Relationship between pain, opioid treatment, and delirium in older emergency department patients

BACKGROUND: Emergency department (ED) stay and its associated conditions (immobility, inadequate hydration and nutrition, lack of stimulation) increase the risk of delirium in older patients. Poorly controlled pain, and paradoxically opioid pain treatment, have also been identified as triggers for delirium. The aim of this study was to assess the relationship between pain, opioid treatment, and delirium in older ED patients. METHODS: A multicenter prospective cohort study was conducted in four hospitals across the province of Quebec (Canada). Patients aged ≥65 years old, waiting for hospital admission between March and July 2015, who were non-delirious upon ED arrival, independent or semi-independent in their daily living activities, and had an ED stay of at least 8 hours were included. Delirium assessments were conducted twice a day during the patient's entire ED stay and their first 24 hours on the hospital ward using the Confusion Assessment Method (CAM). Pain intensity was evaluated using a visual analog scale (VAS: 0-100) during the initial interview, and all opioid treatments were documented. RESULTS: A total of 338 patients were included; 51% were female, mean age was 77 years ± 8. Forty-one patients (12%) experienced delirium during their hospital stay occurring within a mean delay of 47 hours ±19 after ED admission. Among patients with pain intensity ≥65 from VAS (0-100), 26% experienced delirium compared to 11% for patients with pain <65 (p<0.01) and no significant association was found between opioid consumption and delirium (p=0.31). Logistic regression controlling for confounding factors showed that patients with pain intensity ≥65 are 4.4 (95% CI: 1.3-15.4) times more likely to develop delirium than patients who had pain <65. CONCLUSIONS: Severe pain, not opioids, is associated with the development of delirium during ED stay. Adequate pain control during the hospital stay may contribute to a decrease in delirium episodes.