Six-Minute Walking Test and 30 Seconds Chair-Stand-Test as Predictors of Mortality in COPD – A Cohort Study

BACKGROUND: Physical inactivity is strongly associated with worse prognosis in Chronic Obstructive Pulmonary Disease (COPD), and assessment of physical function is very important. The six minute walking test (6MWT) is an established test known to predict mortality in COPD, and 30 seconds chair stand test (30sCST) is a potential alternative test. The study aimed to investigate and compare the associations of 6MWT and 30sCSTs with mortality. METHODS: Data on patient demographics, established mortality predictors and results from 6MWT and 30sCST were collected from 2016 to 2019 from 97 consecutively included patients with COPD. In August 2021, mortality data were retrieved from patient records. Correlation analysis of 6MWT and 30sCST was performed. The predictive abilities of 6MWT and 30sCST, respectively, were analyzed using Kaplan Meyer-curves and Cox regression with adjustment for sex, age, body mass index below 22 and comorbid cardiovascular disease. RESULTS: A positive correlation between 6MWT and 30sCST was shown (r = 0.61, p < 0.0001). Independent associations with mortality were found for 6MWD 250–349 (HR (95% CI) 3.19 (1.12 to 9.10), p = 0.030) and 6MWD <250 (4.27 (1.69 to10.8), p = 0.002) compared with 6MWD ≥350 meters, and for 30sCST <4 (3.31 (1.03 to 10.6), p = 0.045) compared with 30sCST≥11 risings. When both 6MWT and 30sCST were included in the multivariable model, 6MWD 250–349 (3.09 (1.02 to 9.37), p = 0.046) and 6MWD <250 (3.57 (1.26 to 10.1), p = 0.016) compared with 6MWD ≥350 meters predicted mortality. CONCLUSION: 30sCST and 6MWT correlates moderately and are independently associated with mortality in patients with COPD. Although 6MWT is the best predictor of mortality, 30sCST may be used as an alternative to identify patients at risk.