Funding for this research was provided by:
Japan Society for the Promotion of Science (15J03333, 15K03508)
Ministry of Health, Labour and Welfare (H27-Policy-Strategic-011)
ImPACT program of Cabinet Office, Government of Japan (Actualize Energetic Life by Creating Brain Information Industries)
Received: 7 March 2017
Accepted: 8 August 2017
First Online: 15 August 2017
Ethics approval and consent to participate
: The manuscript is a retrospective study using an anonymous claim database. Formal consent is not required for this type of study. This study has been approved by the Institutional Review Board and Ethics Committee of the Graduate School of Business Administration, Keio University (Yokohama, Japan).
: Not applicable.
: The authors declare that they have no competing of interests.
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