The mediating role of kinesiophobia in pain intensity, physical function, and physical activity level in inflammatory arthritis.

Pain is the main symptom of inflammatory arthritis and it can impair physical functional performance and physical activity level. Some individuals can develop kinesiophobia and experience a vicious circle of worsening health. This study aimed to investigate the association between pain and physical functional performance/physical activity and determine whether kinesiophobia mediates this association. This was a cross-sectional study with individuals diagnosed with inflammatory arthritis (rheumatoid arthritis or spondyloarthritis) treated at a Rheumatology Outpatient Clinic. We assessed pain (Visual Analogue Scale), physical activity (International Physical Activity Questionnaire - long form), kinesiophobia (Tampa Scale for Kinesiophobia), and physical functional performance (Handgrip Strength Dynamometry, 30-second Sit-to-Stand test, Static Muscular Endurance test, and Timed Up and Go test). The mediating effect of kinesiophobia on the relationship between pain intensity and physical functional performance/physical activity was analyzed, and the significance of the mediating effect (kinesiophobia) was tested through a bootstrap approach. Thirty-three individuals with inflammatory arthritis (mean age: 48 ± 12 years) participated in the study. Kinesiophobia mediates the relationship between pain intensity and physical functional performance analyzed by the 30-second Sit-to-Stand test [indirect effect (IE)overall = -0.343, bootstrap 95% confidence interval (CI): -0.698 to -0.002] and by knee flexion at 90º of the dominant limb (IEoverall = -1.55, bootstrap 95% CI: -3.43 to -0.237). In conclusion, pain intensity can affect physical functional performance through kinesiophobia in individuals with inflammatory arthritis.