Medication adverse events in the ambulatory setting: A mixed-methods analysis

To characterize ambulatory care adverse drug events reported to the Collaborative Healthcare Patient Safety Organization (CHPSO), a network of 400 hospitals across the United States, and identify addressable contributing factors.

We abstracted deidentified ambulatory care CHPSO reports compiled from May 2012 to October 2018 that included medication-related adverse events to identify implicated medications and contributing factors. We dual-coded 20% of the sample. We quantitatively calculated co-occurring frequent item sets of contributing factors and then applied a qualitative thematic analysis of co-occurring sets of contributing factors for each drug class using an inductive analytic approach to develop formal themes.

Of 1,244 events in the sample, 208 were medication related. The most commonly implicated medication classes were anticoagulants (n = 97, or 46% of events), antibiotics (n = 24, 11%), hypoglycemics (n = 19, 9%), and opioids (n = 17, 8%). For anticoagulants, timely follow-up on supratherapeutic international normalized ratio (INR) values occurred before the development of symptoms. Incident reports citing antibiotics often described prescribing errors and failure to review clinical contraindications. Reports citing hypoglycemic drugs described low blood sugar events due to a lack of patient education or communication. Reports citing opioids described drug-drug interactions, commonly involving benzodiazepines.

Ambulatory care prescribing clinicians and community pharmacists have the potential to mitigate harm related to anticoagulants, antibiotics, hypoglycemics, and opioids. Recommendations include increased follow-up for subtherapeutic INRs, improved medical record integration and chart review for antibiotic prescriptions, enhanced patient education regarding hypoglycemics, and alerts to dissuade coprescription of opioids and benzodiazepines.