Decision aids (DA) are interventions designed to support individuals in making specific and deliberate health- or illness-related choices. The assessment of the quality of DAs is presently under discussion. On the basis of a systematic literature review, this article provides a survey of methods and open questions in quality assessment of DAs. Quality assessment of DAs is presently limited to the evidence of efficacy through controlled trials based on single-outcome measures. However, since DAs are multicomponent interventions, single-outcome trials are insufficient for complete quality assessment; also, it is difficult to identify the causes for the adequacy or inadequacy of a particular DA. The present analysis identified an elaborated and systematic guide to evaluate DAs. On the basis of this instrument, we propose a novel instrument which is aimed at disclosing the complex relation between background theory, methods, and aims of a DA. The proposed instrument is still under development and has to be evaluated in validation studies.
