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Much of the history and physical examination obtained at each
health supervision visit is directed toward the identification of
undetected problems or their risk factors in an effort at secondary
prevention of undesirable outcomes. Screening for these conditions
implies the presumptive identification of disease in an asymptomatic
individual before it becomes clinically evident. Screening is not
diagnostic; a patient with a positive screening test must undergo further
evaluation for definitive diagnosis.1 Pediatricians must
be aware not only of current recommendations regarding screening
and the specific tests available but also of the basic principles
and concepts behind screening in order to evaluate whether a given
program does more good than harm for their particular patients and
community.
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Screening assumes that identified persons will undergo definitive
diagnostic testing and will subsequently benefit by earlier implementation
of treatment or prevention programs. In deciding what conditions
are worth screening for, the clinician must consider the following:
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- Is the disease common in the population and serious enough
to warrant screening?
- Is there an acceptable treatment for the patients who have
the condition?
- Will early diagnosis favorably influence the outcome?
- Is there a good screening test available?2
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The effectiveness of a given screening program can be demonstrated
by performing a randomized clinical trial in which all pertinent outcomes
are evaluated. Unfortunately, such data are often lacking or difficult
to obtain. In the absence of such studies, the value of a given screening
program must be defined in relation to the characteristics of the
condition being screened for, the test being used, the population being
evaluated, and the larger social context in which decisions regarding
the value of detection and the allocation of resources are being
made.
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Identification of conditions for which no treatment exists or
for which the benefit of existing therapy is unproven, is of questionable value,
or is potentially harmful. Even if an effective intervention exists,
the clinician must weigh the potential risks and benefits of the treatment
itself with that of the identified condition and consider the impact
of public acceptance on compliance with recommendations about screening
and treatment.2
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The costs associated with a screening program must be broadly
defined. Costs include not only the screening itself but also the
subsequently required diagnostic, therapeutic, and supportive services.2 The
psychological impact on individuals identified as false positives
and the costs involved in definitive evaluation of these individuals
may be significant and should not be underestimated.3,4 (See
also Chapter 98.)
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Early identification through screening does not always imply
a better outcome. If the health care system or community is unable
to provide the necessary subsequent diagnostic and therapeutic services,
the ultimate value of the screening program is questionable. In
addition, if persons at greatest risk do not avail themselves of
the screening program, or if individuals with abnormal screening
tests do not follow through with subsequent ...