Interrater Reliability of the 6-Minute Walk Test in Women With Hip Fracture.

Abstract

The 6-minute walk test (6MWT) is widely used as a clinical outcome measure. However, the reliability of the 6MWT is unknown in individuals who have recently experienced a hip fracture. The aim of this study was to evaluate the relative and absolute interrater reliability of the 6MWT in individuals with hip fracture. Two senior physical therapy students independently examined a convenience sample of 20 participants in a randomized order. Their assessments were separated by 2 days and followed the guidelines of the American Thoracic Society. Hip fracture-related pain was assessed with the Verbal Ranking Scale. Participants (all women) with a mean (standard deviation) age of 78.1 (5.9) years performed the test at a mean of 31.5 (5.8) days postsurgery. Of the participants, 10 had a cervical fracture and 10 had a trochanteric fracture. Excellent interrater reliability (intraclass correlation coefficient [ICC2.1] = 0.92; 95% confidence interval, 0.81-0.97) was found, and the standard error of measurement and smallest real difference were calculated to be 21.4 and 59.4 m, respectively. Bland-Altman plots revealed no significant difference (mean of 3.2 [31.5] m, P = .83) between the 2 raters, and no heteroscedasticity was observed (r = -0.196, P = .41). By contrast, participants walked an average of 21.7 (22.5) m longer during the second trial (P = .002). Participants with moderate hip fracture-related pain walked a shorter distance than those with no or light pain during the first test (P = .04), but this was not the case during the second test (P = .25). The interrater reliability of the 6MWT is excellent, and changes of more than 21.4 m (group level) and 59.4 m (individual participants with hip fracture) indicate a real change in the 6MWT. Measuring hip fracture-related pain during testing is recommended for individuals with hip fracture who undergo the 6MWT.