Translation and Psychometric Evaluation of the Profile of Fatigue and Discomfort-Sicca Symptoms Inventory (Short Form) for Patients with Primary Sjögren's Syndrome: Validity and Reliability Analysis of the Turkish Version

The study aimed to translate the Profile of Fatigue and Discomfort-Sicca Symptoms Inventory Short Form questionnaire into the Turkish language (PROFAD-SSI-SF-T) and to investigate its psychometric properties. The study was completed by 104 patients with primary Sjögren's syndrome (pSS), and 83 patients filled out the scale a second time after 7 days for the retest measurement. The PROFAD-SSISF-T, Functional Assessment Chronic Illness Therapy (Fatigue) (FACIT-F), EULAR Sjögren's Syndrome Patient Reported Index (ESSPRI), European Quality of Life 5 Dimensions (EQ-5D), and Patient Global Assessment (PaGA) were applied to 104 patients with pSS for convergent validity. PROFAD-SSI-SF-T found excellent internal consistency (Cronbach's α=0.935) and high test- retest reliability (ICC: 0.83; 95% CI: 0.75-0.88). The standard error of measurement ranged from 1.01 to 3.52, and the minimum detectable difference ranged from 0.92 to 1.17. There was a range from low to high correlation between the PROFAD-SSI-SF-T with ESSPRI, FACIT-F, and EQ-5D. There were no floor and ceiling effects in the PROFAD-SSI-SF-T scale. The PROFAD-SSI-SF-T is a valid and reliable scale to evaluate fatigue, discomfort, and sicca symptoms in Turkish patients with primary Sjögren's syndrome.