Psychometric Evaluation of the Persian Version of a Self-Care Evaluation Instrument to Prevent Diabetic Foot in Iranian Patients Predominantly with Type 2 Diabetes Mellitus (P-ISPDF).

Abstract

Objective: To translate and psychometrically validate the Persian version of the Instrument for Self-care in Preventing Diabetic Foot (P-ISPDF) as a reliable, culturally appropriate tool for assessing foot-specific self-care behaviors among Persian-speaking adults, predominantly those with type 2 diabetes mellitus.

Methods: The ISPDF was translated using a forward-backward procedure, followed by expert review (n=5) and cognitive debriefing with patients (n=10). A split-sample design was used: exploratory factor analysis (EFA; n=289) and a series of confirmatory factor analyses (CFAs), including first-order, second-order, and a hierarchical general-factor model in an independent sample (n=250). Items were rated on a 5-point Likert scale (1-5). Reliability (Cronbach's alpha, McDonald's omega, intraclass correlation coefficient [ICC]) and validity (EFA, CFA) were evaluated using SPSS 25, AMOS 24, and JASP.

Results: EFA supported a three-factor structure: self-care maintenance (10 items), monitoring (9 items), and management (7 items). The hierarchical measurement model showed good fit (χ ²/df=2.80, CFI=0.974, TLI=0.954, RMSEA=0.060). Cronbach's alpha was 0.93 for the total scale, with subscale alphas ranging from 0.81 to 0.92. Test-retest reliability was excellent (two-way mixed-effects, absolute agreement ICCs 0.93-0.98 with 95% CIs reported).

Conclusion: The P-ISPDF demonstrated strong reliability and preliminary structural validity. However, due to mixed evidence regarding convergent validity and the absence of external validation, the findings should be interpreted with caution. Further psychometric refinement and longitudinal studies are needed to establish its clinical utility.