Background and importance Ustekinumab is a real option for treating Crohn’s disease (CD) refractory to anti-tumour necrosis factor (anti-TNF) drugs. After a first intravenous dose, it is administered as a subcutaneous maintainance dose every 8–12 weeks.

Some observational studies display that a dosage interval shortening (DIS) may improve clinical results in patients with partial response or early exhaustion of response between different doses.

Aim and objectives Quantifying proportion of patients treated with ustekinumab who require DIS.

Assessing effectiveness and safety of DIS with ustekinumab in refractory CD.

Material and methods We conducted an observational and retrospective research study in adult patients with CD refractory to anti-TNF drugs. Patients started treatment with ustekinumab, firstly intravenous 6 mg/kg, and then subcutaneous 90 mg every 8 weeks. Included in the study were patients with DIS in June 2019–February 2021, with later follow-up of at least 6 months.

Effectiveness: assesed with clinical remission (CRem), defined as obtaining a Harvey–Bradshaw Index (HBI) <4, and clinical response (CResp), defined as a reduction of >3 points in HBI with respect to baseline. Both endpoints were evaluated at 3 and 6 months.

Tolerance/safety: determined at 3 and 6 months. Every discontinuation or adverse event will be notified.

Results Data of 41 patients (21 men) treated with ustekinumab for at least 1 year were obtained. Population had a median of 1.6 previous biological treatments. 15 patients have maintained the initial regimen with ustekinumab. However, 26 patients (63.4%) needed DIS, for partial response (17/26; 65.4%) or early exhaustion of response (9/26; 34.6%). 16 of these had data after DIS of at least 6 months: 7 patients had a dose every 6 weeks, and 7 had a dose every 4 weeks.

CRem was obtained in 10 patients (62.5%) at 3 and 6 months. CResp was reached in 5 patients (31.2%) at 3 months and in 7 patients (43.7%) at 6 months. 2 patients stopped the treatment for ineffectiveness. There were no adverse events or discontinuations for safety reasons associated with DIS.

Conclusion and relevance A high number of patients have required DIS with ustekinumab. DIS of ustekinumab has shown high safety and ability for rescuing a substantial percentage of patients with partial response or early exhaustion of response. Effectiveness results are similar at 3 and 6 months after intensification, which might be important for making decisions about treatment earlier.

Conflict of interest No conflict of interest