#2268 Dialysis patients survival in HD centres from Belgium, Estonia, Spain, and Sweden—association with BMI and hypocalcemia
Authors: Holmar Jana , Luman Merike , Adoberg Annika , Leis Liisi , Paats Joosep , Uhlin Fredrik , Ortiz Alberto , Glorieux Griet , Dhondt Annemieke , Pilt Kristjan , Tanner Risto , Fridolin Ivo 
Published: May 2024

Abstract

Background and Aims
Several factors are known to influence the morbidity and mortality of ESKD patients, among them cardiovascular disease, nutritional status, delivered dialysis dose, uremic toxins levels, and infectious diseases. This observational study aimed to analyse factors that impact the survival of ESKD patients on haemodialysis.

Method
We analysed 3- and 5-year survival of 76 patients during the period of 2018-2023 (17 females, 59 males, aged 63.6 ± 15.9 years) from four separate dialysis centres from countries with diverse life expectancies, renal replacement therapy incidences, and kidney transplant rates: North Estonia Medical Centre, Tallinn, Estonia (21 patients); Linköping University Hospital, Linköping, Sweden (21 patients); Ghent University Hospital, Ghent, Belgium (14 patients) and Fundación Jiménez Díaz University Hospital Health Research Institute, Madrid, Spain (20 patients). We included stable chronic haemodialysis patients receiving three times per week post-dilution ol-HDF treatment. Patients with central dialysis catheter, acute coronary syndrome or stroke within three months were excluded. Cox proportional-hazard regression analysis was used to detect the factors affecting the survival of patients. In the Cox model, the 3-year survival was set as a dependent parameter. Age, gender, BMI, and serum levels of creatinine, phosphate, calcium, total protein, and uric acid were set as independent parameters. Kaplan-Meier survival analysis was performed to study survival in the subgroups of patients.

Results
Out of 76 patients, 22 died in 3-years and 34 in five years (Fig. 1a and b). Our Cox model (adjusted with the age, gender, creatinine, phosphate, total protein, and uric acid serum levels) indicated patients' body mass index (BMI, p = 0.014) and calcium (p = 0.033) levels as statistically significant factors in 3-year survival.
Kaplan-Meier survival analysis showed statistically significant increased survival in the group where BMI was higher than 27.6 kg/m2 (Fig. 2a) and in the group where serum calcium levels were higher than 2.25 mmol/L (Fig. 2b).

Conclusion
This study shows that among prevalent haemodialysis patients 3-year survival is about 65% and 5-year survival 45%, and a higher risk of mortality could be associated with low BMI and low serum calcium levels.
Our findings are in accordance with previous studies, where survival benefit for haemodialysis patients with higher BMI is shown [1, 2]. It is proposed that this phenomenon among advanced CKD patients with higher BMI could be due to better nutritional reserve that helps resist chronic inflammation and wasting. The negative effects of excess calcium load for haemodialysis patients are well known, and nowadays, non-calcium-based phosphorus binders, calcimimetics, and low-calcium concentrates in haemodialysis are used more often, thus putting the patients at risk of hypocalcaemia. Though less studied, long-term hypocalcaemia is shown to increase mortality among haemodialysis patients [3], as concurs with our results. Safe calcium concentration limits for these patients are still debatable and need further investigation.