title: [Levels of evidence are insufficient].
abstract: Medical knowledge is based on various types of research, each with its own 'indication' and 'contraindication'. Although the randomised controlled trial is highly useful to quantify small differences in treatment effects, it is not able to establish all medical knowledge needed at the bedside. In most instances of non-therapeutic research, observational data are more useful. Evaluating all medical knowledge on the basis of a single hierarchy of level of evidence is therefore seriously flawed.
authors.affiliation: Leids Universitair Medisch Centrum, afd. Klinische Epidemiologie, C9-P, Postbus 9600, 2300 RC Leiden. j.p.vandenbroucke@lumc.nl
authors.forename: J P
authors.initials: JP
authors.lastname: Vandenbroucke
mesh_terms: D002983:Clinical Competence; D003695:Delivery of Health Care / Q000592:standards*; D019317:Evidence-Based Medicine; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D016032:Randomized Controlled Trials as Topic