Published: June 16, 2008
Updated: June 19, 2008
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By Duke Medicine News and Communications
DURHAM, NC – Recent studies suggest that large numbers of Americans remain sexually active well into their 60's, 70's and even 80's. But researchers at Duke University Medical Center say seniors may be overlooked as possible carriers of the AIDS virus, and based on a new study, they are recommending screening for most adults ages 55 to75 as a sensible, cost-effective way to prolong life and decrease the spread of the disease.
"Many of us might think of HIV as associated with teens and younger adults, but statistics show that 19 percent of those infected were diagnosed at age 50 or older," says Gillian Sanders, PhD, associate professor of medicine at the Duke Clinical Research Institute and the lead author of the study appearing in the June 17 issue of the Annals of Internal Medicine.
The Centers for Disease Control recommends HIV screening for patients aged 13 to 64, and Sanders says it is clearly cost effective to screen younger populations –- even if the prevalence of the disease is low –- because any benefits will be enjoyed over a much longer period. But HIV is less prevalent among older Americans. In addition, older patients are also more likely to have fewer sex partners and more life-threatening conditions that might make routine screening less economically attractive.
"Until now, we've assumed that screening made a lot of sense in younger people but we really didn't know if it was a good use of our health care resources in older folks," says Sanders. "That's why we needed to do this study."
Sanders worked with colleagues at Stanford University, the Veterans Affairs Palo Alto Health Care System and St. Michael's Hospital in Toronto in evaluating the cost-effectiveness of HIV screening among patients aged 55 to 74.
The authors used a computerized model that tracked older patients over their lifetime. The model noted whether the patients were screened or not, their HIV status, the clinical course of any HIV disease, the cost and consequences of any transmission and the cost and effects of treatment. They also took into account the likelihood of any age and gender-related issues that could shorten the patients' lives.
Cost-effectiveness is often measured in quality-adjusted life-years (QAYLs), a figure that takes into account numerous factors, including the quality of life and the length of life.
The authors noted that the cost-effectiveness of HIV screening was dependent on the prevalence of the disease, the age of the patient, the cost of counseling and whether the patient was sexually active.
Assuming that 0.5 percent of the study population were HIV-positive, the researchers found that HIV screening for patients aged 65 who were not sexually active would cost $55,440 per QALY gained, while screening for sexually-active 65 year olds would cost $30,020 per QALY. Sanders says such figures are within the range of other accepted cost-effective ratios, and in the United States, these would generally be considered "a good use of our health care dollars."
Based on case studies, they also found that screening and early diagnosis for a 65-year old HIV-infected patient could mean an extra half year of life, while for a 75-year old HIV-infected patient, it would mean an extra four months of life.
"This suggests that HIV screening for many older adults is indeed cost-effective, particularly for those who are sexually active," says Sanders, who says some of the newer, lower-cost, streamlined counseling formats might be particularly appropriate for this population.
"All of us also need to remember that age doesn't protect anyone from HIV. You're as vulnerable at 60 as you are at 16."
The study was funded by the Department of Veterans Affairs, the National Institute on Drug Abuse, the National Institute on Aging and the Ontario HIV Treatment Network.
The senior author of the study is Douglas Owens, a senior investigator at the VA Palo Alto Healthcare System and a professor of medicine at Stanford. Other co-authors are Mark Holodniy, also at the VA and a professor of medicine at Stanford, and Ahmed Bayoumi, a professor of medicine and health policy, management and evaluation, at the University of Toronto.