Until now, the COVID-19 pandemic has resulted in at least 27 million cases and over 900,000 deaths worldwide. Bulgaria is one of the countries that is the most severely affected by the COVID-19 pandemic, and the mortality rate is among the highest registered in the world. The aim of this study is to investigate and analyze mortality rates due to the fact of COVID-19 in addition to the most common related underlying medical conditions in those hospitalized to outline the factors that have an impact on the mortality rate due to the fact of COVID-19. A descriptive cross-sectional research design with a retrospective analysis was used to collect data from a total of 128,269 hospitalized patients during the period from April 2020 to November 2021. During the study period, the number of hospital admissions due to the fact of COVID-19 was 5200. The patients' mean age was 67.34 (SD ± 19.65), and 51.7% (2689) of the patients were men. Only 10% of out of a total of 5200 patients did not test positive for COVID-19 upon admission based on the antigen or PCR test. Out of all patients, 41.5% had no underlying medical conditions upon presentation, and the remaining 58.5% had diagnosed comorbidities, varying from one to five. One-third (1470) had a lethal outcome, and the remaining 71.7% recovered from the infection and were discharged from the hospital. Based on the analysis of our results, there is definite evidence that the CFR and susceptibility to symptomatic COVID-19 were higher in the elderly, men, and patients with more comorbidities, especially chronic cardiovascular, metabolic, and respiratory disorders, as well as in those admitted to hospital within 6 h after an emergency ward visit and who had a shorter mean hospital stay.
Keywords: COVID-19; case fatality rate; comorbidity; incidence; multiple chronic conditions; pandemic.