Dear Editor,

We read with interest the article by Kanjanavaikoon et al. [1] published in Clinical Rheumatology. The authors reported a study about age, body mass index, and function as the independent predictors of sarcopenia in axial spondyloarthritis. They found that sarcopenia is common in the population which consists of ax-SpA patients. In their study, Kanjanavaikoon et al. indicated that sarcopenia is related with older age, low BMI, and high BASFI score but not disease activity [1]. We agree that sarcopenia is associated with age and low BMI, but disagree that it is not associated with disease activity.

Recently, some studies have shown that sarcopenia is associated with inflammation [2]. Bano et al. reported that inflammatory cytokines are related with decreased muscle mass and strength. The prolonged presence of elevated inflammatory cytokines in serum may also be related to sarcopenia [3]. In another study Ferri et al. defined that mitochondrial dysfunction is a common condition in inflammation-induced sarcopenia. Prolonged increase in inflammatory cytokines like IL-1β, IL-6, and TNF-α are related with sarcopenia [4].

Sarcopenia was found to be unrelated to disease activity in the study of Kanjanavaikoon et al. However, ax-SpA is an inflammatory disease and when we look at the literature, we can think that the sarcopenia that develops in these patients is due to inflammation. It can be thought that the disease activity parameters are low because this patient group has been receiving anti-inflammatory treatment for a while.