(127) Trends in The Incidence of Immunologic and Oncologic Diseases Before and During COVID-19 Pandemic in the US

Publication Number: 458

Background: Prior research has demonstrated reduced health care resource utilization during the COVID-19 pandemic. However, data on the impact of the pandemic on the incidence of immunologic and oncologic diseases is sparse.

Objectives: To determine the impact of the pandemic on the incidence of select immunologic and oncologic diseases compared to pre-pandemic period in the US.

Methods: In the US Optum claims database we identified all enrolled individuals who were ≥ 18 years of age between Jan 2018 and Aug 2021. We identified incident cases of cancers [colorectal (CRC), breast (BCA), and lung (NSCLC)], multiple sclerosis (MS), atopic dermatitis (AD), and asthma during the study period using first instance of relevant ICD-10 codes (index date). We excluded patients who had < 6 months of enrollment or disease of interest before the index date. Each calendar year was classified into Winter (Dec/Jan/Feb), Spring (March/April/May), Summer (June/July/Aug), and Fall (Sept/Oct/Nov) period, to account for seasonality of COVID-19. We calculated cumulative incidence for each disease for each period. We reported change in incidence using 2018 as the reference seasons to determine trends before and during the COVID-19 pandemic.

Results: We identified ~18 million patients eligible for the study for each cohort. We found that incidence of almost all selected diseases decreased during the pandemic compared to the same period in year 2018. Compared to the corresponding period in 2018 the reported incidence of MS cases decreased between 17% and 83% from March 2020 and August 2021. During the same time period the incidence of cancers decreased between 40% and 86% for CRC, 49% and 91% for BCA, and 25% and 85% for NSCLC, respectively. The incidence of asthma decreased between 12% and 64%, with sharp declines occurring in line with COVID waves. The incidence of AD declined sharply in spring 2020 (17%), however relative to 2018 there was generally no sustained decrease in incidence. In general, the pattern followed the restrictions put forth by the government in response to the COVID-19 waves except for summer 2021 when the incidence rates were the lowest for most diseases in spite of limited social restrictions.

Conclusions: COVID-19 led to an apparent decrease in the incidence of most selected diseases; the change followed the pattern of COVID-19 social restrictions. The decrease could be due to reduced screening or limited encounters of mild cases of the diseases. The results suggest that future studies using data from 2020-2021 should exercise caution while interpreting incidence or prevalence data. In addition, more research is required to facilitate understanding the profile of patients who were newly diagnosed in contrast to those who were not, to comprehend implications for external validity.