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Prevalence of nodules
Evaluating the
diagnostic value
of nodule palpation requires a reference diagnosis
which serves as gold standard. For the data of the graph below,
we have used skin snip diagnosis as the reference.
The proportions of true-positive, false-positive, false-negative and
true-negative diagnoses depend on the age of the patients.
Two main findings are:
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the probability of a true-positive palpation increases strongly with age
(simply because the number of nodules increases with age and thus,
the probability to find at least one of them increases).
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the probability of a true-negative palpation decreases strongly with age
(simply because the number of nodules increases with age and thus,
the probability to find none of them decreases).
These two examples show a major obstacle in the diagnosis of parasitic infections:
the diagnosis result for a patient depends on how many parasites he/she harbours!
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Figure: Age-dependent proportions of 2560 individuals with
true-positive (PTP),
false-positive (PFP),
false-negative (PFN) and
true-negative (PTN) palpation diagnosis,
taking skin snip diagnosis as reference. The proportions are classified
such that sample sizes across age classes are comparable.
(Source: Duerr et al., 2007)
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Related pages:
Nodules,
Diagnosis by palpation of nodules.
Further reading:
Duerr HP, Raddatz G, Eichner M, 2007. Diagnostic value of nodule palpation in onchocerciasis. Transactions of the Royal Society of Tropical Medicine and Hygiene: in press.
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Responsable de cette page:
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Dr. H.-P. Duerr
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Webmaster:
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Prof. Dr. M. Eichner
(dernière modification de cette page:
13 juli 2009)
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Collaborateur:
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Dr. M. Eichner
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Soutenu financièrement par:
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Deutsche Forschungsgemeinschaft (DFG, DI 308/12-1) |
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Traduit en français par:
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Claire Le Roux,
Université de Valenciennes et du Hainaut Cambraisis (UVHC),
Institut des Sciences et Techniques (ISTV), France
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Avertissement:
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L'Université Eberhard Karl de Tübingen,
le Centre Hospitalier Universitaire de Tübingen,
le Département de Biométrie Médicale (IMB),
ainsi que les auteurs de cette page déclinent toute responsabilité pour le contenu des pages auxquelles cette page renvoie
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