Funding for this research was provided by:
Otologic Research Fund of Finland (20170031)
Finnish governmental grant
Received: 9 March 2020
Accepted: 14 May 2020
First Online: 26 June 2020
Ethics approval and consent to participate
: Finnish national law does not require ethics committee approval for registry studies with no patient intervention involved. Permission from the Research Administration of the Hospital District was obtained for this study.
: Not applicable.
: The authors declare that they have no competing interests.