title: [How blind is a double-blind trial really? Validity of controlled investigations].
abstract: During a double blind trial lasting 4 weeks (Diazepam versus Loxapin), two investigators tried to identify the given drug prematurely. Only the more experienced investigator was able to identify the two drugs (p = 0.01). His judgement was based neither on observation of side-effects nor on a clinical improvement but apparently on a summary of particular subtle effects, the cognition of which requires a specific experience. The use of an adequate comparative drug instead of a placebo in a double blind study does not completely prevent a premature decoding but should reduce this risk and therefore increase the validity of the method.
mesh_terms: D001007:Anxiety / Q000188:drug therapy; D002986:Clinical Trials as Topic; D003975:Diazepam / Q000627:therapeutic use; D004311:Double-Blind Method / Q000592:standards*; D004341:Drug Evaluation; D006801:Humans; D008152:Loxapine / Q000627:therapeutic use; D012107:Research Design / Q000592:standards*
chemical_list: D008152:Loxapine; D003975:Diazepam
vernacular_title: Wie blind ist ein Doppelblindversuch wirklich? Zur Frage der Validitt einer kontollierten Untersuchung.