Risk factors for critical outcome of COVID-19 differ according to location: a systematic review and meta-analysis

Abstract

Background The mortality rates of the coronavirus disease 2019 (COVID-19) differ across the globe. While some risk factors for poor prognosis of the disease are known, regional differences are suspected. We reviewed the risk factors for critical outcomes in extensive number of studies according to the study location. Methods We searched the PubMed, Embase, Cochrane Library, and Web of Science literature databases from January 1, 2020 to June 8, 2020. We defined the critical outcome as death, admission to the intensive care unit, or critical type of COVID-19. Candidate variables to predict the critical outcome included patient demographics, underlying medical condition, symptoms, and laboratory findings. Pooled relative risks (RRs) and standardized mean differences were calculated for each variable and were also determined according to the study’s continent. Results A total of 80 studies were included from Asia (n = 48), Europe (n = 22), and North America (n = 10). The risk factors for the critical outcome in the overall population included male sex, age, and all inspected underlying medical conditions. Symptoms of dyspnea, anorexia, dizziness, fatigue, and certain laboratory findings were also indicators of the critical outcome. Subgroup analysis was performed according to study location, and we found several discrepancies. Underlying respiratory disease was associated higher risk of the critical outcome in studies from Asia (pooled RR 2.16 [1.60–2.92] and Europe (pooled RR 1.50 [1.32–1.69]), but not North America. Underlying hepatic disease was associated with a higher risk of the critical outcome from Europe (pooled RR 1.34 [1.15–1.56]), but not from Asia and North America. Symptoms of vomiting (pooled RR 2.43 [1.60–3.69]), anorexia (pooled RR 2.38 [1.45–3.91]), dizziness (pooled RR 2.23 [1.51–3.28]), and fatigue (pooled RR 1.92 [1.23–3.02]) were significantly associated with the critical outcome in studies from Asia, but not from Europe and North America. Hemoglobin and platelet count affected patients differently in Asia compared to those in Europe and North America. Conclusions There are several discrepancies among risk factors for critical outcomes among patients with COVID-19 according to the location of the infected patient.