Validation of the Chinese Manchester foot pain and disability index (C-MFPDI) among patients with inflammatory arthritis

BACKGROUND: The Manchester Foot Pain and Disability Index (MFPDI) is a patient-reported outcome tool used to measure foot pain and foot-related disability. The English version of the MFPDI has been successfully translated into other European languages, but there was no Chinese version to use in Chinese-speaking communities. The cross-sectional correlational study aimed to translate the MFPDI from English into simplified Chinese (C-MFPDI) and to test its psychometric properties among people with inflammatory arthritis in Singapore. METHODS: The MFPDI was translated from English into Chinese using a forward-backward translation framework and was administered to 100 Chinese-speaking people with inflammatory arthritis. From the original 100 participants, 30 participants re-evaluated the C-MFPDI after 2 weeks. A Visual Analogue Scale and the Taiwan Chinese Foot Function Index in simplified Chinese were used to evaluate concurrent validity with the C-MFPDI. Health-related quality of life was assessed using the Chinese version of the European Quality of Life-5 Dimension to test construct validity. RESULTS: The C-MFPDI had a high translation equivalent rate (96.3%) and content validity index (0.92), good internal consistency (Cronbach’s α = 0.90) and test-retest reliability (ICC = 0.87). The concurrent validity of the C-MFPDI was demonstrated to be acceptable through its significantly moderate to strong positive correlations with the Taiwan Chinese Foot Function Index (r = 0.62–0.72, p < 0.01) and Visual Analogue Scale foot pain (r = 0.65, p < 0.01). The C-MFPDI total scores were moderately negatively associated with Chinese European Quality of Life-5 Dimension utility scores (r = − 0.40, p < 0.01). CONCLUSION: The C-MFPDI had good psychometric properties. The C-MFPDI can be used to assess disabling foot pain, impairment and disability in Chinese-speaking people with inflammatory arthritis. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s13047-019-0316-3) contains supplementary material, which is available to authorized users.