Overlapping Asthma Phenotypes Increases Need for Medication

Experts in asthma have been increasing their focus on phenotypes (e.g. transient infant wheezing that does not persist, persistent asthma in an atopic child, aspirin/NSAID-sensitive asthma, neutrophilic and eosinophilic asthma). Phenotype is identified by the patient's clinical presentation. And, experts are beginning to see that some phenotypes respond better to certain treatment approaches. Certain phenotypes can be associated with specific laboratory-defined characteristics (e.g. elevated exhaled nitric oxide, blood eosinophils, fraction of exhaled nitric oxide, etc).

Identifying asthma phenotypes based on noninvasive markers could help clinicians better tailor therapy for people with asthma. In addition, asthma phenotypes may overlap. A new study looks at the overlap of 5 common asthma phenotypes in adults in the United States. Published inClinical and Translational Allergy, the study found that certain phenotypes tend to overlap more frequently than others.

These researchers analyzed data from the National Health and Nutrition Examination Surveys (NHANES) 2007—2012, which included 30,442 adults, with 1,059 having current asthma. They looked at 5 specific phenotypes:

• B-Eos-high [if blood eosinophils (B-Eos) ≥ 300/mm3]
• FeNO-high (FeNO ≥ 35 ppb)
• B-Eos&FeNO-low (B-Eos < 150/mm3 and FeNO < 20 ppb)
• Asthma with obesity (AwObesity) (BMI ≥ 30 kg/m2)
• Asthma with concurrent COPD.

The researchers categorized study participants by age, with 44% of participants aged 44 or younger, and the remainder older than 40. Among study participants, a full 49% had AwObesity, making it the most common phenotype.

In both age groups, the most common overlap was AwObesity associated with either B-Eos-high (15% and 12%, respectively) or B-Eos&FeNO-low asthma. Between 11% and 13% of adults fell into this category of overlap.

Patients who had any phenotype overlap were more likely to need 2 controller medications, and they were more likely to have FEV₁that was less than the lower limit of normal. These patients were also more likely to miss work than others.

This study, like so many others, correlated smoking with the need for more medication.

Reference

Amaral R, Fonseca JA, Jacinto T, et al. Having concomitant asthma phenotypes is common and independently relates to poor lung function in NHANES 2007-2012.Clin Transl Allergy. 2018;8:13.