Diagnosing delirium in patients who are in non-acute care settings is sometimes difficult logistically, since the assessment of delirium has traditionally required a face-to-face interview. Marcantonio and colleagues conducted a study to determine whether delirium could be diagnosed reliably by telephone in patients who, for whatever reason, cannot be interviewed face-to-face.

Patients who were at least 65 years of age and had been admitted to a hospital for surgical repair of a hip fracture were included in the study. Daily interviews to detect delirium were conducted during the hospital stay, and a telephone follow-up was completed one month after surgery. Patients were excluded from the study if they were unable to use a telephone at baseline or were unable to participate in the face-to-face interviews. A face-to-face interview took place as soon as possible after the telephone interview (range: one to four days).

During the telephone interview and the follow-up face-to-face interview, a Mini-Mental State Examination (MMSE), modified for the telephone interview, a Delirium Symptom Interview (DSI) and a Confusion Assessment Method (CAM) diagnostic algorithm were completed. Patients were classified as having delirium if their CAM assessment results were positive or if they were unable to use a telephone because of confusion (that is, if the patient had experienced an acute decline in cognitive functioning since baseline testing).

The study included a total of 41 patients. Of these, 32 percent had dementia before the hip fracture based on the enrollment interview, 37 percent had postoperative delirium and 10 percent were delirious at discharge. The mean length of hospital stay was six (± four) days. Eight of the 41 patients (20 percent) were considered to be delirious at the time of the telephone interview. After the face-to-face interviews, six of the patients (15 percent) were diagnosed with delirium. All of the patients who were delirious at the one-month follow-up had been diagnosed with delirium at some point during their hospitalization, but not necessarily at hospital discharge. None of the patients who were not delirious at the time of the telephone interview was subsequently judged to be delirious during the face-to-face interview.

The authors conclude that a telephone interview that does not suggest new or recurrent delirium can effectively rule out delirium; however, any evidence of delirium during a telephone interview should be confirmed by a face-to-face evaluation by a physician.