Systematic reviews and meta-analyses consistently confirm various clinical signs, biomarkers, and risk factors as independent predictors of COVID-19 severity and mortality (Clinical Predictors of COVID-19 Severity and Mortality: A Perspective, 2021).

Early elevations in inflammatory and cardiac biomarkers reliably predict severe disease and mortality in high-risk patient cohorts (Biomarkers of Cytokine Release Syndrome Predict Disease Severity and Mortality From COVID-19 in Kidney Transplant Recipients., 2020).

Platelet and leukocyte aggregates measured via quantitative phase imaging demonstrate a significant association with COVID-19 severity (Platelet aggregates detected using quantitative phase imaging associate with COVID-19 severity, 2023).

Low blood sodium concentrations are linked to an increased risk and severity of COVID-19 infection (Low blood sodium increases risk and severity of COVID-19: a systematic review, meta-analysis and retrospective cohort study, 2020).

The neutrophil-to-lymphocyte ratio serves as a reliable and independent biomarker associated with disease severity and intensive care needs in SARS-CoV-2 patients (Predictors of disease severity and outcomes in pediatric patients with croup and COVID-19 in the pediatric emergency department., 2023).

Pre-existing chronic conditions such as chronic kidney disease, diabetes, and hypertension are established as significant predictors of COVID-19 mortality (Mortality rate and predictors of COVID-19 inpatients in Ethiopia: a systematic review and meta-analysis, 2023).

Biochemical and hematological parameters like D-dimer, CRP, and LDH function as significant independent risk factors for predicting COVID-19 severity (Associated Biochemical and Hematological Markers in COVID-19 Severity Prediction, 2023).

Hematological biomarkers such as the neutrophil-to-lymphocyte ratio and D-dimer provide valuable tools for early risk assessment in vulnerable populations like COPD patients (Chronic Obstructive Pulmonary Disease and COVID-19: The Impact of Hematological Biomarkers on Disease Severity and Outcomes, 2025).

A history of previous stroke is significantly associated with an increased risk of developing severe COVID-19 and experiencing unfavorable outcomes (Association Between Previous Stroke and Severe COVID-19: A Retrospective Cohort Study and an Overall Review of Meta-Analysis, 2022).

Specific demographic and clinical risk factors, including older age and specific health statuses, effectively predict the incidence and severity of complications like diabetes among COVID-19 patients (Incidence and predictors of diabetes mellitus among severe COVID-19 patients in western Ethiopia: a retrospective cohort study, 2022).

Peripheral hematological markers such as the neutrophil-to-lymphocyte ratio consistently correlate with disease progression and mortality risk in older adults (The neutrophil-to-lymphocyte ratio as a marker of immunosenescence and COVID-19 outcomes in the elderly: A narrative review., 2026).