Japanese Society of Internal Medicine Acta Medica Okayama 0918-2918 62 12 2023 Antimicrobials in the Hospital Are Unevenly Discontinued on Weekdays 1739 1742 EN Hideharu Hagiya Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Mika Uno Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Tsukasa Higashionna Department of Pharmacy, Okayama University Hospital Hiroyuki Honda Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Fumio Otsuka Department of General Medicine, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences Objective　Amid the global spread of antimicrobial resistance, antimicrobial stewardship should be further promoted in the clinical setting. Our previous study suggested an intra-week disproportion of discontinuation of broad-spectrum antibiotics. We therefore explored the generalization of this prescription trend by investi-gating the use of all intravenous antibiotics.<br> Methods　A retrospective, observational study.<br> Patients　Between January 1, 2018, and December 31, 2020, we collected data on the initiation and discon-tinuation of intravenous antimicrobials on each day of the week and on days after holidays at Okayama Uni-versity Hospital, Japan. We compared the monthly antimicrobial prescription initiation and discontinuation using the Kruskal-Wallis test and Mann-Whitney U-test with Bonferroni correction as a post-hoc procedure.<br> Results　Data from 15,293 hospitalized cases were analyzed. The initiation of antimicrobials differed slightly among days of the week, although this trend was clinically insignificant. Compared with the initia-tions, antimicrobial discontinuations were disproportionately biased among the weekdays, tending to occur on Mondays (p<0.001) about twice as often as on other days. Similarly, antimicrobials were unevenly discontin-ued on the day after holidays compared to other days (p<0.001), with an approximately 2-fold difference. The use of antimicrobials in the hospital was thus unequally terminated on weekdays.<br> Conclusion　To further promote antimicrobial stewardship, clinicians should be aware of the influence of behavioral, environmental, and social factors on antimicrobial prescription, which is seemingly beyond medi-cal indications. No potential conflict of interest relevant to this article was reported.