Reliability,Validity And Application Of Three Sit-To-Stand Tests As Tools For Assessing Exercise Tolerance In Patients With Coronary Artery Disease

Objective:The 6-Minute walk test（6MWT）has been used to evaluate exercise tolerance in patients with coronary artery disease（CAD）,which has good reliability and validity.However,the clinical application of 6MWT is still inconvenient due to the high requirements of site and environment.As another type of test for evaluating exercise tolerance,sit-to-stand test（STS test）has low requirements for testing environment,takes less time,is a simple and easy to perform and is relatively easier to apply in the clinic setting.However,there is no evidence to show the efficacy of STS tests in patients with CAD and the feasibility of predicting the risk of cardiovascular events.Therefore,the aims were to investigate the test-retest reliability,convergent and known-groups validity of STS tests for assessing exercise tolerance in patients with CAD,and to explore the feasibility of STS tests for predicting the risk level of cardiovascular events in patients with CAD.Methods:The study was approved by the Ethics Committee of Xinhua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine and Shanghai University of Sports,and 112 patients with CAD were recruited from October 2020 to September 2021 in the Department of Cardiology of Xinhua Hospital Affiliated to Shanghai Jiaotong University School of Medicine.Each participant performed 6MWT,five times STS（FTSTS）,30-second STS（30-s STS）and 1-minute STS（1-min STS）tests in a randomized order in one trial.Subjects were given a 30-minute rest period after 6MWT and a 5-minute rest period between each STS test.Patients were measured for heart rate,blood pressure,blood oxygen,dyspnea and fatigue at baseline and immediately after tests.Among those who completed the above tests,thirty participants were randomly invited to repeat the same test sequence on the next day.The ability of the three STS tests to distinguish between the high and low risk of cardiovascular events was analyzed by using the receiver operating characteristic curves（ROC curve）referred to a previous study that a 6MWT distance of 419 meters was used as the threshold of high and low risk of cardiovascular events.Left Ventricular Ejection Fraction（LVEF）obtained by echocardiographic assessment over a 3-month period was used as an index of cardiac function in patients,and the relationship between the three STS tests and cardiac function was analyzed using the Spearman correlation coefficient.Results:Of the 112 patients with CAD included in the study,the mean age was 63.9±8.8 years and 69%were male.The mean age of the 30 patients who participated in the STS test-retest was 64.3±7.3 years,53%were male.（1）The test-retest reliability results showed that the intraclass correlation coefficient（ICC）for FTSTS,30-s STS and 1-min STS tests were 0.96（95%CI:0.92-0.98）,0.95（95%CI:0.91-0.98）and 0.96（95%CI:0.91-0.98）,respectively,with standard errors of measurement（SEM）0.40 seconds,0.65 and 1.39 repetitions,the minimal detectable change with 95%confidence interval(MDC₉₅)were calculated as 1.1 seconds,1.8 and3.9 repetitions.（2）The convergent validity results presented that all 3 STS tests were moderately strongly significantly correlated with 6MWT（FTSTS test,r=-0.53,p<0.001;30-s STS test,r=0.57,p<0.001;1-min STS test,r=0.55,p<0.001）.（3）The known-groups validity results demonstrated that patients in the myocardial infarction（MI）group took significantly more time to complete the FTSTS test（12.9±3.3 vs 11.5±2.8 seconds,p=0.009,95%CI:0.3 to 2.6）,completed fewer repetitions in 30-s STS test（12.4±2.9 vs 14.4±3.3 repetitions,p=0.002,95%CI:-3.1 to-0.7）and 1-min STS test（24.1±5.9 vs.27.5±6.8 repetitions,p=0.006,95%CI:-5.9 to-1.0）and a significantly shorter distance for the 6MWT（431.5±64.6 vs 480.3±57.3meters,p<0.001,95%CI:-71.7 to-25.9）compared to the non-MI group.