Identification of Adverse Drug Withdrawal Events after Older Adults Discontinue Statins

Abstract Assessing the safety of deprescribing interventions is difficult due to inadequate methods of accurately identifying adverse drug withdrawal events (ADWE) at scale. We explored methods to identify ADWEs after a medication discontinuation using electronic health record (EHR) data, and report on the relationship between statin discontinuations and potential ADWEs. The study population was older adults (65+), taking a statin, and had a confirmed statin discontinuation by chart review. Potential ADWEs were identified by ICD-10 and procedure codes (e.g. stroke, carotid artery disease, ischemic heart disease, coronary artery bypass graft, or percutaneous coronary intervention) within a 12-month time frame following the discontinuation. Two clinicians adjudicated each record to determine if the identified events were related to discontinuations and could constitute ADWEs. Outcome categories were: doubtful, possible, probable, or definite ADWE. Among 44 potential ADWEs, 48% (21/44) were determined to be doubtful (e.g. stroke during the 12 months following statin discontinuation was more likely related to atrial fibrillation than discontinuation), 48% (21/44) as possible (e.g. myocardial infarction (MI) occurred after discontinuation, but cancer may have also contributed to the MI), 4% (2/44) as probable (e.g. factors other than discontinuation couldn’t explain the ADWE), and 0% (0/44) as definite (e.g. same as probable, and confirmed improvement in medical condition after restarting of statin). These exploratory methods of identifying possible ADWEs with ICD-10 and procedure codes after a confirmed discontinuation, while still requiring record review, are new tools that could be enhanced and applied at scale in future deprescribing studies classes to assess safety.