Validity and Reliability of the German Version of the Locomotor Capabilities Index-5 (LCI-5).

BACKGROUND Before foreign language questionnaires, such as patient reported outcome measures (PROMs), can be scientifically used in the national language, guideline-based translation, cultural adaptation and comprehensive verification of their validity and reliability are needed. The aim of this study was to assess the psychometric properties of the German version of the LCI-5 (LCI-5-D) on a sample of people with lower limb amputation (LLA). METHODS The LCI-5 was translated into German (LCI-5-D) based on the ISPOR guidelines for cross-cultural adaptation following pilot testing. The final LCI-5-D was administered to n = 52 lower limb amputees in order to determine the validity and reliability of both the total score and the subscores ("basic items" and "advanced items"). Internal consistency (Cronbach's alpha), test-retest reliability (ICC2,1), standard error of the mean (SEM), minimal detectable change (MDC), item-to-total correlation, and item-to-subscale correlation were calculated. Floor and ceiling effects were checked. For construct validity, the Rivermead Mobility Index (RMI) and timed up and go (TUG) test were correlated, and differences of defined subgroups (amputation height and prosthesis user type) were calculated. RESULTS On average, the score of the LCI-5-D was 40.13 ± 16.64 points. High ceiling effects were present for the subscale "basic items" (57.7% maximum score). Internal consistency showed excellent results (Cronbach's α = 0.97). A strong correlation to the RMI (r = 0.863; p < 0.001) and to the TUG (r = - 0.714; p < 0.001) demonstrated construct validity. Test-rest reliability was measured after an averaged time span of 5.3 ± 2.47 days and resulted in very high reliability [ICC (2,1) = 0.97; p < 0.001]. MDC was 7.57 points for the total score. CONCLUSION The LCI-5-D is a valid and reliable PROM for measuring mobility with prostheses in German-speaking lower limb amputees, which is rather suitable for people with low to moderate mobility abilities. It can be used in a German-speaking population.