Outpatient insulin-related adverse events due to mix-up errors: Findings from two national surveillance systems, United States, 2012-2017.

Purpose: We used data from two public health surveillance systems for national estimates and detailed descriptions of insulin mix-up errors resulting in emergency department (ED) visits and other serious adverse events to help inform prevention efforts.

Methods: ED visits involving patients seeking care for insulin medication errors collected by the NEISS-CADES project in 2012-2017 and voluntary reports of serious insulin medication errors submitted to the US Food and Drug Administration (FDA) in 2016-2017 were analyzed. National estimates of insulin product prescriptions dispensed from retail pharmacies were obtained from IQVIA National Prescription Audit.

Results: Between 2012 and 2017, based on 514 NEISS-CADES cases, there were an estimated 5636 (95% CI, 4143-7128) ED visits annually for insulin mix-up errors; overall, over three-quarters (77.5%; 95% CI, 71.6%-83.3%) involved taking rapid-acting instead of long-acting insulin. Between 2012 and 2017, the proportion of mix-up errors among all estimated ED visits for all insulin errors decreased by 60%; concurrently, the proportion of pens among all insulin package types dispensed increased by 50%. Among 58 voluntary reports submitted to FAERS, over one-half (56.9%) of cases involved taking rapid- instead of long-acting insulin. Among 27 cases with documented contributing factors, approximately one-half involved patients having difficulty differentiating products.

Conclusions: Among all ED visits for insulin errors collected by NEISS-CADES in 2012-2017, the proportion involving mix-up errors has declined. Continued reductions may require additional prevention strategies, including improving insulin distinctiveness, particularly for rapid- vs long-acting insulins. Ongoing national surveillance is important for identifying the impact of interventions.