Table 1

Eligibility criteria

Inclusion criteriaExclusion criteria
PopulationGeneral population infected with COVID-19
(both sexes, all ages).
Special populations such as studying only cancer patients or persons with diabetes.
ExposureAge, in years.All other exposures that do not include age.
Comparator/controlAge reference, in years.
OutcomesDue to infection with COVID-19: risk of hospitalisation, admission to ICU, intubation and death.
Risks measured as HRs, risk ratios and ORs.
Other outcomes, including outcomes of composite disease severity.
Study designCross-sectional, case–control and cohort studies.Randomized Controlled Trials (RCTs), qualitative studies, ecological studies, case reports, experiments, congress abstracts and posters.
  • Excluded are studies only reporting univariate (unadjusted) effect values of age.

  • Excluded are studies in which the age effect is not adjusted at least for three comorbidities listed here: diabetes mellitus, cardiovascular disease, cancer or immunodeficiency, chronic kidney disease, chronic liver disease and chronic pulmonary disease.

  • ICU, intensive care unit.