METHODS
This study included all PHO certificated by JSPHO in Japan as of November 15, 2021. JSPHO is the primary and largest professional society in the field of pediatric oncology in Japan. We extracted the name and affiliation of all PHO from the official JSPHO webpage (https://www.jspho.org/activity/certification_application.html). Then, we collected payment data concerning lecturing, writing, and consulting from a total of 92 pharmaceutical companies belonging to the Japan Pharmaceutical Manufacturers Association and other associated companies between 2016 and 2019, as we described previously.6-8 After data collection, descriptive analysis of payment data was conducted overall, including average and median monetary values per physician and proportion of physicians receiving payments. Also, Gini index was used to assess the inequality of payment distribution.6
All statistical analyses were performed using Microsoft Excel, version 16.0 (Microsoft Corp), and Stata version 15 (Stata Corporation). This study was approved by the Ethics Committee of the Medical Governance Research Institute before the study begun.