***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
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    Input: BACKGROUND Despite the current Centers for Medicare and Medicaid Services coverage criteria for carotid artery stenting ( CAS ) , consensus regarding its appropriateness in patients with carotid artery stenosis has not been reached . This is one of the first population -based studies to use a dedicated administrative convention for the endovascular procedure to address whether there is a cohort of patients in whom CAS is more beneficial than carotid endarterectomy ( CEA ) . METHODS We analyzed in-hospital mortality , postoperative stroke , and combined postoperative stoke/mortality in 47,752 CAS or CEA hospitalizations , matched by propensity score , in discharge data sets obtained from the states of New York and California for the years 2005 to 2007 . Other outcomes included postoperative complications , length of stay , and volume- outcome relationships . RESULTS For symptomatic patients undergoing CAS  , rates were significantly higher for in-hospital mortality ( 3.7 % vs 1.3 % ) and combined stroke/mortality ( 8.3 % vs 4.6 % ) compared with CEA . For asymptomatic patients , there was no statistical difference between mortality ( 0.6 % vs 0.4 % ) , stroke ( 2.0 % vs 1.8 % ) , or combined stroke/mortality ( 2.4 % vs 1.9 % ) across the endovascular and open procedures , respectively . Postoperative respiratory and urinary complications as well as cranial neuropathy were more common after CEA , whereas postoperative complications , including device malfunction and hypotension , were more frequent after CAS . We did not find a volume- outcome relationship for CEA , but one did exist for CAS . CONCLUSIONS In symptomatic patients with carotid artery stenosis , the most appropriate procedure appears to be CEA , whereas CAS appears to be a suitable minimally invasive approach for asymptomatic patients . On the basis of these results and data from recent multicenter r and omized trials , the use of CAS in symptomatic patients should be approached with caution Background and Purpose — Little is known about the significance of patient characteristics , clinical indications , and technical details on the risk of carotid angioplasty and stenting ( CAS ) . The purpose of this study was to test these parameters as to their predictive value for the peri-interventional risk of CAS . Methods — Pro-CAS is a prospect i ve , multicenter registry of CAS . Logistic regression analysis of possible predictive factors was performed on 5341 interventions that had been entered by 25 clinical centers between July 1999 and June 2005 . Results — The combined in-hospital mortality and stroke rate was 3.6 % . The following were found to be significant predictors of peri-interventional stroke and death : center experience ( ≤50 versus 51 to 150 versus ≥151 interventions ) , age , prior symptoms , primary intervention as compared with intervention for restenosis , angioplasty without stent , predilatation , and heparin dosage > 5000 IU . No statistically significant result was found for year of intervention , patient volume , gender , interval between symptoms and CAS , ocular versus neurological symptoms , side of CAS , degree of stenosis of the target lesion , presence of contralateral high-degree stenosis or occlusion , method of gaining access to the carotids , stent type , and use of a protection system . Conclusions — Our findings underline the need for dedicated training and strict credentialing rules for CAS . In addition , they might help to identify subgroups of patients at differential risk for CAS and carotid endarterectomy and yield a basis for correcting risks due to differences in case mix in reports about CAS BACKGROUND To isolate hospital effects on risk‐st and ardized hospital‐readmission rates , we examined readmission outcomes among patients who had multiple admissions for a similar diagnosis at more than one hospital within a given year . METHODS We divided the Centers for Medicare and Medicaid Services hospital‐wide readmission measure cohort from July 2014 through June 2015 into two r and om sample s. All the patients in the cohort were Medicare recipients who were at least 65 years of age . We used the first sample to calculate the  risk‐st and ardized readmission rate  within 30 days for each hospital , and we classified hospitals into performance quartiles , with a lower readmission rate indicating better performance ( performance‐classification sample ) . The study sample ( identified from the second sample ) included patients who had two admissions for similar diagnoses at different hospitals that occurred more than 1 month and less than 1 year apart , and we compared the observed readmission rates among patients who had been admitted to hospitals in different performance quartiles . RESULTS In the performance‐classification sample , the median risk‐st and ardized readmission rate was 15.5 % ( interquartile range , 15.3 to 15.8 ) . The study sample included 37,508 patients who had two admissions for similar diagnoses at a total of 4272 different hospitals .  