***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 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The gold st and ard test for the diagnosis of coronary artery disease ( CAD ) is conventional coronary angiography ( C-CAG ) . Lately , multislice computed tomographic coronary angiography ( MSCT-CAG ) demonstrated a high sensitivity and a negative predictive value for a CAD primary diagnosis when compared with C-CAG . The aim of our study is to prospect ively assess the safety of ruling out CAD based solely on a normal MSCT-CAG result . METHODS From June 15 , 2004 , to January 20 , 2006 , consecutive patients initially scheduled for C-CAG for a primary diagnosis of CAD underwent MSCT-CAG instead . Patients with a highly calcified coronary network or with an abnormal or a noninterpretable MSCT-CAG result underwent secondary C-CAG and were excluded from the study . We included patients whose diagnosis of CAD was ruled out by a normal MSCT-CAG result ; in those patients , C-CAG was not performed . All patients underwent further follow-up with clinical end points ( death , subsequent C-CAG , and myocardial infa rct ion ) . RESULTS In 141 patients ,  MSCT-CAG results were considered normal . During the follow-up period ( mean , 14.7 months ) , those patients experienced 0 % mortality , a 3.5 % rate of subsequent C-CAG  , and a 0.7 % rate of myocardial infa rct ion . The risks of subsequent death , new referral for C-CAG , or coronary events compare favorably with those following normal C-CAG , which were 0.4 % , 4.3 % , and 0.6 % , respectively . CONCLUSIONS Multislice computed tomographic CAG safely rules out CAD in patients with suspected disease and allows patients to be managed less invasively , by reducing the number in whom C-CAG has to be performed BACKGROUND The objective of this study was to examine the association of Joint National Committee ( JNC-V ) blood pressure and National Cholesterol Education Program ( NCEP ) cholesterol categories with coronary heart disease ( CHD ) risk , to incorporate them into coronary prediction algorithms , and to compare the discrimination properties of this approach with other noncategorical prediction functions . METHODS AND RESULTS This work was design ed as a prospect i ve , single-center study in the setting of a community-based cohort . The patients were 2489 men and 2856 women 30 to 74 years old at baseline with 12 years of follow-up . During the 12 years of follow-up , a total of 383 men and 227 women developed  CHD , which was significantly associated with categories of blood pressure , total cholesterol , LDL cholesterol , and HDL cholesterol ( all P<.001 ) . Sex-specific prediction equations were formulated to predict CHD risk according to age , diabetes , smoking , JNC-V blood pressure categories , and NCEP total cholesterol and LDL cholesterol categories . The accuracy of this categorical approach was found to be comparable to CHD prediction when the continuous variables themselves were used . After adjustment for other factors , approximately 28 % of CHD events in men and 29 % in women were attributable to blood pressure levels that exceeded high normal ( > or = 130/85 ) . The corresponding multivariable-adjusted attributable risk percent associated with elevated total cholesterol ( > or = 200 mg/dL ) was 27 % in men and 34 % in women . CONCLUSIONS Recommended guidelines of blood pressure , total cholesterol , and LDL cholesterol effectively predict CHD risk in a middle-aged white population sample . A simple coronary disease prediction algorithm was developed using categorical variables , which allows physicians to predict multivariate CHD risk in patients without overt CHD Background . Multislice computed tomography coronary angiography ( CTA ) was proposed as a method for investigating possible coronary artery disease ( CAD ) in patients who present with chest pain but with a low to intermediate likelihood of CAD . Sixty-four-channel CTA was compared prospect ively with 99mTc-tetrofosmin myocardial perfusion scintigraphy ( MPS ) ( as the gold st and ard in the detection of flow-limiting stenoses ) for the detection of functionally significant CAD . Methods and Results . Fifty-two consecutive symptomatic patients with a low to intermediate likelihood of coronary artery disease , and who were referred for MPS  , also underwent CTA .  