Hypertension and other comorbidities associated with increased mortality in hospitalized adult patients with COVID-19 in spain: a descriptive, retrospective, nationwide study

Despite the high rates of COVID-19 vaccination achieved in Spain, work must continue to ensure that vulnerable populations are protected. The aim of this study was to identify comorbidities associated with increased mortality in adult patients hospitalized with COVID-19 in Spain. We obtained all hospital discharge data for COVID-19-related diseases from January 2020 to December, 2021. Specific data were collected on potential poor prognostic risk factors, such as solid tumours, haematological malignancies, immunodeficiencies, diabetes, hypertension, cardiopulmonary disease, chronic lower respiratory tract disease, COPD, or liver disease. There were 751,598 hospitalizations for COVID-19 in adults in Spain between 2020 and 2021, with a hospitalization rate of 958.57 per 100,000, reaching 4439.36 hospitalizations per 100,000 persons in patients ≥ 80 years. The case fatality rate in adults hospitalized with COVID-19 was 13.7%, and it exceeded 24% in those ≥ 80 years. Hospitalized adult patients with COVID-19 with any of the comorbidities studied were 4.70 times more likely to die than those without comorbidities. The risk of death increased by a factor of 6.25 for patients with solid tumours, 7.98 for patients with haematologic malignancies, 4.81 for patients with diabetes or 4.22 for patients with hypertension. When stratified by age, comorbidities conferred the largest relative mortality increases in younger adults (e.g., hypertension in 60–64-year-olds: CFR 7.34%, OR 3.13 [95% CI 2.79–3.51] vs. no comorbidities). In‑hospital mortality associated with COVID‑19 increased markedly with age, but comorbidities conferred substantial additional risk across all age groups, with particularly high relative risks in younger adults. These findings support the continued prioritization of older adults and targeted high‑risk groups, including younger patients with chronic conditions such as hypertension and diabetes, for preventive interventions.