Etiologies of Delirium and Their Relationship to Reversibility and Motor Subtype in Cancer Patients

Background: Delirium is one of the most commonly encountered complications in patients with cancer. The etiology of delirium in cancer is often multi-factorial, and few reports have examined the causes of delirium. This study investigated the causes of delirium and their association with reversibility and motor subtypes of delirium in cancer patients. Methods: The subjects were inpatients with cancer who had been referred to our Department of Psychiatry and diagnosed with delirium by psychiatrists. The causes of delirium were determined using standard operationalized criteria. The association between delirium reversibility and each clinical factor was examined in detail and longitudinally. Results: Data were available from a total of 100 patients. Among them, 58% had hyperactive delirium and 14% had hypoactive delirium. Delirium improved in 56% of the patients after 1 week of standard treatment. The most frequent causes of delirium were opioids (29%), inflammation (27%), dehydration and/or sodium level abnormalities (15%). While two or more causes were identified in 40% or more of the cases, the cause of delirium was not identified in 20% of the patients. Neither reversibility nor motor subtypes of delirium was associated with any specific etiological factor. Conclusions: When treating delirium, prevalences of the causes of delirium, as identified in this study, should be kept in mind. Further research is required to investigate what specific treatments may facilitate the prompt recovery from delirium among cancer patients.