"There are two key findings here," said Dr. Margaret L. Brandeau of Stanford University, who co-authored the operations research study about the value of HIV screening and counseling programs for women. "One is that relapses occur, even at the best treatment programs. And two, even when there’s a relapse, a temporary reduction in risky behavior can still lead to diminishing the spread of the HIV infection."
The article appears in a special issue about AIDS in Interfaces: An International Journal of the Institute for Operations Research and the Management Sciences. Dr. Brandeau is the issue’s special editor. She and other contributors to the issue will offer papers and oral presentations at the 12th World AIDS Conference in Geneva from June 28 to July 3.
Screening and Counseling Women
The study evaluates the effectiveness of three different kinds of programs: programs that target (1) women who are intravenous drug users (IDUs); (2) women who are IDUs and women who have high risk sexual partners; and (3) all women.
These programs screen women to determine whether they carry the AIDS virus and offer counseling on ways to reduce the chance of contracting or spreading HIV.
The study looks at the programs’ costs and benefits, both in preventing the spread of HIV and in dollar measures of medical bills and earnings. In particular, it helps policy makers who are devising programs determine a break-even success rate, given that a percentage of women who initially reduce their high-risk behavior eventually relapse partially or completely.
Small Changes, Big Impact
Results of math modeling show that success is highest among a targeted group of intravenous drug users. The researchers modeled a group of 10,000 intravenous drug using women over a two-year period. If there are 25% relapses to risky behavior during the period, there would be prevention of 1 infection in infants, 72 infections in adults, and $16 million in savings. If relapses climbed to 50%, there would still be prevention of 1 infection in infants, 66 infections in adults, and $11.8 million in savings.
In contrast, a perfect success rate without relapses would prevent 1 infection in infants, prevent 78 infections in adults, and save $19.9 million in earnings and medical expenses.
The rate of success is slightly diminished in the second group (women who are intravenous drug users and women who have high risk sexual partners), whose members’ risk of infection is lower.
The study analyzes data from an earlier study in California by the authors. Based on previous findings, it assumes that, on average, counseling and testing result in an initial 15% reduction in risky behavior. The authors used operations research techniques in their analysis, including a dynamic model of the HIV epidemic and an economic model that assesses the costs and benefits.
The authors found that programs aimed at the third group - the entire population of women - require a greater degree of behavior change in to achieve cost effectiveness. Initial rates of change in behavior must be as high as 23% if the expense reaching out to such a large group is to be cost-effective.
Glass Half Full, Not Half Empty
The study offers a significant conclusion: "Counseling and testing need not eliminate risk behaviors totally, nor produce permanent reductions in risk behaviors; even interventions short of this ideal will provide benefits that outweigh their costs."
Nevertheless, the authors caution, " Our study underscores the critical importance of developing behavioral interventions that produce sustained reductions in risk behavior. Although the break-even levels of risk behavior reduction are still relatively low for screening directed to women IDUs, the benefit of even these programs is markedly diminished by relapse."
This study and previous research have already improved the design and evaluation of HIV interventions, the authors point out. One benefit is on focus: Public health officials no longer limit their counseling to the initiation of safe behavior; now they continue working to maintain safe behavior over a period of time.
Another benefit is in improved attitude: Researchers now credit intervention, even if it doesn’t completely change their subjects. Looking at the glass as half full rather than half empty, they look at programs that produce an incomplete change in risky behavior not as failures but as partial - and welcome - successes.
The study, "Effect of Relapse to High-Risk Behavior on the Costs and Benefits of a Program to Screen Women for Human Immunodeficiency Virus," was written by Dr. Brandeau; Dr. Douglas K. Owens of the Veterans Affairs Palo Alto Health Care System and Stanford University; and Carol H. Sox of Dartmouth Medical School.
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.