Ethical approval and consent to participate
All procedures involving human participants were performed in accordance with the Ethical Standards of the Institutional and/or the National Research Committee and with the 1964 Helsinki Declaration, including its later amendments, or comparable ethical standards. Ethical approval for conducting this study was obtained from the Epidemiologic Research Ethics Committee of Gunma University (no. 24-26).
Consent for publication
Not applicable.
Availability of data and materials
The datasets used and/or analysed during this study are available from the corresponding author on reasonable request.
Competing interests
The authors declare that they have no competing interest.
Funding
This study was not funded by any institution and organization.
Author’s contributions
Tomomi Ogata designed the study, conducted the questionnaire survey, collected and analyzed data, drafted the manuscript, and submitted the final version; Kazuhiro Muramatsu designed the study, collected the data, and drafted the manuscript; Kaori Irahara designed the study and conducted the questionnaire survey and collected data; Hiroshi Ozawa designed the study; Motoki Iwasaki provided advice on the data analysis and drafting of the manuscript; Hirokazu Arakawa coordinated and supervised data collection and drafting of the manuscript. All authors approved the final manuscript for submission.
Acknowledgements
The authors thank all the doctors who answered our questionnaire on CCHS patients in Japan: Dr. Akaishi M, Dr. Araki A, Dr. Daimon Y, Dr. Dobata T, Dr. Endou T, Dr. Fukumoto K, Dr. Hasegawa H, Dr. Hashimoto K, Dr. Hashimoto Y, Dr. Hayakawa M, Dr. Hayasaka K, Dr. Hayashi T, Dr. Hino H, Dr. Honda Y, Dr. Hoshino R, Dr. Hosoya M, Dr. Ii C, Dr. Iio K, Dr. Ikeda T, Dr. Iseki T, Dr. Ishitate M, Dr. Ito K, Dr. Itomi K, Dr. Kagimoto S, Dr. Kai M, Dr. Kako Y, Dr. Kanaoka H, Dr. Katayama Y, Dr. Kato M, Dr. Kawase C, Dr. Kawawaki H, Dr. Kikuchi M, Dr. Kinoshita H, Dr. Kishida M, Dr. Koike Y, Dr. Kondo Y, Dr. Koyama N, Dr. Kubo M, Dr. Kusuda T, Dr. Maeda T, Dr. Maruyama A, Dr. Maruyama K, Dr. Maruyama S, Dr. Matsuoka T, Dr. Michihiro N, Dr. Minamitani T, Dr. Misawa M, Dr. Miyakawa T, Dr. Miyamoto K, Dr. Miyamoto Y, Dr. Miyata M, Dr. Miyoshi Y, Dr. Morita K, Dr. Mouri J, Dr. Murakoshi T, Dr. Nagaoka Y, Dr. Nagase H, Dr. Nakahara A, Dr. Nakajima S, Dr. Nakamura Y, Dr. Narumi T, Dr. Niimi N, Dr. Nishikura N, Dr. Nogami K, Dr. Ochiai F, Dr. Ogata S, Dr. Ohishi Y, Dr. Ohnishi A, Dr. Ohshiro T, Dr. Okamatsu Y, Dr. Okano R, Dr. Okazaki S, Dr. Sakamoto H, Dr. Sasaki A, Dr. Sasaki M, Dr. Sato Tatsuharu, Dr. Sato Takumi, Dr. Shiiki T, Dr. Shimazu T, Dr. Shinoda K, Dr. Shiraishi H, Dr. Sudo A, Dr. Sugai M, Dr. Sugiyama T, Dr. Suzuki Y, Dr. Takahata Y, Dr. Tamaki K, Dr. Tanaka R, Dr. Tanaka S, Dr. Tanano A, Dr. Tanda K, Dr. Tateishi H, Dr. Tokuyama H, Dr. Tsuda H, Dr. Tsugawa J, Dr. Tsuruta S, Dr. Tuchiya K, Dr. Udagawa N, Dr. Ueda N, Dr. Ueda Y, Dr. Ueno S, Dr. Uryu H, Dr. Wakatsuki M, Dr. Watanabe S, Dr. Watanabe T, Dr. Yagi H, Dr. Yamada Y, Dr. Yamanaka G, Dr. Yanai A, Dr. Yokoi K, Dr. Yokoyama N, and Dr. Yoshii M.