Kärkkäinen, Sanna http://orcid.org/0000-0002-5808-6420
Silventoinen, Karri
Svedberg, Pia http://orcid.org/0000-0001-7952-3418
Ropponen, Annina http://orcid.org/0000-0003-3031-5823
Funding for this research was provided by:
Karolinska Institutet
Article History
Received: 19 March 2019
Accepted: 3 December 2019
First Online: 11 December 2019
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.
: The study protocol and study management were designed and performed in accordance with the Code of Ethics of the World Medical Association. The study protocol, where only already-existing epidemiological data were used, has been approved by the Social Insurance Institution and the earnings-related pension institutes of Finland that have jointly granted the permission to use the register data for this study through the TwinKela project. This present analysis did not involve any contact to the study participants.