Potentially inappropriate prescribing and the risk of adverse drug reactions in critically ill older adults

Background: Potentially inappropriate medication (PIM) use in the elderly is associated with increased risk of adverse drug reactions (ADRs), but there is limited information regarding PIM use in the intensive care unit (ICU) setting. Objective: The aim of the study is to describe the prevalence and factors associated with the use of PIM and the occurrence of PIM-related adverse reactions in the critically ill elderly. Methods: This study enrolled all critically ill older adults (60 years or more) admitted to medical or cardiovascular ICUs between January and December 2013, in a large tertiary teaching hospital. For all patients, clinical pharmacists listed the medications given during the ICU stay and data on drugs were analyzed using 2012 Beers Criteria, to identify the prevalence of PIM. For each identified PIM the medical records were analyzed to evaluate factors associated with its use. The frequency of ADRs and, the causal relationship between PIM and the ADRs identified were also evaluated through review of medical records. Results: According to 2012 Beers Criteria, 98.2% of elderly patients used at least one PIM (n=599), of which 24.8% were newly started in the ICUs. In 29.6% of PIMs, there was a clinical circumstance that justified their prescription. The number of PIMs was associated with ICU length of stay and total number of medications. There was at least one ADR identified in 17.8% of patients; more than 40% were attributed to PIM, but there was no statistical association. Conclusions: There is a high prevalence of PIM used in acutely ill older people, but they do not seem to be the major cause of adverse drug reactions in this population. Although many PIMs had a clinical circumstance that led to their prescription during the course of ICU hospitalization, many were still present upon hospital discharge. Therefore, prescription of PIMs should be minimized to improve the safety of elderly patients