A nationwide survey on therapeutic drug monitoring of anti-tumour necrosis factor agents for inflammatory bowel disease.

Background: Routine therapeutic drug monitoring (TDM) during treatment with anti-tumour necrosis factor (anti-TNF) agents in inflammatory bowel disease may increase treatment efficacy and cost-effectiveness, and reduce the risk of loss of response.
Aims: To assess the current use of anti-TNF agent TDM, including trough concentration and anti-drug antibodies, among gastroenterology practitioners in New Zealand.
Methods: A web-based survey was delivered to gastroenterologists and advanced trainees in New Zealand, identified by the New Zealand Society of Gastroenterology.
Results: The response rate was 36% (48/134). Adalimumab was the most common initial anti-TNF agent used (78%, infliximab 22%). Ninety-three percent of those who completed the survey used TDM, mainly in cases of non-response or loss or response. Most respondents (93% and 83% for adalimumab and infliximab, respectively) measured trough concentrations within 24 h prior to the next administration. In patients in clinical remission but with endoscopic inflammation on anti-TNF agents, 72% would measure drug concentrations. In the presence of anti-drug antibodies, 45% would add an immunomodulator in patients with active disease and 47% would add an immunomodulator in patients in remission. With low trough concentrations, 77% would make no changes if the patient was in remission, and 75% would increase the dose in case of active disease.
Conclusion: TDM was routinely used among inflammatory bowel disease gastroenterology clinicians who responded to this survey. However, interpretation of results and decision-making is variable, suggesting more guidance is required.
(© 2020 Royal Australasian College of Physicians.)