Vascular access type, inflammatory markers, and mortality in incident hemodialysis patients: the Choices for Healthy Outcomes in Caring for End-Stage Renal Disease (CHOICE) Study

Abstract

Background: Few reports have shown an association between access type and inflammatory marker levels in a longitudinal cohort. We investigated the role of access type on serial levels of inflammatory markers and the role of inflammatory markers in mediating the association of access type and risk of mortality in a prospective study of incident dialysis patients.

Study design: Cohort study, post hoc analysis of the CHOICE (Choices for Healthy Outcomes in Caring for ESRD) Study.

Setting & participants: In 583 participants, inflammation was assessed by measuring serum C-reactive protein (CRP) and interleukin 6 (IL-6) after access placement and at multiple times during 3 years' follow-up. Type of access was categorized as central venous catheter (CVC), arteriovenous graft (AVG), and arteriovenous fistula (AVF), and changes over time were recorded.

Predictor: Access type, age, sex, race, body mass index, diabetes, cardiovascular disease, and serum albumin level.

Outcomes: CRP level, IL-6 level, and mortality.

Measurements: We used mixed-effects pattern mixture models to study the association between access type and repeated measurements of inflammation and survival analysis to investigate the association of access type and mortality, adjusting for predictors.

Results: In a mixed-effects pattern mixture model, compared with AVFs, the presence of CVCs and AVGs was associated with 62% (P=0.02) and 30% (P=0.05) increases in average CRP levels, respectively. A Cox proportional hazards model yielded nonsignificant associations of CVC and AVG use (vs AVFs) with risk of mortality when adjusted for inflammatory marker levels. Higher CRP levels were associated with increased risk of CVC failure than lower CRP levels.

Limitations: CRP and IL-6 measurements not performed for all hemodialysis patients.

Conclusions: CVCs, compared with AVFs, are associated with a greater state of inflammation in incident hemodialysis patients, and the association of catheter use and mortality may be mediated by access-induced inflammation. Our findings support recommendations for the early removal or avoidance of CVC placements.

Keywords: C-reactive protein (CRP); Cox proportional hazard model; access failure; access patency; biomarker; central venous catheter (CVC); end-stage renal disease (ESRD); hemodialysis; inflammation; interleukin 6 (IL-6); mixed-effects model; vascular access type.

Figure 1

Percent Change associated with C-Reactive Protein at time following insertion of central venous catheter and arteriovenous fistula. Upper and lower limits of the lines at each time point represent 95% confidence intervals.

Figure 2

Percent Change associated with interleukin-6 at time following insertion of central venous catheter and arteriovenous fistula. Upper and lower limits of the lines at each time point represent 95% confidence intervals.

Figure 3

Cumulative probability curve for central venous catheter failure rate in patients with varying CRP levels within the first year from dialysis initiation.