Predicting Outcomes and Tailoring Therapy in the Diagnosis and Treatment of IBD.

Standard laboratory indicators of inflammation such as erythrocyte sedimentation rate and C-reactive protein are of little value in the diagnosis of inflammatory bowel disease. Serologic markers for anti-Saccharomyces cerevisiae antibodies and perinuclear antineutrophil cytoplasmic antibodies have been available for some time but are not sufficiently specific or sensitive for use in first-line screening. The second- and third-generation serologic panels have increased sensitivity and specificity, and the addition of assays for anti-outer membrane porin protein C immunoglobulin A and anti-CBir1 have led to the identification of unique subsets of Crohn's disease patients at risk for more complicated and severe forms of disease. This may prove useful in determining whether early aggressive therapy is warranted. Tests are also available for genotyping patients before starting azathioprine and for monitoring clinical response once the patients are receiving the immunomodulator. For patients on anti-tumor necrosis factor-alfa therapy, a dual test measuring serum levels of infliximab and antibodies against infliximab can aid physicians in determining dose and infusion intervals, as well as alert them to the possibility of infusion reactions and/or a reduced duration of efficacy.