Validity of reported post-acute health outcomes in children with SARS-CoV-2 infection: a systematic review
Authors: Hirt Julian , Janiaud Perrine , Gloy Viktoria , Schandelmaier Stefan , Pereira Tiago V. , Contopoulos-Ioannidis Despina G. , Goodman Steven N. , Ioannidis John P. A. , Munkholm Klaus , Hemkens Lars G. 
Published: March 2022

ABSTRACTImportanceThere is concern that post-acute SARS-CoV-2 infection health outcomes (“post-COVID syndrome”) in children could be a serious problem but at the same time there is concern about the validity of reported associations between infection and long-term outcomes.ObjectiveTo systematically assess the validity of reported post-acute SARS-CoV-2 infection health outcomes in children.Evidence ReviewA search on PubMed and Web of Science was conducted to identify studies published up to January 22, 2022, that reported on post-acute SARS-CoV-2 infection health outcomes in children (<18 years) with follow-up of ≥2 months since detection of infection or ≥1 month since recovery from acute illness. We assessed the consideration of confounding bias and causality, and the risk of bias.Findings21 studies including 81,896 children reported up to 97 symptoms with follow-up periods of 2-11.5 months. Fifteen studies had no control group. The reported proportion of children with post-COVID syndrome was between 0% and 66.5% in children with SARS-CoV-2 infection (n=16,986) and 2% to 53.3% in children without SARS-CoV-2 infection (n=64,910). Only 2 studies made a clear causal interpretation of an association of SARS-CoV-2 infection and the main outcome of “post-COVID syndrome” and provided recommendations regarding prevention measures. Two studies mentioned potential limitations in the conclusion of the main text but none of the 21 studies mentioned any limitations in the abstract nor made a clear statement for cautious interpretation. The validity of all 21 studies was seriously limited due to an overall critical risk of bias (critical risk for confounding bias [n=21]; serious or critical risk for selection bias [n=19]; serious risk for misclassification bias [n=3], for bias due to missing data [n=14] and for outcome measurement [n=12]; and critical risk for selective reporting bias [n=16]).Conclusions and RelevanceThe validity of reported post-acute SARS-CoV-2 infection health outcomes in children is critically limited. None of the studies provided evidence with reasonable certainty on whether SARS-CoV-2 infection has an impact on post-acute health outcomes, let alone to what extent. Children and their families urgently need much more reliable and methodologically robust evidence to address their concerns and improve care.KEY POINTSQuestionHow valid are the reported results on health outcomes in children after acute SARS-CoV-2 infection?FindingsWe identified 21 studies with only 6 using a controlled design. Reported post-acute health-outcomes were numerous and heterogeneous. The reported proportion of children with post-COVID syndrome was up to 66.5% in children with and 53.3% in children without SARS-CoV-2 infection. All studies had seriously limited validity due to critical and serious risk of bias in multiple domains.MeaningThe validity of reported post-acute SARS-CoV-2 infection health outcomes in children is critically limited and methodological robust evidence is urgently needed.