***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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    ***EXAMPLES*** 
    Input: Since the 1950s carotid endarterectomy has been performed in patients with symptomatic carotid artery stenosis , based on suggestive but inconclusive evidence for its effectiveness . Only during the last 5 years have r and omized studies clarified the indications for surgery . In preparing this report , panel members used the same rules of evidence used in the previous report1 2 ( Table ⇓ ) . View this table : Table 1 . Levels of Evidence and Grading of Recommendations Few studies have analyzed control of risk factors in a r and omized , prospect i ve manner following carotid endarterectomy . However , a wealth of data are available regarding the general relationship between risk factor control and stroke risk . These data provide some guidance for the care of endarterectomy patients . # # # Hypertension Hypertension is the most powerful , prevalent , and treatable risk factor for stroke.3 Both systolic and diastolic blood pressure are independently related to stroke incidence . Isolated systolic hypertension , which is common in the elderly , also considerably increases risk of stroke . Reduction of elevated blood pressure significantly lowers risk of stroke . Meta-analyses of r and omized trials found that an average reduction in diastolic blood pressure of 6 mm Hg produces a 42 % reduction in stroke incidence.3 4 Treatment of isolated systolic hypertension in people older than 60 years also reduces stroke incidence by 36 % without an excessive number of side effects such as depression or dementia.5 Long-term care of patients after endarterectomy should include careful control of hypertension ( Grade A recommendation for treatment of hypertension in general ; Grade C recommendation for postendarterectomy care ) . Perioperative treatment of hypertension  after carotid endarterectomy represents a special situation . Poor control of blood pressure after endarterectomy increases risk of cerebral hyperperfusion syndrome.6 7 8 9 This complication is characterized by unilateral headache , seizures , and occasionally altered mental status or focal neurological signs . Neuroimaging may show intracerebral hemorrhages10 11 12 or white OBJECTIVE In large r and omized trials , carotid endarterectomy ( CEA ) for asymptomatic stenosis has shown a net benefit compared with best medical treatment . To justify an increased number of procedures for this indication , the perioperative risk of stroke or death must not exceed that of the trials . The aim of this study was to evaluate the outcome in routine clinical practice in Sweden in a population -based study . METHODS The Swedish Vascular Registry ( Swedvasc ) covers all centers performing CEA . Data on all registered CEAs during 1994 to 2003 were analyzed both for the whole time period and for two 5-year periods to study alterations over time . Four validation procedures of the registry were performed . Medical records were review ed for both a r and om sample and a target sample ( a total of 12 % of the CEAs for asymptomatic stenosis ) . Swedvasc data were cross-matched with the In-Patient-Registry ( used for reimbursement ) and the Population -registry ( death ) . RESULTS A total of 6182 CEAs were registered , 671 being for asymptomatic stenosis . In the validation process , no missed registration of major stroke or death was found . Patients with asymptomatic stenosis had , when the whole time-period was analyzed , a perioperative combined stroke or death rate of 2.1 % . Outcome improved over time ; the combined stroke or death rate decreased from 3.3 % ( 11/330 ) from 1994 to 1998 to 0.9 % ( 3/341 ) from 1999 to 2003 ( P = .026 ) . During the second time period , no patient with a perioperative major stroke or death was reported . CONCLUSIONS This extensively vali date d national audit of CEA for patients with asymptomatic carotid artery stenosis showed results well comparable with those of the r and omized trials . The results improved over time Background and Purpose — In the 1980s , carotid endarterectomy was controversial because proof of efficacy was lacking , complication rates were high , and one third of cases were reported to be inappropriate . Since publication of several r and omized controlled trials ( RCTs ) , rates of carotid endarterectomy have doubled nationwide . This study assesses the appropriateness and use of carotid