Testing for ANCA and/or ASCA serum markers is eligible for payment for patients with persistent and recurring symptoms of IBD and an established diagnosis of IBD, but in whom the distinction between UC and CD has not been made after conventional work-up. Scientific evidence does not demonstrate the clinical usefulness of testing ANCA and/or ASCA serum markers as a first screen for IBD and as a confirmatory test for UC or CD. Therefore, testing in these cases in considered investigational/experimental and is not eligible for payment.
Description
Inflammatory Bowel Disease (IBD) is a chronic inflammatory disease of the gastrointestinal tract. Ulcerative colitis (UC) and Crohn's disease (CD) are two types of IBD, both of which present with symptoms of diarrhea and abdominal pain. The large intestine (colon) can be inflamed in ulcerative colitis, involving the inner lining of the colon, or by Crohn's disease, which extends the inflammation deeper into the intestine wall. Crohn's disease can also involve the small intestine, or can involve both the small and large intestine.
In approximately 90% of cases, a definitive diagnosis of inflammatory bowel disease can be made by a combination of standard diagnostic modalities (e.g., clinical course, radiographic studies, endoscopy, and interpretation of biopsy material). The histologic description of the biopsied tissue is a crucial factor in establishing the diagnosis. After IBD is diagnosed, it is sometimes difficult to distinguish between UC and CD. This occurs in approximately 10-15% of patients diagnosed with IBD.
Two serum antibody markers, anti-neutrophil cytoplasmic antibody (ANCA) for UC and anti-Saccharomyces cerevisiae antibody (ASCA) for CD have the potential to improve the efficiency and accuracy of diagnosing IBD and to potentially decrease the extent of the diagnostic work-up or to avoid invasive diagnostic imaging. Most clinical laboratories can perform testing for the ANCA marker. However, testing is not as widely available for the ASCA marker. There are no specific CPT codes for the detection of ANCA or ASCA markers.
Prometheus, Inc. has developed a proprietary testing system that uses combinations of tests for ANCA and/or ASCA to aid in the diagnosis of IBD and to differentiate between Crohn's disease and ulcerative colitis. The Prometheus system first screens for ANCA or ASCA using an ELISA (enzyme linked immunoabsorbent assay) test. If the screening test is positive for ANCA, further analysis is performed by indirect immunofluorescence (IIF) to determine the specific staining pattern. Specific enzyme reagents proprietary to the company are used to distinguish between true positives and artifacts of fixation when a perinuclear pattern is obtained by the staining. The specificity of the test is increased compared to other laboratories, according to Prometheus. If the screening for ASCA is positive, further analysis is performed by an ELISA microplate assay. When the antibody level exceeds a predetermined cut-off point, positive specimens are identified. Other laboratories can perform a similar method of detecting ANCA and ASCA compared to Prometheus. However, the methods by other laboratories are not an exact duplication of the Prometheus methods. |
