Abstract: TH-PO855

Peritoneal Inflammation Increases over Time, with an Associated Increase in Plasma IL-6 Predicting Worse Survival: Results From the Global Fluid Study

Session Information

  • Peritoneal Dialysis - I
    November 02, 2017 | Location: Hall H, Morial Convention Center
    Abstract Time: 10:00 AM - 10:00 AM

Category: Dialysis

  • 608 Peritoneal Dialysis

Authors

  • Elphick, Emma H., Keele University, Stoke on Trent, United Kingdom
  • Zavvos, Vasileios, Cardiff University, Cardiff, United Kingdom
  • Davies, Simon J., Keele University, Stoke on Trent, United Kingdom
  • Topley, Nicholas, Cardiff University, Cardiff, United Kingdom
  • Fraser, Donald, Cardiff University, Cardiff, United Kingdom
  • Lambie, Mark, Keele University, Stoke on Trent, United Kingdom
Background

Local peritoneal inflammation is a feature of peritoneal dialysis (PD) treatment and high concentrations of dialysate IL-6 (dIL6) are a strong determinant of solute transport. Solute transport increases during long term PD but it is unknown whether dialysate IL-6 rises. Plasma IL-6 (pIL6) is an independent predictor of patient survival but whether dialysate IL-6 contributes to plasma levels is unknown.

Methods

We conducted a longitudinal analysis of the Global Fluid study, a multinational cohort study from UK, Canada and Korea. All incident patients with 3 or more paired dialysate/plasma samples were assayed for IL-6 by electrochemiluminescence. A linear mixed model with random intercept/slopes was used, including time on PD, centre, dIL6, gender, baseline age, comorbidity score and urine volume with backwards selection, for log transformed pIL6. An unadjusted joint longitudinal survival model (JLSM) assessed pIL6 values and changes over time on survival.

Results

There were 217 patients with 1274 measurements, with a median follow up time of 2.2 years from 6 centres. Over time there is a significant increase in dIL6 (1.17 pg/ml/year 95% CI 1.11 to 1.24) and pIL6 (1.08 pg/ml/year per year 95% CI 1.02 to 2.24). In the multivariate model pIL6 was significantly positively associated with dIL6 (β =0.099 95% CI 0.063 to 0.135) and negatively associated with urine volume (coeff=-0.0058 95% CI 0.0020 to 0.010 p=0.005, time interaction coeff=-0.019 95% CI -0.032 to -0.005 p=0.006). In adjusted Cox models, time varying pIL6 was negatively associated with survival (HR 4.51 per log10 order, 95% CI 1.85 to 11.0). In a JLSM there was a significant negative effect on survival of pIL6 values (β=4.31 95% CI 2.73 to 5.90) and trajectories over time (β=-23398 95% CI -31313 to -15483). pIL6 trajectories were a better predictor of survival than raw values (AIC 1283 vs AIC 1333 respectively) or combined raw values with trajectories (AIC 1331).

Conclusion

There is a rise in pIL6 over time, associated with increasing dIL6 and decreasing urine volume. pIL6 is a strong predictor of mortality, and the rate of increase in pIL6 is a stronger predictor of mortality than the absolute value.