Background and Importance Ustekinumab (UST) is an anti-IL-12/23 antibody which is used in Crohn disease. Although the dosage form is defined in its data sheet, in the clinical practice, intensifications and intravenous reinductions are performed when there is a loss or inadequate of response.

Aim and Objectives To describe and evaluate the different dosage regimens of UST performed in patients with Crohn disease by relating them to biomarkers of inflammation and clinical data.

Material and Methods Observational, retrospective and descriptive study included patients with Crohn disease who started with UST (January 2017-April 2022).

Data obtained from electronic medical records was: previous treatments, faecal calprotectin (Fcal) and C-reactive protein (CRP) levels, stools daily (SD) and abdominal pain (AP), and dosage regimen.

Results 45 patients were included, 68.8% women with a mean age of 49.2. Previous treatments: adalimumab (75.5%), azathioprine (71%), infliximab (51%), vedolizumab (11%) and methotrexate (8.8%). 31% of the patients had received two anti-TNFα.

Initially, 46.6% of the patients presented AP, 31% >5 SD, Fcal 382 mg/kg(30–1919) and CRP 18.3 mg/dl(<1-92).

64.4% patients underwent dose escalation: to every 4 weeks (93.1%), 6 weeks (3.4%) and 8 weeks (3.4%). Prior to this intensification, 31% presented AP, 24.1% >5 SD, mean Fcal 401.2 (11–2625) and CRP 10.4(<1–40.3) .The mean time to first intensification was 426 (147–1157) days.

2 patients required a second intensification.

6 patients also underwent intravenous reinduction, who presented: 33% AP, 83.3% > 5 SD, Fcal 818 (45–1492) and CRP 18(5–23). The time from the first intensification to reinduction was 338(145-730) days. 3 patients required a second reinduction as they all presented >5 SD, Fcal 941(297–2032) and CRP 4.13.

Currently, 88.8% of patients continue with UST. Patients without intensification present Fcal 146.77 and CRP 3, while those with a shortened dosage interval present clinical remission with Fcal 175.56 and CRP 4.01. Those who had also undergone at least one reinduction presented clinical remission too with Fcal 382 and CRP 7.5.

Conclusion and Relevance UST was effective in the majority of our cohort of patients. More than half of the patients required shortening of dosage interval and a fifth part of these also required one or two intravenous reinductions to control the disease.

Conflict of Interest No conflict of interest