Confusion in the hospitalized elderly: incidence, onset, and associated factors.

Seventy-one non-surgical patients over age 60 years were studied to obtain information about the incidence, onset and variables associated with the onset of confusion. The incidence of confusion was 38%; 27 of the 71 subjects developed confusion during hospitalization. Nineteen of the 27 patients developed confusion by the second day of hospitalization; no new cases of confusion were detected after the sixth day of hospitalization. An examination of the psychophysiologic variables associated with the onset of confusion produced a profile of the confused elderly patient. Confused patients were: hypernatremic, hypokalemic, hyperglycemic, hypotensive, had elevated blood levels of creatinine and urea nitrogen, received more medications, were more frequently perceived by nurses as confused, had more orienting objects in their immediate environment, and fewer interactions with significant others. Recommendations for the continued investigation and care of confused patients are offered.