Letter to editor: The waist circumference-adjusted associations between hyperuricemia and other lifestyle-related diseases: methodological issues in cross-sectional study.

Dear Editor-in-Chief

We studied the article written by Miyagami et al. [1] that published in Diabetology & Metabolic Syndrome journal in February 2017. The aim of this study was the relationship between hyperuricemia and lifestyle-related diseases after adjusting with waist circumference (WC). Finally, the authors of this study concluded that Hyperuricemia is an independent predictor of several lifestyle-related diseases, even after adjusting for age, WC, and lifestyle in both sexes which is closely related with insulin resistance. Hyperuricemia might require greater attention during the prevention of lifestyle-related diseases and future cardiovascular disease [1]. However, although this was an appropriate research and its results were very interesting, some methodological issues should be considered.

Miyagami et al. [1] evaluated the predictive performance hyperuricemia on several lifestyle-related diseases in a cross-sectional study, whereas longitudinal researches are necessary for making assumptions in clinical prediction models [2]. In other words, assurance of the temporality assumption presence (the dependent variable has to occur after the independent variable) is essential in the prediction model. Thus, prediction models resulting from cross-sectional designs can be misleading [2, 3].

Considering the predictive performance of hyperuricemia on several lifestyle-related diseases is an optimistic interpretation. The internal and external validation of the prediction model must be done through bootstrapping and split-validation, respectively [4].

Therefore, according to the above explanation, it is necessary considering to this point in interpretation of results of this study for readers.