Intra-tester and inter-tester reliability of chest expansion measurement in clients with ankylosing spondylitis and healthy individuals.

The purpose of this study was to examine the intra-tester and inter-tester reliability of chest expansion (CE) using a tape measure, in people with ankylosing spondylitis (AS) and healthy subjects. Twenty-two subjects with AS with a mean age of 41.4 years and 25 healthy subjects with a mean age of 41.0 years were tested in two arm positions: hands on head and arms at the sides, the tape measure being placed at the level of xiphisternum. There were three testers for subjects with AS and two testers for healthy subjects. Three trials in both arm positions were recorded by each tester on two separate occasions which were 10 minutes apart. Results showed intraclass correlation coefficients (ICC) for intra-tester reliability good (0.85 to 0.97) across the occasions. Intraclass correlation coefficients for inter-tester reliability were also very good (0.93 to 0.97). As reliability is good it is suggested that CE can be used for monitoring disease progression and efficacy of intervention with confidence within tester and between testers.