Adverse Drug Reactions Due to Opioid Use in Oldest-Old Patients Visiting the Emergency Unit of the Geneva Geriatric Hospital.

Opioid use has much increased in several countries during the last two decades, accompanied by a rise in associated morbidity and mortality, especially in the United States. Data on a possible opioid crisis are scarcer in Europe. We performed a study aiming to assess the frequency of adverse drug reactions (ADR) related to opioids in patients presenting to the emergency unit (EU) of a geriatric tertiary Swiss University Hospital. This particular setting is intended for patients aged 75 and older. Our retrospective, monocentric survey of opioid use and related ADR was conducted over two months in 2018. The main and secondary outcomes were the frequency of EU visits considered due to an opioid ADR and insufficient pain relief, respectively. Current opioid use was identified in 20.3% (n=99) of the 487 included EU visits (mean age 86). An ADR was the suspected cause of the EU visit in 22 opioid users, mainly fall-related injury and gastrointestinal disorders. All these patients had at least one comorbid condition. In 19/22 cases (86%) of ADR, a drug-drug interaction might have been involved. In 12 opioid users (12%), insufficient pain relief was suspected as the cause of the EU visit. In conclusion, one-third of opioid users visiting a geriatric EU consulted for a problem related to its use mainly adverse drug-related reaction (22%) followed by insufficient pain relief (12%).