Background/Aims: Despite the advent of advanced therapies, cases of so-called “difficult-to-treat” (D2T) ulcerative colitis (UC) persist. This study aims to clarify the epidemiological and clinical characteristics of patients with D2T UC. Methods: We conducted a nested case-control study using the Medical Data Vision Claims Database in patients with UC who began an advanced therapy (biologics, advanced small molecules, calcineurin inhibitors) from January 2018 through April 2023. D2T UC patients were defined as having 2 or more switches of advanced therapies, or as undergoing surgery for UC, within 2 years after the first advanced therapy. Results: Four hundred and one (16.7%) and 1,996 patients (83.3%) met the definitions of patients with D2T UC and non-D2T UC, respectively. After 1:1 matching by index year, 355 patients per group were included in the analysis. Multivariate logistic regression analyses, including sensitivity analyses based on follow-up period after the first advanced therapy, showed that a prescribed corticosteroid dose of ≥ 30 mg/day during the 6-month baseline period was associated with D2T UC. In D2T UC patients, median duration of the first advanced therapy was 99 days, and median number of advanced therapies per year was 1.7. The first advanced therapy was continued for 2 years in 78% of patients with non-D2T UC. Conclusions The proportion of D2T UC patients among UC patients starting advanced therapy was 16.7%. The factor most associated with D2T UC was the need for a corticosteroid dose ≥ 30 mg/day during the 6 months before initiation of advanced therapy.

　　With the revision of the Medical Service Law in April 2005, it has become incumbent on clinical engineers to take charge of medical equipment in their hospital and to run a maintenance check on the equipment at regular intervals.　　However, it is difficult to show what clinical engineers have done as visualized achievements, for no insurance mark to the maintenance and management business itself.　　By using the accumulated maintenance records and a new medical equipment management system - the Arcadia company’s “CEIA system” installed in April 2010. We considered the cost performance of the medical equipment could be enhanced through the efforts of clinical engineers.　　For this purpose, we made the list of technical fees to be paid if a clinical engineer should entrust temporarily the maintenance management to an equipment maker and calculated the cost item by item.　　Moreover, the items which were checked and repaired were divided into those “outsourced” and those taken care of by hospital clinical engineers. When trial calculations were made using “in-house processing-outsourcing＝achievements” formula, we had about 50 million yen or more.