Abstract: Objective:Follow⁃up of patients with anuria on long⁃term maintenance peritoneal dialysis (PD) presents significant challenges, and the risks of all⁃cause mortality and technical failure are high. This study uses baseline information from outpatient follow⁃up data to  predict  and  analyze  the  above  risks  for  this  group  of  people.    Methodology:This  single⁃ center retrospective study  included  PD  patients  who  were  regularly  followed  up  on  dialysis  for ≥5  years  and  whose  urine volume≤100  ml/24h  for  3  at  least  months.  Using  the  outpatient  follow⁃up  records  in  2019  as  the  baseline,  information including demographic information, laboratory tests and other information were collected. The study subjects will continue to be followed  up  until  July  2024,  and  the  observation  endpoints  are  defined  as  all⁃cause  mortality,  and  technical  failure. Technical failure was defined as conversion to hemodialysis lasting 3 months or  more.  The patients were divided into groups based on whether death or technical failure occurred, and the differences in baseline parameters between the two groups were  compared.  The  predictive  value  of  the  baseline  parameters  was  analyzed  using  receiver  operating  curve  (ROC )   and 

multivariate COX regression.    Results:A total  of 255 patients were included, with an average  age  of 53.0± 12.6 years, of whom 104 (40.7%) were male. The median (quartile) dialysis months at the time of inclusion in the study was 79 (65-105) months, and the total urea clearance index (Kt/V) 1.76±0.42, high peritoneal transport/high average transport in 73 cases (28.6%). By the end of  the  follow⁃up  period, a  total  of  121 end⁃point  events  were  recorded, including 29 deaths  and 92 technical failures.  Grouped  according  to  whether  death  or  technical  failure  occurred,  there  were  statistically  significant differences in  the  age,  body  mass  index,  serum  uric  acid,  serum  albumin,  serum  sodium,  serum  creatinine  (Scr)  and cystatin C (CysC)  concentration ratio (Cr/CysC), total Kt/V and peritoneal  transport  types, (all  P<0.05).  Evaluated by the occurrence of all⁃cause mortality or technical failure, the largest variable in the area under the ROC curve is Cr/CysC, followed by total  Kt/V.  The  average  Cr/CysC  level  of  all  patients  was  1.91 ± 0.56.  Multivariate  COX  regression  analysis showed that  the  independent  influencing  factors  of  all⁃cause  mortality  or  technical  failure  were  age,  gender, total  Kt/V, peritoneal transport type and Cr/CysC, while the independent influencing factors of all⁃cause mortality were age, gender, total Kt/V and Cr/CysC. Patients were  divided  into  three  groups  based  on  total  Kt/V  1.70  and  Cr/CysC  1.90  (closest  to  the average Cr/CysC). Both the patient survival curve and the technical survival curve indicate that  patients with baseline total Kt/V<1.70 and Cr/CysC<1.90 have a poor outcomes (P<0.01).    Conclusion:The baseline Cr/CysC level in patients with long⁃term maintenance  PD  and  anuria  is  an  independent  influencing  factor  for  all⁃cause  mortality  and  technical  failure. Cr/CysC combined with total Kt/V is helpful in judging the prognosis of such patients.

Key words: peritoneal dialysis   , total urea clearance index   , serum creatinine/cystatin C ratio