Daniel B. Walsh

Longitudinal comparison of dialysis access methods: Risk factors for failure

PURPOSE To compare dialysis access patency rates and identify risk factors for failure. METHODS All access procedures at our institution from 1987 to 1996 were reviewed. Primary procedures were surgically implanted dual-lumen central venous hemodialysis catheters (SIHCs), peritoneal dialysis catheters (PDCs), arteriovenous fistulas (AVFs), and prosthetic shunts (PTFEs). RESULTS Five hundred eighty-five primary procedures (236 PTFEs, 87 AVFs, 112 SIHCs, and 150 PDCs) and 259 secondary procedures (215 PTFEs, 14 AVFs, 0 SIHCs, and 30 PDCs) were performed on 350 patients. By life table analysis, SIHCs exhibited the lowest primary patency rate (9% at 1 year; p < 0.0001), whereas PDCs had the highest primary patency rate (57% at 1 year; p < 0.02). The primary patency rates of AVFs and PTFEs was similar, with 43% and 41% 1-year patency rates, respectively (p = 0.70). Less-stringent reporting methods would have increased apparent 1-year patency rates by 9% to 41%. With regard to secondary patency, there was no significant difference between PTFEs and PDCs, with 1-year patency rates of 59% and 70%, respectively (p = 0.62), but PTFEs were more frequently revised. In addition, there was no significant difference between AVF and PTFE secondary patency rates, with 1-year patency rates of 46% and 59%, respectively. Early differences in patency rates for AVFs, PTFEs, and PDCs diminished over time, and at 4 years AVFs had the best secondary patency rate (p = 0.6). The most common reasons for access failure were: PTFEs, thrombosis; AVFs, thrombosis and failure to mature; SIHCs, inadequate dialysis; PDCs, infection and inadequate exchange. By regression analysis, a history of a previous unsalvageable PTFE was the only significant risk factor for failure of a subsequent PTFE (p < 0.01), and the risk of graft failure increased exponentially with the number of previous PTFE shunts. Diabetes was the only significant risk factor for failure of PDCs (p < 0.02; odds ratio, 2.0). CONCLUSIONS The patency rate for PTFEs is similar to that for AVFs, but AVFs require fewer revisions. When replacing a failed access graft, the risk of PTFE failure increases with the number of prior unsalvageable PTFE shunts. PDCs have excellent patency rates, but failure rates are doubled in patients with diabetes. Because of poor patency rates and inadequate dialysis flow rates, SIHCs should be avoided when possible. Reporting methods dramatically affect apparent patency rates, and reporting standards are needed to allow meaningful comparisons in the dialysis access literature.

Cost-effectiveness of carotid endarterectomy in asymptomatic patients ☆ ☆☆

PURPOSE The purpose of this study was to determine the cost-effectiveness of carotid endarterectomy for treating asymptomatic patients with > or = 60% internal carotid stenosis, based on outcomes reported in the Asymptomatic Carotid Atherosclerosis Study (ACAS). METHODS A cost-effectiveness analysis was performed using a Markov decision model in which the probabilities for base-case analysis (average age, 67 years; 66% male; perioperative stroke plus death rate, 2.3%; ipsilateral stroke rate during medical management, 2.3% per year) were based on ACAS. The model assumed that patients who had TIAs or minor strokes during medical management crossed over to surgical treatment, and used the NASCET data to model the outcome of these now-symptomatic patients. Average cost of surgery (

Current use of inferior vena cava filters

8500), major stroke (

Femorofemoral versus aortobifemoral bypass: outcome and hemodynamic results.

34,000 plus

Carotid duplex criteria for a 60% or greater angiographic stenosis: Variation according to equipment

18,000 per year), and other costs were based on local cost determinations plus a review of the published literature. Cost-effectiveness was calculated as the incremental cost of surgery per quality-adjusted life year (QALY) saved when compared with medical treatment, discounting at 5% per year. Sensitivity analysis was performed to determine the impact of key variables on cost-effectiveness. RESULTS In the base-case analysis, surgical treatment improved quality-adjusted life expectancy from 7.87 to 8.12 QALYs, at an incremental lifetime cost of

The role of calcium ions and calcium channel entry blockers in experimental ischemia-reperfusion-induced liver injury

2041. This yielded an incremental cost-effectiveness ratio of

Vein adaptation to the hemodynamic environment of infrainguinal grafts.

8,000 per QALY saved by surgical compared with medical treatment. The high cost of care after major stroke during medical management largely offset the initial cost of endarterectomy in the surgical group. Furthermore, 26% of medically managed patients eventually underwent endarterectomy because of symptom development, which also decreased the cost differential. Sensitivity analysis demonstrated that the relative cost of surgical treatment increased substantially with increasing age, increasing perioperative stroke rate, and decreasing stroke rate during medical management. CONCLUSION For the typical asymptomatic patient in ACAS with > or = 60% carotid stenosis, our results indicate that carotid endarterectomy is cost-effective when compared with other commonly accepted health care practices. Surgery does not appear cost-effective in very elderly patients, in settings where the operative stroke risk is high, or in patients with very low stroke risk without surgery.

Thrombolysis of occluded infrainguinal vein grafts: predictors of outcome.

