Funding for this research was provided by:
Yrjö Jahnssonin Säätiö (20187105, 6900)
First Online: 3 November 2019
Compliance with ethical standards
: The authors declare that they have no conflict of interest.
: The Ethics Committee of the National Institute for Health and Welfare, Finland, approved the research protocol (THL/1122/6.02.01/2014). Potential participants were informed about the voluntary participation and gave verbal informed consent. Permission to use the register data was obtained from the Statistics Finland. The statistical analyses were conducted in a protected environment including a remote access system provided by the Statistics Finland. In addition, the results were transferred to the authors through a screening process.