Incidence and Preventability of Medication Errors and ADEs in Ambulatory Care Older Patients.

Objective: To assess the incidence of medication errors, adverse drug events (ADEs), and potential ADEs (poADEs) in patients 65 years of age and older.

Design: This is a retrospective cohort study (2011 to 2014).

Setting: The study was performed at a section 330 federally funded ambulatory health care center.

Patients: The study was a convenience sample selected in a nonrandomized way from event reports filed in those years.

Intervention: Data were collected through event reports and medical record review. Descriptive statistics and chi-square were employed to analyze data.

Results: During the study period, at least one medication error, poADE, or ADE report was documented in 170 out of 2,218 older patients (incidence: 12.5, 9.4, and 5.0 per 100 patient-years, respectively); 42.9% of ADEs were preventable. The chronic conditions most frequently related to ADEs were diabetes (18%), hypertension (18%), and hyperlipidemia (12%). The use of hypoglycemic agents was commonly associated with ADEs (14%; P = 0.001). An increased number of prescribed medications were significantly associated with all the adverse events.

Conclusions: Medication errors, poADEs, and ADEs are common in patients 65 years of age or older taking more than three medications. Almost half of the detected ADEs were preventable.