Delirium after cardiac surgery: a critical review.

Numerous articles have been published investigating the incidence of and risk factors for delirium after cardiac surgery. Smith and Dimsdale reviewed the literature on postcardiotomy delirium in 1987 using a meta-analysis of 44 research studies. However, doubts about their methods and results caused the authors to re-examine the literature using these 44 references as well as computerized literature searches to gather research and review papers from medical journals. Delirium after cardiac surgery appeared to be ill-defined in most of these studies. The methods and instruments used to assess delirium proved to be very different, and the patient samples were rather heterogeneous. Therefore, in most cases, the results are not comparable. Only a small number of the studies that were examined fit the criteria for statistical meta-analysis. On the basis of our analysis, a tentative conclusion may be drawn that the incidence of postcardiotomy delirium has declined slightly and that no strong risk factors have yet been identified.