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Article History

Received: 15 November 2017

Accepted: 4 April 2018

First Online: 13 April 2018

Ethics approval and consent to participate

: Ethical approval for the study was obtained from National Institute for Health and Welfare (former National Research and Development Centre for Welfare and Health). The respondents were asked their informed consent for future follow-ups in the first wave in 2006. Moreover, the survey scripts at both waves reminded the participants that the participation was voluntary and they were under no obligation to complete and/or submit the survey and that by responding to the survey participants were consenting to participate in the study.

: The authors declare that they have no competing interests.

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