Adverse drug events as a cause of hospitalization in older adults.

Older adults are about four to seven times more likely than younger persons to experience adverse drug events (ADEs) that cause hospitalization, especially if they are women and take multiple medications. The prevalence of drug-related hospitalizations has been reported to be as high as 31%, with large heterogeneity between different studies, depending on study setting (all hospital admissions or only acute hospital admissions), study population (entire hospital, specific wards, selected population and/or age groups), type of drug-related problem measured (adverse drug reaction or ADE), method of data collection (chart review, spontaneous reporting or database research) and method and definition used to detect ADEs. The higher risk of drug-related hospitalizations in older adults is mainly caused by age-related pharmacokinetic and pharmacodynamic changes, a higher number of chronic conditions and polypharmacy, which is often associated with the use of potentially inappropriate drugs. Other factors that have been involved are errors related to prescription or administration of drugs, medication non-adherence and inadequate monitoring of pharmacological therapies. A few commonly used drugs are responsible for the majority of emergency hospitalizations in older subjects, i.e. warfarin, oral antiplatelet agents, insulin and oral hypoglycaemic agents, central nervous system agents. The aims of the present review are to summarize recent evidence concerning drug-related hospitalization in older adults, to assess the contribution of specific medications, and to identify potential interventions able to reduce the occurrence of these drug-related events, as they are, at least partly, potentially preventable.