Clinical subtypes of delirium and their relevance for daily clinical practice: a systematic review

Background: Delirium is a disorder that besides four essential features consists of different combinations of symptoms. We reviewed the clinical classification of clusters of symptoms in two or three delirium subtypes. The possible implications of this subtype classification may be several. The investigation and exploration of clinical subtypes of delirium may provide information concerning the etiology, the pathogenesis, and the prognosis of delirium, but also may have therapeutic consequences.

Methods: We searched several database for English-language articles. Selected articles were cross-checked for other relevant publications.

Data synthesis and conclusion: We conducted a systematic review and retrieved ten clinical studies. The studies described in this review show different results, partly due to methodological problems and possibly by lack of a standard classification for delirium subtypes. According to the present literature a useful and reproducible method to classify (patterns of) symptoms in delirium subtypes seems to be the general rating of and division in to psychomotor subtypes. The Memorial Delirium Assessment Scale (MDAS) and the Dublin Delirium Assessment Scale (DAS) appear to be reliable methods, together with the new version of the Delirium Rating Scale (DRS-R-98).