Root Cause Analysis of Ambulatory Adverse Drug Events That Present to the Emergency Department

Adverse drug events (ADEs) among patients self-administering medications in home/community settings are a common cause of emergency department (ED) visits, but the causes of these ambulatory ADEs remain unclear. Root cause analysis, rarely applied in outpatient settings, may reveal the underlying factors that contribute to adverse events.

To elicit patient and provider perspectives on ambulatory ADEs and apply root cause analysis methodology to identify cross-cutting themes among these events.

Emergency department clinical pharmacists screened, identified, and enrolled a convenience sample of adult patients 18 years or older who presented to a single, urban, academic ED with symptoms or diagnoses consistent with suspected ADEs. Semistructured phone interviews were conducted with the patients and their providers. We conducted a qualitative analysis. We applied a prespecified version of the injury prevention framework (deductive coding), identifying themes relating to the agent (drug), host (patient), and environment (social and health systems). These themes were used to construct a root cause analysis for each ADE.

From 18 interviews overall, we identified the following themes within the injury prevention framework. Agent factors included high-risk drugs, narrow therapeutic indices, and uncommon severe effects. Host factors included patient capacity or understanding of how to use medications, awareness of side effects, mistrust of the medical system, patients with multiple comorbidities, difficult risk-benefit assessments, and high health-care users. Environmental factors included lack of social support, and health systems issues included access to care, encompassing medication availability, access to specialists, and a lack of continuity and communication among prescribing physicians. Root cause analysis revealed multiple underlying factors relating to agent, host, and environment for each event.

Patient and physician perspectives can inform a root cause analysis of ambulatory ADEs. Such methodology may be applied to understand the factors that contribute to ambulatory ADEs and serve as the formative work for future interventions improving home/community medication use.