Clinical research The reproducibility and sensitivity of the 6-min walk test in elderly patients with chronic heart failure

Aims The 6-min walk test (6-MWT) is used to estimate functional capacity. However, in elderly patients with chronic heart failure (CHF): (i) 1 year reproducibility of the 6-MWT; (ii) sensitivity of the 6-MWT to self-perceived changes in symptoms of heart failure; and (iii) implications for patient numbers required for studies using the 6-MWT as an endpoint have not been described. Methods and results One thousand and seventy-seven patients with CHF, aged. 60, with NYHA Class II were recruited. Heart failure symptom assessment was determined using a questionnaire related to aspects of physical function, and patients performed a baseline 6-MWT, with follow-up 1 year later. Seventy-four patients with unchanged symptoms had an unchanged 6-MWT distance, with an overall intraclass correlation coefficient of 0.80 (95 % CI 0.69–0.87). Four hundred and twenty-three patients reported an improvement in symptoms during follow-up. There was a negative correlation (r 20.55; P 0.0001) between D symptoms and D 6-MWT (i.e. a reduced 6-MWT distance is associ-ated with reduced symptom severity at follow-up). Five hundred and sixteen patients reported worsen-ing symptoms of heart failure, a moderate inverse correlation (r 20.53; P 0.0001) was displayed between D symptoms and D 6-MWT. For all patients, irrespective of symptom status, a high inverse cor-relation (r 20.75; P 0.0001) was evident. On the basis of the data for patients with unchanged symptoms, it is calculated that to detect an increase in 6-MWT of 50 m, with 90 % power, a study size of approximately 120 is required. Conclusion In elderly patients with CHF, the 6-MWTshows satisfactory agreement when repeated 1 year later. Change in 6-MWT distance is sensitive to change in self-perceived symptoms of heart failure