Most arteriovenous grafts fail due to irreversible thrombosis, superimposed on hemodynamically significant vascular stenosis. Previous studies observed the highest frequency of stenosis at the venous anastomosis, without addressing the timing of stenosis. The present study quantified time to symptomatic stenosis at different vascular locations, and related it to permanent graft failure. A prospective computerized vascular access database was queried retrospectively to identify 309 hemodialysis patients receiving new upper extremity grafts during a 4-year period at a large dialysis center. For each vascular site we calculated the time to symptomatic stenosis using survival techniques. The cumulative likelihood of symptomatic stenosis at 2 years was 67% for venous anastomotic stenosis, 19% for intra-graft stenosis, 16% for venous outlet stenosis, 13% for central vein stenosis, and 5% for arterial anastomotic stenosis. The cumulative risk of graft failure at 2 years was 40%. Stenosis at the venous anastomosis was twice as likely as cumulative graft failure (hazard ratio [HR] 1.95; 95% confidence interval [CI], 1.65-2.52, p < 0.001). In contrast, intra-graft stenosis was half as likely as cumulative graft failure (HR 0.45; 95% CI, 0.36-0.61, p < 0.001). Central vein stenosis was more likely in patients with a previous ipsilateral catheter compared with those without one (HR 2.40; 95% CI, 1.39-5.58, p = 0.004). Symptomatic stenosis occurs much earlier at the venous anastomosis compared with other vascular sites. Moreover, preexisting ipsilateral internal jugular dialysis catheters more than double the risk of central vein stenosis.

Fistula use for dialysis is less frequent among obese than non-obese patients. This discrepancy may be due to a lower rate of fistula placement in obese patients, a higher primary failure rate (fistulas that are never usable for dialysis), or a higher secondary failure rate (fistulas that fail after being used successfully for dialysis). Using a prospective, computerized vascular access database, we identified all patients receiving a first fistula or graft at our institution during a 2-year period. The access outcomes were compared between obese (body mass index (BMI) >or=30 kg/m2) and non-obese (BMI<30 kg/m2) patients. Fistula placement was equally likely between obese and non-obese patients (47.4 vs 47.1%). The primary failure rate of fistulas was similar in both groups (46 vs 41%, P=0.45). Among those fistulas that were usable for dialysis, the secondary survival was worse in obese patients (hazard ratio 2.74; 95% confidence interval (CI), 1.48-7.90; P=0.004). Secondary fistula survival in obese vs non-obese patients was 68 vs 92% at 1 year, 59 vs 78% at 2 years, and 47 vs 70% at 3 years. On multiple variable survival analysis with age, sex, race, diabetes, coronary artery disease, peripheral vascular disease, fistula location, surgeon, and obesity in the model, obesity was the only significant factor predicting secondary fistula failure (hazards ratio 2.93; 95% CI, 1.44-5.93; P=0.004). In conclusion, long-term fistula survival is worse in obese than non-obese patients, owing to a higher secondary failure rate.