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Topic: Specificity (tests)

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	Prostate Cancer Tests Vary in Specificity, Sensitivity
		Some tests are more sensitive for identifying patients with cancer and others are more specific, meaning that fewer patients without cancer test false positive.
		The Total PSA test, which measures nanograms of PSA per milliliter of blood, is a more sensitive test.
		The Free PSA test, which measures the percentage of PSA that is not bound to proteins in the blood, is more specific.
	healthlink.mcw.edu /article/1018800849.html (437 words)

	Title 21 Code of Federal Regulations
		Specificity and avidity tests shall be performed using test procedures approved by the Director, Center for Biologics Evaluation and Research (HFN-830), Food and Drug Administration, 8800 Rockville Pike, Bethesda, MD 20892.
		Each of these tests shall be conducted and interpreted independently, and any discrepancy between the results of these two tests shall be resolved by testing with at least one additional antiserum before concluding that the antigen is present or absent.
		To be satisfactory for release, each filling of Hepatitis B Surface Antigen shall be tested against the Reference Hepatitis B Antiserum Panel and shall be sufficiently potent to be able to detect the antibody in the appropriate sera of the reference panel by all test methods recommended by the manufacturer in the package insert.
	www.betterchem.com /21cfr/21cfr660.htm (6444 words)

	Statistical Guidance on Reporting Results from Studies Evaluating Diagnostic Tests; Draft Guidance for Industry and FDA ...
		A diagnostic test is a measurement used to indicate the presence or absence of a specific disease or condition in a patient from a specific patient population.
		When the new test is compared to clinical status or to a perfect standard, the sensitivity of the new test is estimated as the proportion of specimens from diseased patients where the test is positive.
		Similarly, the specificity of the test is estimated as the proportion of specimens from non-diseased patients where the test is negative (See the Appendix for an example of this calculation).
	www.fda.gov /cdrh/osb/guidance/1428.html (5884 words)

	UKBTS Guidelines - Production and use of reagents (Site not responding. Last check: 2007-10-17)
		For specificity testing, red cells stored in the liquid state in a medium not specifically formulated to preserve the reactivity of antigens, should be used within 7 days of collection.
		Specificity should be determined by testing the reagent with red cells from a minimum of 4 different donors known to express the antigen corresponding to the specificity of the reagent and 4 different individuals known to lack that antigen.
		Tests for the presence of contaminating ABO antibodies should be performed with red cells from a minimum of 2 individuals of group A1 and 2 of group B who lack the antigen corresponding to the antibody specificity under test.
	www.transfusionguidelines.org.uk /uk_guidelines/ukbts6_143.html (2599 words)

	s000911a - Intrinsic Factor Antibody Tests, Sensitivity & Specificity
		Tests for pernicious anemia: serum intrinsic factor blocking antibody.
		This highly sensitive test can be combined further with the highly specific serum anti-intrinsic factor antibody test for the presumptive diagnosis of pernicious anemia when definitive tests (the Schilling test or gastric analysis for intrinsic factor) cannot be done or results are inconclusive.
		Sensitivity, specificity, and accuracy of the dual-isotope Schilling test were 83%, 98%, and 94% for pernicious anemia, and 67%, 90%, and 86% for malabsorption syndrome, respectively.
	www.emory.edu /WHSCL/grady/amreport/litsrch00/s000911a.html (3683 words)

	EVALUATING DIAGNOSTIC AND SCREENING TESTS (Site not responding. Last check: 2007-10-17)
		A diagnostic test is valid if it detects most people with the target disorder and excludes most people without the disorder, and if a positive test usually indicates that the disorder is present (Greenhaigh T 1997).
		Specificity: Specificity is the proportion of truly non-diseased person who are so identified by the test (Last JM 1995.
		A test which is good in a clinical setting may be completely useless in a community setting (if used as a screening test) because prevalence rates tend to be lower in the community.
	www.sunmed.org /Dia.html (1616 words)

	EVALUATION OF DIAGNOSTIC TESTS: THE EPIDEMIOLOGICAL APPROACH[1] - DANIEL F. FEGAN
		At the population level the use of diagnostic tests is made more complicated by population effects such as prevalence of the pathogen, expression and impact of the disease on the population and potential for pathogen spread among others.
		In addition to the sensitivity and specificity of the test, the number of animals from the group which are tested (the sample size), the true prevalence and the number of positives required to classify the population as infected are important.
		As a general rule of thumb, a test with at least 95% sensitivity and 75% specificity should be used to rule out a disease and one with at least 95% specificity and 75% sensitivity used to rule in a disease (Pfeiffer, 1998).
	www.fao.org /DOCREP/005/X4946E/x4946e0b.htm (3190 words)

	Comparison of Two ELISA Screening Tests and a Non-Commercial Glutaraldehyde Coagulation Screening Test for the ...
		In contrast, tests such as the glutaraldehyde coagulation test is a non-specific test, because it detects other proteins in addition to immunoglobulins, such as fibrinogen, acute phase proteins, albumin, and hemoglobin [13].
		The sensitivity (Se), specificity (Sp), and prevalence (P) of FPT were calculated for each screening test by the formulas shown in Table 1, using a statistical software program [e] Ninety-five percent confidence intervals were determined for the Se and Sp of all screening tests as well as the prevalence.
		The PPV of the test was markedly improved with the modification to SNAP ELISA 2.
	www.ivis.org /proceedings/AAEP/2003/mccluret/chapter_frm.asp?LA=1 (3122 words)

