Cross-Cultural Adaptation, Validity, and Reliability of the Persian Translation of the Merle d'Aubigné-Postel Score

The Merle d'Aubigné--Postel (MDP) score is a widely used patient-reported outcome measure (PROM) for assessing hip function for pain, walking ability, and mobility. Despite its widespread international use, no validated Persian version has been available to date. This study aimed to translate and culturally adapt the MDP score into Persian and evaluate its reliability and validity in Persian-speaking patients undergoing total hip arthroplasty (THA).

Following Guillemin et al. guidelines, Persian translation was done using a forward--backward process, followed by expert review and pretesting with 20 patients to ensure clarity and cultural relevance. The adapted instrument was validated in 103 Persian-speaking patients who had undergone THA with at least one year of follow-up. Internal consistency (Cronbach's alpha), test--retest reliability (intraclass correlation coefficient [ICC]), construct validity (correlation with the Harris Hip Score [HHS]), criterion validity (correlation with HHS and the Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]), and content validity (floor and ceiling effects) were evaluated. Inter-rater reliability for mobility was assessed by three orthopedic residents.

The Persian MDP score demonstrated high internal consistency (α= 0.74) and excellent test--retest reliability (ICC= 0.95; 95%CI: 0.91--0.98). Inter-rater reliability for mobility was excellent (ICC= 0.89; 95%CI: 0.82--0.94). Construct validity was supported by strong domain-specific correlations (e.g., MDP pain vs. HHS pain: r= 0.73; 95%CI: 0.62--0.81). Criterion validity was confirmed by strong correlations with WOMAC (r= 0.745; 95%CI: 0.65--0.82) and HHS (r= 0.753; 95%CI: 0.66--0.83). Content validity showed no floor effect (0%) and an acceptable ceiling effect (14.5%).

The Persian MDP score is a valid and reliable instrument for assessing outcomes after THA in Persian-speaking patients. Its simplicity and strong psychometric properties support its use in clinical and research settings. However, the observed ceiling effect should be considered for excellent postoperative outcomes.