Development and evaluation of frailty index for patients with systemic lupus erythematosus in China

Objective To develop and validate a frailty assessment scale tailored for patients with systemic lupus erythematosus (SLE). Methods Based on the theory of the frailty integration model, an initial draft of the frailty index questionnaire was developed through a comprehensive literature review and a two - round Delphi expert consultation. The final version of the scale was formed through a pre - survey and a formal survey. The validity of the questionnaire was tested using content validity, structural validity, and criterion - related validity. The reliability was evaluated using Cronbach’s α coefficient, split - half reliability, and test - retest reliability. Results The initial item pool of the scale contained 3 dimensions and 32 items. After two rounds of Delphi expert consultations, the draft scale was refined to 21 items across 3 dimensions. Pilot testing with 50 SLE patients further reduced it to 14 items. The formal content validity Cronbach’s α coefficient was 0.809, the split - half reliability was 0.745, the KMO was 0.820, and the Bartlett’s test value was 2915.855 ( p < 0.001). The results of exploratory factor analysis showed that, except for a few items, the correlation coefficient between the score of each item and its score in the corresponding dimension was greater than 0.4, and the overall correlation coefficient was 0.832 ( p < 0.001). The optimal cutoff value for the pre - frailty stage was 28.5, and that for the frailty stage was 40.5. Conclusion The frailty index scale developed in this study is a valid and reliable tool for assessing frailty in SLE patients in China, with potential utility in clinical and research settings.