Interleukin-6 is an independent predictor of mortality in patients starting dialysis treatment.
BACKGROUND
The mortality rate is high among end-stage renal disease (ESRD) patients, and recent evidence suggests that this may be linked to inflammation. The activity of interleukin-6 (IL-6) and its soluble receptor (sIL-6R) are markedly up-regulated in ESRD patients, and plasma IL-6 levels predict outcome in haemodialysis (HD) patients. However, it has not been established whether elevated plasma IL-6 also predicts outcome in ESRD patients treated by peritoneal dialysis (PD), and how it relates to the data on HD patients. The predictive power of sIL-6R levels on outcome is also unknown in this patient population.


METHODS
To determine whether or not plasma IL-6 and sIL-6R predict patient survival, we studied 173 ESRD patients (62% males, 53+/-1 years of age) near the initiation of dialysis treatment (99 PD, 74 HD patients). The patients were followed for a mean period of 3.1+/-0.1 years (range 0.1-7.1 years) and were stratified at the start of dialysis treatment according to age, gender, presence of cardiovascular disease, malnutrition (determined by subjective global assessment), diabetes mellitus, and IL-6 and sIL-6R plasma levels.


RESULTS
A significantly different (P<0.0001) mortality rate was observed in different groups when patients were divided into quartiles according to IL-6 levels. Furthermore, the same differences were observed, less notably however, for sIL-6R (P<0.05). When patients were stratified according to IL-6 quartiles and analysed separately according to the different initial treatment groups, a similar profile of survival was observed for PD (P<0.01) and HD (P<0.05) patients. In a Cox proportional hazard model adjusting for the impact of age, malnutrition, diabetes mellitus and male gender, log IL-6 values were independently associated with poor outcome (P<0.05).


CONCLUSIONS
The present study demonstrates that the strong predictive value of elevated IL-6 levels for poor outcome in ESRD patients is similar in both HD and PD patients starting treatment.
Division of Renal Medicine, Department of Clinical Science, Karolinska Institutet, Huddinge University Hospital, Stockholm, Sweden. roberto.pecoits-filho@klinvet.ki.se
Roberto
R
Pecoits-Filho
Peter
P
Bárány
Bengt
B
Lindholm
Olof
O
Heimbürger
Peter
P
Stenvinkel
D015415:Biomarkers / Q000097:blood; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D007676:Kidney Failure, Chronic / Q000276:immunology / Q000401:mortality / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D010530:Peritoneal Dialysis / Q000401:mortality*; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D019947:Receptors, Interleukin-6 / Q000097:blood; D006435:Renal Dialysis / Q000401:mortality*; D015996:Survival Rate; D013997:Time Factors; D016896:Treatment Outcome
D015415:Biomarkers; D015850:Interleukin-6; D019947:Receptors, Interleukin-6