Authors of paper

1. Nikolaos Kamperidis,
2. Paul Middleton,
3. Tracey Tyrrell,
4. Ioannis Stasinos,
5. Naila Arebi

 

To switch infliximab or not to switch infliximab that may be the question for many physicians looking after Inflammatory Bowel Disease…Prior to our ability to measure infliximab drug levels or ‘therapeutic drug monitoring’ (TDM) this may have been a bit of a guesswork based on patients’ clinical state and investigations performed. With TDM many physicians will have a new weapon in their infantry to help them decide what to do with a Crohn’s disease patient on infliximab. What therapeutic drug monitoring provides are a drug level and the presence or absence of antibodies to that drug.

 

Broadly speaking the results from the TDM will tell you three things

 

1. Antibodies to the infliximab and low drug levels -> switch drug usually within class (another anti-TNF)
2. No antibodies but low drug levels-> increase either the dose or the frequency
3. No antibodies and therapeutic drug levels but still have active disease-> switch to a non-anti-TNF biologic

 

This paper was one of those excellent real-world data papers that explored the effect of therapeutic drug monitoring on patient outcomes. The beauty of real world data is that it provides us data on what this medicine is doing to Mr Joe Bloggs who is usually a very different patient from those that were so perfectly selected in that (often industry funded) randomised placebo-controlled drug trial. Hence showing some real-world effect of what that drug is actually doing in my clinical practice.

 

This paper looked at two outcomes. The clinicians’ response to each therapeutic drug level requested and treatment discontinuation because of secondary loss of response or a serious adverse event. They then compared if there were differences in outcomes between pre-and post-introduction of therapeutic drug monitoring.

 

So all sounds quite cool? One would make the assumption that TDM must change outcome right? Well, read on to maybe some mixed and surprising results…

 

What this study in fact showed was that only 22% of TDM requests were followed by change in patient management.  The authors therefore suggested that TDM did not change the outcome for the patient management in the majority of cases. However, what they did show that in patients whom never had TDM tested there was an 8-fold risk of drug discontinuation and a 2.5-fold risk of surgery. How many of these patients could have prevented drug discontinuation if they had TDM remains unclear but certainly this paper shows that there may be some benefits in doing regular TDM and supports the findings from the TAXIT study which highlighted better outcomes with target trough levels in those using infliximab.

 

Read the full version here at Frontline Gastroenterology

 

https://fg.bmj.com/content/early/2019/02/01/flgastro-2018-101024