Hariyanto TI, Putri C, Hananto JE, et al. - This study’s findings demonstrate that delirium is an important marker for distinguishing individuals at higher risk of developing poor COVID-19 outcomes. Delirium should be added as one of the common presenting symptoms of COVID-19 in older populations.

• Researchers systematically search the PubMed and Google Scholar databases using specific keywords related to our aims until January 30th, 2021.

• The meta-analysis enrolled 20 studies.

• Results exhibited that delirium symptoms on admission was correlated with poor outcomes from COVID-19 [OR 2.36 (95% CI 1.80–3.09), p < 0.00001, I2 = 76%, random-effect models] and its subgroup which consist of severe COVID-19 [OR 3.89 (95% CI 1.72–8.75), p = 0.001, I2 = 91%, random-effect models], and mortality from COVID-19 [OR 1.90 (95% CI 1.55–2.33), p < 0.00001, I2 = 36%, random-effect models].

• Meta-regression demonstrated that the relationship was affected by age (p = 0.005).