Performance of sit-to-stand, timed up-and-go, and six-minute walk tests in home and office settings in patients with idiopathic inflammatory myopathy.

Background: Patients with idiopathic inflammatory myopathies (IIM) frequently experience limitations in their physical function. Sit-to-stand (STS), timed-up-and-go (TUG), and six-minute walk distance (6MWD) are task-oriented functional tests that can provide objective information about physical function. In this study, we assess their measurement properties in office and home settings.

Methods: Adults with IIM were enrolled in a prospective study. Patients performed the functional tests (STS, TUG, 6MWD) at 0-, 3- and 6-months, and self-performed these tests at home within 14-days of the visit. Several patient centered outcome measures (PCOMs) were obtained: fatigue (visual analog scale [VAS]), pain (VAS), quality of life (SF-36), physical function (PROMIS, SF36), and physical activity (Actigraphy). Spearman correlation, effect size, standardized response mean, and regression models were used to assess cross-sectional and longitudinal association between functional tests and other measures.

Results: Fifty patients (mean age 51.6, 60% female) were enrolled. Twenty-four, 23, and 20 completed at-home STS, TUG, and 6MWD, respectively. STS and TUG showed strong test-retest reliability at both home and office settings. 6MWD was significantly higher at office setting, whereas TUG/STS was comparable between home and office. All three functional tests significantly discriminated between active vs inactive disease and had significant cross sectional and longitudinal association with PCOMs of physical function, quality of life, and physical activity.

Conclusion: STS, TUG and 6MWD have good test-retest reliability, validity and responsiveness. 6MWD has poor reliability when self-performed at home, while STS/TUG perform similarly in the office and home settings.