Investigation of the validity and reliability of the L test in children with cerebral palsy

Abstract

Background: The L test is a modified version of the Timed Up and Go Test (TUG), with a walking path that is L-shaped. The L test is a more comprehensive test since it includes a longer walking path than TUG and turning in both directions. Objective: This study aimed to examine the reliability and validity of the L test, and the minimal detectable change (MDC) in children with cerebral palsy (CP). Methods: The study included 80 children with CP at levels 1 and 2 according to the Gross Motor Function Classification System (GMFCS). The Intraclass Correlation Coefficient (ICC) was used to assess the reliability of the L test according to GMFCS level. MDC estimates were calculated using baseline data. The correlations of the L test with TUG and the Timed up and Down Stairs Test (TUDS) were assessed for convergent validity. Results: Intra-rater (ICC 0.903-0.985 for level 1-2) and inter-rater (ICC 0.806-0.937 for level 1-2) reliability of the L test were determined to be excellent. A moderate correlation was found between the L test and TUG (r: 0.691) and TUDS (r: 0.546) for level 1; a moderate correlation was found between the L test and TUG (r: 0.625) and a high correlation was found between the L test and TUDS (r: 0.734) for level 2. The MDC values in terms of intra-rater were 1.44-2.21 s for level 1-2, and 1.30-1.57 s for level 2 in terms of inter-rater, respectively. Conclusion: The results of this study showed that the L test is a valid and reliable method in the assessment of functional mobility in children with CP.