<div>Legend: <sup>a</sup> Inflation in US dollars was adjusted to 2021
value using the Consumer Price Index Inflation Calculator of the U.S.
Bureau of Labor Statistics. <sup>b</sup> Per-physician payment
was calculated among physicians receiving payments.</div><div>*p&lt;0.001</div><div>Abbreviations: 95% confidence interval (95% CI), interquartile range
(IQR), SD (standard deviation)</div><div></div><div></div><div>Supplemental Material 1. Detailed data analysis methodology</div><div>The extracted payment data was descriptively analyzed, including
average, standard deviation, median, and interquartile range.
Per-physician payments were calculated among physicians who received
payments, as the majority of gastroenterologists did not receive
research payments from the healthcare industry. The payments were
analyzed by payment year and content of payments. For associated
research payments, per-physician payments were calculated as total
payments divided by the number of principal investigators in a research
payment, and total research payments were calculated by the number of
gastroenterologists times the payment per principal investigator because
some research payments included principal investigators with other
specialties.</div><div>Furthermore, the study assessed yearly trends in the number of
gastroenterologists receiving payments and per-physician payments using
population-averaged generalized estimating equations (GEE) at the
individual physician level. The annual number of physicians receiving
payments and per-physician payments were examined using log-linked GEE
with Poisson distribution and negative binomial GEE, respectively.
Additionally, the trend in the total amounts of annual research payments
was assessed by a linear GEE model. Inflation in US dollars was adjusted
to 2021-dollar values using a Consumer Price Index inflation calculator
of the U.S. Bureau of Labor Statistics (
https://www.bls.gov/data/inflation_calculator.htm). Institutional
board review and approval were not required for this study, as the study
was designed as a non-human subjects study of publicly-available data.</div><div></div><div>Supplemental Material 2. Associated research payments to preclinical
trials and registered clinical trials between 2014 and 2021.</div>