Abstract
Increased age appears to be a strong risk factor for COVID-19 severe outcomes. However, studies do not sufficiently consider the age-dependency of other important factors influencing the course of disease. The aim of this review was to quantify the isolated effect of age on severe COVID-19 outcomes. We searched Pubmed to find relevant studies published in 2020. Two independent reviewers evaluated them using predefined inclusion and exclusion criteria. We extracted the results and assessed seven domains of bias for each study. After adjusting for important age-related risk factors, the isolated effect of age was estimated using meta-regression. Twelve studies met our inclusion criteria: four studies for COVID-19 disease severity, seven for mortality, and one for admission to ICU. The crude effect of age (5.2% and 13.4% higher risk of disease severity and death per age year, respectively) substantially decreased when adjusting for important age-dependent risk factors (diabetes, hypertension, coronary heart disease/cerebrovascular disease, compromised immunity, previous respiratory disease, renal disease). Adjusting for all six comorbidities indicates a 2.7% risk increase for disease severity (two studies), and no additional risk of death per year of age (five studies). The indication of a rather weak influence of age on COVID-19 disease severity after adjustment for important age-dependent risk factors should be taken in consideration when implementing age-related preventative measures (e.g., age-dependent work restrictions).
Highlights
The first cluster of cases of Coronavirus disease 2019 (COVID-19) was reported in Wuhan (Huban province, China) in December 2019
National health institutions such as the Robert Koch Institute (RKI) in Germany and the Centers for Disease Control (CDC) in the United States routinely report COVID-19 cases and deaths stratified by age
We evaluated the study as having a high risk of bias because not all age-related risk factors were considered, and because biomarkers which were already reflective of COVID-19 disease severity were used for the risk analysis
Summary
The first cluster of cases of Coronavirus disease 2019 (COVID-19) was reported in Wuhan (Huban province, China) in December 2019. An increase in COVID-19 disease severity with increased patient age has been widely noted [1,2,3,4]. National health institutions such as the Robert Koch Institute (RKI) in Germany and the Centers for Disease Control (CDC) in the United States routinely report COVID-19 cases and deaths stratified by age. They have described an increase in mortality with increasing age. In its COVID-19 informational report, the RKI states “the risk of severe diseases increases steadily from 50 to 60 years of age” [5]
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