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Trends in Incident Hemodialysis Access and Mortality
788 Abstracts
adjusted P value for heterogeneity by sex 0.33) and those for women and men at less than 10% predict a 5-year absolute cardiovascular risk adjusted heterogeneity (P ¼ .11). The proportional reductions in major coronary events, coronary revascularization, and stroke also did not differ significantly by sex. No adverse effect on rates of cancer incidence or non-cardiovascular mortality was noted for either sex. Benefits translated to all-cause mortality reductions with statin therapy for both women (rate ratio, 0.91; 99% CI, 0.84-0.99) and men (rate ratio, 0.90, 99% CI, 0.86-0.95; adjusted heterogeneity, P ¼ .43). Comment: The article should go a long way towards assuaging any doubts with regard to the benefits vs risk of statin therapy in men and women. Respective of sex, statins appear to reduce cardiovascular events and all-cause mortality. Benefits greatly exceed known hazards even among individuals at low absolute cardiovascular risk. Results suggest that with the availability of generic statins there is an effective means to prevent cardiovascular disease among women as well as men in both developed and developing countries. Vertebral Artery Hypoplasia and Vertebral Artery Dissection: A Hospital-Based Cohort Study Zhou M, Zheng H, Gong S, et al. Neurology 2015;84:818-24. Conclusions: Spontaneous vertebral artery dissection (sVAD) is associated with ipsilateral vertebral artery hypoplasia (VAH). sVAD occurs more frequently in hypoplastic vertebral arteries than in normal ones. Summary: Vertebral arteries are often asymmetric in size. The left is generally more dominant than the right, with left dominance occurring in 50% of cases and similarly sized vertebral arteries occurring in 25% of cases (Katsanos AH et al, Eur Neurol 2013;70:78-83). Vertebral artery hypoplasia is congenitally present in 10% of normal individuals (Hu XY et al, Neuroradiology 2013;55:291-5). There is no specific definition of VAH but it has been described as arteries <2 to <3 mm in diameter or when there is a caliber discrepancy $ 1:1.7 (Park JH et al, J Neurol Neurosurg Psychiatry 2007;78:954-8, and Perren F et al, Neurology 2007;68:65-7). There is increasing thought that VAH is a predisposing risk factor for sVAD. The authors therefore conducted a retrospective, hospital-based cohort study to evaluate whether VAH is associated with an increased risk of ipsilateral sVAD. They also tried to determine whether sVAD tended to be ipsilateral to VAH. This was a case-controlled series with a population composed of 112 patients with sVAD and 224 age- and sexmatched controls treated between 2005 and 2013 at a single high-volume center. VAH and sVAD were diagnosed with digital subtraction angiography combined with noninvasive imaging findings. Logistic regression was performed to identify independent risk factors for sVAD. Relationships between sVAD and VAH and the likelihood of ipsilateral (vs contralateral) presentation were also assessed. VAH was more frequent in patients with sVAD than in controls in univariate analysis (30.4% vs 17.4%; odds ratio [OR], 2.1; 95% confidence interval [CI], 1.2-3.6; P ¼ .008) and in multivariate regression analysis adjusted for migraine, hyper homocysteinemia, smoking, trivial trauma, prior infection, and known associated connective tissue/vascular disorders (OR, 2.0; 95% CI, 1.13.5; P ¼ .017). Migraine, current smoking, and trivial trauma were associated with sVAD in multivariate models. sVAD was more frequently
JOURNAL OF VASCULAR SURGERY September 2015
detected in hypoplastic than dominant vertebral arteries (68.0% vs 32.0%; OR, 4.1; 95% CI, 1.7-9.7; P ¼ .002). Comment: The pathogenesis of sVAD is largely unknown. In cases of VAH, the authors postulate that mean volume flow and velocity may be decreased within the vessel making them prone to collapse as a result of the Bernoulli Effect. Resulting unequal mechanical forces, resulting from asymptomatic vertebral artery flow, might therefore influence morphologic deformation resulting in increased arterial susceptibility for a local angiopathy thereby increasing susceptibility to dissection. The idea is obviously speculation but the theory does incorporate both hemodynamic, anatomic and physiologic parameters to explain the author’s observations and seems reasonable and worth considering. Trends in Incident Hemodialysis Access and Mortality Malas MB, Canner JK, Hicks CW, et al. JAMA Surg 2015;150:441-8. Conclusions: Current incident arteriovenous fistula practice is far short of recommendations first made in 1997 and has an adverse impact