Incidence of cognitive impairment and risk factors associated with prognosis in maintenance hemodialysis patients

Objective To investigate the incidence and prognosis of cognitive impairment and to find out the risk factors associated with the outcome for better understanding and preventing cognitive impairment in maintenance hemodialysis (MHD) patients. Methods The patients who met the criteria as below: MHD patients (≥3 months) in Renji Hospital, Shanghai Jiao Tong University School of Medicine from January 2000 to July 2014, ≥18 years old were enrolled and could carry on the montreal cognitive assessment (MoCA) of voluntary cooperation. According to the score of MoCA, all enrolled patients were divided into two groups: cognitive impairment (MoCA<26) group and non-cognitive impairment (MoCA≥26) group. The follow-up period was 3 years. There were 130 males, and the incidence, demography data, medical history, hemodialysis data, laboratory examination and prognosis of cognitive impairment in hemodialysis patients were prospectively compared and analyzed. Logistic regression analysis was used to investigate the risk factors of cognitive impairment. Kaplan-Meier survival curve and Cox regression model were used for prognostic analysis. Results A total of 219 MHD patients were enrolled. The incidence of cognitive impairment in MHD patients was 51.6%. There were 130 males, and the ratio of male to female was 1.46∶1. Age was (60.07±12.44) years old and dialysis vintage was (100.79±70.23) months. Compared with non-cognitive impairment group (n=106), patients in cognitive impairment group (n=113) were older, and had higher proportion of education status<12 years, history of diabetes and anuria (all P<0.05); however, the post-dialysis systolic pressure, pre-dialysis diastolic pressure, post-dialysis diastolic pressure, platelet and spKt/V were lower (all P<0.05). Multivariate logistic regression analysis showed that education status<12 years (OR=3.428, 95%CI 1.919-6.125, P<0.001), post-dialysis diastolic pressure<73 mmHg (OR=2.234, 95%CI 1.253-3.984, P=0.006) and spKt/V<1.72(OR=1.982, 95%CI 1.102-3.564, P=0.022) were the independent risk factors for cognitive impairment in MHD patients. The Kaplan-Meier survival curve analysis showed that the survival rate of patients with cognitive impairment was lower than that of non-cognitive impairment group in MHD patients during 3 years follow-up (χ2=3.977, P=0.046). Multivariate Cox regression analysis showed that cognitive impairment was an independent risk factor for death in MHD patients (RR=2.661, 95%CI 0.967-7.321, P=0.058). Conclusions Cognitive impairment is one of the common complications and an independent risk factor for death in MHD patients. The mortality is high in patients who suffer cognitive impairment. Education status<12 years, post-dialysis diastolic pressure<73 mmHg and spKt/V<1.72 are the independent risk factors for cognitive impairment in MHD patients. Key words: Renal dialysis; Cognitive dysfunction; Incidence; Prognosis; Risk factor