Hirotaka Iijima1, Kanako Shimoura2, Ryo Eguchi3, Tomoki Aoyama4, Masaki Takahashi5. 1. Department of System Design Engineering, Faculty of Science and Technology, Keio University, Yokohama, Japan; Department of Physical Therapy, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan; Japan Society for the Promotion of Science, Tokyo, Japan. Electronic address: iijima.hirotaka.4m@yt.sd.keio.ac.jp. 2. Department of Physical Therapy, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan. Electronic address: shimoura.kanako.53s@st.kyoto-u.ac.jp. 3. School of Science for Open and Environmental Systems, Graduate School of Science and Technology, Keio University, Yokohama, Japan. Electronic address: eguchi.ryo@keio.jp. 4. Department of Physical Therapy, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto, Japan. Electronic address: aoyama.tomoki.4e@kyoto-u.ac.jp. 5. Department of System Design Engineering, Faculty of Science and Technology, Keio University, Yokohama, Japan. Electronic address: takahashi@sd.keio.ac.jp.
Abstract
BACKGROUND: Stair climbing is the task first affected in patients with knee osteoarthritis (OA); therefore, the precise measurement of time required to climb stairs is important to identify mobility limitations, particularly in the early phase of knee OA. RESEARCH QUESTION: This study aimed to examine the test-retest reliability, measurement error, and concurrent validity of the stopwatch-based stair-climb test (SCT) in adults with pre-radiographic to mild knee OA. METHODS: Fifty-nine participants (mean age, 59.1 [range, 50-69] years; 72.9% female) with Kellgren and Lawrence grade ≤2 disease underwent an 11-step SCT (11-SCT) in accordance with the Osteoarthritis Research Society International recommended method while wearing pressure sensor-mounted standard shoes that is used as a gold standard procedure. Test-retest reliability, measurement errors, and the concurrent validity of the stopwatch-based 11-SCT were evaluated. RESULTS: The test-retest reliability of the stopwatch-based 11-SCT was excellent (intra-class correlation coefficient1,1 [ICC1,1], 0.952; 95% confidence interval [CI], 0.560 to 0.985; p < 0.001) and the minimal detectable change95 was 0.102 s. Concurrent validity was excellent (ICC2,1: 0.957; 95% CI: 0.661 to 0.986; p < 0.001). SIGNIFICANCE: The stopwatch-based 11-SCT had high test-retest reliability and high concurrent validity, which justify its clinical use for identifying mobility limitations in individuals with pre-radiographic to mild knee OA. A difference of 0.2 s in the stopwatch-based 11-SCT time would be considered a true difference beyond a 95% measurement error.
BACKGROUND: Stair climbing is the task first affected in patients with knee osteoarthritis (OA); therefore, the precise measurement of time required to climb stairs is important to identify mobility limitations, particularly in the early phase of knee OA. RESEARCH QUESTION: This study aimed to examine the test-retest reliability, measurement error, and concurrent validity of the stopwatch-based stair-climb test (SCT) in adults with pre-radiographic to mild knee OA. METHODS: Fifty-nine participants (mean age, 59.1 [range, 50-69] years; 72.9% female) with Kellgren and Lawrence grade ≤2 disease underwent an 11-step SCT (11-SCT) in accordance with the Osteoarthritis Research Society International recommended method while wearing pressure sensor-mounted standard shoes that is used as a gold standard procedure. Test-retest reliability, measurement errors, and the concurrent validity of the stopwatch-based 11-SCT were evaluated. RESULTS: The test-retest reliability of the stopwatch-based 11-SCT was excellent (intra-class correlation coefficient1,1 [ICC1,1], 0.952; 95% confidence interval [CI], 0.560 to 0.985; p < 0.001) and the minimal detectable change95 was 0.102 s. Concurrent validity was excellent (ICC2,1: 0.957; 95% CI: 0.661 to 0.986; p < 0.001). SIGNIFICANCE: The stopwatch-based 11-SCT had high test-retest reliability and high concurrent validity, which justify its clinical use for identifying mobility limitations in individuals with pre-radiographic to mild knee OA. A difference of 0.2 s in the stopwatch-based 11-SCT time would be considered a true difference beyond a 95% measurement error.