Loftus, Edward V.

Abstract Background We sought to estimate the incidence of home parenteral nutrition (HPN) use in a population-based cohort of patients with Crohn disease (CD), and to assess clinical outcomes and complications associated with HPN. Methods We used the Rochester Epidemiology Project (REP) to identify residents of Olmsted County, who were diagnosed with CD between 1970 and 2011, and required HPN. Results Fourteen out of 429 patients (3.3%) with CD received HPN (86% female). Eleven patients (79%) had moderate–severe CD and 12 patients (86%) had fistulizing disease. Thirteen patients (93%) underwent surgery, primarily due to obstruction. Among CD incidence cases, the cumulative incidence of HPN from the date of CD diagnosis was 0% at 1 year, 0.5% at 5 years, 0.8% at 10 years, and 2.4% at 20 years. Indications for HPN included short bowel syndrome in 64%, malnutrition in 29%, and bowel rest in 21%. The median duration of HPN was 2.5 years. There was an average weight gain of 1.2 kg at 6 months, an average weight loss of 1.4 kg at 1 year, and a further weight loss of 2.2 kg at 2 years from the start of HPN. Patients were hospitalized a mean of 5 times after the start of HPN, mainly due to catheter-related bloodstream infections and thrombosis. Conclusions Less than 4% of patients with CD need HPN. Most have moderate to severe disease with short bowel syndrome or malnutrition. Possible reasons for the patients’ weight loss could be noncompliance, and increased metabolic needs because of active disease.

This article reviews therapeutic drug monitoring (TDM) use for current inflammatory bowel disease (IBD) treatments. IBD comprises Crohn’s disease and ulcerative colitis-chronic gastrointestinal inflammatory disorders. Treatment options for moderate to severe IBD include thiopurines; methotrexate; biologic agents targeting tumor necrosis factor, α4β7 integrin or interleukins 12 and 23; and Janus kinase inhibitors. TDM is recommended to guide treatment decisions for some of these agents. Published literature concerning TDM for IBD treatments was reviewed. S.D.L., R.S., and E.V.L. drew on their clinical experiences. Polymorphisms resulting in altered enzymatic activity inactivating thiopurine metabolites can lead to myelotoxicity and hepatotoxicity. Increased elimination of biologic agents can result from immunogenicity or higher disease activity, leading to low drug concentration and consequent nonresponse or loss of response. TDM may aid treatment and dose decisions for individual patients, based on monitoring metabolite levels for thiopurines, or serum drug trough concentration and antidrug antibody levels for biologic agents. Challenges remain around TDM implementation in IBD, including the lack of uniform assay methods and guidance for interpreting results. The Janus kinase inhibitor tofacitinib is not impacted by enzyme polymorphisms or disease activity, and is not expected to stimulate the formation of neutralizing antidrug antibodies. TDM is associated with implementation challenges, despite the recommendation of its use for guiding many IBD treatments. Newer small molecules with less susceptibility to patient variability factors may fulfill the unmet need of treatment options that do not require TDM, although further study is required to confirm this.