Peer Review #2 of "A systematic review and realist synthesis on toilet paper hoarding: COVID or not COVID, that is the question (v0.1)"

Abstract

To explore whether the coronavirus disease 2019 (COVID-19) pandemic is associated with toilet paper hoarding and to assess which risk factors are associated with the risk of toilet paper hoarding.Design: A systematic review and realist review were conducted.Data sources: PubMed, Web of Science, Scopus and PsycINFO were searched (systematic review). PubMed, pre-prints and grey literature were also searched (realist review). The databases were searched from inception until June 2020. Study selection:There were no restrictions on the study design.Outcomes and measures: For the systematic review, toilet paper hoarding was the main outcome, and pathological use of toilet paper was the secondary outcome. For the realist review, the contextmechanisms-outcome (CMO) scheme included the COVID-19 pandemic (context), four proposed mechanisms, and one outcome (toilet paper hoarding). The four potential mechanisms were 1) gastrointestinal mechanisms of COVID-19 (e.g., diarrhoea), 2) social cognitive biases, 3) stress-related factors (mental illnesses, personality traits), and 4) cultural aspects (e.g., differences between countries).Eligibility criteria for selecting studies: All studies of human populations were considered (including general population studies and clinical studies of patients suffering from mental health problems). Results:The systematic review identified 14 studies (8 studies for the main outcome, 6 studies for the secondary outcome). Three surveys identified the role of the COVID-19 threat in toilet paper hoarding in the general population. One study pointed to an association between a personality trait (conscientiousness) and toilet paper buying and stockpiling as well as an additional significant indirect effect of emotionality through the perceived threat of COVID-19 on toilet paper buying and stockpiling. Six case reports of pathological use of toilet paper were also identified, although none of them were associated with the COVID-19 pandemic. The realist review suggested that of all the mechanisms, social cognitive biases and a bandwagon effect were potential contributors to toilet paper hoarding in the general population. The stressful situation (COVID-19 pandemic) and some personality traits (conscientiousness) were found to be associated with toilet paper hoarding. Cultural differences were