The CTA data sets were analyzed by two experienced observers who were blinded to the MPS data , and coronary artery segments were reported as < 50 % , 50 % to 69 % , 70 % to 99 % stenoses , or occluded . The MPS images were similarly analyzed for inducible perfusion abnormalities , and coronary territories were identified . At the patient level , agreement between CTA and MPS for CTA lesions at ≥50 % was 87 % ( sensitivity , 100 % ; specificity , 84 % ; positive predictive value , 50 % ; negative predictive value , 100 % ) . For CTA lesions , agreement at ≥70 % was 96 % ( sensitivity , 86 % ; specificity , 98 % ; positive predictive value , 86 % ; negative predictive value , 98 % ) . Conclusions . In patients with a low to intermediate likelihood of CAD , there is good correlation between MPS and CTA for the detection of functionally significant coronary artery stenoses  when CTA detects a narrowing of ≥70 % severity . Computed tomography coronary angiography stenoses of 70 % should be used to determine functional significance , and not 50 % , as is the usual practice at present BACKGROUND Multidetector computed tomography ( MDCT ) has high diagnostic value for detecting or excluding coronary artery stenosis . We examined performance characteristics of MDCT for diagnosing or excluding an acute coronary syndrome in patients presenting to the emergency department ( ED ) with possible ischemic chest pain and examined relation to clinical outcome during a 15-month follow-up period . METHODS AND RESULTS We prospect ively studied 58 patients ( 56+/-10 years of age , 36 % female ) with chest pain possibly ischemic in origin and no new ECG changes or elevated biomarkers . The patients underwent 64-slice contrast-enhanced MDCT , which showed normal coronary vessels ( no or trivial atheroma ) in 15 patients , nonobstructive plaque in 20 ( MDCT-negative patients ) , and obstructive coronary disease ( > or = 50 % luminal narrowing ) in 23 ( MDCT-positive group ) . By further investigation ( new elevation of cardiac biomarkers , abnormal myocardial perfusion scintigraphy and /or invasive angiography ) , acute coronary syndrome was diagnosed in 20 of the 23 MDCT-positive patients ( ED MDCT sensitivity 100 % [ 20/20 ] , specificity 92 % [ 35/38 ] , positive predictive value 87 % [ 20/23 ] , negative predictive value 100 % [ 35/35 ] ) . During a 15-month follow-up period , no deaths or myocardial infa rct ions occurred in the 35 patients discharged from the ED after initial triage and MDCT findings . One patient underwent late  percutaneous coronary intervention ( late major adverse cardiovascular events rate , 2.8 % ) . Overall , ED MDCT sensitivity for predicting major adverse cardiovascular events ( death , myocardial infa rct ion , or revascularization ) during hospitalization and follow-up was 92 % ( 12/13 ) , specificity was 76 % ( 34/45 ) , positive predictive value was 52 % ( 12/23 ) , and negative predictive value was 97 % ( 34/35 ) . CONCLUSIONS We found that 64-slice cardiac MDCT is a potentially valuable diagnostic tool in ED patients with chest pain of uncertain origin , providing early direct noninvasive visualization of coronary anatomy . ED MDCT had high positive predictive value for diagnosing acute coronary syndrome , whereas a negative MDCT study predicted a low rate of major adverse cardiovascular events and favorable outcome during follow-up OBJECTIVES This study sought to compare the safety , diagnostic efficacy , and efficiency of multi-slice computed tomography ( MSCT ) with st and ard diagnostic evaluation of low-risk acute chest pain patients . BACKGROUND Over 1 million patients have emergency center evaluations for acute chest pain annually , at an estimated diagnostic cost of over $ 10 billion . Multi-slice computed tomography has a high negative predictive value for exclusion of coronary artery stenoses . METHODS We r and omized patients to MSCT ( n = 99 ) versus SOC ( n = 98 ) protocol s. The MSCT patients with minimal disease were discharged ; those with stenosis > 70 % underwent catheterization , whereas cases with intermediate lesions or non-diagnostic scans underwent stress testing . Outcomes included : safety ( freedom from major adverse events over 6 months ) , diagnostic efficacy ( clinical ly correct and definitive diagnosis ) , as well as time and cost of care . RESULTS Both approaches were completely ( 100 % ) safe . The MSCT alone immediately excluded or identified coronary disease as the source of chest pain in 75 % of patients , including 67 with normal coronary arteries and 8 with severe disease referred for invasive evaluation . The remaining 25 % of patients required stress testing , owing to intermediate severity lesions or non-diagnostic scans . During the index visit , MSCT evaluation reduced diagnostic time compared with SOC ( 3.4 h vs. 15.0 h , p < 0.001 ) and lowered costs ( 1,586 dollars vs. 1,872 dollars , p < 0.001 ) . Importantly , MSCT patients required fewer repeat evaluations for recurrent chest pain  ( MSCT , 2 of 99 ( 2.0 % ) patients vs. SOC , 7 