Association of vascular access flow with short-term and long-term mortality in chronic haemodialysis patients: a retrospective cohort study

OBJECTIVES To investigate the impact of vascular access flow (Qa) on vascular and all-cause mortality in chronic haemodialysis (HD) patients. DESIGN Observational cohort study. SETTING Single centre. PARTICIPANTS Adult chronic HD patients at the HD unit of Shin Kong Wu Ho-Su Memorial Hospital between 1 January 2003 and 31 December 2003 were recruited. Patients were excluded if they had arteriovenous fistula or arteriovenous graft failure within 3 months before the date of Qa measurement, were aged <18 years and had Qa levels of ≥2000mL/min. A total of 378 adult chronic HD patients were eventually enrolled for the study. INTERVENTIONS The selected patients were evaluated with Qa and cardiac index (CI). They were divided into four groups according to three Qa cut-off points (500, 1000 and 1500 mL/min). PRIMARY AND SECONDARY OUTCOME MEASURES Short-term and long-term vascular (cardiovascular or cerebrovascular) and all-cause mortality. RESULTS Qa was positively correlated with CI (r=0.48, p<0.001). A Qa level of <1000 mL/min was independently associated with 1-year all-cause mortality (adjusted OR, 6.04; 95% CI 1.64 to 22.16; p=0.007). Kaplan-Meier analysis revealed that the cumulative incidence rates of all-cause and vascular mortality were significantly higher in the patients with a Qa level of <1000 mL/min (log-rank test; all p<0.01). Furthermore, a Qa level of <1000 mL/min was independently associated with long-term all-cause mortality (adjusted HR, 1.62; 95% CI 1.11 to 2.37; p=0.013); however, the risk of vascular mortality did not significantly increase after adjustment for confounders. CONCLUSIONS Qa is moderately correlated with cardiac function, and a Qa level of <1000 mL/min is an independent risk factor for both short-term and long-term all-cause mortality in chronic HD patients.