 It
is well known that HIV treatment lowers viral load and consequently
decreases the likelihood of passing on the virus through sex or
needle sharing. HIV screening enables people to start ART
in a timely manner, and studies also show that when people learn
their status, they typically reduce risky behavior that could transmit
the virus to other.
Public health experts have called for expanding HIV screening and
treatment -- perhaps even for all
HIV positive people regardless of CD4 T-cell count -- as part
of a comprehensive approach to prevention.
Adding to the body of mathematical models estimating the effects
of "test-and-treat," Elisa Long from Yale School of Management
and colleagues looked at how expanded screening, wider use of ART,
and interventions to reduce risk behavior might affect the U.S.
epidemic.
The researchers constructed a dynamic mathematical model of HIV
transmission and disease progression, as well as a cost-effectiveness
analysis, using data from published medical literature.
They focused on 2 target populations, one high-risk (injection drug
users and men who have sex with men [MSM]), the other low-risk (everyone
age 15 to 64 years), over 2 time horizons, 20 years or lifetime.
They estimated costs and benefits based on quality-adjusted life-years
(QALYs), a measure of survival that takes into account quality of
life.
Results
 |
According to the model, 1-time HIV screening of low-risk people
plus annual screening of high-risk individuals could prevent
6.7% -- or more than 80,000 -- of a projected 1.23 million
new infections over 20 years, if people reduced sexual activity
by 20% after testing. |
|
The
cost of this strategy was estimated at $22,382 per quality-adjusted
life-year gained. |
|
Expanding
ART use to 75% of eligible individuals could prevent 10.3%
of projected new infections, at a cost of $20,300 per quality-adjusted
life-year gained. |
|
A
combined screening and expanded treatment strategy could prevent
17.3% -- or more than 200,000 -- of projected infections at
a cost of $21,580 per quality-adjusted life-year gained. |
|
However,
if sexual activity did not decrease after testing, expanded
screening could prevent just 3.7% of projected new infections.
|
|
Earlier
ART initiation at a CD4 count above 350 cells/mm3 could prevent
20% to 28% of new infections. |
|
Counseling
and additional efforts to reduce high-risk behavior could
reduce new infections by 65%. |
|
Annual HIV screening, plus risk-reduction efforts that decrease
risky behavior by 50%, plus ART initiation for 90% of symptomatic
individuals could reduce new infections to fewer than 35,000
per year, down from the current
estimate of approximately 56,000. |
Based on these findings, the study authors concluded, "Expanding
HIV screening and treatment simultaneously offers the greatest health
benefit and is cost-effective."
Importantly, this model did not look at the more controversial approach
of treating everyone diagnosed as HIV positive, but rather treating
symptomatic people and those with a CD4 count below 350 cells/mm3,
the threshold in the previous U.S. ART guidelines -- now
raised to 500 cells/mm3.
However, the researchers added, "even substantial expansion
of HIV screening and treatment programs is not sufficient to markedly
reduce the U.S. HIV epidemic without substantial reductions in risk
behavior."
"[O]ur analysis highlights the importance of emphasizing risk
behavior reduction as HIV screening and treatment becomes increasingly
available," they elaborated in their discussion. "For
example, in addition to expanded screening and treatment, a 50%
reduction in sexual risk behaviors among MSM and needle sharing
among injection drug users could prevent 65% of new infections,
reducing HIV incidence to approximately 20 000 cases per year. This
suggests that programs to reduce risk behavior among high-risk persons
will probably be a key component of a successful prevention program.
If, however, uninfected persons increase risk behavior after screening,
some of the benefits would be attenuated."
Finally,
they noted, "Compared with other disease screening programs
in the U.S., 1-time HIV screening of low-risk persons and annual
screening of high-risk persons is economically attractive, with
a cost-effectiveness ratio less than $23,000 per QALY gained.
This compares favorably with other accepted interventions, including
screening for type 2 diabetes and breast cancer mammography."
Investigator
affiliations: Yale School of Management, New Haven, CT; Stanford
University, Stanford, CA; Veterans Affairs Palo Alto Health Care
System, Palo Alto, CA.
1/28/11
Reference
E Long, ML Brandeau, and DK Owens. The cost-effectiveness and
population outcomes of expanded HIV screening and antiretroviral
treatment in the United States. Annals of Internal Medicine
153(12): 778-789 (Abstract).
December 21, 2010.
Other Source
M
Fox. Better HIV screening worthwhile in U.S., study finds: 'one-time
screening of all adults would prevent 81,000 HIV-infections.'
Reuters Health. December 20, 2010.
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