Reliability and validity of the Chinese version of the functional status score for the ICU (FSS-ICU) after translation and cross-cultural adaptation.

Purpose: The Functional Status Score for the Intensive Care Unit (FSS-ICU) is designed to assess the physical functional status of patients in ICU settings. This study aimed to translate and culturally adapt the FSS-ICU for the Chinese context and to evaluate its reliability and validity.

Methods: Following Beaton's translation model, the original FSS-ICU was subjected to forward translation, back-translation, and synthesis. After cultural adaptation and preliminary testing, the Chinese version of the FSS-ICU was established, and then two rehabilitation therapists assessed the functional status of 51 ICU patients using this scale, evaluating its reliability and validity.

Results: The Chinese version of the FSS-ICU exhibits excellent internal consistency with a Cronbach's alpha coefficient of 0.934. The inter-rater and intra-rater correlation coefficients are 0.995 and 0.997, respectively. Both item-level and scale-level content validity indices are 1.00. The FSS-ICU demonstrates good convergent validity with other physical function assessment tools (Medical Research Council Sum-Score, grip strength, the Intensive Care Unit Mobility Scale), with |r| values all above 0.5, and satisfactory discriminant validity with non-physical function assessment indicators (body mass index, blood glucose), with |r| values all below 0.2. Additionally, it demonstrated no ceiling or floor effects.

Conclusion: The Chinese FSS-ICU, demonstrating strong reliability and validity, can serve as an effective assessment tool for physical function in ICU patients.