Validity and reliability of the timed-stands test for patients with rheumatoid arthritis and other chronic diseases.

The timed-stands test (TST) is a simple measure of lower extremity strength which correlates with age in healthy people. We validated the TST as a functional assessment tool against other measurements of functional capacity and comorbidity in 147 patients with rheumatoid arthritis (RA) or other chronic diseases. The TST was significantly impacted by RA disease activity and by comorbidity. Age affected TST only in patients without arthritis or life threatening disease. TST is a simple, reproducible measure of lower extremity function that was valid in this patient population.