SP692IMPACT OF NUTRITIONAL STATUS ON SKIN AUTOFLUORESCENCE IN HAEMODIALYSIS PATIENTS

Abstract

INTRODUCTION AND AIMS: Skin autofluorescence (SAF), a measurement of skin accumulation of advanced glycation end-products (AGEs), has been reported to be an independent predictor of survival in haemodialysis (HD) patients but the mechanism of this association is not completely understood. AGEs are uremic toxins rapidly formed during oxidative stress which is associated with systemic inflammation. AGEs are also formed in food and ∼10% of the ingested AGEs are absorbed. Oxidative stress and inflammation have been implicated in the development of malnutrition which has also been strongly associated with cardiovascular mortality in dialysis patients. We aimed to investigate the impact of several nutritional factors as potential determinants of SAF. METHODS: SAF was measured in 76 HD patients using a validated Autofluorescence Reader and a validated food frequency questionnaire was used to assess dietary AGE intake. Energy, fat and protein intake were also assessed, as well as handgrip strength (HGS), mid-arm muscle circumference (MAMC) and routine biochemical variables. Subjective Global Assessment (SGA) was performed to evaluate nutritional status. RESULTS: Median age and SAF were 68.0 (IQR 56.0 to 75.7) years and 3.3 (2.7 to 3.8) arbitrary units (AU), respectively. Diabetes and obesity were present in 29 patients (38.2%) each. SGA revealed that 30 patients (39.5%) were malnourished (of which 6 [8%] had severe malnutrition) whereas 46 were well nourished (60.5%). Median dietary AGE intake was high at 12920.3 (9140.3, 16984.0) kilounits (kU)/day compared with a recommended intake of less than 8000 kU/day. Median energy and protein intake were low (20.1 [16.0 to 24.0] kcal/kg/day and 0.8 [0.6 to 1.0] g/kg/day, respectively) compared to the recommendations for dialysis patients (35 kcal/kg/day and 1.2 g/kg/ day). SAF was significantly higher in patients with prior coronary heart disease (CHD) and in current smokers. There was a significant positive correlation between SAF, C reactive protein and dialysis vintage. Additionally, SAF correlated significantly and negatively with HGS, serum calcium, albumin, total protein and serum cholesterol, as well as energy, protein, fat and dietary AGE intake. Malnourished patients had higher SAF levels than well-nourished patients. Malnutrition was more evident in patients with CHD. Energy and fat intake, MAMC and HGS were significantly lower in patients with malnutrition compared to well-nourished patients. Multiple linear regression analysis showed that dialysis vintage, current smoking, lower HGS and lower protein intake were independent predictors of increased SAF levels, but energy intake and AGE intake were not. CONCLUSIONS: Malnutrition is a frequent complication in HD patients and was associated with elevated SAF levels, presence of CHD, low energy and fat intake and decreased HGS. The unexpected finding of an inverse relationship between SAF and dietary AGE intake is probably explained by the association of higher SAF with several markers of malnutrition. Ongoing follow-up of participants will investigate changes in SAF levels over time, one-year survival and the impact of a dietetic intervention to reduce SAF levels.