Accumulation of advanced glycation end products in intensive care patients

Introduction

Oxidative stress plays an important role in the course and eventual outcome of a majority of patients admitted to the ICU. Markers to estimate oxidative stress are not readily available in a clinical setting. Recently, advanced glycation endproducts (AGEs), compounds that accumulate with age and play an important role in the development of end organ damage in several conditions, have emerged as one of the very few stable end products of oxidative stress. Skin autofluorescence (AF) is a validated marker of tissue content of AGEs, and can be rapidly and noninvasively measured. We hypothesized that AGEs, measured by AF accumulate in ICU patients, are a prognostic factor for outcome.

Methods

Skin AF was measured using an AGE reader in 40 consecutive ICU patients (with a small subgroup of five diabetic patients), age >18 years. As a comparison, historical data of a non-diabetic control group (n = 231) and a diabetic control group (n = 973) were also used to calculate age-adjusted AF levels (AF-adj). Values are expressed as the median and interquartile range (P25–P75). Differences between groups were tested by the Mann–Whitney U test. P < 0.05 was considered statistically significant.

Results

AF-adj values were higher in nondiabetic ICU patients (0.333 (0.002–0.676)) than in nondiabetic controls (-0.070 (-0.290 to 0.240); P < 0.001). AF-adj values were also higher in diabetic ICU patients (0.770 (0.566–0.892)), compared with diabetic controls (0.000 (0.000–0.000); P < 0.001). No differences in skin AF were observed between acute or planned admissions, nor was skin AF related to severity of disease as estimated by the APACHE II score, length of ICU and hospital stays or mortality.

Conclusion

Acute AGE accumulation occurs in ICU patients, probably reflecting oxidative stress. The group was too small to allow any conclusions on the possible predictive value of skin AF for prognosis for patients on the ICU. Further studies should reveal whether AGE accumulation will be a useful parameter in ICU patients.