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Vol. 33, 2011
Advance Access publication:
May 19, 2011
Routine Screening for Chronic Human Immunodeficiency Virus Infection: Why
Don’t the Guidelines Agree?
* Correspondence to Dr. Roger Chou, Department of Medical Informatics and Clinical Epidemiology, Oregon Health and Science
University, 3181 SW Sam Jackson Park Road, Mail Code: BICC, Portland, OR 97239 (e-mail: email@example.com).
Accepted for publication January 6, 2011.
Infection with human immunodeficiency virus remains a major public health problem in the United States.
Prominent guidelines from the U.S. Preventive Services Task Force and the Centers for Disease Control and
Prevention differ in their recommendations on whether and how to screen adults and adolescents not known to be
at higher risk. These discrepancies have led to controversy and debate as well as confusion among clinicians. This
article reviews principles of screening, explains specific issues related to screening for human immunodeficiency
virus, reviews the discrepancies between the US Preventive Services Task Force and the Centers for Disease
Control and Prevention guidelines and the methods used in each guideline, and describes potential reasons for the
discrepancies. The case of screening for human immunodeficiency virus illustrates how discrepancies between
guidelines may be related to different guideline development methods as well as the different perspectives of the
guideline development groups.
guidelines as topic; health planning guidelines; HIV; mass screening
Abbreviations: CDC, Centers for Disease Control and Prevention; HAART, highly active antiretroviral therapy; HIV, human
immunodeficiency virus; QALY, quality-adjusted life-year; USPSTF, U.S. Preventive Services Task Force.
Infection with human immunodeficiency virus (HIV) re-
mains a major public health problem in the United States. In
2006, 1.1 million US persons 13 years of age or older were
estimated to be living with HIVinfection (1), with an annual
incidence of about 56,000 new infections (2). The life ex-
pectancy of HIV-infected persons is now approaching that
of uninfected persons, primarily because of the effectiveness
and use of highly active antiretroviral therapy (HAART) (3,
4). Nonetheless, HIV infection remains incurable, and the
vast majority of patients started on HAART require indefi-
nite treatment, with its associated short- and long-term ad-
verse effects (5, 6). Although less common in the HAART
era, opportunistic infections still occur in patients with more
advanced HIV infection (acquired immunodeficiency syn-
drome) and are linked with serious morbidity and mortality.
Chronic HIV infection is associated with an average undis-
counted lifetime cost of over $500,000 and an average dis-
counted lifetime cost of more than $300,000 (both estimates
in 2004 US dollars) (7).
About 21% of patients with HIV infection are thought to
be unaware of their status (1). Screening could identify such
persons before they develop symptoms or complications
associated with chronic immune deficiency, which typically
occur only after many years of infection (8). Identification
of infected persons could allow earlier initiation of HAART
therapy or prophylaxis for opportunistic infections, thus re-
ducing the morbidity and mortality associated with ad-
vanced disease. Importantly, screening could also reduce
the incidence of new HIV infections. Persons unaware of
their HIV-positive status may unknowingly put uninfected
individuals at risk because of risky sexual or intravenous
drug use behaviors. Knowledge of positive HIV serostatus
could reduce such behaviors, thus resulting in lower trans-
mission rates (9). Even for persons who continue to engage
in risky behaviors, earlier initiation of HAART therapy
could decrease risk of transmission by reducing viral
load—which predicts the degree of infectiousness—to
lower or undetectable levels (10).
Clinicians look to screening guidelines to help guide their
practice, and they receive recommendations from many dif-
ferent organizations, including professional societies, gov-
ernmental agencies, health care payers, and others. In some
7Epidemiol Rev 2011;33:7–19
by guest on November 14, 2015
cases, screening recommendations from different groups
largely agree with one another, and clinical decisions are
relatively straightforward. For example, there is little debate
regarding screening for high blood pressure. In other cases,
screening recommendations disagree or conflict with one
another in important ways. Recent examples include mam-
mography screening of women 40–50 years of age (11),
prostate cancer screening (12, 13), colon cancer screening
(14), and screening for lipid disorders in children (15, 16).
Such discrepancies are a source of confusion and frustration
to clinicians, who would like to have consistent guidance
about what to do.