The observed readmission rate was consistently higher among patients admitted to hospitals in a worse‐performing quartile than among those admitted to hospitals in a better‐performing quartile , but the only significant difference was observed when the patients were admitted to hospitals in which one was in the best‐performing quartile and the other was in the worst‐performing quartile ( absolute difference in readmission rate , 2.0 percentage points ; 95 % confidence interval , 0.4 to 3.5 ; P=0.001 ) . CONCLUSIONS When the same patients were admitted with similar diagnoses to hospitals in the best‐performing quartile as compared with the worst‐performing quartile of hospital readmission performance , there was a significant difference in rates of readmission within 30 days . The findings suggest that hospital quality contributes in part to readmission rates independent of factors involving patients . ( Funded by Yale – New Haven Hospital Center for Outcomes Research and Evaluation and others . IMPORTANCE Retrospective studies of large administrative data bases have shown higher mortality for procedures performed by low-volume surgeons , but the adequacy of risk adjustment in those studies is in doubt . OBJECTIVE To determine whether the relationship between surgeon volume and outcomes is an artifact of case mix using a prospect i ve sample of carotid endarterectomy cases . DESIGN Observational cohort study from January 1 , 2008 , through December 31 , 2010 , with preoperative , immediate postoperative , and 30-day postoperative assessment s acquired by independent monitors . SETTING Urban , tertiary academic medical center . PATIENTS All 841 patients who underwent carotid endarterectomy performed by a vascular surgeon or cerebrovascular neurosurgeon at the institution . INTERVENTION Carotid endarterectomy without another concurrent surgery . MAIN OUTCOME MEASURES Stroke , death , and other surgical complications occurring within 30 days of surgery along with other case data . A low-volume surgeon performed 40 or fewer cases per year . Variables used in a comparison administrative data base study , as well as variables identified by our univariate analysis , were used for adjusted analyses to assess for an association between low-volume surgeons and the rate of stroke and death as well as other complications . RESULTS The rate of stroke and death was 6.9 % for low-volume surgeons and 2.0 % for high-volume surgeons ( P = .001 ) . Complications were similarly higher ( 13.4 % vs 7.2 % , P = .008 ) . Low-volume surgeons performed more nonelective cases . Low-volume surgeons were significantly associated with stroke and death in the unadjusted analysis as well as after adjustment with variables used in the administrative data base study ( odds ratio , 3.61 ; 95 % CI , 1.70 - 7.67 , and odds ratio , 3.68 ; 95 % CI , 1.72 - 7.89 , respectively ) . However , adjusting for the significant disparity of American Society of Anesthesiologists Physical Status classification in case mix eliminated the effect of surgeon volume on the rate of stroke and death ( odds ratio , 1.65 ; 95 % CI , 0.59 - 4.64 ) and other complications . CONCLUSIONS AND RELEVANCE Variables selected for risk adjustment in studies using administrative data bases appear to be inadequate to control for case mix bias between low-volume and high-volume surgeons . Risk adjustment should empirically analyze for case mix imbalances between surgeons to identify meaningful risk modifiers in clinical practice such as the American Society of Anesthesiologists Physical Status classification . A true relationship between surgeon volume and outcomes remains uncertain , and caution is advised in developing policies based on these findings Background and Purpose — Investigational carotid stenting for extracranial carotid stenosis has demonstrated procedural results approaching those reported with endarterectomy , but with limited cost and long-term data . This study compared the in-hospital outcomes and costs of these 2 revascularization strategies at a single institution and the long-term effectiveness of carotid stenting . Methods — Data for 136 endarterectomies and 136 carotid stent procedures