Postoperative Ustekinumab Drug Levels and Disease Activity in Patients with Crohn's Disease.

Aims: This study investigated how post-operative ustekinumab levels relate to surgery type, endoscopic, biochemical, and clinical outcomes in patients with Crohn's Disease.

Methods: A retrospective study of patients with Crohn's Disease with a disease-related operation between 2016 and 2022 assessed outcomes based on ustekinumab levels. Patients were included if they had an ustekinumab trough level within two years post-operatively. Patients were separated into groups based on whether their ustekinumab trough levels were adequate, defined as ≥ 4 μg/mL, or suboptimal < 4 μg/mL. A subset of patients with ustekinumab levels taken within two years both before and after surgery was compared to non-surgical treatment-escalated controls outside the initial patient set. Harvey-Bradshaw index was used to evaluate clinical disease activity. Rutgeert's and Simple Endoscopic Score for Crohn's Disease was used to evaluate endoscopic disease activity. C-reactive protein and fecal calprotectin values were collected to evaluate the molecular inflammatory disease state. CBC data were used to evaluate anemia.

Results: Forty-four patients were identified, which had ustekinumab levels after Crohn's Disease-related surgery. Twelve of these patients had pre-operative levels and were compared to 26 non-surgical treatment-escalated controls. No relationship between ustekinumab levels and endoscopic or clinical disease activity post-operatively was found. This also held true when looking at different surgery types. Adequate levels of ustekinumab post-operatively yielded lower risk of anemia. Surgery itself did not have an impact on ustekinumab levels.

Conclusions: This study provided new insights into how post-operative ustekinumab levels impact several factors in patients having undergone Crohn's disease-related surgery.