	Screening Tests To Detect
		For endocervical swab specimens, the sensitivity of LCR (85.5%) exceeded that of culture (74.7%) by 10.8% and that of the hybridization test (61.9%) by 23.6%.
		Testing to satisfy the first purpose requires a method that is highly sensitive, whereas satisfying the second purpose requires a method that is highly specific.
		Using highly specific tests is critical with preadolescent children for whom the diagnosis of a sexually transmitted infection might lead to initiation of an investigation for child abuse.
	www.cdc.gov /mmwr/preview/mmwrhtml/rr5115a1.htm (15820 words)

	eMedicine - Screening and Diagnostic Tests : Article by Theodore Gaeta, DO, MPH (Site not responding. Last check: 2007-10-17)
		Specificity is important when one is screening for rare diseases because false-positive results are possible when the test is not specific.
		Similarly, the specificity of a test is determined by identifying the proportion of patients without disease in whom the test result is negative, as follows: d/(b + d), where b is the number of true-negative results, and d is the number of false-positive results.
		The operating characteristics of a test or procedure cannot, per se, be used to determine the presence or absence of disease, unless the test result is always positive when disease is present (ie, 100% sensitivity) or always negative when the disease is absent (ie, 100% specificity).
	www.emedicine.com /emerg/topic779.htm (3101 words)

	NZPPS paper - Changes In Plant Attack Over Time In No-Choice Tests: An Indicator Of Specificity (Site not responding. Last check: 2007-10-17)
		No-choice testing of insects for extended periods is considered by some weed biological control practitioners to be inappropriate for host range testing due to apparent acceptance of hosts that are not accepted in multiple choice tests.
		In the host specificity testing of potential weed biocontrol agents, multiple choice tests in which candidate agents are given access to a number of plant species including the target weed are often favoured, partly because this can be an efficient method of screening several test plants.
		If the proportion accepting the test plant is close to zero when not deprived, but increases with increasing deprivation, then not only can we conclude that deprivation is partially responsible for the acceptance, but we get an indication of the circumstances under which this insect may utilise this plant in the field.
	www.hortnet.co.nz /publications/nzpps/proceedings/97/97_214.htm (2210 words)

	BMJ Education and debate
		The validity of urine testing for glucose in diagnosing diabetes has been looked at by Andersson and colleagues,(3) whose data I have adapted for use (expressed as a proportion of 1000 subjects tested) in table 3.
		Although the sensitivity and specificity of a test are virtually constant whatever the prevalence of the condition, the positive and negative predictive values depend crucially on prevalence.
		The Guthrie heel-prick screening test for congenital hypothyroidism, performed on all babies in Britain soon after birth, is over 99% sensitive but has a positive predictive value of only 6% (it picks up almost all babies with the condition at the expense of a high false positive rate),(10) and rightly so.
	bmj.bmjjournals.com /archive/7107/7107ed.htm (3137 words)

	Novel Internet-based Tool for Correcting Apparent Sensitivity and Specificity of Diagnostic Tests to Adjust for ...
		The sensitivity and specificity of the test is given by Se1 and Sp1 when at least 85% of maximum heart rate is achieved and by Se2 and Sp2 when less than 85% of maximum heart rate is achieved.
		true-positive (TP) and false-negative (FN) and specificity (Sp)
		A model for assessing the sensitivity and specificity of tests subject to selection bias: application to exercise radionuclide ventriculography for diagnosis of coronary artery disease.
	radiographics.rsnajnls.org /cgi/content/full/22/2/e4 (3181 words)

	Rapid Diagnostic Tests : Accuracy of Diagnostic Tests
		The sensitivity of a test is the probability that it will produce a true positive result when used on an infected population (as compared to a reference or "gold standard").
		The specificity of a test is the probability that a test will produce a true negative result when used on a noninfected population (as determined by a reference or "gold standard").
		This article describes the sensitivity and specificity of several rapid HIV diagnostic tests, both individually and in a testing algorithm using several tests.
	www.rapid-diagnostics.org /accuracy.htm (944 words)

	CSS Style Attribute Specificity Tests (Site not responding. Last check: 2007-10-17)
		In all cases, the prerequisite tests must have green (text/fill) to pass, and the color of the (text/fill) in the specificity test corresponds to the colors below.
		SVG: Prerequisite test #1, Prerequisite test #2, Style attribute specificity test
		XHTML: Prerequisite test #1, Prerequisite test #2, Style attribute specificity test
	dbaron.org /css/test/sas (84 words)

	Polymerase Chain Reaction for the Diagnosis of HIV Infection in Adults: A Meta-Analysis with Recommendations for ...
		The lower estimate (thin line) was calculated by including indeterminate PCR test results to determine a conservative estimate for sensitivity and specificity.
		It is assumed that PCR has a joint sensitivity and specificity between 97.0 (thin curves) and 98.1 (thick curves), consistent with the upper- and lower-estimate summary receiver-operating characteristic curve based on all 96 included studies.
		and specificity of the enzyme immunoassay to be 99.68% and 98.46%,
	www.annals.org /cgi/content/full/124/9/803 (8795 words)

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