Model-informed precision dosing of infliximab (intravenously administered) using a Bayesian forecasting software tool. Doses and dosing intervals will be derived from the software tool, aiming to maintain adequate exposure (trough concentration target 5 mg/L).

The treating physician adjusted the intravenously administered infliximab doses and dosing intervals without being guided by a model-informed precision dosing software tool. The primary objective was to extend the dosing interval. Therefore, dose de-escalation (interval extension with/without dose adjustment) were performed following a scheme at the treating physician's discretion.

Infliximab (Inflectra® [Pfizer]), dosage determined using model-informed precision dosing, intravenously administered

The proportion of patients maintaining steroid-free, combined clinical and biological remission during one year after infliximab dose de-escalation based on a standard dosing algorithm versus a model-informed dosing algorithm.

Combined clinical and biological remission is defined based on patient-reported outcomes (rectal bleeding score = 0 + stool frequency score ≤1 [ulcerative colitis], mean daily abdominal pain score ≤1 + liquid stool frequency score ≤1.5 [Crohn's disease]) together with normal C-reactive protein (<5 mg/L) and faecal calprotectin (<250 mg/kg). Steroid-free indicates the absence of any dose of any oral or rectal steroid use.

The proportion of patients maintaining steroid-free, combined clinical and biological remission at one year after infliximab dose de-escalation based on a standard dosing algorithm versus a model-informed dosing algorithm.

Combined clinical and biological remission is defined based on patient-reported outcomes (rectal bleeding score = 0 + stool frequency score ≤1 [ulcerative colitis], mean daily abdominal pain score ≤1 + liquid stool frequency score ≤1.5 [Crohn's disease]) together with normal C-reactive protein (<5 mg/L) and faecal calprotectin (<250 mg/kg). Steroid-free indicates the absence of any dose of any oral or rectal steroid use.

The proportion of patients maintaining steroid-free clinical remission at and during one year after infliximab dose de-escalation based on a standard dosing algorithm versus a model-informed dosing algorithm.

Clinical remission is defined based on patient-reported outcomes (rectal bleeding score = 0 + stool frequency score ≤1 [ulcerative colitis], mean daily abdominal pain score ≤1 + liquid stool frequency score ≤1.5 [Crohn's disease]).

Steroid-free indicates the absence of any dose of any oral or rectal steroid use.