Subtypes of AERD (Samter's Triad)
Not all Aspirin Exacerbated Respiratory Disease patients are the same. A 2014 study identified four classes, or subtypes, of AERD (Samter's Triad) patients:
Class 1: moderate asthma, severe sinus symptoms, and blood eosinophilia (18.9% of patients). These patients had the most severe chronic sinus symptoms. Asthma ranged from mild to severe in these patients, with 34% having mild asthma, 29% having moderate asthma, and 10% having severe asthma. 87% of the people in this group required either inhaled or systemic steroid medications for asthma.
Class 2: mild and relatively well-controlled asthma with low health care use (34.8% of patients). This subtype had the highest proportion of male patients. These patients had the lowest number of ED visits or hospitalizations for asthma. 26% of the people in this group had good control of asthma without any corticosteroid treatment at all.
Class 3: severe and poorly controlled asthma with severe exacerbations and airway obstruction (41.3% of patients). Female patients outnumbered male patients in this group. Almost all of the people in this group had high rates of ED visits and hospitalizations for asthma.
Class 4: poorly controlled asthma with frequent and severe exacerbations in female subjects (5.0% of patients). Half of these patients had childhood onset asthma and 41% were obese.
Other interesting findings from this study:
Patients with the most severe upper airway (sinus) symptoms generally had higher levels of blood eosinophilia. Eosinophils are a type of disease-fighting white blood cell. Having high levels of eosinophils in the blood is called eosinophilia. Blood eosinophila can indicate infection, allergic reaction, or other inflammatory conditions.
Only about half of the patients studied, regardless of subtype, had positive skin prick test results for any allergens.
Why Does Subtype Matter?
This information is relatively new. In the future, researchers may be able to develop more individualized treatment plans based on subtype information. The finding that females appear more likely to develop the most severe forms of this disease is also of great interest. Other studies have found that the disease is slightly more common in women and that women tend to develop the disease earlier in life than men. Other research has found that about 24% of females with AERD have premenstrual worsening of asthma and sinus symptoms.
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