In contrast, a study on the impact of coexisting FM on disease activity in 126 patients with psoriatic arthritis (n = 64) and RA (n = 62) demonstrated that, unlike in psoriatic arthritis, no statistically significant correlation was observed between the FiRST score and disease activity parameters (CRP and DAS28) in RA patients [27]. Here, CRP is linked to psoriatic arthritis.