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Study Shows Undiagnosed Hereditary Angioedema Can Lead to Unnecessary Surgeries, Testing in Patients with Abdominal Pain

Researchers presenting at 63rd Annual AAAAI Meeting conclude that physician education is key to avoiding these interventions

San Diego, CA — 27 February 2007

A chart review conducted by researchers at the Institute for Asthma and Allergy showed that hereditary angioedema (HAE) patients who present only with recurrent severe abdominal pain frequently undergo unnecessary surgeries and diagnostic tests prior to diagnosis. The data were presented today at the 63rd Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI).

HAE is a genetic disorder caused by an inherited deficiency of C1-inhibitor (C1-INH). Symptoms include episodes of edema or swelling in the hands and feet, the face, the abdomen, and/or the larynx. Diagnosis of HAE requires a blood test to confirm low or abnormal levels of C1-INH.

“Severe acute abdominal pain is a common presentation of HAE, but it can be a diagnostic challenge to physicians when it is the only presenting symptom, especially if there is no family history,” said Dr. H. Henry Li of the Institute for Asthma and Allergy in Wheaton, Maryland and lead author of the study. “Our findings suggest that unnecessary diagnostic tests and surgeries in patients presenting only with severe acute abdominal pain could be avoided through increased education of healthcare professionals.”

Today’s Presentation: Study Design
A chart review conducted at the Institute for Asthma and Allergy identified all patients with a diagnosis of hereditary angioedema who reported abdominal pain as the initial or the major presentation. Diagnostic procedures for abdominal pain that were performed prior to the diagnosis of HAE were reviewed and summarized.

Key Findings
At least four of the 28 patients had undergone exploratory abdominal surgeries for acute severe abdominal pain before they were diagnosed with HAE. Two of them had an appendectomy. Another patient underwent several surgeries and procedures during abdominal HAE attacks. An exploratory surgery in this patient following abdominal pain thought to be due to an ectopic pregnancy was negative. The other patient had extensive GI evaluation for recurrent severe abdominal pain. Endoscopic examination and small bowel biopsy could not determine the underlying etiology. All four of these patients were later diagnosed with hereditary angioedema. The common factor shared by these patients was severe acute abdominal pain as the sole presentation during HAE attacks.

About Hereditary Angioedema (HAE)
HAE due to C1-INH deficiency is characterized by relapsing, self-limiting episodes of edema at various body sites – mostly subcutaneous tissue, the wall of the intestine, and the larynx.

There are estimates of 6,000 to 10,000 or more people with HAE in the United States. Patients who have abdominal attacks experience episodes of severe pain, diarrhea, nausea, and vomiting caused by swelling of the intestinal wall. Attacks that involve the face and throat can result in airway closure, asphyxiation and, if left untreated, death. HAE is caused by a genetic deficiency of C1-INH, which is inherited in an autosomal dominant manner.

I.M.P.A.C.T. Trial Under Way in North America, Europe
No government-approved pharmaceutical product indicated specifically for treatment of acute HAE attacks, including abdominal attacks, is available in North America. CSL Behring is currently conducting International Multi-centre Prospective Angioedema C1-inhibitor Trials (I.M.P.A.C.T.). The purpose of this Phase II/III study, which is being conducted at 45 sites in North America and Europe, is to demonstrate in a prospective and double-blind fashion that human pasteurized C1-INH concentrate leads to faster relief of acute symptoms of abdominal and facial attacks compared to placebo. The results of this global clinical trial will be submitted to the U.S. Food & Drug Administration and Health Canada in support of applications to license C1-INH concentrate for use in North America.

CSL Behring has manufactured and sold C1-INH concentrate for over 20 years in Germany, Austria, Switzerland, and several other countries in which it is licensed under the trade name Berinert® P for the treatment of acute HAE attacks.

About CSL Behring
CSL Behring is a global leader in the plasma protein biotherapeutics industry. Passionate about improving the quality of patients' lives, CSL Behring manufactures and markets a range of safe and effective plasma-derived and recombinant products and related services. The company's therapies are used in the treatment of immune deficiency disorders, hemophilia, von Willebrand disease, other bleeding disorders and inherited emphysema. Other products are used for the prevention of hemolytic diseases in the newborn, in cardiac surgery, organ transplantation and in the treatment of burns. The company also operates one of the world's largest plasma collection networks, ZLB Plasma. CSL Behring is a subsidiary of CSL Limited, a biopharmaceutical company with headquarters in Melbourne, Australia. For more information, visit www.cslbehring.com.

Sheila A. Burke, Director, Communications & Public Relations
Worldwide Commercial Operations
CSL Behring

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