Critical Appraisal
The Interpretation of Test Results

Michael Binder and Stephan Dreiseitl

Critical Appraisal Review covers various topics in epidemiology and related fields that are useful to the practicing physician in understanding and using published studies on skin disease topics. Readers may suggest future topics for this series by writing to the Editorial Office.

Sensitivity, specificity, predictive values positive and negative, and ROC curves are basic terms with broad applicability that are often indespensible for intellegent discussion of testing, screening, and other issues in clinical epidemiology. You need to know them if you are to understand these issues. Here is a guide.

Martin A. Weinstock


Background: Dermatologists need to interpret an increasing number of research studies and diagnostic tests. Understanding the techniques for interpreting test results and making decisions based upon those tests represent important tools for decision making for both clinicians and researchers.

Objective: This article focuses briefly on the key parameters of diagnostic tests: sensitivity, specificity, prevalence, predictive values, likelihood ratios, and the concept of receiver-operating-characteristic (ROC) curves. A simple example is presented in a step-by-step manner.

Conclusion: The principles of interpreting test results are easy to learn and applicable in daily clinical routine. Therefore, dermatologists should be familiar with the concepts outlined in this paper.


Antécédents: Les dermatologues doivent interpréter un nombre croissant de rapports de recherche et d’examens diagnostiques. Les techniques d’interprétation et les méthodes décisionnelles fondées sur ces examens sont d’importants outils pour les cliniciens comme pour les chercheurs.

Objectif: Présenter étape par étape un exemple simple de la vérification des paramètres essentiels des examens diagnostiques, brièvement évoqué dans l’article, soit: sensibilité, spécificité, prévalence, valeurs prédictives, rapports de vraisemblance et concept des courbes ROC.

Conclusion: Les principes de l’interprétation des résultats d’examens s’apprennent et s’appliquent facilement dans la pratique quotidienne. Les dermatologues devraient donc bien comprendre les concepts abordés dans l’article.

Received 8/19/99. Accepted for publication 10/12/99.

Decision Systems Group, Brigham and Women’s Hospital, Division of Health Science Technology, Harvard Medical School, Massachusetts Instititute of Technology, Boston, Massachusetts, USA

Michael Binder, MD, was supported by a grant from the Max Kade Foundation, and Stephan

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JCMS 3(6) Contents