Prediction of survival in hemodialysis patients with sodium gradient before and after hemodialysis session

Aim: Hemodialysis (HD) patients have an expected lifespan that is approximately one-fifth of that of the general population. Cardiovascular deaths resulting from volume shifts, malnutrition, and infections rank among the primary causes of mortality. Volume changes in HD patients are commonly assessed by the sodium gradient before and after the dialysis session as well as by the interdialytic weight gain relative to dry weight (% IDWG/DW). This study aims to observationally evaluate the effects of volume assessment parameters during HD sessions, alongside the impact of infection and nutritional status, on patient survival. Materials and Methods: This prospective study evaluated the demographic and HD session data of prevalent HD patients followed between January 2022 and April 2024 at Uşak Education and Research Hospital, Eşme State Hospital, and Banaz State Hospital. Patients were divided into two groups based on survival status. Data were analysed using Statistical Packages of Social Sciences (SPSS for Windows, version 22.0) software. One-way ANOVA and independent sample test were used to compare the groups. Mann-Whitney test and correlation analyses were used for group comparisons. Statistical significance level was evaluated at 95% confidence interval and p˂0.05 was accepted. Results: A total of 171 prevalent HD patients were included, with a mean age of 65,27 ± 14,03 years (range 29–89) and 43,28% being female. Diabetes mellitus was present in 77 patients (45%), and hypertension in 141 patients (82%). Over a mean follow-up period of 28 months, 34 patients (19,88%) died. The mean age of survivors was 63,62 ± 13,78 years compared to 71,69 ± 13,31 years for non-survivors (p = 0.0022). The causes of death were sepsis 13 (38%), cardiovascular disease 9 (26%), pulmonary failure 8 (24%), cerebrovascular events 2 (6%), and other causes 2 (6%). ix Regarding vascular access, 74 patients (43,27%) had an arteriovenous fistula (AVF) and 97 patients (56,73%) had an HD catheter. Among survivors, 67 patients (48,91%) used an AVF and 70 (51,09%) used a catheter, whereas in the non-survivor group, only 7 patients (20,59%) had an AVF and 27 (79,41%) had a catheter (p = 0,0033 for AVF, p = 0,0095 for catheter). The interdialytic weight gain relative to dry weight in 2022 was 3,35 ± 1,18 kg in survivors versus 3,24 ± 0,71 kg in non-survivors (p = 0,700). In 2023, these values were 3,25 ± 1,12 kg for survivors and 2,96 ± 1,00 kg for non-survivors (p = 0,254); in 2024, they were 3,26 ± 1,1 kg and 2,81 ± 1,03 kg, respectively (p = 0,235). Overall, the mean interdialytic weight gain was 3,27 ± 1,09 kg for survivors and 2,99 ± 0,95 kg for non-survivors (p = 0,225). Pre-HD systolic blood pressure was 140,43 ± 23,06 mmHg in survivors and 128,70 ± 27,88 mmHg in non-survivors (p = 0,0284). The mean pre-HD sodium level was 138,32 ± 2,15 mEq/L in survivors compared to 137,98 ± 3,12 mEq/L in non-survivors (p = 0,4771). Post-HD sodium levels were 139,19 ± 1,24 mEq/L in survivors and 139,06 ± 1,74 mEq/L in non-survivors (p = 0,8364). Serum albumin levels were significantly higher in survivors (37,41 ± 3,88 g/dL) than in non-survivors (32,26 ± 4,38 g/dL, p = 0,0001). Calcium levels were 8,23 ± 0,65 mg/dL in survivors versus 8,05 ± 0,58 mg/dL in non-survivors (p = 0,0984). Phosphorus levels were 4,93 ± 1,14 mg/dL in survivors and 4,29 ± 1,14 mg/dL in non-survivors (p = 0,000). Parathyroid hormone levels averaged 567,4 ± 338,7 pg/mL in survivors and 331,32 ± 216,33 pg/mL in non-survivors (p = 0,0001). C-reactive protein (CRP) levels were 21,47 ± 18,48 mg/L in survivors and 40,38 ± 39,74 mg/L in non-survivors (p = 0,012). Hemoglobin levels were 10,52 ± 1,26 g/dL in survivors versus 9,85 ± 1,12 g/dL in non-survivors (p = 0,013). Conclusions: The predominance of catheter use as vascular access in our study cohort may be attributable to the deferral of elective procedures during the COVID-19 pandemic. This situation appears to be associated with poorer survival in patients with catheter access, particularly those with infections, malnutrition, and anemia. The pre- and post-HD sodium gradient did not demonstrate a significant impact on survival, a finding that may be due to the limited sample size and relatively short follow-up duration. Key words: Hemodialysis, interdialytic weight gain, malnutrition