Ethical research in delirium: arguments for including decisionally incapacitated subjects.

Here we describe how more important findings were obtained in a delirium study by using an informal assessment of mental capacity, and, in those who lacked capacity, obtaining consent later when or if capacity returned or a proxy was found. From a total of 233 patients 23 patients lacked capacity as judged by our informal capacity judgment and 210 did not. Of those who lacked capacity, 13 agreed to enter in the study. Six of them regained capacity later. When these 13 participants were excluded from analysis, significant findings were no longer evident. These results show that by the inclusion of subjects who lacked capacity the results of analyses of the condition from whish they suffer are altered. We suggest that this approach to the study of delirium is more ethical than the usual system of strict exclusion of people who lack capacity to give consent and for whom assent is not available.