Kazan Medical Journal · Oct 9, 2026
Hospital mortality considering comorbidity and patient age across successive epidemic waves: a descriptive study
By Khabriev RU, Krasnov AE, Мингазова ЭН
BACKGROUND: Comorbidity increases the risk of adverse outcomes in COVID-19; therefore, a systematic assessment of the pattern of concomitant diseases and the demographic characteristics of deceased patients is necessary for subsequent risk stratification and justifying patient triage in a hospital setting. AIM: To analyze the association of comorbid pathology with in-hospital mortality in patients with COVID-19 based on the assessment of the pattern of concomitant diseases and the age of patients who died in the hospital. METHODS: A descriptive study (case series) of in-hospital deaths among patients with COVID-19 was conducted at the Republican Clinical Hospital named after Prof. A.F. Agafonov, Ministry of Health of the Republic of Tatarstan, in 2020–2022. Deaths among patients aged ≥18 years with confirmed COVID-19 were included if the minimally necessary data were available: age, sex, year of death, and concomitant diagnoses coded in accordance with the International Classification of Diseases, 10th Revision. Age- and sex-related characteristics, the distribution of deaths by year, and the frequency of concomitant conditions coded according to the International Classification of Diseases, 10th Revision (0, absence; 1, presence) were assessed, with acute complications analyzed separately. Descriptive statistics were used (median [Me], interquartile range [Q1–Q3], proportions with 95% CIs), as well as between-group comparisons (χ² or Fisher exact test), with p 0.05 considered statistically significant. RESULTS: The maximum proportion of deaths was registered among patients aged 60–74 years (42.6%), which allows this group to be considered the “core” of in-hospital mortality. Among the deceased, women predominated (62.3%), and their proportion increased in older groups (p = 5.22 × 10⁻⁵). The temporal structure of deaths was characterized by their concentration in 2021 (84.3%) compared with 2020 (10.4%) and 2022 (5.3%). The comorbidity profile was predominantly represented by chronic non-infectious diseases: arterial hypertension (81.7%), chronic heart failure (58.4%), chronic ischemic heart disease (33.1%), conduction disorders (12.3%), and atrial fibrillation/flutter (11.7%); type 2 diabetes mellitus (35.9%), obesity (29.0%), chronic kidney disease (20.4%), and anemia (17.5%). CONCLUSION: In-hospital mortality in COVID-19 was predominantly formed among older patients with severe comorbidity; age and sex must be taken into account in subsequent multifactorial models and in the development of recommendations for risk stratification and patient triage.