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 (β = 2.9, 95%CI 2.4–3.4, adjusted R(2) = 88), 0.4 (β = 0.4, 95%CI 0.04–0.72, adjusted R(2) = 54), 1.6 (β = 1.6, 95%CI 1.1–2.1, adjusted R(2) = 85), and 1.1 (β = 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. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13643-021-01636-2.