IntroductionThe proportion of older people in the general population is steadily increasing and the fastest growing segment of that population during the past decade is older than 75 years. With this increases in prevalence of elderly people, proportion of prevalent chronic kidney disease (CKD) increased in parallel [1,2]. In spite of these situations, the appropriate treatment of older patients with CKD remains unclear. Moreover, there are a lot of unresolved problems in real world [3]. For example, are there any differences in underlying renal diseases in CKD patients <75 and >75 years?; what are the age-related risk factors for progression to end-stage renal disease (ESRD) and incidence of cardiovascular disease (CVD) [4,5]; is a chance of more cohesive multidisciplinary team approach to CKD producing catastrophic results in elderly CKD patients [6]. Previous reported cross sectional cohort studies failed to reveal what factors are more important for progression to ESRD and for occurrence of CVD in these populations [7]. Besides, it still remains uncertain whether the effects of multidisciplinary care are beneficial or not. Two studies correlated multidisciplinary care with modest improvements in survival [8], but another study showed no differences in kidney function or mortality between patients who received multidisciplinary, intensive care and those who did not [6].Therefore, in the present study, the longitudinal follow-up of elderly patients with stage 4 CKD was carried out in a single center in order to evaluate the characteristics and the prognosis of stage 4 CKD patients >75 years in comparison with those between 74 and 65 years and outcome of late nephrology referral in these patients. Subjects and MethodsThis was a prospective, observational, single-center cohort study. This study was conducted in accordance with the Declaration of Helsinki. Approval for the study was obtained from the Saitama Medical University Ethics Committee, and written informed consent was obtained from each participant.Patients were recruited from specialist renal clinics at Kidney Abstract Background: Although age had a strong effect on the risk of development to end-stage renal disease (ESRD), it is reported that stage 4 CKD patients aged >75 years were less likely to subsequently commence renal replacement therapy (RRT) than those aged <75 years. In the present study, the longitudinal follow-up of elderly patients with stage 4 CKD was carried out in a single center in order to evaluate the prognosis of the patients >75 years in comparison with those between 74 and 65 years and to characterize patients with stage 4 CKD older than 75 years.