Translation, Cross-Cultural Adaptation, and Psychometric Properties of the Arabic Version of the MOS Pain Effect Scale in Individuals with Multiple Sclerosis.

Purpose: This study aimed to translate the Pain Effects Scale (PES) into Arabic, evaluate its cultural adaptation, and assess its psychometric properties (validity and reliability) among patients with Multiple Sclerosis (MS). Method: The translation and cultural adaptation followed published guidelines. A total of 121 patients with MS completed the PES and several other assessments: the Short-Form McGill Pain Questionnaire (SF-MPQ), the Patient Health Questionnaire-9 (PHQ-9), the Modified Fatigue Impact Scale (MFIS), and the Multiple Sclerosis Impact Scale (MSIS-29), to evaluate construct validity. Reliability was assessed after two weeks using the intraclass correlation coefficient (ICC) and internal consistency (Cronbach's α). Results: The Arabic version of Pain Effects Scale PES-Ar demonstrated good internal consistency (Cronbach's α = 0.910) and strong test-retest reliability (ICC (2,1) = 0.88; 95% CI: 0.85-0.92). The corrected item-total correlations for all six items ranged from 0.591 to 0.840. No floor or ceiling effects were observed. Content validity indices were high (I-CVI and S-CVI = 1.00). Construct validity was supported by moderate correlations with PHQ-9 (r = 0.677), MFIS (r = 0.66), and SF-MPQ (r = 0.586), and a weak correlation with the MSIS-29. Conclusions: The PES-Ar showed strong validity and reliability for assessing the impact of pain in Arabic-speaking individuals with MS in Saudi Arabia.