Feb. 9, 2005  Routine population-wide screening for human immunodeficiency
virus (HIV) may be cost-effective, according to the results of two cost-
effectiveness analyses published in the Feb. 10 issue of the New England Journal
of Medicine. The editorialist agrees and suggests that in the era of highly
active antiretroviral therapy (HAART), not performing screening would be a
disservice to patients.

"The costs, benefits, and cost-effectiveness of screening for HIV in health care
settings during the era of HAART have not been determined," write Gillian D.
Sanders, PhD, from the Duke Clinical Research Institute of Duke University in
Durham, North Carolina, and colleagues. "[U.S. Centers for Disease Control
and Prevention] (CDC) data indicate that in 41% of HIV-positive patients, the
acquired immunodeficiency syndrome (AIDS) develops within a year after they
received the diagnosis, suggesting that opportunities for preventing adverse
outcomes were missed."

The investigators developed a Markov model of costs, quality of life, and
survival associated with an HIV-screening program compared with current
practice.
In this model, symptom-based case finding identified symptomatic patients, who
started treatment when their CD4 count dropped to 350 cells per cubic
millimeter. CD4 levels and viral load defined disease progression, and the
probability of sexual transmission was estimated from viral load, knowledge of
HIV
status, and efficacy of counseling.

Assuming that the prevalence of unidentified HIV infection was 1%, screening
increased life expectancy by 5.48 days, or 4.70 quality-adjusted days. The
estimated cost was $194 per screened patient, yielding a cost-effectiveness
ratio of $15,078 per quality-adjusted life-year. If the prevalence of
unidentified
HIV infection exceeded 0.05%, screening cost less than $50,000 per
quality-adjusted life-year.

When HIV transmission was excluded, the cost-effectiveness of screening was
$41,736 per quality-adjusted life-year. Compared with one-time screening,
screening every five years cost $57,138 per quality-adjusted life-year, but was
more attractive in settings with a high incidence of infection.

"Our results were sensitive to the efficacy of behavior modification, the
benefit of early identification and therapy, and the prevalence and incidence of
HIV
infection," the authors write. "The cost-effectiveness of routine HIV screening
in health care settings, even in relatively low-prevalence populations, is
similar
to that of commonly accepted interventions, and such programs should be
expanded."

The authors note that the main benefit of screening is that people identified as
having HIV can begin lifesaving HAART before severe immunologic
destruction has occurred, but that the best time to begin HAART is
controversial. The ongoing Strategies for Management of Antiretroviral Therapy
(SMART)
study should help address the latter issue.

"Given the inadequacies of current testing, we believe the case for systematic
voluntary HIV screening in health care settings is now compelling," the
authors conclude. "In many health care settings, HIV screening will provide
important health benefits for a reasonable investment in health care resources."

The Health Services Research and Development Service, Department of Veterans
Affairs; the Ontario HIV Treatment Network; and the National Institute on
Drug Abuse supported this study.

The objectives of the second study were to estimate the clinical consequences of
delayed HIV detection, to determine the cost-effectiveness of the
guidelines for expanded HIV counseling, testing, and referral (HIVCTR) in
populations with different risks of HIV, and to illustrate how publicly
available data
could help address questions of value for money in HIVCTR.

"Although the CDC [recommends] routine HIVCTR in settings with at least a 1%
prevalence of HIV, roughly 280,000 Americans are unaware of their HIV
infection," write A. David Paltiel, PhD, from Yale School of Medicine in New
Haven, Connecticut, and colleagues.

The investigators developed a computer simulation model of HIV screening and
treatment to compare routine, voluntary HIVCTR with current practice in
three target populations. These included a "high-risk" group (3.0% prevalence of
undiagnosed HIV infection; 1.2% annual incidence); "CDC threshold" (1.0%
and 0.12%, respectively); and "US general" (0.1% and 0.01%). Input data were
derived from clinical trials and observational cohorts, and outcomes included
quality-adjusted survival, cost, and cost-effectiveness.

In the high-risk group, adding one-time screening for HIV antibodies with an
enzyme-linked immunosorbent assay (ELISA) to current practice was associated
with earlier diagnosis of HIV (mean CD4 cell count at diagnosis, 210 vs. 154 per
cubic millimeter). One-time screening was also associated with increased
average survival in HIV-infected patients, with quality-adjusted survival, 220.7
months vs. 219.8 months for current practice.

Incremental cost-effectiveness for one-time screening was $36,000 for each
quality-adjusted life-year gained, compared with $50,000 per quality-adjusted
life-
year gained for testing every five years, and $63,000 per quality-adjusted
life-year gained for testing every three years.

In the CDC threshold group, the cost-effectiveness ratio for one-time screening
with ELISA was $38,000 per quality-adjusted life-year gained, compared with
$71,000 per quality-adjusted life-year gained for testing every five years, and
$85,000 per quality-adjusted life-year gained for testing every three years. In
the
general U.S. population, the cost of one-time screening was $113,000 per
quality-adjusted life-year gained.

"In all but the lowest-risk populations, routine, voluntary screening for HIV
once every three to five years is justified on both clinical and
cost-effectiveness
grounds," the authors write. "One-time screening in the general population may
also be cost-effective."

Limitations of this analysis include inability to definitively address whether
an existing HIVCTR program in the highest-risk populations should be expanded to
include people at lower-than-average risk, less conclusive findings with regard
to the choice of testing technology, and three principal sources of uncertainty
identified by sensitivity analyses.

The National Institute of Mental Health, the National Institute of Allergy and
Infectious Diseases, the National Institute on Drug Abuse, and the CDC
supported this study.

In an accompanying editorial, Samuel A. Bozzette, MD, PhD, from the RAND
Corporation in Santa Monica, California, and the University of California San
Diego, calls routine screening for HIV infection "timely and cost-effective." He
notes that these analyses do not incorporate certain secondary benefits of
screening, such as preservation of health and productivity and reduced
transmission. "Given the availability of effective therapy and preventive
measures, it
is possible to improve care and perhaps influence the course of the epidemic
through widespread, effective, and cost-effective screening," Dr. Bozzette
writes. "Such programs will have a relatively high yield but must be designed
with great caution to avoid difficulties related to the use of profiling, the
stigma of
testing, and community acceptance.? Failure to implement widespread routine
screening for HIV infection represents a critical disservice to patients who are
currently infected, those at risk for infection, and the future health of the
nation."

Dr. Bozzette reports having received grant support from the Oversight Committee
for the Evaluation of the Metabolic Complications of HAARTherapy
convened by the European Agency for the Evaluation of Medicinal Products.
Members include Abbott Laboratories, Boehringer Ingelheim, Bristol-Myers
Squibb, Gilead Sciences, GlaxoSmithKline, Hoffmann--La Roche, Merck Research
Laboratories, and Pfizer.

N Engl J Med. 2005;352:570-585, 586-595, 620-621

Reviewed by Gary D. Vogin, MD

Author: Laurie Barclay, MD
Medscape Medical News 2005. © 2005 Medscape