| Interventions |
The participants will be enrolled into this study since they are about to start ustekinumab therapy for Crohn's disease regardless of this study participation. As part of usual care, participants will receive a single weight-based ustekinumab IV induction dose at week 0 (260mg for weight equal or less than 55kg; 390mg for weight >55kg and equal or less than 85kg; 520mg for weight >85kg). At week 8, and every 8 weeks thereafter, participants will receive standard dosing of ustekinumab 90mg subcutaneous maintenance through to the end of study period. Patients who have an inadequate response can undergo dose escalation of ustekinumab by the study team as per standard care via compassionate dosing. There will be six study visits, including the baseline visit, over 27 monthsfollow-up period for participants who achieve and maintain clinical response to ustekinumab. All study visits will occur as per standard of care to conform to the Australian Pharmaceutical Benefits Scheme assessment criteria At each study visit, participants will receive standard clinical care by their inflammatory bowel disease treatment team, which may include clinical assessment and standard local laboratory pathology tests. Additionally, the study team and the participants are required to complete questionnaires to assess secondary outcomes, and additional blood samples will be collected at each study visit to assess pharmacokinetics/ immunogenicity and pharmacodynamic markers associated with response to ustekinumab. This will add additional 15-30min to their usual clinic visits. The questionnaires will be administered by the investigators at each site which can include both doctors or research assistants who have been delegated to this projects. Participants also have the option to |