Skin autofluorescence and malnutrition as predictors of mortality in persons receiving dialysis: a prospective cohort study

Abstract

Background: Skin autofluorescence (SAF), which is a measure of accumulation of advanced glycation end-products (AGE), and malnutrition are each associated with higher mortality in dialysis populations, although no studies have investigated these potentially related associations together. We simultaneously assessed SAF and malnutrition as risk factors for mortality in persons receiving dialysis. Methods: SAF was measured in 120 haemodialysis and 31 peritoneal dialysis patients using an AGE Reader (DiagnOptics, Groningen, The Netherlands). Dietary AGE, energy, protein and fat intake, handgrip strength, anthropometry, biochemistry and Subjective Global Assessment were also evaluated. Time to event was days from baseline to death, kidney transplantation or 30 September 2018. Results: Median observation time was 576 days, during which 33 (21.9%) patients died. Those who died had higher baseline SAF levels [3.8 ± 1.0 versus 3.3 ± 0.8 arbitrary units (AU); P = 0.001] and were more likely to be malnourished (58% versus 31%; P = 0.006). Malnourished persons who died had higher SAF values than those who died but were well-nourished (4.2 ± 1.1 versus 3.3 ± 0.7 AU; P = 0.007). Survival was significantly better in participants with baseline SAF below the median and in those well-nourished than those with baseline SAF above the median and in those malnourished, respectively. Multivariable analysis identified SAF [hazards ratio (HR) = 1.44; 95% confidence interval (CI) = 1.05–1.97; P = 0.02], malnutrition (HR = 2.35; 95% CI = 1.16–4.78; P = 0.02) and chronological age (HR = 1.60; 95% CI = 1.10–2.33; P = 0.01) as independent predictors of mortality. Conclusions: Although higher SAF and malnutrition are potentially inter-related, they were both independently associated with increased mortality in this population. Interventions to improve outcomes by reducing SAF through correction of malnutrition or dietary AGE restriction require testing in prospective studies.