Change in Vascular Access and Mortality in Maintenance Hemodialysis Patients

Background

We hypothesized that a change from central venous catheters to a fistula or graft would improve short-term mortality risk in maintenance hemodialysis patients.

Design

Prospective observational study.

Setting & Participants

All maintenance in-center hemodialysis patients treated in Fresenius Medical Care, North America legacy facilities alive on January 1, 2007 with baseline laboratory data from December 2006.

Predictor

Access type (fistula, catheter, or graft), determined on December 31, 2006, and monthly thereafter. Conversion from a catheter to a fistula or graft during the 4-month period from January 1 to April 30, 2007.

Outcome

Mortality was tracked from May 1, 2007, to December 31, 2007. Standard and time-dependent Cox models were used to determine hazard risks (HRs) of death with and without adjustment for case-mix and laboratory values.

Results

At baseline, 79,545 patients had 43% fistulas, 29% catheters, and 27% grafts. Mean age was 62 ± 15 years, 54% were men, 51% were white, and 53% had diabetes. Compared with fistulas, unadjusted HRs of death were higher for grafts (1.22) and catheters (1.76; P < 0.001). In adjusted models, overall risk for grafts was decreased to 1.05 (95% limits, 1.003-1.100; P < 0.05) and approached that for fistulas consistently across multiple strata. Compared with patients who continued using a catheter, those who converted to either a graft or fistula had an HR of 0.69, whereas those who converted from a graft or fistula to a catheter had increased HRs to 2.12 (both P < 0.001). Similar trends were observed in the subset of incident patients (vintage < 90 days at study onset).

Limitations

Observational design with residual confounding from unmeasured patient, facility, and treatment-related factors.

Conclusions

Catheters have the worst associated mortality risk. Changing from a catheter to a fistula or graft is associated with significantly improved survival. The risk for grafts approached that of fistulas, providing an alternative to prolonged catheter exposure and potentially less hazardous “bridge” toward a fistula.

Index Words: Hemodialysis, mortality risk, end-stage renal disease (ESRD), outcomes, vascular access