Population-Based Incidence of Acute and Chronic Urticaria in Southern California: 2017-2022

Annual variations in the population-based incidence of acute urticaria (AU) and chronic urticaria (CU) are poorly understood, specifically in relationship to non-COVID-19 viral respiratory infections (NCVRIs).

To determine the annual incidence of AU and CU, health care utilization for NCVRIs and demographic associations across 3 periods: pre-COVID-19, COVID-19 without vaccinations, and COVID-19 with vaccinations.

The researchers reviewed the medical records from 2017 to 2022 of all Kaiser Permanente Southern California Health Plan members with and without urticaria leading to health care utilization.

There was a total of 7,404,343 unique individuals with any Kaiser Permanente Southern California Health Plan coverage between 2017 and 2022, contributing to 26,852,884 patient-years of follow-up. The annual incidence of AU per 100,000 patient-years was 1543 in 2017, 1533 in 2018, 1586 in 2019, 1194 in 2020, 1345 in 2021, and 1434 in 2022. The annual incidence of CU per 100,000 patient-years was 101 in 2017, 113 in 2018, 123 in 2019, 95 in 2020, 113 in 2021, and 129 in 2022. The number of annual health care visits for NCVRIs per 100,000 patient-years was 14,588 in 2017, 13,409 in 2018, 14,843 in 2019, 8671 in 2020, 6507 in 2021, and 11,191 in 2022. There was a significant correlation between NCVRIs and AU (r = 0.82, P = .05) but not between NCVRIs and CU (r = 0.10, P = .86).

There was a decrease in AU incidence during the COVID-19 era before and after vaccines. AU may be associated with NCVRIs.