Elevated eosinophil levels increased risk for asthma exacerbation

Adults with persistent asthma who had elevated eosinophil levels were at increased risk for exacerbations, according to research presented at the 2014 American Thoracic Society International Conference in San Diego.

“Eosinophils are known to be involved in the pathophysiology of asthma, and determining their relation with asthma exacerbations may allow us to determine in advance which of these patients needs targeted interventions,” researcher Robert Zeiger, MD, PhD, physician investigator at Kaiser Permanente, San Diego, said in a press release. “In our study, elevated blood eosinophil levels were found to be a risk factor for subsequent exacerbations in adult asthma patients.”

Zeiger and colleagues used Kaiser Permanente Southern California pharmacy and health care data to study 2,392 patients (aged 18 to 64 years; 70.4% women) with persistent asthma. Patients had blood eosinophil measured in 2010, with analyses adjusted for demographics, comorbidities, and asthma burden and care used to determine the rate between eosinophil levels and exacerbation rates in 2011.

Asthma emergency department visits or hospitalizations requiring systemic corticosteroid dispensing within 7 days defined exacerbations.

Fifty-two percent of patients were minorities, 81.9% had more than a high school education, 53.3% were obese and 6.5% were infrequent current smokers.

“At baseline, step-care treatment level based on Global Initiative for Asthma definitions were 24%, 32%, and 44% for steps 1/2, step 3, and steps 4/5, respectively,” the researchers reported.

Asthma exacerbation occurred at a rate of 0.41 events per person-year (95% CI, 0.37-0.45), which rose with higher step care level (P<.01). Future asthma exacerbation risk was most related to a cut-point of at least 400/mm3.

After adjustments for multiple baseline features, an elevated eospinophil level at baseline was independently associated with asthma exacerbations in 2011 (adjusted RR=1.31; 95% CI, 1.07-1.6). History of prior asthma exacerbations, steps 4/5 care, being female, ≥7 short-acting beta-agonist canister-dispensing (all P<.01), being black (P=.01) and obesity (P=.02) were also linked to increased exacerbations.

“If our findings can be replicated in other populations and settings, measurement of blood eosinophil levels may help guide treatment for patients at the greatest risk for exacerbations,” Zeiger said.

For more information:

Zeiger RS. #50175. Presented at: 2014 American Thoracic Society International Conference; May 16-21; San Diego

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