Translation and validation of the Persian version of diabetic foot ulcer scaleshort form (DFS-SF)

Abstract

Foot ulcer in diabetic patients could often result in significantly impaired quality of life. This study aimed to translate and validate the DFS-SF in Iran. The DFS-SF was translated into Persian, and then its validity and reliability were tested in 262 patients with DFUs. Content validity was evaluated using content validity ratio (CVR) and content validity index (CVI), and criterion validity was assessed through Spearman's correlation between dimensions of the DFS-SF and the EQ-5D-5L. Construct validity was measured using exploratory factor analysis (EFA) and confirmatory factor analysis (CFA), and convergent-discriminant validity was examined by calculating the average variance extracted (AVE) and composite reliability (CR). Cronbach's alpha and intraclass correlation coefficient (ICC) were calculated to evaluate the reliability of the measure. CVR ≥0.66 and CVI = 0.81 were calculated. Spearman's correlation ranged from 0.23 to 0.78 across all dimensions. The results of EFA showed that all six dimensions of the DFS-SF had an eigenvalue more than 1; accounting for 68.88% of the total variance. CFA confirmed the DFS-SF as a six-dimension structure with good fit indices of χ2/df = 2.15 < 5, RMSEA = 0.06 < 0.08, CFI = 0.91 ≥ 0.90, TLI = 0.90 ≥ 0.90, and RMR = 0.04, as well as with adequate fit indices of GFI = 0.84 ≤ 0.90, NFI = 0.86 ≤ 0.90. Estimates of ≥0.50 for AVE were not observed in two of the six dimensions and CR ≥0.70 was obtained for all dimensions. The reliability was calculated with a Cronbach's alpha of 0.89 and ICC >0.69 for all dimensions. Our findings confirmed the validity and reliability of the Persian DFS-SF; therefore, it can be used to assess QoL in patients with DFSs in clinical and research settings in Iran.