Autoimmune conditions, allergies, asthma more likely in HAE: Study
Higher prevalence of these conditions seen for patients vs. general population
The prevalence of certain conditions — namely, allergies, autoimmune diseases, and asthma — is higher among people with hereditary angioedema (HAE) than in the general population, according to a new study from Canada.
The data specifically showed that the proportion of HAE patients who reported having autoimmune conditions was approximately four times higher compared with individuals from the general population in Canada. Allergies were two times more commonly reported among people with HAE, while asthma was nearly two times more commonly seen in patients.
Overall, the study found “an increased prevalence of certain comorbidities [or co-occurring conditions] compared to the general Canadian population,” and highlighted the need for clinician awareness.
“It is important to increase awareness among physicians who care for HAE patients on the relationship between HAE and comorbidities, to optimize the care of these patients,” the researchers wrote.
The study, “Comorbidities in Canadian patients with hereditary angioedema: a quantitative survey study,” was published in the journal Allergy, Asthma & Clinical Immunology. It was funded by CSL Behring, a company that markets several HAE therapies; three of the 12 researchers are employed by CSL Behring Canada.
Investigating coexistent conditions among HAE patients in Canada
HAE is commonly caused by mutations in the SERPING1 gene that impair the production (HAE type 1) or function (HAE type 2) of a protein called C1-inhibitor, or C1-INH. This results in the overproduction of a signaling molecule called bradykinin. High levels of bradykinin cause fluid to leak from blood vessels and accumulate in the deeper layers of the skin or mucous membranes, leading to the swelling attacks that characterize HAE.
Less frequently, HAE is caused by mutations in other genes, and patients have normal levels and function of C1-INH. This rarer HAE subtype is known as HAE type 3 or HAE with normal C1-INH (HAE nC1-INH).
Besides regulating bradykinin production, C1-INH also regulates certain components of the body’s immune system. Its deficiency has been linked to an increased risk of autoimmune diseases.
However, “the effects of C1-INH deficiency and its consequences are yet to be fully understood, and additional evidence linking HAE to an increased risk of developing autoimmune diseases, malignancies or other comorbidities is needed,” the researchers wrote.
To learn more about the prevalence of coexistent conditions in people with HAE, the team of researchers conducted a quantitative survey involving patients enrolled in a support program, called CSL Behring PLUS+, offered by CSL Behring. The reported prevalence of such comorbidities was then compared with that of the general Canadian population.
A total of 123 patients, with a mean age of 44.9, were enrolled in the study. The vast majority (81%) were women. Nearly half (46%) had HAE type 1, followed by HAE nC1-INH, affecting 24%, and HAE type 2, diagnosed in 14%. In 16%, the HAE type was unknown.
Patients were more commonly diagnosed up to five years after their first symptoms appeared, and the majority started treatment in the same year as their diagnosis. Most (85%)were on long-term prophylaxis to prevent HAE attacks, plus on-demand treatment to treat acute attacks. The other 15% used only on-demand therapies. Plasma-derived C1-INH was the most commonly used treatment, both as prophylaxis and as an on-demand therapy.
HAE patients 4 times more likely to have autoimmune conditions
Overall, patients reported having an average of 4.3 comorbidities. The most common were related to the respiratory system (39%; e.g. allergies and asthma), followed by the immune system (38%), and the neurological system (37%; e.g. anxiety and depression).
The proportion of HAE patients who reported having allergies was two times higher than the general Canadian population (54% vs. 27%). The reported allergies were to medications, pollen, and pet dander. Allergies were most frequently reported in people with HAE nC1-INH and among those with an autoimmune condition.
The prevalence of autoimmune conditions was approximately four times higher among HAE patients compared with the general population (31% vs. 5%-8%). The most commonly reported autoimmune diseases affected the skin (e.g. psoriasis), joints (e.g. rheumatoid arthritis), and digestive tract (e.g. inflammatory bowel disease). The prevalence of autoimmune diseases was similar across all HAE types, but was two times higher among women compared with men.
Asthma was also more frequently reported by HAE patients than by people from the general population (17% vs. 8-11%).
This study confirms that HAE patients suffer from more than just the symptoms of angioedema. … Healthcare professionals should be aware of the potentially increased risk of autoimmune conditions, allergies, and asthma in patients with HAE.
In most cases, patients were diagnosed with a coexistent condition before receiving their HAE diagnosis, with 63% reporting their comorbidity as being well to very well controlled.
Patients receiving prophylactic treatment with plasma-derived C1-INH reported their comorbidity to be better controlled compared with those who were on other preventive therapies. Better comorbidity control was also seen among patients with HAE type 1 and HAE nC1-INH compared with those with HAE type 2 and in those with an unknown HAE type.
“This study confirms that HAE patients suffer from more than just the symptoms of angioedema,” the researchers wrote, noting that the conditions “[contribute] to a less positive overall health status.”
“Healthcare professionals should be aware of the potentially increased risk of autoimmune conditions, allergies, and asthma in patients with HAE,” the team concluded.
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