Abstract Body: Background:
In 2022, stroke shifted from the fourth to the fifth leading cause of death in the U.S. as COVID-19 temporarily took its place. Despite this change, stroke remains a significant cause of mortality and long-term disability in the U.S. This study analyzes trends in in-hospital mortality among stroke-related hospitalizations in California from 2016 to 2022, with a particular focus on the pandemic years.

Methods:
This retrospective analysis utilized patient discharge data from the California Department of Health Care Access and Information, screening nearly 25 million inpatient events for stroke-related ICD-10-CM diagnosis codes (I60-I63) among individuals 20 and older. Multivariate logistic regression (MLR) analysis assessed the impact of the pre- and post-COVID-19 periods on in-hospital mortality, adjusting for confounders such as age, gender, race and ethnicity, geographic regions, and payer source. Results were interpreted using Adjusted Odds Ratios (AOR).

Results:
The study identified 590,801 stroke-related hospitalizations and 66,096 in-hospital deaths (11.2%). Initially, the age-and-sex-adjusted in-hospital mortality rate decreased from 28.88 per 100,000 in 2016 to 27.38 in 2019. However, with the onset of COVID-19 in 2020, the rate increased to 27.94, peaking in 2021 at 30.78 during the pandemic's height. In 2022, the rate slightly declined to 28.30 but remained above pre-pandemic levels.

Similar trends from 2016 to 2022 were observed in age-adjusted rates for males, which increased from 27.77 to 29.73, and for females, which decreased from 29.91 to 26.98. The gap between male and female mortality rates widened significantly during the pandemic, with male mortality peaking in 2021 with a difference of 3.75.

MLR analysis revealed a 22.6% increase in in-hospital mortality during the post-COVID period compared to the pre-COVID period (AOR=1.23, p<0.001). Additionally, male mortality was 25.3% higher than female mortality (AOR=1.25, p<0.001). Racial disparities were also noted, with Asians having a 53.9% higher prevalence of stroke compared to Whites (AOR=1.54, p<0.001), followed by Blacks at 38.8%.

Conclusion:
The COVID-19 pandemic significantly impacted in-hospital stroke mortality rates in California, particularly during the peak in 2021. The study highlights the differential impact on males, who experienced higher mortality increases, and the pronounced racial disparities, with Asians and Blacks showing higher prevalence rates compared to Whites.