Functional impairment in video terminal operators is related to low-grade inflammation

Abstract

Progressive functional impairments develop with chronic repetitive tasks possibly involving inflammatory mediators. Aim of this study was to analyze systemic inflammatory changes in relation to the possible occurrence of pain and/or disability in video terminal operators (VTOs) undergoing upper-extremity repetitive stress due to chronic overuse. Pain assessments, classification, and grade of impairment relied on self-report questionnaires administered to 21 VTOs and to 21 matched controls. The inflammatory status of the enrolled subjects was analyzed by determination of serum high sensitive C-reactive protein (hs-CRP) as well as systemic levels or monocyte expression of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Serum levels of both cytokines were increased in VTOs compared to controls (P=0.005 for TNF-α and P=0.004 for IL-6). TNF-α levels correlated to IL-6 (P=0.019), which, in turn, was associated to increased hs-CRP (P=0.012). DASH score allowed to categorize VTOs according to disability. VTOs with mild (DASH=22) or moderate (DASH=46) disability (n=10) had higher serum hs-CRP (P=0.001) and IL-6 (P=0.035) levels than VTOs without disabilities (DASH<17) (n=11). Monocyte stimulatory TNF-α expression was increased in individuals with mild/moderate disability. Monocyte expression of TNF-α was independently associated to that of IL-6, which, in turn, was associated to increased systemic hs-CRP levels together with mild/moderate functional impairment and weekly commitment to the display screen. The results here reported indicate the occurrence of a low-grade inflammatory condition in VTOs with mild/moderate disability, which might allow the early recognition of arising musculoskeletal disorders induced by repetitive stress.