Change of prognostic nutritional index after three months of initial hemodialysis is a predictor of long-term outcomes for patients with uremia

Nutritional status and immune function have a significant impact on the prognosis of patients undergoing maintenance hemodialysis (MHD). Previous studies have shown that the Geriatric Nutritional Risk Index (GNRI) and the Prognostic Nutritional Index (PNI) at the initiation of dialysis can be used to assess the prognosis of MHD. However, as the physical status of patients are usually unstable in the early stage of dialysis, we hypothesized that the nutritional status and immune function after a certain period of stable dialysis might be more closely related to the prognosis. This study conducted a retrospective analysis of patients who started MHD between January 1, 2019 and December 31, 2021. A total of 200 patients were included, with 66 patients succumbing during follow-up. Both initial PNI and initial GNRI exhibited a negative correlation with all-cause mortality (p=0.019 and p=0.046, respectively). After three months of MHD, both PNI and GNRI increased in most patients; however, only the PNI measured after three months was significantly associated with prognosis and higher PNI was associated with a better prognosis (p<0.001). Multivariate Cox regression analyses indicated that only PNI after three months of MHD was linked to prognosis (p=0.004). Kaplan-Meier curves demonstrated patients experiencing a decrease in PNI following three months of MHD had poorer prognoses compared to those whose PNI increased (p=0.004). Furthermore, the predictive value of PNI after three months of MHD was evident in both younger (<60 years old; p=0.024) and older (>60 years old; p=0.022) patient groups. Both the PNI and GNRI showed a downward trend before death, but only PNI had a significant decline (p=0.03, compared with PNI after three months of MHD). In conclusion, for patients undergoing MHD, the correlation between PNI and prognosis is closer than that of GNRI, and the PNI after three months of MHD is a statistically significant but moderate predictor of long-term outcomes.