of 99 ( 7 % ) patients ; p = 0.10 ) . CONCLUSIONS Multi-slice computed tomographic coronary angiography can definitively establish or exclude coronary disease as the cause of chest pain . However , inability to determine the physiological significance of intermediate severity coronary lesions and cases with inadequate image quality are present limitations . ( Study of Coronary Artery Computed Tomography to Diagnose Emergency Chest Pain CR ; http:// clinical trials.gov/ct/show/NCT00273832?order=1 ; NCT00273832 ) Diagnosis is a critical component of health care , and clinicians , policymakers , and patients routinely face a range of questions regarding diagnostic tests . They want to know whether testing improves outcome ; what test to use , purchase , or recommend in practice guidelines ; and how to interpret test results . Well- design ed  diagnostic test accuracy studies can help in making these decisions , provided that they transparently and fully report their participants , tests , methods , and results as facilitated , for example , by the STARD ( St and ards for Reporting of Diagnostic Accuracy ) statement ( 1 ) . That 25-item checklist was published in many journals and is now adopted by more than 200 scientific journals worldwide . As in other areas of science , systematic review s and meta- analysis of accuracy studies can be used to obtain more precise estimates when small studies addressing the same test and patients in the same setting are available . Review s can also be useful to establish whether and how scientific findings vary by particular subgroups , and may provide summary estimates with a stronger generalizability than estimates from a single study . Systematic review s may help identify the risk for bias that may be present in the original studies and can be used to address questions that were not directly considered in the primary studies , such as comparisons between tests . The Cochrane Collaboration is the largest international organization preparing , maintaining , and promoting systematic review s to help people make well-informed decisions about health care ( 2 ) . The Collaboration decided in 2003 to make preparations for including systematic review s of diagnostic test accuracy in their Cochrane Data base of Systematic Review s. To enable this , a working group ( Appendix ) . was formed to develop methodology , software , and a h and book The first diagnostic test accuracy review was published in the Cochrane Data base in October 2008 . In this paper , we review recent method ological developments concerning problem formulation , location of literature , quality assessment , and meta- analysis of diagnostic accuracy studies by using our experience from the work on the Cochrane H and book . The information presented here is based on the recent literature and up date s previously published guidelines by Irwig and colleagues ( 3 ) . Definition of the Objectives of the Review Diagnostic test accuracy refers to the ability of a test to distinguish between patients with disease ( or more generally , a specified target condition ) and those without . In a study of test accuracy , the results of the test under evaluation , the index test , are compared with those of the reference st and ard determined in the same patients . The reference st and ard is an agreed-on and accurate method for identifying patients who have the target condition . Test results are typically categorized as positive or negative for the target condition . By using such binary test outcomes , the accuracy is most often expressed as the test 's sensitivity ( the proportion of patients with positive results on the reference st and ard that are also positive on the index test ) and specificity ( the proportion of patients with negative results on the reference st and ard that are also negative on the index test ) . Other measures have been proposed and are in use ( 46 ) . It has long been recognized that test accuracy is not a fixed property of a test . It can vary between patient subgroups , with their spectrum of disease , with the clinical setting , or with the test interpreters and may depend on the results of previous testing . For this reason , inclusion of these elements in the study question is essential . In order to make a policy decision to promote use of a new index test , evidence is required that using the new 
    Output:
    
Stratifying by no CAD , nonobstructive CAD ( worst stenosis < 50 % ) , or obstructive CAD , there were incrementally increasing adverse events .
CONCLUSIONS Adverse cardiovascular events among patients with normal findings on CCTA are rare .
There are incrementally increasing future MACE with increasing CAD by CCTA