Test–retest reliability of six-minute walk tests over a one-year period in patients with chronic heart failure

Abstract

Purpose: The aims of this study were to determine the test–retest reliability of the duplicated six-minute walk test (6MWT) in patients with chronic heart failure (HF), and to evaluate its variation over time. Methods: Forty-six patients (9 women) with HF performed duplicated 6MWT every third month for 1 year (5 follow-ups), for a total of 198 paired tests. The patients completed two 6MWT on the same day with a 45-min seated rest between tests. Results: The mean distance in metres, for the first (6MWT1) versus the second (6MWT2), for each follow-up, was 408 ± 100 versus 411 ± 96, 449 ± 94 versus 465 ± 94, 464 ± 96 versus 473 ± 100, 462 ± 103 versus 468 ± 104 and 472 ± 105 versus 482 ± 107. On average, a marginally, clinically insignificant longer walked distance, 9 m (2.0%), was seen in the second 6MWT. The standard error of a single determination (Smethod) ranged from 2.4% to 3.9% over the study period, and the intraclass correlation coefficient (ICC) ranged from 0.96 to 0.99 (CI 95% 0.94–0.99). The variation over time of ICC or Smethod was not statistically significant. Conclusion: The 6MWT is highly reliable over time in patients with HF, and one test is, therefore, sufficient in clinical follow-ups.