The effect of age on the incidence of COVID-19 complications: a systematic review and meta-analysis

Background The coronavirus (COVID-19) pandemic was reported from Wuhan, China, on December 31, 2019, and the pandemic was spread to more than 212 countries in the globe. This meta-analysis aimed to assess the pooled incidence of COVID-19 complications and to identify the association between the incidence of complications and age. Methods Comprehensive databases, PubMed, Hinari, and Google Scholar, were used to locate potential articles for this review. Data were extracted using Microsoft Excel and imported to the STATA/MP version 16.0 software for analysis. Heterogeneity between studies was assessed using the Cochrane Q test statistics and I-2 test, and small study effect was checked using Egger's statistical test at 5% significant level. Sensitivity analysis was checked. A random-effects model was conducted to estimate the pooled incidence of COVID-19 complications. Univariate meta-regression was conducted to identify the association between the mean ages with each complication. Results From the total of 1237 studies, 12 studies were included with a total of 3064 COVID-19 patients. The most complications were acute respiratory distress syndrome (30.93%, 95%CI 21.3-40.6%) followed by acute liver injury (22.8%, 95%CI 14-31.5%), shock (10.9%, 95%CI 7.4-14.4%), acute kidney injury (7%, 95%CI 3.8-10.4%), and acute cardiac injury (6.4%, 95%CI 2.8-15.6%). Univariate meta-regression revealed that as the mean age increased by 1 year, the incidence of acute respiratory distress syndrome, acute kidney injury, acute cardiac injury, and shock increased by a factor of 2.9 (beta = 2.9, 95%CI 2.4-3.4, adjusted R-2 = 88), 0.4 (beta = 0.4, 95%CI 0.04-0.72, adjusted R-2 = 54), 1.6 (beta = 1.6, 95%CI 1.1-2.1, adjusted R-2 = 85), and 1.1 (beta = 1.1, 95%CI 0.8-1.5, adjusted R-2 = 26) times respectively. Conclusion Significant complications of COVID-19 viral infections were reported. Older populations were a high-risk group of developing adverse complications as compared to their counterparts. Health care professionals should give primary attention to those risk group individuals.