In the case of HIV screening, prominent guidelines from
the U.S. Preventive Services Task Force (USPSTF) (17) and
the Centers for Disease Control and Prevention (CDC) (18)
include some discordant recommendations, which have led
to controversy and debate. The main area of discrepancy
concerns whether to routinely perform HIV screening in
persons not known to be at high risk and, to a lesser degree,
how to implement screening in clinical practice.
The discrepancies between the USPSTF and CDC HIV
screening guidelines provide an opportunity to explore how
groups can examine essentially the same evidence about
a screening intervention, yet reach different conclusions
about what should be done. Understanding the reasons for
the discrepancies can provide insight into how different
methods for evaluating evidence and generating recommen-
dations as well as different perspectivescan affect theguide-
line development process.
PRINCIPLES OF SCREENING
If a patient asks a medical practitioner for help, the doctor
does the best he can. He is not responsible for defects in
medical knowledge. If, however, the practitioner initiates
screening procedures he is inavery different situation. He
should, in our view, have conclusive evidence that screen-
ing can alter the natural history of the disease in a signif-
icant proportion of those screened.
A. L. Cochrane and W.W.Holland, 1971 (19, p. 3).
Screening has been defined as ‘‘the systematic application
of a test or inquiry, to identify individuals at sufficient risk of
a specific disorder to warrant further investigation or direct
preventive action, amongst people who have not sought
medical attention on account of symptoms of that disorder’’
(20, p. 12). The purpose of screening is to help identify
a condition before it would typically be diagnosed based
on the presence of clinical signs or symptoms.
Screening and early detection intuitively seem desirable
(21), which has led to a tendency to assume that screening
interventions are beneficial, or that doing something to de-
tect a disease is inherently better than doing nothing. Un-
fortunately, knowing whether it makes sense to offer
a screening intervention is not so straightforward. In 1975,
Frame and Carlson (22) presented criteria that should be met
for a disease to merit consideration for screening (Table 1).
Similar criteria have been utilized by numerous groups eval-
uating screening interventions, including the World Health
Organization (23), the Canadian Task Force on Preventive
Health Care (24), the USPSTF (25), the UK National
Screening Committee (26), and the Australian Government
Department of Health and Aging (27). The disease should
have an important societal burden based on its prevalence
and effects on quality of life or mortality, there should be an
asymptomatic phase in which early treatment is more effec-
tive than treatment delayed until the development of symp-
toms, and there should be acceptable screening tests as well
as treatments. Ultimately, screening interventions that
meet all these criteria must also be shown to be associated
with benefits that clearly outweigh the harms.
A critical difference between screening and most other
medical interventions is that it is performed on people not
seeking help for a symptom. This difference has important
ethical implications because every adverse outcome of
screening is iatrogenic and could have been avoided. These
include the effects of labeling a patient with a disease, the
anxiety associated with the screening test, the harms of
screening and subsequent interventions, and the burdens
and costs associated with screening. Because the popula-
tions affected by screening are often large and the condi-
tions to be detected usually uncommon, harms incurred by
even a small percentage of those screened can affect a large
number of people (25). In addition, since screening is per-
formed on persons who do not have recognized symptoms
or signs of the targetcondition, there is the real potential that
the screening intervention and subsequent treatments could
make them worse. One example is breast self-examination
for breast cancer screening, which was associated with no
improvement in breast-cancer-related mortality compared
with no breast self-examination in randomized trials but
increased the number of biopsies by 50%–100% (28).
Therefore, the potential for doing greater harm than good
must be taken seriously, and convincing evidence of benefits
should be required before a screening intervention is
SPECIFIC ISSUES RELATED TO HIV SCREENING
Current USPSTF (17, 29) and CDC (18) guidelines
largely agree with regard to many aspects related to HIV
Table 1. Six Criteria That Should Be Met to Justify Screeninga
1The disease should have a significant effect on
quantity or quality of life.
2The incidence of the condition should be sufficient to
justify the cost of screening.
3The disease should have an asymptomatic period during
which detection and treatment significantly reduce
morbidity and/or mortality.
4Tests should be available at reasonable cost to detect
the condition during the asymptomatic period.
5Acceptable methods of treatment should be available.
6Treatment during the asymptomatic phase should yield
a therapeutic result superior to that obtained by
delaying treatment until symptoms appear.
aSource: Frame and Carlson (22).
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