The Frequency of Missed Delirium in Patients Referred to Palliative Care in a Comprehensive Cancer Center

Background: Delirium is one of the most common neuropsychiatric complications in advanced cancer patients with a frequency of up to 85 % before death. It is associated with adverse clinical outcomes such as increased morbidity and mortality as well as significant family and patient distress. The aim of our study is to determine at the frequency of missed delirium (MD) and identify factors associated with MD.

Methods: Seven hundred seventy-one consecutive palliative care inpatient consults from August 1, 2009 to January 31, 2010 were reviewed. Demographics, Memorial Delirium Assessment Scale (MDAS), Edmonton Symptom Assessment Scale (ESAS), primary referral symptom, Eastern Cooperative Oncology Group (ECOG), and physician diagnosis of delirium were collected along with delirium etiology, subtype, and reversibility. Delirium was diagnosed with a MDAS score of ≥ 7 or by a palliative medicine specialist using Diagnostic and Statistical Manual of Mental Disorders, 4th Edition Text Revision (DSM-IV TR) Criteria. MD was reported in those patients found to have delirium by the palliative medicine specialists but were referred by the primary team for other reasons besides delirium. Chi-squared test and Wilcoxon-Mann-Whitney test were used to examine the difference on measurements among or between different groups. Univariate logistic regression model was applied to assess for associations for MD.

Results: Two hundred fifty-two (33 %) had a diagnosis of delirium by the palliative medicine specialist. One hundred fifty-three (61 %) were missed by the primary referring team. Females comprised 53 % (n = 81), white 62 % (n = 95), and pain was the most common referral symptom (n = 77, 50 %). Hypoactive delirium was the most common subtype of delirium in MD (n = 47, 63 %). Opioid-related delirium was the most common etiology of MD (n = 47, 31 %). Patients referred for pain were more likely to have MD (odds ratio (OR) = 2.57, p = 0.0109). Of the 82 patients with delirium that was reversed, 67 % (n = 55) had a diagnosis of MD.

Conclusion: Sixty-one percent of patients with a diagnosis of delirium by a palliative care specialist were missed by the primary referring team. Patients with MD were frequently referred for pain. Universal screening of cancer patients for delirium is recommended.