Sitting time is negatively related to microvascular endothelium-dependent function in rheumatoid arthritis.

BACKGROUND: Sedentary behaviour is linked to increased cardiovascular disease risk in Rheumatoid Arthritis (RA), but the biological processes underlying this relationship are not understood. OBJECTIVES: To investigate the cross-sectional associations of habitual sedentary behaviour, with endothelial function in RA. METHODS: Sixty-eight RA patients (Mage = 55 ±â€¯12 years) underwent Laser Doppler Imaging with iontophoresis, to assess microvascular endothelium-dependent (acetylcholine, ACh) and endothelium-independent (sodium nitroprusside, SNP) function. Large-vessel endothelium-dependent and endothelium-independent functions were measured via flow-mediated dilation (FMD) and glyceryl trinitrate dilation (GTN), respectively. Habitual sedentary behaviour (hours/week sitting) was self-reported (International Physical Activity Questionnaire). RESULTS: Regressions revealed sitting time significantly negatively predicted microvascular endothelium-dependent function (ACh, unstandardizedß = -3.25, p = .02, 95% CI [-6.07, -.42], R2 = 0.06), but did not associate with other endothelial function outcomes (SNP, FMD, GTN). CONCLUSION: Habitual sedentary behaviour (sitting time) appears to be adversely linked to microvascular endothelium-dependent function among people living with RA.