at a tertiary-care community hospital were obtained . The primary clinical outcome measures were in-hospital major ipsilateral stroke and death . In-hospital direct variable costs and length of stay were the primary economic measures . Information on restenosis and late ipsilateral stroke for the stent group was available at 2-year follow-up . Results — These nonr and omized groups were similar , but the endarterectomy group had more symptomatic patients ( 42 % versus 31%;P = 0.0004 ) , and the stent group had more NASCET-excluded patients ( 68 % versus 35%;P < 0.0001 ) . In-hospital major ipsilateral stroke and death occurred more frequently in the surgical group , but the difference was not significant ( 2.9 % versus 0%;P = 0.1 ) . Minor ipsilateral strokes were similar ( 2.2 % versus 2.9%;P = NS ) . Cost ( $ 5409 versus $ 3417;P < 0.0001 ) and length of stay ( 3.0 versus 1.4 days;P < 0.0001 ) were significantly greater for the surgical group . In the stent group , 6-month angiographic restenosis was 3.1 % , and 2-year ipsilateral major stroke rate was 0 % . Conclusions — In-hospital outcomes with carotid stenting were similar to those with endarterectomy but were achieved in patients with significantly more comorbidities . Cost and re source utilization with stenting were substantially less than those with endarterectomy . At 2 years , carotid stenting appeared not only durable but also effective in stroke prevention Objectives Carotid endarterectomy ( CEA ) is st and ard treatment for symptomatic carotid artery stenosis but carries a risk of stroke , myocardial infa rct ion ( MI ) , or death . This study investigated risk factors for these procedural complications occurring within 30 days of endarterectomy in the International Carotid Stenting Study ( ICSS ) . Methods Patients with recently symptomatic carotid stenosis > 50 % were r and omly allocated to endarterectomy or stenting . Analysis is reported of patients in ICSS assigned to endarterectomy and limited to those in whom CEA was initiated . The occurrence of stroke , MI , or death within 30 days of the procedure was reported by investigators and adjudicated . Demographic and technical risk factors for these complications were analysed sequentially in a binomial regression analysis and subsequently in a multivariable model . Results Eight-hundred and twenty-one patients were included in the analysis . The risk of stroke , MI , or death within 30 days of CEA was 4.0 % . The risk was higher in female patients ( risk ratio [ RR ] 1.98 , 95 % CI 1.02–3.87 , p = .05 ) and with increasing baseline diastolic blood pressure ( dBP ) ( RR 1.30 per + 10 mmHg , 95 % CI 1.02–1.66 , p = .04 ) . Mean baseline dBP , obtained at the time of r and omization in the trial , was 78 mmHg ( SD 13 mmHg ) . In a multivariable model , only dBP remained a significant predictor . The risk was not related to the type of surgical reconstruction , anaesthetic technique , or perioperative medication regimen . Patients undergoing CEA  stayed a median of 4 days before discharge , and 21.2 % of events occurred on or after the day of discharge . Conclusions Increasing diastolic blood pressure was the only independent risk factor for stroke , MI , or death following CEA . Cautious attention to blood pressure control following symptoms attributable to carotid stenosis could reduce the risks associated with subsequent CEA Summary Background Stents are an alternative treatment to carotid endarterectomy for symptomatic carotid stenosis , but previous trials have not established equivalent safety and efficacy . We compared the safety of carotid artery stenting with that of carotid endarterectomy . Methods The International Carotid Stenting Study ( ICSS ) is a multicentre , international , r and omised controlled trial with blinded adjudication of outcomes . Patients with recently symptomatic carotid artery stenosis were r and omly assigned in a 1:1 ratio to receive carotid artery stenting or carotid endarterectomy . R and omisation was by telephone call or fax to a central computerised service and was stratified by centre with minimisation for sex , age , contralateral occlusion , and side of the r and omised artery . Patients and investigators were not masked to treatment assignment . Patients were followed up by independent clinicians not directly involved in delivering the r and omised treatment . The primary outcome measure of the trial is the 3- 
    Output:
    
Conclusions : We found a decreased risk of procedural death and stroke after CEA and CAS for high operator and high hospital volume , indicating that aim ing for a high volume may help to reduce procedural complications .