Intraperitoneal interleukin-6 levels predict peritoneal solute transport rate: a prospective cohort study.

BACKGROUND

To evaluate the association of dialysate interleukin-6 (IL-6), a marker of ongoing peritoneal inflammation, with the alteration of peritoneal solute transport rate (PSTR) in continuous ambulatory peritoneal dialysis (CAPD) patients.

METHODS

Stable CAPD patients were enrolled in the present study. A total of 128 patients were analyzed in this prospective study. IL-6 concentration in the overnight effluent was determined and expressed as the IL-6 appearance rate (IL-6AR). Mass transfer area coefficients of creatinine (MTACcr) were measured at enrollment and 12 months later. Logistic regression was used to examine the association between IL-6AR and change in MTACcr.

RESULTS

Multivariable linear regression showed that historical glucose exposure was significantly associated with dialysate IL-6AR level [β = 0.008 (0.001-0.015), p = 0.021]. After 12 months, MTACcr was significantly increased [6.40 (4.70-8.75) vs. 7.14 (5.69-8.73) ml/min, p = 0.004], while ultrafiltration capacity decreased [4 h UF 340 (220-400) vs. 280 (180-380) ml, p = 0.006]. Compared to the patients with stable PSTR, the dialysate IL-6AR in patients with increasing PSTR was significantly higher [277.08 (247.45-349.53) vs. 263.18 (69.94-286.72) pg/min, p = 0.015]. Patients with increasing PSTR had lower residual renal function [0.79 (0-2.12) vs. 1.70 (0.39-3.38) ml/min, p = 0.006] and less urine output [225 (0-600) vs. 500 (125-900) ml/24 h, p = 0.014]. Logistic analysis showed that both high dialysate IL-6AR [OR 1.333 and 95% CI (1.024-1.735), p = 0.033] and low RRF [OR 0.831 and 95% CI (0.699-0.988), p = 0.036] were independent risk factors for increasing PSTR.

CONCLUSIONS

This prospective study suggests that intraperitoneal IL-6 is a predictor of increasing PSTR in peritoneal dialysis patients.