Outpatient harm often due to adverse drug events

Adverse drug events commonly occur in the outpatient setting and are often serious, a study has shown. In addition, adverse event (AE) rates are greater in older adults.

A retrospective review was conducted using electronic health records (HER) of 11 outpatient sites in Massachusetts, US, in 2018, involving a total of 3,103 patients (mean age 52 years) who received outpatient care. Nurse reviewers used a trigger method to identify AEs, while physicians reviewed the findings, ranked the severity, and assessed preventability.

The authors used generalized estimating equations to examine the association of having at least one AE with age, sex, race, and primary insurance. They also analysed the differences in AE rates across sites.

Of the patients, the majority were female (59.8 percent), White (75.1 percent), and English speakers (90.8 percent). Most of them were privately insured (70.4 percent) and had an average of four outpatient encounters in 2018.

In general, 7.0 percent (95 percent confidence interval [CI], 4.6‒9.3) of the patients experienced at least one AE (8.6 evens per 100 patients annually). The most common AE was adverse drug events (63.8 percent), followed by healthcare-related infections (14.8 percent), and surgical or procedural events (14.2 percent).

Severity was serious in 14.7 percent of AEs, life-threatening in 2.1 percent, and nonfatal. Of the AEs, about one in four (23.2 percent) were preventable.

Having at least one AE was negatively associated with younger age (18‒44 years; standardized risk difference [SRD], ‒0.05, 95 percent CI, ‒0.09 to ‒0.02) and positively with Black race (SRD, 0.09, 95 percent CI, 0.01‒0.17). Across sites, 1.8 percent to 23.6 percent of patients had one or more AE, with clinical AE category varying significantly.

“Interventions to curtail outpatient harm are urgently needed,” the authors said.