on mortality in patients with end-stage renal disease. Summary: Dogma is that hemodialysis initiated via an arteriovenous fistula has lower infection risk, fewer hospitalizations, and lower total costs associated with hemodialysis than renal replacement therapy initiated with hemodialysis catheters. The author’s study sought to evaluate whether the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines (DOQI) for a 50% or greater incidence rate for arteriovenous fistula have been met, and whether there are adverse effects of failure or delay in creating functional, permanent access on mortality. The study was retrospective and was conducted using the U.S. Renal Data System. It included all patients with end-stage renal disease in the United States without prior renal replacement therapy, who had incident vascular access for hemodialysis created between January 1, 2006, and December 31, 2010. There were 510,000 patients included. Main outcome measures included incident vascular access use rates and mortality. Relative mortality was quantified using multivariable Cox proportional hazard methods. Exact matching and propensity score-matching techniques were used to better account for confounding by indication. Of the 510,000 patients included in the study, 82.6% initiated hemodialysis via a dialysis catheter, 14% had initial hemodialysis via arteriovenous fistula and 3.4% via an arteriovenous graft. AVF use increased only minimally from 12.2% in 2006 to 15.0% in 2010. Patients initiating hemodialysis with AVF had 35% lower mortality than those with initiation of dialysis with catheters (adjusted hazard ratio, 0.65; 95% confidence interval, 0.64-0.66; P < .001). Those beginning hemodialysis with an AVF had 23% lower mortality than those initiating with a catheter while awaiting maturation of a fistula (adjusted hazard ratio, 0.77; 95% confidence nterval, 0.76-0.79; P < .001). Comment: The United States is obviously a long way from compliance with the DOQI guidelines. Reasons are likely multiple, including patient, physician, social, and health policy, and perhaps even reimbursement factors. The relative contributions of each of these factors should be determined to ascertain whether there is any so-called low-hanging fruit that could be most rapidly addressed in an effort to improve the horrendous mortality rates of the hemodialysis patient population.
adjusted P value for heterogeneity by sex 0.33) and those for women and men at less than 10% predict a 5-year absolute cardiovascular risk adjusted heterogeneity (P ¼ .11). The proportional reductions in major coronary events, coronary revascularization, and stroke also did not differ significantly by sex. No adverse effect on rates of cancer incidence or non-cardiovascular mortality was noted for either sex. Benefits translated to all-cause mortality reductions with statin therapy for both women (rate ratio, 0.91; 99% CI, 0.84-0.99) and men (rate ratio, 0.90, 99% CI, 0.86-0.95; adjusted heterogeneity, P ¼ .43). Comment: The article should go a long way towards assuaging any doubts with regard to the benefits vs risk of statin therapy in men and women. Respective of sex, statins appear to reduce cardiovascular events and all-cause mortality. Benefits greatly exceed known hazards even among individuals at low absolute cardiovascular risk. Results suggest that with the availability of generic statins there is an effective means to prevent cardiovascular disease among women as well as men in both developed and developing countries. Vertebral Artery Hypoplasia and Vertebral Artery Dissection: A Hospital-Based Cohort Study Zhou M, Zheng H, Gong S, et al. Neurology 2015;84:818-24. Conclusions: Spontaneous vertebral artery dissection (sVAD) is associated with ipsilateral vertebral artery hypoplasia (VAH). sVAD occurs more frequently in hypoplastic vertebral arteries than in normal ones. Summary: Vertebral arteries are often asymmetric in size. The left is generally more dominant than the right, with left dominance occurring in 50% of cases and similarly sized vertebral arteries occurring in 25% of cases (Katsanos AH et al, Eur Neurol 2013;70:78-83). Vertebral artery hypoplasia is congenitally present in 10% of normal individuals (Hu XY et al, Neuroradiology 2013;55:291-5). There is no specific definition of VAH but it has been described as arteries <2 to <3 mm in diameter or when there is a caliber discrepancy $ 1:1.7 (Park JH et al, J Neurol Neurosurg Psychiatry 2007;78:954-8, and Perren F et al, Neurology 2007;68:65-7). There is increasing thought that VAH is a predisposing risk factor for sVAD. The authors therefore conducted a retrospective, hospital-based