Reliability, validity and responsiveness of the German self-reported foot and ankle score (SEFAS) in patients with foot or ankle surgery

BACKGROUND: Patient-reported outcome measures are a critical tool in evaluating the efficacy of orthopedic procedures and are increasingly used in clinical trials to assess outcomes of health care. The intention of this study was to develop and culturally adapt a German version of the Self-reported Foot and Ankle Score (SEFAS) and to evaluate reliability, validity and responsiveness. METHODS: According to Cross Cultural Adaptation of Self-Reported Measure guidelines forward and backward translation has been performed. The German SEFAS was investigated in 177 consecutive patients. 177 Patients completed the German SEFAS, Foot and Ankle Outcome Score (FAOS), Short-Form 36 and numeric scales for pain and disability (NRS) before and 118 patients 6 months after foot or ankle surgery. Test-Retest reliability, internal consistency, floor and ceiling effects, construct validity and minimal important change were analyzed. RESULTS: The German SEFAS demonstrated excellent test-retest reliability with ICC values of 0.97. Cronbach’s alpha (α) value of 0.89 demonstrated strong internal consistency. No floor or ceiling effects were observed for the German version of the SEFAS. As hypothesized SEFAS correlated strongly with FAOS and SF-36 domains. It showed moderate (ES/SRM > 0.5) responsiveness between preoperative assessment and postoperative follow-up. CONCLUSION: The German version of the SEFAS demonstrated good psychometric properties. It proofed to be a valid and reliable instrument for use in foot and ankle patients. TRIAL REGISTRATION: DRKS00007585. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s12891-017-1772-1) contains supplementary material, which is available to authorized users.