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Use Blood Tests to Manage Loss of Response to Infliximab

Summary and Comment |
June 7, 2013

Use Blood Tests to Manage Loss of Response to Infliximab

  1. Douglas K. Rex, MDAU061

A modeling study suggests that more reliance on serum tests of infliximab levels and anti-infliximab antibodies is needed.

  1. Douglas K. Rex, MDAU061

Patients with inflammatory bowel disease who are treated with infliximab and lose their response in a clinical setting are often managed with a dose increase (from 5 mg/kg to 10 mg/kg), a shortened interval between doses, or both. Recently, it has become possible to measure serum infliximab levels and anti-infliximab antibodies (ATI). The use of these tests has been endorsed to determine whether the infliximab dose should be adjusted or the patient switched to alternative therapies. Now, investigators compare the cost-effectiveness of this testing strategy with empiric dose adjustment.

In the decision analytic model used in this study, the testing strategy involves switching to a different tumor necrosis factor antagonist in the presence of ATI. Patients without ATI and with a therapeutic drug concentration undergo additional imaging to determine the presence of active disease. If infliximab levels are therapeutic and inflammation is evident, therapy is switched to a different class, including surgery. If patients are without active inflammation while on standard infliximab doses of 5 mg/kg every 8 weeks, their symptoms are presumed to be from a source other than Crohn disease, and appropriate treatments are added. If patients lack measurable ATI and have subtherapeutic infliximab levels, then the infliximab dose is increased.

The testing strategy resulted in similar quality-adjusted life-years but was less expensive compared with empiric therapy ($US 31,870 vs. $US 37,266 per quality-adjusted life-year).

Comment

These results may seem surprising to some clinicians, given that the assays for infliximab serum levels and anti-infliximab antibody levels can be expensive. Nonetheless, the results suggest that we should rely more heavily on infliximab levels and anti-infliximab antibodies in patients on standard doses of infliximab with persistent symptoms.

  • Disclosures for Douglas K. Rex, MD at time of publication Consultant / Advisory board Exact Sciences; Ferring Pharmaceuticals; Given Imaging; Olympus Speaker’s bureau Boston Scientific; Braintree; Ferring Pharmaceuticals Grant / research support Battelle; Braintree; Northwestern University; Olympus America Editorial boards Annals of Gastroenterology and Hepatology; Comparative Effectiveness Research; Expert Review of Gastroenterology and Hepatology; Gastroenterology; Gastroenterology and Hepatology News; Gastroenterology Report; Gastroenterology Research and Practice; Journal of Clinical Gastroenterology; Techniques in Gastrointestinal Endoscopy; World Journal of Gastroenterology; World Journal of Gastrointestinal Oncology; World Journal of Gastrointestinal Pathophysiology; World Journal of Gastrointestinal Pharmacology and Therapeutics

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