Article History
Received: 10 November 2020
Accepted: 5 January 2021
First Online: 12 January 2021
Compliance with ethical standards
:
: On behalf of all authors, the corresponding author states that there is no conflict of interest.
: This retrospective study in which all the procedures being performed were part of the routine care was approved by the institutional review board of the Hokkaido Medical Center for Child Health and Rehabilitation (No. 216, October 12th, 2020).
: This study has not contained images or data that may reveal the identities of study participants.
: This study has not contained images or data that may reveal the identities of study participants.
: All statistical analyses were performed with EZR (Saitama Medical Center, Jichi Medical University, Saitama, Japan) on R commander (The R Foundation for Statistical Computing, Vienna, Austria<i>).</i>