| Interventions |
The intervention will be prospective adjustments of infliximab dosing based on infliximab blood levels tested using a new point of care (POC) test, Quantum Blue Infliximab Assay, manufactured by Buhlmann Laboratories and approved for use in the European Union. Patients currently receive infliximab therapy on a 6- or 8-weekly schedule; POC testing and dose adjustments will occur 6-8 weekly according to this schedule. The intervention period will be 12 months from the commencement of the intervention. All eligible patients will have undergone infliximab induction, and will now be on maintenance infliximab therapy; starting dose of infliximab for this study will be the patient current prescribed dose. All patients receiving infliximab infusions at this institution have established peripheral access lines, and it is routine practice for blood samples to be taken before each infusion to test biochemistry, FBE and infliximab levels via ELISA assay. Patients will have an additional 10ml of blood taken from this line, at the same time as other blood tests, by the clinic nurse, which will be applied to the POC test, which produces a result within 60 minutes. No adherence monitoring strategies are in place. The dosing algorithm used to prospectively adjust infliximab doses is as follows: Infliximab trough concentration and dose adjustments: If 0-0.9ug/ml then increase by 3mg/kg If 1-1.9ug/ml then increase by 2mg/kg If 2-2.9ug/ml then increase by 1mg/kg If 3-7ug/ml - therapeutic range, no action If 7.1-9ug/ml then decrease by 1mg/kg If >9ug/ml then decrease by 2mg/kg |