Mediating effect of gait speed on the relationship between ankle-brachial index and mild cognitive impairment in hemodialysis patients.

ABSTRACT

BACKGROUND: Patients undergoing hemodialysis are highly predisposed to arterial disease, poor physical performance, and cognitive impairment. However, the connection between them is not yet known. We aimed to investigate the mediating effect of physical performance on the relationship between arterial stiffness and mild cognitive impairment (MCI). METHODS: We conducted a multicenter cross-sectional study. The final analyzed hemodialysis patients comprised 616 subjects (men 391, women 225) from seven dialysis units in Shanghai, China. MCI was assessed by Mini-Mental State Examination (MMSE) and the Instrumental Activities of Daily Living (IADL) scale. Arterial function was measured by ankle-brachial index (ABI) and branchial-ankle pulse-wave velocity (baPWV). Physical function was assessed by the Short Physical Performance Battery (SPPB). Logistic regression and mediation model were used to analysis. RESULTS: The mean age of the final analysis sample (n = 616) was 59.0 ± 12.0 years. Hemodialysis patients with MCI were more likely to have lower ABI (p < 0.001) and higher baPWV (p < 0.01). After adjusting for covariates, lower ABI (abnormal ≤0.9 and borderline 0.91-0.99) were positively associated with MCI (OR = 4.43, 95% CI = 1.89-10.39; OR = 4.83, 95% CI = 1.61-14.46). SPPB total score and its components standing balance, gait speed score were negatively associated with MCI. In the mediational model, gait speed played a mediating role (indirect effect ab = -0.21; 95% CI = -0.58 to -0.03) in the association of ABI (≤0.9) and MMSE, while standing balance and chair stands did not. CONCLUSIONS: Lower gait speed mediates a positive association between ABI and MCI in hemodialysis patients. Suitable interventions for physical performance, especially gait speed, may reduce the risk of MCI in hemodialysis patients.