Authors (including presenting author) :
WONG CK(1), Tam OY (1), TUNG LH(1), CHEUNG CH(1), Kwan WS(1), Mak MY(1)
Affiliation :
(1) Department of Physiotherapy, Tuen Mun Hospital, New Territories West Cluster, Hospital Authority, Hong Kong
Introduction :
6-minute walk test (6MWT) is a well recognized field test for functional assessment and its prognostic value in post-operative outcome in major surgeries. Previous studies suggested that walking fewer than 400 meters in 6MWT was related to more postoperative complications following a major surgery (1). On the other hand, slower walking speed and greater fall risk are also common in frail patients with underlying comorbidities (2). A simpler and safer functional screening tool may therefore be needed for these patients without undergoing through a 6MWT. Time-up-and-go test (TUGT), which assesses mobility and balance, is an easily administered functional screening test. Previous study already established 13 seconds as the cut off point for high fall risk in community dwelling adults (3). However there is currently no literature in Hong Kong to examine the relationship between TUGT and 6MWT and the cut-off point for TUGT to predict the performance in 6MWT, and thereby estimating postoperative outcome.
Objectives :
To determine the correlation between TUGT and 6MWT and the cut-off point for TUGT to stratify patients into “high risk” (6MWT < 400m) or “low risk” group (6MWT >= 400m)
Methodology :
A retrospective study was undertaken for patients who would undergo non-cardiac surgery in Tuen Mun Hospital from Jan, 2022 to Oct, 2022. Patients being referred to the “High Risk Clinic” by anesthetists in the preoperative phase were recruited. Data of 6MWT distance (meter) and TUGT time (sec) were captured. Pearson’s correlation analysis was used to determine the correlation between 6MWT distance and TUGT time. Receiver operating characteristics (ROC) curve analysis was used to determine the cut-off of TUGT time in predicting the benchmark of 400m in 6MWT. The optimal cut-off point was determined with sensitivity of 1.0 to include all patients achieving 400m in 6MWT, in other words, any time more than this cut-off point of TUGT would fall into high risk group failing to achieve 400m in 6MWT.
Result & Outcome :
There were 256 patients being referred to High Risk Clinic and underwent TUGT & 6MWT for functional assessment between Jan, 2022 to Oct, 2022. 124 patients (82 males and 42 females; mean age = 72.88 years old), whose 6MWT failed to walk more than 400m, were classified as high risk group while 132 patients (100 males and 32 females, mean age = 66.76) were classified as low risk group. TUGT is negatively correlated with 6MWT (Pearson’s r = -0.772, p < 0.0.5). The cut off of TUGT time to predict low perioperative risk was 16.5s (sensitivity = 1.0, 1-specificity = 0.605;). The area under the curve of the ROC curve by TUGT is 0.899. Conclusion The TUGT is a useful and quick functional screening tool to predict the 6MWT distance. Our study demonstrated that any time longer than 16.5s in TUGT would likely walk fewer than the 400m risk stratification benchmark in 6MWT. TUGT is also commonly included in the physical domain of frailty measurement, where prior studies showed its predictability in postoperative conditions too (4,5). From a practical perspective, TUGT can serve as a triage tool for postoperative risk and to enhance assessment safety in field test administration given its correlation to fall risk. This cohort of frail patients perhaps warrants a more comprehensive cardiopulmonary exercise test (CPEX).
