Association between COVID-19 Mortality and Underlying Disease; Tehran, Iran.

Introduction: Coronavirus disease has emerged as one of the major health challenges in the 21st century. This study aimed to investigate the association between COVID-19 mortality and underlying disease in Tehran. Methods: The retrospective, epidemiological study was conducted from January 1, 2019, to May 31, 2021, in hospitals in Tehran, Iran based on the International Classification of Diseases (ICD-11). Data concerning coronary cases with underlying disease (8018) and related demographic and clinical characteristics are collected by hospitals. Additionally, logistic regression was examined to determine the association between COVID-19 mortality and underlying disease. Results: The result shows that incurable diseases (47.3%) and cancer (67.7%) had the lowest while; pulmonary disease showed the highest recovery day (80.7%) between various underlying conditions. In addition, cancer and pulmonary disease show 10.41 and 7.3 hospitalization days, respectively. The logistic regression analysis revealed that mortality in cases with cancer as an underlying disease is 4.72 times higher than in cases without cancer (95% CI: 4.08-5.46). Moreover, the adjusted regression analysis showed that the mortality in multiple underlying conditions such as cancer, respiratory issues, cardiovascular problems, and diabetes are 5.48, 2.75, 4.081, and 3.162 times higher, respectively ( Conclusion: The findings of this study provide valuable insights into how specific underlying health conditions can increase the risk of COVID-19 mortality, hospitalization, and recovery time.