Depression and serum interleukin-6 levels in patients on dialysis

Depression is a common psychiatric problem in patients undergoing dialysis. Several studies have been performed to validate the association between depression and inflammation in haemodialysis patients. The levels of proinflammatory cytokines are increased in chronic renal failure patients, as in depression. The objective of this study was to compare the incidence of depression in the patients on dialysis (on hemodialysis /HD/ and on continuous ambulatory peritoneal dialysis /CAPD/), and a relationship between depression and the presence of inflammation.

88 patients (52 on HD and 36 on CAPD) were enrolled in this study. Depressive symptoms were measured with the Beck Depression Inventory (BDI). The BDI is a 21-item self-report instrument, and the elevated symptoms of depression were defined as a BDI score ≥16. HD patients were treated with high-flux polysulphone biocompatible dialyzers and CAPD patients were treated with usual dwell time (4-6 hours during the day and 8-10 hours at night). The presence of an inflammatory state was assesded by determinations of plasma interleukin-6 (IL-6) levels.

Depression (BDI ≥16) was present in 28.4% of dialysis patients, 35% of patients on hemodialysis (HD) and 18.1% of patients on continous ambulatory peritoneal dialysis (CAPD). The BDI score was significantly lower in CAPD patients comparing to HD patients, as well as the levels of albumin, C-reactive protein (CRP) and interleukin-6 (IL-6). IL-6 serum levels were similar in patients with depression and patients without depression in the whole group, as in HD patients. In CAPD patients without depression IL-6 levels were significantly lower.

The prevalence of depression was higher in HD comparing to CAPD patients. Although IL-6 level was higher in HD compared to CAPD patients, the relationship between depression and presence of inflammation parametars were observed in CAPD, but not in HD patients.