Predictors of clinical evolution of SARS‐CoV‐2 infection in hematological patients: A SYSTEMATIC REVIEW AND META‐ANALYSIS

Abstract Main aim of this systematic review is to quantify the risk and identify predictors of clinical evolution of SARS‐CoV‐2 in hematological patients compared to different control populations. Two independent reviewers screened the literature assessing clinical outcomes of SARS‐CoV‐2 infection in adult patients with active hematological malignancies published up to June 2021. Primary outcome was COVID‐19 related mortality, secondary outcomes were hospital and intensive‐care admission, mechanical ventilation (MV), and thromboembolic events. Variables related to study setting, baseline patients' demographic, comorbidities, underlying hematological disease, ongoing chemotherapy, COVID‐19 presentation, and treatments were extracted. A total of 67 studies including 10,061 hematological patients and 111,143 controls were included. Most of the studies were retrospective cohorts (51 studies, 76%) and only 19 (13%) provided data for a control group. A significant increased risk of clinical progression in the hematological population compared to the controls was found in terms of COVID‐19 related mortality (OR, 2.12; 95% CI, 1.77–2.54), hospitalization (OR, 1.98; 95% CI, 1.15–3.43), intensive‐care admission (OR, 1.77; 95% CI, 1.38–2.26), and MV (OR, 2.17; 95% CI, 1.71–2.75). The risk remained significantly higher in the subgroup analysis comparing hematological patients versus solid cancer. Meta‐regression analysis of uncontrolled studies showed that older age, male sex, and hypertension were significantly related to worse clinical outcomes of COVID‐19 in hematological population. Older age and hypertension were found to be associated also to thromboembolic events. In conclusion, hematological patients have a higher risk of COVID‐19 clinical progression compared to both the general population and to patients with solid cancer.