（4）The correlation between STS tests and LVEF showed that the three STS tests were weakly to moderately significantly correlated with LVEF（FTSTS test,r=-0.27,p=0.003;30-s STS test,r=0.31,p=0.001;1-min STS test,r=0.27,p=0.004）.（5）Comparative analysis of hemodynamic,dyspnea and fatigue changes before and after the test were showed.There were no statistical differences in heart rate,blood pressure,blood oxygen,dyspnea and fatigue before each test（p>0.05）.Comparative analysis of the heart rate changes before and after the test showed that the heart rate of FTSTS test（71.1±6.8 vs 73.8±7.8 beats/min,p<0.001,%change+3.8%）,30-s STS test（72.7±8.6 vs 79.6±9.2 beats/min,p<0.001,%change+9.5%）,1-min STS test（72.3±8.2 vs 87.5±8.9 beats/min,p<0.001,%change+21.0%）and 6MWT（72.9±8.3 vs85.9±8.4 beats/min,p<0.001,%change+17.8%）were significantly higher after tests;comparative analysis of the systolic blood pressure changes before and after the test showed that systolic blood pressure of FTSTS test（124.9±13.3 vs 130.4±12.4 mm Hg,p<0.001,%change+4.4%）,30-s STS test（125.3±13.5 vs 139.4±16.3 mm Hg,p<0.001,%change+11.3%）,1-min STS test（128.2±12.6 vs 149.3±14.8 mm Hg,p<0.001,%change+16.5%）and 6MWT（125.0±12.5 vs 146.8±14.1,p<0.001,%change+17.4%）were greatly higher after tests;comparative analysis of the diastolic blood pressure changes before and after the test showed that diastolic blood pressure had a significant increase in 30-s STS test（74.3±8.4 vs 83.0±8.7 mm Hg,p<0.001,%change+11.7%）,1-min STS test（75.3±7.5 vs 84.5±8.8 mm Hg,p<0.001,%change+12.2%）and 6MWT（73.0±9.7 vs 81.5±8.6 mm Hg,p<0.001,%change+11.6%）after tests;comparative analysis of the blood oxygen saturation changes before and after the test showed that the blood oxygen saturation of FTSTS test（98±1 vs 97±1%,p<0.001）,30-s STS test（98±1 vs 96±2%,p<0.001）,1-min STS test（98±1 vs 94±2%,p<0.001）and 6MWT（98±1 vs 94±2%,p<0.001）were significantly reduced after tests;comparative analysis of dyspnea changes before and after the test showed that the dyspnea had a significant increase in FTSTS test（0.1±0.2 vs 0.3±0.4,p<0.001）,30-s STS test（0.1±0.2 vs 2.4±0.6,p<0.001）,1-min STS test（0.1±0.3 vs 4.0±0.8,p<0.001）and 6MWT（0.1±0.3 vs 4.0±0.9,p<0.001）were significantly aggravated;comparative analysis of self-perceived fatigue levels changes before and after the test showed that the self-perceived fatigue levels of30-s STS test（0.2±0.6 vs 2.4±1.1,p<0.001）,1-min STS test（0.2±0.5 vs 4.2±1.7,p<0.001）and 6MWT（0.2±0.4 vs 4.0±0.9,p<0.001）were significantly aggravated.The above results showed that the degree of physiological changes in the 1-min STS test was closest to that of the 6MWT.（6）The results of the ROC curve analysis showed that the area under the curve for FTSTS test to differentiate between high and low risk of cardiovascular events was 0.80（sensitivity:75.0%,specificity:73.8%,optimal cut-off:11.7 seconds）,and 0.83（sensitivity:75.0%,specificity:76.2%,optimal cut-off:12 repetitions）and 0.80（sensitivity:71.4%,specificity:73.8%,optimal cut-off:23 repetitions）for the area under the curve for 30-s STS and 1-min STS test.Conclusion:（1）The FTSTS test,30-s STS test and 1-min STS test all have excellent test-retest reliability and good convergent and known-groups validity,can be used to evaluate exercise tolerance in patients with CAD;among them,the degree of physiological changes in patients completing the 1-min STS test is closest to the 6MWT and can be used as an alternative to the 6MWT to improve the convenience of clinical evaluation of exercise tolerance in patients with CAD.（2）The MDC₉₅ values of FTSTS,30-s STS and 1-min STS tests were 1.1 seconds,1.8and 3.9 repetitions,respectively,with small measurement errors,which provided references for changes when different STS tests are used for intervention efficiency evaluation.（3）All three STS test performances were significantly correlated with left heart function in patients with CAD,and all of them could better predict the risk of cardiovascular events in patients with CAD,so they have high clinical application value and are suitable for clinical application and promotion in cardiac rehabilitation.