge
The study addresses a conundrum facing researchers: Since it is impossible to know how many cases of HIV would have occurred in the absence of concerted prevention efforts, how does one count what doesn’t happen?
Evaluating the impact of public policy interventions is necessary in the current climate of fiscal restraint. Economic information is vital to policymakers who must make tactical choices and plan budgets to slow the spread of the AIDS virus.
Given the complexity of HIV, the UBC team’s approach has been to mathematically simulate the epidemic and, more significantly, possible interventions to prevent its transmission. This project is a first step toward a comprehensive evaluation of the costs and benefits of preventive interventions in the spread of HIV.
Large-Scale Approach
In proposing their model, the researchers observe that there have been few large scale efforts at evaluating prevention programs. Previous research has often considered specific populations -- for example gay men in one city or intravenous drug users in another -- and has rarely examined how populations interact and affect one another - vital when considering transmission of an infection. They also observe that evaluation tools covered in academic literature frequently don’t credit the full impact of interventions in the context of an infectious disease, often overlooking the multiplier effect: One less infection today translates into more than one case averted.
The Data
In developing their model, the researchers divided the Canadian population into 12 groups based on gender, sexual orientation, and injection drug behavior. Each of the 12 groups was also divided into risk factors of high, medium, and low. People could acquire the infection through sharing injection equipment or through risky sexual contact.
The researchers adapted a theory about the way people change -- the social theory of stages of behavior change -- and focused on two stages -- contemplation of change and action -- to evaluate the degree to which prevention programs influence participants. The prevention techniques evaluated are generalized into three categories according to intensity (high, medium and low).
Data on the financial cost of HIV prevention in Canada is based on a 1997 study by Canadian Policy Research Networks, Inc.
The paper, "Modeling the Impact of Prevention in the Spread of HIV for the Purposes of Economic Evaluation" is by Nancy L. Meagher, Robin A. Hanvelt, Tobin T. Copley, David G. Schneider, and Stephen A. Marion of the Department of Health Care and Epidemiology, University of British Columbia in Vancouver. Nancy L. Meagher, Robin A. Hanvelt, Tobin T. Copley, and David G. Schneider are also affiliated with the British Columbia Centre for Excellence in HIVA/AIDS, St. Paul’s Hospital, Vancouver and the Centre for Health Services and Policy Research, Univeristy of British Columbia, Vancouver.
For additional information on the conference, including a full list of workshops, visit the web site at http://www2.informs.org/Conf/Seattle98/
The Institute for Operations Research and the Management Sciences (INFORMS) is an international scientific society with 12,000 members, including Nobel Prize laureates, dedicated to applying scientific methods to help improve decision-making, management, and operations. Members of INFORMS work primarily in business, government, and academia. They are represented in fields as diverse as airlines, health care, law enforcement, the military, the stock market, and telecommunications.