Predictors of autonomic neuropathy in rheumatoid arthritis

Autonomic dysfunction occurs in rheumatoid arthritis (RA). However, the association between the autonomic dysfunction and inflammation has not been investigated in RA. We investigated the relationship between inflammation and ANS function in RA.

In this cross-sectional study, 25 RA patients and 25 age and sex-matched healthy controls were recruited. Autonomic function assessed by five cardiovascular reflex tests according to Ewing. Parasympathetic dysfunction established by applying three tests: heart rate response to deep breath (HRD) and standing (HRS) and Valsalva tests. Sympathetic dysfunction examined by applying two tests: BP response to standing and handgrip test. Peripheral sympathetic autonomic function assessed by Sudoscan through measurement of electrochemical skin conductance of hands and feet. Sudoscan investigates the sweat gland activity and used as a surrogate to study the damage of sympathetic sudomotor nerves in neuropathy. It is an indirect assessment tool of sudomotor function. Disease-specific and inflammatory measures (DAS 28, ESR, CRP, TNF-α, IL-6 and IL-1) were determined.

RA patients had significantly impaired HRD, HRS, BP response to hand grip and sudomotor function as compared to healthy controls. Pro-inflammatory cytokines were significantly higher in RA as compared to healthy controls (p<0.05). DAS 28 significantly correlated with HRD in RA. ESR significantly correlated with HRD and HRS. TNF-α significantly correlated with HRD, HRS, BP response to standing and sudomotor function. Significant correlation was found between IL-6 and HRS. Seropositive patients had more pronounced CAN and sudomotor dysfunction.

Autonomic dysfunction in RA is related to disease activity, seropositivity and pro-inflammatory cytokines.