***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 — Frailty is an emerging concept in medicine yet to be explored as a risk factor in cardiac surgery . Where elderly patients are increasingly referred for cardiac surgery , the prevalence of a frail group among these is also on the rise . We assessed frailty as a risk factor for adverse outcomes after cardiac surgery . Methods and Results — Functional measures of frailty and clinical data were collected prospect ively for all cardiac surgery patients at a single center . Frailty was defined as any impairment in activities of daily living ( Katz index ) , ambulation , or a documented history of dementia .  Of 3826 patients , 157 ( 4.1 % ) were frail . Frail patients were older , were more likely to be female , and had risk factors for adverse surgical outcomes . By logistic regression , frailty was an independent predictor of in-hospital mortality ( odds ratio 1.8 , 95 % CI 1.1 to 3.0 ) , as well as institutional discharge ( odds ratio 6.3 , 95 % CI 4.2 to 9.4 ) . Frailty was an independent predictor of reduced midterm survival ( hazard ratio 1.5 , 95 % CI 1.1 to 2.2 ) . Conclusions — Frailty is a risk for postoperative complications and an independent predictor of in-hospital mortality , institutional discharge , and reduced midterm survival . Frailty screening improves risk assessment in cardiac surgery patients and may identify a subgroup of patients who may benefit from innovative processes of care OBJECTIVES The purpose of this study was to test the value of gait speed , a clinical marker for frailty , to improve the prediction of mortality and major morbidity in elderly patients undergoing cardiac surgery . BACKGROUND It is increasingly difficult to predict the elderly patient 's risk posed by cardiac surgery because existing risk assessment tools are incomplete . METHODS A multicenter prospect i ve cohort of elderly patients undergoing cardiac surgery was assembled at 4 tertiary care hospitals between 2008 and 2009 . Patients were eligible if they were 70 years of age or older and were scheduled for coronary artery bypass and /or valve replacement or repair . The primary predictor was slow gait speed , defined as a time taken to walk 5 m of ≥ 6 s. The primary end point was a composite of in-hospital post-operative mortality or major morbidity . RESULTS The cohort consisted of 131 patients with a mean age of 75.8 ± 4.4 years ; 34 % were female patients . Sixty patients ( 46 % ) were classified as slow walkers before cardiac surgery . Slow walkers were more likely to be female ( 43 % vs. 25 % , p = 0.03 ) and diabetic ( 50 % vs. 28 % , p = 0.01 ) . Thirty patients ( 23 % ) experienced the primary composite end point of mortality or major morbidity after cardiac surgery . Slow gait speed was an independent predictor of the composite end point after adjusting for the Society of Thoracic Surgeons risk score ( odds ratio : 3.05 ; 95 % confidence interval : 1.23 to 7.54 ) . CONCLUSIONS Gait speed is a simple and effective test that may identify a subset of vulnerable elderly patients at incrementally higher risk of mortality and major morbidity after cardiac surgery BACKGROUND AND PURPOSE The interpretation of patient scores on clinical tests of physical mobility is limited by a lack of data describing the range of performance among people without disabilities . The purpose of this study was to provide data for 4 common clinical tests in a sample of community-dwelling older adults . SUBJECTS Ninety-six community-dwelling elderly people ( 61 - 89 years of age ) with independent functioning performed 4 clinical tests . METHODS Data were collected on the  Six-Minute Walk Test ( 6MW ) , Berg Balance Scale ( BBS ) , and Timed Up & Go Test ( TUG ) and during comfortable- and fast-speed walking ( CGS and FGS ) . Intraclass correlation coefficients ( ICCs ) were used to determine the test-retest reliability for the 6MW , TUG , CGS , and FGS measurements . Data were analyzed by gender and age ( 60 - 69 , 70 - 79 , and 80 - 89 years ) cohorts , similar to previous studies . Means , st and ard deviations , and 95 % confidence intervals for each measurement were calculated for each cohort . RESULTS The 6MW , TUG , CGS , and FGS measurements showed high test-retest reliability ( ICC [2,1]=.95-.97 ) . Mean test scores showed a trend of age-related declines for the 6MW , BBS , TUG , CGS , and FGS for both male and female subjects . DISCUSSION AND CONCLUSION Preliminary descriptive data suggest that physical therapists should use age-related data when interpreting patient data obtained for the 6MW , BBS , TUG , CGS and FGS . Further data on these clinical tests with larger sample sizes are needed to serve as a reference for patient comparisons Gremeaux V , Deley G , Duclay J , Antoine D , Hannequin A , Casillas JM : The 200-m fast-walk test compared with the 6-min walk test and the maximal cardiopulmonary test : A pilot study . Objective : The 200-m fast-walk test has been proposed as a high- intensity performance test in healthy , elderly subjects . Adaptation of low-risk coronary artery disease patients during this test were compared with those in a 6-min walk test and a maximal cardiopulmonary exercise test . Design : Thirty patients with stable coronary artery disease ( 51.9 ± 8.7 yrs ) , referred to the cardiac rehabilitation department , performed a cardiopulmonary exercise test , then a 200-m fast-walk test and a 6-min walk test in a r and om order , before and after the training period ( 6 wks , 3 days per week ) . Heart rate was monitored during each test . Peak workload of cardiopulmonary exercise test , distance walked on the 6-min walk test , and time to perform the 200-m fast-walk test were measured . A sub sample of ten patients performed the exercise test with gas exchange measurements , with ventilatory threshold determination . Results : All subjects completed walk tests without complaint or incidents . Compared with the cardiopulmonary exercise test , the cardiac relative intensity was higher during the 200-m fast-walk test than during the 6-min walk test , both before ( 89.6 % vs. 78.1 % of cardiopulmonary exercise test maximal heart rate ; P < 0.05 ) and after ( 83.8 % vs. 74.3 % ; P < 0.05 ) training . Among the sub sample of ten patients , the 200-m fast-walk test heart rate was significantly higher than the ventilatory threshold heart rate , which did not differ from the 6-min walk test heart rate . The 200-m fast-walk test time significantly decreased after training ( −9.1 % , P < 0.01 ) . Conclusion : In patients with coronary artery disease at low risk , the 200-m fast-walk test explores higher levels of cardiorespiratory capacity than the 6-min walk test . Thus , this could be a useful field test in complement to the cardiopulmonary exercise test to assess functional capacity improvement and up date training targets regularly during the course of high-intensity rehabilitation programs in this population OBJECTIVE To estimate the minimal clinical ly important difference ( MCID ) for the 6-minute walk test ( 6MWT ) and the 200-m fast-walk test ( FWT ) in patients with coronary artery disease ( CAD ) during a cardiac rehabilitation program . DESIGN Prospect i ve study using distribution- and anchor-based methods . SETTING Out patients from a cardiac rehabilitation unit . PARTICIPANTS Stable patients with CAD ( N=81 ; 77 men ; mean±SD age , 58.1±8.7y ) enrolled 31±12.1 days after an acute coronary syndrome ( ACS ) . INTERVENTIONS Not applicable . MAIN OUTCOME MEASURES  6MWT and 200-m FWT results before and after an 8-week cardiac rehabilitation program and at the 6th and 12th sessions . Patients and physiotherapists who supervised the training were asked to provide a global rating of perceived change in walking ability while blinded to changes in walk test performances . RESULTS Mean change in 6MWT distance ( 6MWD ) in patients who reported no change was -6.5 m versus 23.3 m in those who believed their performance had improved ( P<.001 ) . This result was consistent with the MCID determined by using the distribution method ( 23 m ) . Considering a 25-m cutoff , positive and negative predictive values were 0.9 and .63 , respectively . Conversely , there was no