cohort study to evaluate whether VAH is associated with an increased risk of ipsilateral sVAD. They also tried to determine whether sVAD tended to be ipsilateral to VAH. This was a case-controlled series with a population composed of 112 patients with sVAD and 224 age- and sexmatched controls treated between 2005 and 2013 at a single high-volume center. VAH and sVAD were diagnosed with digital subtraction angiography combined with noninvasive imaging findings. Logistic regression was performed to identify independent risk factors for sVAD. Relationships between sVAD and VAH and the likelihood of ipsilateral (vs contralateral) presentation were also assessed. VAH was more frequent in patients with sVAD than in controls in univariate analysis (30.4% vs 17.4%; odds ratio [OR], 2.1; 95% confidence interval [CI], 1.2-3.6; P ¼ .008) and in multivariate regression analysis adjusted for migraine, hyper homocysteinemia, smoking, trivial trauma, prior infection, and known associated connective tissue/vascular disorders (OR, 2.0; 95% CI, 1.13.5; P ¼ .017). Migraine, current smoking, and trivial trauma were associated with sVAD in multivariate models. sVAD was more frequently
JOURNAL OF VASCULAR SURGERY September 2015
detected in hypoplastic than dominant vertebral arteries (68.0% vs 32.0%; OR, 4.1; 95% CI, 1.7-9.7; P ¼ .002). Comment: The pathogenesis of sVAD is largely unknown. In cases of VAH, the authors postulate that mean volume flow and velocity may be decreased within the vessel making them prone to collapse as a result of the Bernoulli Effect. Resulting unequal mechanical forces, resulting from asymptomatic vertebral artery flow, might therefore influence morphologic deformation resulting in increased arterial susceptibility for a local angiopathy thereby increasing susceptibility to dissection. The idea is obviously speculation but the theory does incorporate both hemodynamic, anatomic and physiologic parameters to explain the author’s observations and seems reasonable and worth considering. Trends in Incident Hemodialysis Access and Mortality Malas MB, Canner JK, Hicks CW, et al. JAMA Surg 2015;150:441-8. Conclusions: Current incident arteriovenous fistula practice is far short of recommendations first made in 1997 and has an adverse impact on mortality in patients with end-stage renal disease. Summary: Dogma is that hemodialysis initiated via an arteriovenous fistula has lower infection risk, fewer hospitalizations, and lower total costs associated with hemodialysis than renal replacement therapy initiated with hemodialysis catheters. The author’s study sought to evaluate whether the National Kidney Foundation-Kidney Disease Outcomes Quality Initiative guidelines (DOQI) for a 50% or greater incidence rate for arteriovenous fistula have been met, and whether there are adverse effects of failure or delay in creating functional, permanent access on mortality. The study was retrospective and was conducted using the U.S. Renal Data System. It included all patients with end-stage renal disease in the United States without prior renal replacement therapy, who had incident vascular access for hemodialysis created between January 1, 2006, and December 31, 2010. There were 510,000 patients included. Main outcome measures included incident vascular access use rates and mortality. Relative mortality was quantified using multivariable Cox proportional hazard methods. Exact matching and propensity score-matching techniques were used to better account for confounding by indication. Of the 510,000 patients included in the study, 82.6% initiated hemodialysis via a dialysis catheter, 14% had initial hemodialysis via arteriovenous fistula and 3.4% via an arteriovenous graft. AVF use increased only minimally from 12.2% in 2006 to 15.0% in 2010. Patients initiating hemodialysis with AVF had 35% lower mortality than those with initiation of dialysis with catheters (adjusted hazard ratio, 0.65; 95% confidence interval, 0.64-0.66; P < .001). Those beginning hemodialysis with an AVF had 23% lower mortality than those initiating with a catheter while awaiting maturation of a fistula (adjusted hazard ratio, 0.77; 95% confidence nterval, 0.76-0.79; P < .001). Comment: The United States is obviously a long way from compliance with the DOQI guidelines. Reasons are likely multiple, including patient, physician, social, and health policy, and perhaps even reimbursement factors. The relative contributions of each of these factors should be determined to ascertain whether there is any so-called low-hanging fruit that could be most rapidly addressed in an effort to improve the horrendous mortality rates of the hemodialysis patient population.