The isolated effect of age on the risk of COVID-19 severe outcomes: a systematic review with meta-analysis

Abstract

IntroductionIncreased age has been reported to be a factor for COVID-19 severe outcomes. However, many studies do not consider the age dependency of comorbidities, which influence the course of disease. Protection strategies often target individuals after a certain age, which may not necessarily be evidence based. The aim of this review was to quantify the isolated effect of age on hospitalisation, admission to intensive care unit (ICU), mechanical ventilation and death.MethodsThis review was based on an umbrella review, in which Pubmed, Embase and preprint databases were searched on 10 December 2020, for relevant reviews on COVID-19 disease severity. Two independent reviewers evaluated the primary studies using predefined inclusion and exclusion criteria. The results were extracted, and each study was assessed for risk of bias. The isolated effect of age was estimated by meta-analysis, and the quality of evidence was assessed using Grades of Recommendations, Assessment, Development, and Evaluation framework.ResultsSeventy studies met our inclusion criteria (case mortality: n=14, in-hospital mortality: n=44, hospitalisation: n=16, admission to ICU: n=12, mechanical ventilation: n=7). The risk of in-hospital and case mortality increased per age year by 5.7% and 7.4%, respectively (effect size (ES) in-hospital mortality=1.057, 95% CI 1.038 to 1.054; ES case mortality=1.074, 95% CI 1.061 to 1.087), while the risk of hospitalisation increased by 3.4% per age year (ES=1.034, 95% CI 1.021 to 1.048). No increased risk was observed for ICU admission and intubation by age year. There was no evidence of a specific age threshold at which the risk accelerates considerably. The confidence of evidence was high for mortality and hospitalisation.ConclusionsOur results show a best-possible quantification of the increase in COVID-19 disease severity due to age. Rather than implementing age thresholds, prevention programmes should consider the continuous increase in risk. There is a need for continuous, high-quality research and ‘living’ reviews to evaluate the evidence throughout the pandemic, as results may change due to varying circumstances.

In-hospital mortality and severe outcomes after hospital discharge due to COVID-19: A prospective multicenter study from Brazil

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

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Temporal trends in within-city inequities in COVID-19 incidence rate by area-level deprivation in Madrid, Spain

“…To account for the role of age in determining testing practices and influencing the probability of transmission, we adjusted for the percentage of people aged 65 years or older in the BHZ. During the first wave, testing was only available for hospitalized patients, and, as hospitalization increases with age ( Romero Starke et al, 2021 ), this could mean that, during the first wave (but not after that), the probability of getting tested was higher in older people. Second, to describe the time trends of inequities by deprivation in COVID-19 confirmed cases, we fitted the same type of models by month.…”