Limitations
Our study has some limitations. The cross-sectional design precludes longitudinal analysis, and the focus on a single set of guidelines may not be generalizable to other fields or countries. The payment data was extracted from a secondary database maintained by a non-profit research organization, which includes nearly all personal payment data collected from each pharmaceutical company. Additionally, there are no legal regulations requiring pharmaceutical companies to accurately disclose their payments to physicians in Japan. Therefore, we cannot exclude the possibility of errors in the payment data disclosed by the companies.