difference in 200-m FWT performance between these 2 groups ( 0.1 vs -1.4s , respectively ) . There was poor agreement with the physiotherapist 's perceived change . CONCLUSIONS The MCID for 6MWD in patients with CAD after ACS was 25 m . This result will help physicians interpret 6MWD change and help research ers estimate sample sizes in further studies using 6MWD as an endpoint BACKGROUND Our purpose was to evaluate the reliability , validity , and responsiveness of the 6-minute walk test ( 6MWT ) in patients with heart failure ( HF ) enrolled in the R and omized Evaluation of Strategies for Left Ventricular Dysfunction ( RESOLVD ) pilot study . METHODS A total of 768 patients was enrolled in a multicenter r and omized clinical trial evaluating the effect of c and esartan , enalapril , and metoprolol on left ventricular ejection fraction ( LVEF ) , 6MWT distance , neurohormones , and quality of life . The 6MWT was performed once at screening and twice at baseline , 18 weeks , and 43 weeks by a st and ardized method . RESULTS Test-retest reliability at baseline ( intraclass correlation coefficient [ ICC ] = 0.90 ) , 18 weeks ( ICC = 0.88 ) , and 43 weeks ( ICC = 0.91 ) was very good . Baseline 6MWT distance was weakly inversely correlated to the quality -of-life cumulative score ( r = -0.26 , P = .0001 ) and moderately inversely correlated to the New York Heart Association functional classification ( NYHA-FC ) ( r = -0.43 , P = .001 ) . In the RESOLVD study , the 6MWT was not responsive to change when effect sizes and st and ardized response means were used . Disease-specific quality of life was responsive to change in patients treated with c and esartan and enalapril and NYHA-FC was responsive to change in the c and esartan and enalapril combination and for enalapril alone with small effect sizes . The 6MWT , NYHA-FC , and quality of life were not responsive to change during the metoprolol or placebo phase . CONCLUSIONS The 6MWT is highly reproducible in patients with symptoms of HF . It is somewhat correlated to NYHA-FC and quality of life . Overall , quality of life was most responsive to change , whereas 6MWT and NYHA-FC were comparable but less responsive to change in the RESOLVD study BACKGROUND We investigated the effects of c and esartan ( an angiotensin II antagonist ) alone , enalapril alone , and their combination on exercise tolerance , ventricular function , quality of life ( QOL ) , neurohormone levels , and tolerability in congestive heart failure ( CHF ) . METHODS AND RESULTS Seven hundred sixty-eight patients in New York Heart Association functional class ( NYHA-FC ) II to IV with ejection fraction ( EF ) < 0.40 and a 6-minute walk distance ( 6MWD ) < 500 m received either c and esartan ( 4 , 8 , or 16 mg ) ,  c and esartan ( 4 or 8 mg ) plus  20 mg  of enalapril , or  20 mg of enalapril  for 43 weeks . There were no differences among groups with regard to 6MWD , NYHA-FC , or QOL . EF increased ( P = NS ) more with c and esartan-plus-enalapril therapy ( 0.025+/-0.004 ) than with c and esartan alone ( 0.015+/-0.004 ) or enalapril alone(0.015+/-0.005 ) . End-diastolic ( EDV ) and end-systolic ( ESV ) volumes increased less with combination therapy ( EDV 8+/-4 mL ; ESV 1+/-4 mL ; P<0.01 ) than with c and esartan alone ( EDV 27+/-4 mL ; ESV 18+/-3 mL ) or enalapril alone ( EDV 23+/-7 mL ; ESV 14+/-6 mL ) . Blood pressure decreased with combination therapy ( 6+/-1/4+/-1 mm Hg ) compared with c and esartan or enalapril alone ( P<0.05 ) . Aldosterone decreased ( P<0.05 ) with combination therapy ( 23.2+/-5.3 pg/mL ) at 17 but not 43 weeks compared with c and esartan ( 0.7+/-7.8 pg/mL ) or enalapril ( -0.8+/-11 . 3 pg/mL ) . Brain natriuretic peptide decreased with combination therapy ( 5.8+/-2.7 pmol/L ; P<0.01 ) compared with c 
    Output:
    
The results did not show the relation between the six-minute walk distance and adverse events after CABG .
The predictive power of the distance walked for death in HF patients undergoing cardiac surgery was not found .
It is not yet proved if the change in the six-minute walk distance is associated with prognosis .