To study possible changes in the clinical use of inferior vena cava (IVC) filters caused by the introduction of percutaneous delivery systems, we reviewed all patients who underwent placement of IVC filters at our institution from 1988 to 1991. Eighty-four patients (52 men and 32 women) ranging in age from 18 to 90 years (mean 67 years) were identified. Filters were required because of contraindications to anticogulation in 64% anticoagulation failure in 25%, and preoperative prophylaxis in 11% of patients. The underlying disease was lower extremity deep vein thrombosis in 50% and pulmonary embolism in 45% of patients. Five percent of patients received prophylactic filters without documented thromboembolism. All filters were placed percutaneously by interventional radiologists, 77 through the common femoral vein and 7 through the internal jugular vein. Three types of filters were used. One procedure-related death occurred because of acute IVC occlusion. Fatal pulmonary embolism within 48 hours after filter placement was documented in one patient and suspected in one late death. No other clinically apparent pulmonary embolism or leg swelling occurred after filter placement. Minor complications related to filter placement occurred in 13 patients, but none required operative intervention. Analysis of complication rates of the three filter types was precluded by the small sample size. After a mean follow-up of 11 months, 42 patients (50%) had died of malignancy (n = 25), multisystem organ failure (MSOF; n = 7), cardiovascular events (n = 4), recurrent pulmonary embolism (n = 2), cerebrovascular events (n = 4), or an unknown cause (n = 1). Twenty-three patients (27%) died before hospital discharge.(ABSTRACT TRUNCATED AT 250 WORDS)

Fate of the contralateral leg after infrainguinal bypass

PURPOSE Femorofemoral bypass (FFB) is used in selected patients when aortobifemoral bypass (AFB) is believed to be inappropriate because of high operative risk or predominantly unilateral iliac artery occlusive disease. We examined concurrent patients who underwent either FFB or AFB to better understand the appropriate use of FFB. METHODS The characteristics and outcomes of patients who underwent FFB and AFB during 1986 to 1991 at our institution were retrospectively reviewed. Primary measures of outcome included patient survival, graft patency, limb salvage, and hemodynamic performance of FFB and AFB. Further analysis was performed after substratification for low versus high risk and claudication versus limb threat as the indication for surgery. RESULTS FFB was performed in older patients with more medical comorbidities when compared with AFB. Long-term graft patency was inferior after FFB compared with AFB (60% vs 85% at 3 years, p < 0.01). However, both FFB and AFB achieved limb salvage in more than 85% of patients at 3 years. When patients at low risk undergoing nonemergency AFB were compared with patients at low risk who underwent FFB and who had no contraindication to AFB, FFB proved inferior to AFB as measured by graft patency (primary patency 61% vs 87% at 3 years, p < 0.03) and hemodynamic performance (predicted ankle-brachial index with perfect outflow 0.82 after FFB vs 1.03 after AFB). On the basis of a detailed analysis of patient and graft risk factors, we could not explain the inferior patency rate of FFB, although our analysis suggested that inadequate inflow may contribute. CONCLUSIONS FFB is inferior to AFB as measured by patency and hemodynamic function. This inferior performance is independent of indications for FFB. AFB should remain the standard therapy for patients at low risk with iliac occlusive disease, but FFB provides adequate function and limb salvage in patients at high risk.

Metastatic cancer. A relative contraindication to vena cava filter placement.

PURPOSE The purpose of this study was to evaluate the carotid duplex criteria for a > or = 60% angiographic internal carotid artery (ICA) stenosis and the degree of variation among duplex scanners. METHODS Carotid duplex criteria for a > or = 60% angiographic stenosis were evaluated in two ICAVL-accredited vascular laboratories with different brands of duplex scanners (Siemens-Quantum and Diasonics in Laboratory A, ATL and Diasonics in Laboratory B). Analysis was performed for 360 carotid bifurcations in 180 consecutive patients who had concurrent angiographic and duplex evaluation. Blinded angiogram evaluation was performed with precision electronic calipers on magnified views, with stenosis calculated by criteria of the Asymptomatic Carotid Atherosclerosis Study and the North American Symptomatic Carotid Endarterectomy Trial. Duplex data included internal carotid artery peak systolic velocity (ICA PSV), ICA end-diastolic velocity, and the ratio of ICA PSV to common carotid artery (CCA) PSV (ICA/CCA ratio). RESULTS The most accurate determination of a > or = 60% ICA stenosis was obtained with ICA/CCA ratio and ICA PSV, but the optimal threshold differed for all four scanners. The optimal ICA/CCA ratio varied from 2.6 to 3.3, and the optimal ICA PSV varied from 190 to 240 cm/sec. All four scanners produced criteria that give a positive predictive value > 90% while maintaining accuracy at > or = 90%. Logarithmic transformation of duplex variables created a linear relationship between duplex values and angiographic stenosis, allowing statistical evaluation of scanner operating characteristics by linear regression analysis and analysis of covariance. This analysis revealed that the mathematic equation relating duplex values with angiographic percent stenosis was statistically different for one of the four scanners (p < 0.05). Scanner differences did not appear to be due to technologists, because the regression lines were nearly identical for the two Diasonics scanners despite use by different technologists. Ignoring the significant difference in operating characteristics for one of the four scanners would result in a mean error for predicting a 60% stenosis of 14% to 18% (equating a 46% or 78% stenosis with a 60% stenosis). CONCLUSIONS We conclude that the correlation of duplex data with angiographic percent stenosis and the duplex criteria for a > or = 60% stenosis are machine-specific. Regression analysis can determine whether apparent differences are due to chance or significant differences in scanner characteristics. Future studies should include regression analysis according to equipment type.