Funding for this research was provided by:
Forskningsrådet om Hälsa, Arbetsliv och Välfärd (2015-00480)
Received: 18 November 2020
Accepted: 26 April 2021
First Online: 2 June 2021
: The present study was originally approved by the Swedish Central Ethical Review Board (reg. no. Ö 29–2011), including permission to access and use the present data from Swedish population registers held at public agencies.. Due to the death of the original applicant, Ragnar Westerling, who was the senior researcher accountable for the research project, an amendment was submitted and approved by the Swedish Ethical Review Authority; registration number 2020–04203. The study conforms to the Declaration of Helsinki. Due to the nature of the study, consent to participate was not possible to obtain.
: Not applicable.
: The authors declare that they have no competing interests.