Cross-cultural validation of the Lower Extremity Functional Scale in Serbian postmenopausal women with knee osteoarthritis.

Objective: Translation and cross-cultural validation of the Serbian version of the Lower Extremity Functional Scale (Srb-LEFS).

Methods: This prospective cross-sectional study initially included 186 postmenopausal women aged 60 to 75 years who underwent an x-ray examination of both knees, along with body mass, body height, waist circumference, knee range of motion, and blood pressure measurements. The laboratory analyses included the evaluation of fasting glucose levels and lipid profile. All participants completed the LEFS, Lequesne index, and 36-Item Short-Form Survey-RAND.

Results: The analyses revealed good internal consistency (α = 0.95), good test-retest reliability, and a two-factor structure of the Srb-LEFS. Concurrent validity analysis confirmed a significant positive correlation between Srb-LEFS scores and the 36-Item Short-Form Survey-RAND Physical Functioning subscale ( r = 0.889, P < 0.0001), the Lequesne index ( r = -0.976, P < 0.0001), and the Numeric Rating Scale for pain ( r = -0.762, P < 0.0001). Convergent validity analyses revealed a statistically significant negative correlation between the Srb-LEFS scores and age ( r = -0.25, P = 0.006), body mass index ( r = -0.31, P < 0.01), and waist circumference ( r = -0.37, P < 0.0001). The Srb-LEFS scores were statistically significantly higher among participants that reported moderate physical activity levels, as well as those that had fewer comorbidities, minor structural knee damage, greater knee range of motion, and greater quadriceps femoris muscle strength.

Conclusions: The Serbian version of the LEFS is feasible, valid, and reliable for use in both clinical practice and clinical studies to assess self-reported physical functioning in older individuals with knee osteoarthritis.