MO931: Serum Uric Acid—A Marker of Malnutrition and Mortality in Patients Undergoing Maintenance Haemodialysis

Malnutrition in patients on maintenance haemodialysis (HD) develops along different pathways, and factors contributing to the development of malnutrition may be categorized as of iatrogenic and non-iatrogenic origins. Iatrogenic factors are an inadvertent consequence of dialysis for HD patients (e.g. removal of uremic solutes), whereas non-iatrogenic factors develop spontaneously from different factors accompanying the progression of kidney disease but are not related to the primary treatment (e.g. low dietary energy and protein intake). Malnutrition is prevalent in 28%–54% HD patients and is an important risk factor for mortality. The aim of our study was to investigate the impact of serum uric acid (SUA) and other non-invasive markers of malnutrition on the survival of maintenance HD patients.

We performed a study on 77 HD patients without malignant disease who were observed from January 2016 until their death or January 2021. Their median age was 63.0 (IQR 19) years, and their dialysis vintage was 1449 (IQR 1848) days. We recorded past medical history, laboratory tests and basic demographic data and performed bioelectrical impedance analysis with BodyStat (BodyStat Ltd). Patients who were at risk for malnutrition, based on nutrition screening tools, received oral nutritional supplements (ONS). SUA was measured every 2 months and the mean value was used for analysis. Kaplan–Meier survival analysis and Cox's regression were performed.

Included patients (51.9% males) had diabetes mellitus (33.8%), arterial hypertension (87.0%), ischemic heart disease (24.7%), chronic obstructive lung disease (3.9%), liver disease (3.9%) and were smokers (14.3%). They received an ONS in 63.6%. During the observation period, 50.6% of them died. We created tertile groups (low, medium and high) based on mean SUA < 294 μmol/L, 294–337 μmol/L and > 337 μmol/L, respectively. The low group had significantly lower body mass index (BMI) (P = 0.044), total iron binding capacity (TIBC) (P = 0.001), phase angle (P = 0.003) and dry lean mass (DLM) (P = 0.048), however there were no significant differences in prescription of ONS (P = 0.092). Kaplan–Meier survival analysis showed significantly higher mortality for patients in the low tertile group (P = 0.004). In Cox's regression model, SUA remained significant when adjusted for age, sex, BMI and comorbidities (P = 0.026). However, when adjusting for other markers of malnutrition and receiving ONS, only phase angle, albumin, DLM, fat free mass index and TIBC remained statistically significant.

Low SUA levels in chronic HD patients are associated with lower survival and can help identify individuals who are at risk for malnutrition. Further studies should be done to guide possible interventions.