Abstract: PostScript Provenance and peer review Not commissioned; externally peer reviewed. To cite Derkinderen P, Noble W, Neunlist M, et al. Gut 2021;70:2010–2012. Received 26 October 2020 Revised 29 October 2020 Accepted 3 November 2020 Published Online First 17 November 2020 Gut 2021;70:2010–2012. doi:10.1136/ gutjnl-2020-323482 ORCID iD Pascal Derkinderen http://o​ rcid.​org/​0000-​0001-​8792-​ 2582 References 1 Lee H-­S, Lobbestael E, Vermeire S, et al. Inflammatory bowel disease and Parkinson’s disease: common pathophysiological links. Gut 2021;70:408–17. 2 De Guilhem De Lataillade A, Lebouvier T, Noble W, et al. Enteric synucleinopathy: real entity or only a trendy concept? Free Neuropathology 2020;26:Seiten. 3 Prigent A, Lionnet A, Durieu E, et al. Enteric alpha-­ synuclein expression is increased in Crohn’s disease. Acta Neuropathol 2019;137:359–61. 4 Prigent A, Chapelet G, De Guilhem de Lataillade A, et al. Tau accumulates in Crohn’s disease gut. Faseb J 2020;34:9285–96. 5 Borghammer P, Van Den Berge N. Brain-­First versus Gut-­First Parkinson’s disease: a hypothesis. J Parkinsons Dis 2019;9:S281–95. 6 Johnson ME, Stecher B, Labrie V, et al. Triggers, facilitators, and Aggravators: redefining Parkinson’s disease pathogenesis. Trends Neurosci 2019;42:4–13. Figure 1 Kaplan-­Meier curve stratified by proton pump inhibitor (PPI) use before and after propensity score matching. Given these conflicting findings, we conducted this territory-­ wide study to investigate whether PPI or famotidine use was associated with a higher risk of severe disease using propensity score matching. The detailed methodology of the present analyses is shown in the online supplemental appendix. A total of 4445 patients (median age 44.8 years old, 95% CI: (28.9 to 60.8)); 50% male) were diagnosed with the COVID-19 infection between Proton pump inhibitor or famotidine use and severe COVID-19 disease: a propensity score-m ­ atched territory-­ wide study We read the recent articles published in Gut on the relationship between proton pump inhibitor (PPI) use and outcomes in COVID-19 with great interest.1 2 In the meta-­ analysis, the authors found that current or regular PPI users were more likely to have severe outcomes of COVID-19 than non-­ users, but no significant association was observed for previous PPI use.2 The reason may be reduced secretion of gastric acid that can neutralise the SARS-­ CoV-2. By contrast, the use of famotidine, another medication for gastric ulcers or gastro-­ oesophageal reflux disease, was asso- Figure 2 Kaplan-­Meier curve stratified by ciated with better clinical outcomes in famotidine use before and after propensity some studies,3 4 but not others.5 6 score matching. 2012 Gut October 2021 Vol 70 No 10 Gut: first published as 10.1136/gutjnl-2020-323668 on 4 December 2020. © Author(s) (or their employer(s)) 2021. No commercial re-­use. See rights and permissions. Published by BMJ. 1 January 2020 and 22 August 2020 in Hong Kong public hospitals or their associated ambulatory/outpatient facilities. On follow-­up until 8 September 2020, a total of 212 patients (4.8%) met the primary outcome of need for intensive care unit (ICU) admission or intubation, or death (online supplemental figure 1). The median duration between hospitalisation admission and ICU admission, intubation or death were 35 (95% CI: 24.5 to 50.5), 33 (95% CI: 21.0 to 140.0)..