endarterectomy since publication of the RCTs . Methods — Using the literature , we developed a list of 1557 mutually exclusive indications for carotid endarterectomy  and asked a panel of national experts to rate the appropriateness of each indication using the R AND methodology . We used these ratings to assess appropriateness in a sample of 2124 patients who underwent the procedure in 1997 to 1998 in 6 hospitals . We also analyzed the reasons for the procedure and rates of death , stroke , and myocardial infa rct ion within 30 days of surgery . Results — Overall , 84.9 % of operations were done for appropriate reasons , 4.5 % for uncertain reasons , and 10.6 % for inappropriate reasons . Among procedures considered inappropriate , the most common reasons were high comorbidity ( 46.6 % ) and minimal stenosis ( 27.1 % ) . Overall , 72.5 % were asymptomatic , 17.4 % had a carotid transient ischemic attack , and 10.1 % had a stroke . The 30-day rate of death or stroke was 5.47 % for symptomatic patients and 2.26 % for asymptomatic patients . Among patients having combined carotid and coronary artery bypass graft surgery , the rate was 10.32 % . The complication rate in asymptomatic patients with high comorbidity was 5.56 % . Conclusions — Since the RCTs , rates of overuse appear to have fallen considerably , although they are still significant . A major shift has occurred toward operating on asymptomatic patients . Although overall complication rates were low , rates among asymptomatic patients with high comorbidity exceeded recommended thresholds Context . Black patients and Hispanic patients receive carotid endarterectomy ( CEA ) at lower rates than white patients . It is unclear whether worse surgical outcomes are influencing clinical decision-making regarding use of the operation among minority group patients . Objective . To determine if there are racial differences in postoperative outcomes for patients undergoing CEA at Veterans Affairs ( VA ) medical centers . Design . Secondary analysis of data from an ongoing , prospect i ve study on surgical quality and outcomes in the VA health care system . Setting . One hundred thirty-two VA Medical Centers that were part of the VA National Surgical Quality Improvement Program . Patients . A cohort of 6551 men ( 91.4 % white , 5.3 % black , and 3.3 % Hispanic ) who had CEA performed between October 1 , 1994 and September 30 , 1997 . Main Outcome Measures . Primary outcomes were stroke or death and stroke , myocardial infa rct ion ( MI ) , or death within 30 days of the operation . Results . Thirty-day postoperative rates of stroke or death and of stroke , MI , or death were generally low for all racial/ethnic groups , ranging between 2.6 % and 6.5 % . Within clinical states that define indications for CEA , rates were also low ( 1.6 % to 3.2 % ) among asymptomatic patients across racial/ethnic groups . However , among patients with transient ischemic attack ( TIA ) , Hispanic patients had significantly worse outcomes than white patients with a postoperative rate of stroke or death of 10.5 % ( P < 0.05 ) and stroke , MI , or death of 13.2 % ( P < 0.05 ) compared with 3.1 % to 3.5 % for white patients . Hispanic patients did not differ from black patients for stroke , death/stroke , death , or MI . Conclusion . Rates of major postoperative complications after CEA are low within the VA and similar across racial/ethnic groups with the possible exception of Hispanic men with TIA . Further investigation of this elevated complication rate among Hispanic men with TIA may be warranted OBJECTIVES The purpose of this study was to assess the effect of community-wide performance measurement and feedback on key processes and outcomes of  carotid endarterectomy ( CEA ) .  METHODS Complete medical record ( hospital chart ) review for indications , care processes , and outcomes was performed on a r and om sample of Medicare patients undergoing CEA in 10 states ( Arkansas , Georgia , Illinois , Indiana , Iowa , Kentucky , Michigan , Nebraska , Ohio , Oklahoma ) during baseline ( Jun 1 , 1995 to May 31 , 1996 ) and remeasurement ( Jun 1 , 1998 to May 31 , 1999 ) periods . In addition to review of the index hospital stay , hospital admissions within 30 days of the procedure were review ed and the Medicare enrollment data base queried to identify out-of-hospital deaths , to determine 30-day outcome results . The baseline data by state were provided to the Medicare Quality Improvement Organizations ( QIOs ) in the respective states , and quality improvement initiatives were encouraged . RESULTS We review ed 9945 primary CEA alone procedures , 236 CEA and coronary artery bypass grafting ( CABG ) procedures , and 380 repeat  CEA  operations during the baseline period ( B ) , and 9745 primary CEA alone procedures , 233 CEA and CABG procedures , and 401 repeat CEA operations during the remeasurement period ( R ) . There was a significant decrease in the combined event rate ( 30-day stroke or mortality ) for CEA alone procedures between baseline and remeasurement ( B , 5.6 % ; R , 5.0 % ) . A decrease occurred in each of the indication strata ; transient ischemic attack or stroke ( B , 7.7 % ; R , 6.9 % ) , nonspecific symptoms ( B , 5.9 % ; R , 5.4 % ) , and no symptoms ( B , 4.1 % ; R , 3.8 % ) . The combined event rate also decreased for CEA and CABG ( B , 17.4 % ; R , 13.3 % ) and repeat CEA operations ( B , 6.8 % ; R , 5.7 % ) . The remeasurement period state-to-state variation in combined event rate for CEA alone ranged from 2.7 % ( Georgia ) to 5.9 % ( Indiana ) for all indications combined , from 4.4 % ( Georgia ) to 10.9 % ( Michigan ) in patients with recent transient ischemia or stroke , from 1.4 % ( Georgia ) to 6.0 % ( Oklahoma ) in patients with no symptoms , and from 3.7 % ( Georgia ) to 7.9 % ( Indiana ) in patients with nonspecific symptoms . There were significant increases in preoperative  antiplatelet administration  ( 62%-67 % ; P < .0001 ) and patching ( 29%-45 % ; P = .05 ) from baseline to remeasurement in the CEA alone subset . Preoperative antiplatelet administration and patching were associated with improved outcomes in the combined baseline and remeasurement data . CONCLUSIONS Community-wide quality improvement initiatives with performance measurement and confidential reporting of provider level data can lead to improvement in important care processes and outcomes . There is considerable variation between states in outcome and process , and thus continued room for improvement . Quality improvement projects that include st and ardized confidential outcome reporting should be encouraged . Preoperative antiplatelet therapy administration and patching rates should be considered as evidence -based performance measures Background and Purpose — The European Carotid Surgery Trial ( ECST ) and North American Symptomatic Carotid Endarterectomy Trial ( NASCET ) have shown that endarterectomy reduces the risk of stroke in certain patients with recently symptomatic carotid stenosis . However , they differed in the degree of stenosis above which surgery was reported to be effective . This disparity has led to inconsistent clinical recommendations but may have been due to differences between the trials in the methods of measurement of carotid stenosis and definitions of outcome events . Methods — To allow direct comparison of analyses from ECST and NASCET , we remeasured the prer and omization ECST carotid angiograms  and redefined the outcome events the same way as in NASCET . Results — We r and omized 3018 patients and followed them up for a mean of 73 months . Surgery reduced the 5-year risk of any stroke or surgical death by 5.7 % ( 95 % CI , 0 to 11.6 ) in patients with 50 % to 69 % stenosis ( n=646 , P = 0.05 ) and by 21.2 % ( 95 % CI , 12.9 to 29.4 ) in patients with 70 % to 99 % stenosis without “ near occlusion ” ( n=429 , P < 0.0001 ) . These benefits were maintained at the 10-year follow-up . However , surgery was of no benefit in patients ( n=125 ) with near occlusion . The effect of surgery in this group was highly significantly different from that in patients with 70 % to 99 % stenosis without near occlusion ( P = 0.002 ) . Surgery was harmful in patients with < 30 % stenosis ( n=1321 , P = 0.007 ) and of no benefit in patients with 30 % to 49 % stenosis ( n=478 , P = 0.6 ) . Conclusions — Results of the ECST and NASCET were consistent when analyzed in the same way . In ECST , surgery was highly beneficial for 70 % to 99 % stenosis and moderately beneficial for 50 % to 69 % stenosis . However , contrary to clinical recommend 
    Output:
    
However , the average age of patients having CEA  has continued to increase during this period .
There is no evidence of a systematic reduction over the last decade in the published risks due to CEA for symptomatic stenosis .
The lower proportion of non-fatal operative strokes in surgeon-only studies suggests that some minor operative strokes have been missed