Letter in response to article in journal of infection: "Clinical characteristics of 345 patients with coronavirus disease 2019 in Japan: A multicenter retrospective study".

We read with great interest the study by Ishii M et al., in which hyperuricemia was deemed a novel risk factor for COVID-related death. In this study, severity was defined as the need for oxygen supplementation. Respiratory failure is indeed the most important pathology that contributes to the severity of COVID-19. Obesity is associated with restrictive breathing patterns and reduced lung volumes and is a risk factor for acute respiratory distress syndrome. Furthermore, it is also reported as an independent risk factor for the severity of COVID-19. , We have previously reported that the association of hypertension, diabetes, and ethnicities, all of which that correlate to obesity, with the severity of COVID-19 and H1N1 may be confounded by obesity to a considerable extent. Hyperuricemia and obesity are known to be significantly correlated. Although multiple regression analysis showed that hyperuricemia is an independent risk factor for COVID-related death, the analysis did not include obesity or body mass index as an explanatory variable. Therefore, to truly show that hyperuricemia is a novel risk factor for COVID-related death, a multiple regression analysis including obesity as an explanatory variable is warranted.

Declaration of Competing Interest

None.