Validation of the Japanese translation of the Dysphagia Handicap Index

Chihiro Oda,1,2 Toshiyuki Yamamoto,3 Yutaka Fukumoto,4 Keigo Nakayama,1 Masako Sato,1 Miho Murata,3 Yoko Kobayashi1 1Department of Physical Rehabilitation, National Center Hospital, National Center of Neurology and Psychiatry, 2Department of Rehabilitation Medicine, Showa University School ofMedicine, 3Department of Neurology, 4Department of Dentistry, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, Japan Background: We developed, and examined the reliability and validity of, a Japanese version of the Dysphagia Handicap Index (DHI; DHI-J), which is a self-reported measure to assess the quality of life (QOL) of individuals with dysphagia. Participants and methods: The DHI-J was developed via the back-translation method: the DHI was translated into Japanese and then translated back into English by a native English speaker. The back translation was discussed with and approved by the DHI’s lead author. A total of 229patients (119 males, 110 females; median age: 66 years) who underwent videofluorography at our hospital between January and December 2013 and 65 controls (23 males, 42 females; median age: 44 years) were included in the study. All the subjects completed the DHI-J and self-reported their dysphagia severity. Twenty-three patients repeated the procedure 1 week later. Patients’ swallowing function was classified as “normal”, “moderately impaired”, or “severely impaired”, and the DHI-J total scores were compared between the severity groups. Results: The internal consistency of the DHI-J was high (Cronbach’s α=0.95), as was the test–retest reliability of the 23 patients who answered the questionnaire twice (intraclass correlation coefficient =0.98, P