[Acute confusion syndrome in the hospitalized elderly].

Our purpose was to determine the in-hospital incidence of delirium among elderly patients, its relation to previous cognitive impairment and the time between admission and its development. We performed an observational study of follow-up in the internal medicine area of a university hospital. We included consecutively and prospectively every patient 70 years or older upon admission. Patients with delirium on admission were excluded, as also were those taking antipsychotic drugs, with severe language or audition impairment, or coming from other sites of internation. We subsequently eliminated patients whose follow-up had not ended by the time the study was concluded, and patients in whom psychosis was diagnosed. Clinical and laboratory data were collected, and patients were prospectively followed until discharge from the hospital, using the Confusion-Assessment-Method (CAM) for the diagnosis of delirium. We analyzed 61 patients of whom 13 developed delirium while hospitalized (in-hospital incidence: 21.31%--CI 95%: 11.03-31.59%). Patients with delirium had had lower scores on Mini Mental State upon admission (median 17 vs 22; p 0.001). During the first 4 days of hospitalization 58.3% of delirium cases occurred not modifying the duration of hospitalization (average: 10.22 days vs 14.38; p = NS). We conclude that the incidence of delirium is high among hospitalized elderly patients specially during the first days, and in those with previous cognitive impairment. We suggest that delirium could be an associated disorder in severe diseases among patients with previous cognitive damage.