Prognostic factors for mortality, ICU and hospital admission due to SARS-CoV-2: A systematic review and meta-analysis of cohort studies in Europe

BackgroundAs mortality from COVID-19 is strongly age-dependent, we aimed to identify population subgroups at an elevated risk for adverse outcomes from COVID-19 using age/gender-adjusted data from European cohort studies with the aim to identify populations that could potentially benefit from booster vaccinations. MethodsWe performed a systematic literature review and meta-analysis to investigate the role of underlying medical conditions as prognostic factors for adverse outcomes due to SARS-CoV-2, including death, hospitalisation, Intensive Care Unit (ICU) admission, and mechanical ventilation within three separate settings (community, hospital and ICU). Cohort studies that reported at least age and gender-adjusted data from Europe were identified through a search of peer-reviewed articles published until 11th June 2021 in Ovid Medline and Embase. Results are presented as Odds Ratios (ORs) with 95% confidence intervals (95%C.I.) and absolute risk differences (RD) in deaths per 1,000 COVID-19 patients. FindingsWe included 88 cohort studies with age/gender adjusted data from 6,653,207 SARS-CoV-2 patients from Europe. Hospital-based mortality was associated with high and moderate certainty evidence for solid organ tumours, diabetes mellitus, renal disease, arrhythmia, ischemic heart disease, liver disease, and obesity, while a higher risk, albeit with low certainty, was noted for chronic obstructive pulmonary disease and heart failure. Community-based mortality was associated with a history of heart failure, stroke, diabetes, and end-stage renal disease. Evidence of high/moderate certainty revealed a strong association between hospitalisation for COVID-19 and solid organ transplant recipients, sleep apnoea, diabetes, stroke, and liver disease. InterpretationThe results confirmed the strong association between specific prognostic factors and mortality and hospital admission. Prioritisation of booster vaccinations and the implementation of non-pharmaceutical protective measures for these populations may contribute to a reduction in COVID-19 mortality, ICU and hospital admissions. FundingEuropean Centre for Disease Prevention and Control (ECDC) under specific contract No. 10 ECD.11843 within Framework contract ECDC/2019/001 Lot 1B.