Correlations between 6-minute walk test, chair-rise test, and lower extremity functional scale among patients with hypophosphatasia.

Abstract

Hypophosphatasia (HPP) is a rare disease characterized by skeletal and nonskeletal manifestations that can increase patient disability. The 6-Minute Walk Test (6MWT) is frequently used to assess mobility in patients with HPP, although the test is laborious to conduct in clinical practice. The purpose of the current study was to determine correlations between time to complete the 6MWT, time to complete the Chair-Rise Test (CRT), and scores on the Lower Extremity Functional Scale (LEFS) in adults with HPP. Pearson correlations between time to complete outcomes on the 6MWT and CRT, time to complete the 6MWT and scores on the LEFS, and time to complete the CRT and scores on the LEFS were calculated using de-identified data from adults with HPP who had first onset of symptoms in childhood. All patients were enrolled in the previously conducted, observational EmPATHY study. Pearson correlation analyses showed inverse correlations between 6MWT and CRT outcomes (<i>r</i> = -0.584) and between CRT and LEFS outcomes (<i>r</i> = -0.596) and a direct correlation between 6MWT and LEFS outcomes (<i>r</i> = 0.808). Time to complete the 6MWT was correlated with time to complete the CRT and scores on the LEFS in adults with HPP. CRT and LEFS may be suitable, expeditious options to amend or substitute 6MWT when assessing functional status in patients with HPP.