Efficiency and nutritional parameters in an elderly high risk population on hemodialysis and hemodiafiltration in Italy and France: different treatments with similar names?

Background: Choice of dialysis is context sensitive, explored for PD and extracorporeal dialysis, but less studied for haemodialysis (HD) and hemodiafiltration (HDF), both widely employed in Italy and France; reasons of choice and differences in prescriptions may impact on dialysis-related variables, particularly relevant in elderly, high-comorbidity patients. Methods: The study involved two high-comorbidity in-hospital cohorts, treated in Centers with similar characteristics, in Italy (Cagliari) and France (Le Mans). All patients (204) agreed to participate. Stable cases on thrice-weekly dialysis, with at least 2 months follow-up were selected (180 patients, Males 59.4%, median age 71 years, vintage 4.3 years, Charlson index 9). Univariate and multivariate correlations between baseline data, HD-HDF, dialysis efficiency and nutritional markers were assessed. Results: In Le Mans HDF was mainly chosen to increase efficiency (large surface dialysers, high convective volume; 76.3% of the patients), in Cagliari to improve tolerance (smaller surfaces, lower convective volume; 59% of patients). Kt/V was similar in HD and HDF, and in both settings(median Kt/V Daugirdas 2: 1.6); in the setting of high efficiency no correlation was found between Kt/V, BMI, urea, creatinine, n-PCR and phosphate. The relationship between Kt/V and albumin was divergent: a weak consensual increase was present in Cagliari, a decrease in Le Mans, suggesting a role of albumin losses with high convective volumes. In the multivariate analysis, after adjustment for other covariates (including comorbidity and type of treatment) low albumin level < 3.5 g/dl was highly correlated with setting of study: Le Mans (OR: 7.155 (2.955-17.324)). The multivariate analysis confirmed a role of type of treatment, with higher risk of low albumin levels in HDF (OR: 3.592 (1.466-8.801)), and of comorbidity (Charlson index> = 7 (OR: 3.153 (1.311-7.582)), MIS index> = 7 (OR: 5.916 (2.457-14.241)). Conclusions: The different prescriptions of HD and HDF may have similar effects on dialysis efficiency, but diverging effects on crucial nutritional markers, such as albumin levels, probably more evident in high-comorbidity populations.