Risk for Asthma Treatment Failure Rises With Age

Susan London

June 15, 2015

Age is a risk factor for treatment failure in adults who have mild to moderate asthma, according to a large, retrospective cohort study published online June 11 in the American Journal of Respiratory and Critical Care Medicine.

Patients aged 30 years and older had a near doubling of the odds of treatment failure relative to younger patients, the data show. In addition, the odds rose steadily with age within that group.

"Our data suggest that age may...be an important phenotype to consider when predicting response to therapy even among mild-moderate asthmatics," write Ryan M. Dunn, MD, from National Jewish Health in Denver, Colorado, and colleagues. "The evolving recognition of the heterogeneity of asthma has suggested that specific patient populations may benefit from more individualized treatment paradigms. Future prospective well-designed trials will be required to determine if older patients may benefit from a different treatment approach than younger patients," they add.

The investigators analyzed data from the Asthma Clinical Research Network, identifying 1200 nonsmoking patients with mild to moderate disease participating in 10 network trials conducted between 1993 and 2003. They were predominantly white and had a median age of 30 years.

Overall, 13.7% of the patients had a treatment failure, defined as an asthma exacerbation requiring steroids or an emergency department visit, a worsening of lung function, increased use of asthma rescue medication, or failure as judged by the physician.

The failure rate was higher for patients aged 30 years and older than for their younger peers (17.3% vs. 10.3%). The difference translated to significantly increased adjusted risk for the older group (odds ratio, 1.82; 95% confidence interval, 1.30 - 2.54; P < .001).

In addition, the odds of failure increased steadily with age for patients aged 30 years and older. Specifically, they rose by 2% with each additional 1 year of age, 13% with each additional 5 years of age, and 27% with each additional 10 years of age.

When it came to the type of therapy, age was a strong risk factor for failure on inhaled corticosteroids. The odds were sharply higher for patients aged 30 years and older vs younger peers receiving these medications (odds ratio, 2.79; 95% confidence interval, 1.40 - 5.58; P = .0037), and rose with each year above that age.

In contrast, neither sex nor body mass index significantly predicted treatment failure.

A study limitation was the relatively young age of the included patients, the investigators acknowledge, with the majority of the participants younger than 45 years. Nonetheless, "[t]he decreased responsiveness to therapy with increasing age among mild-moderate asthmatics is a novel finding that warrants further study."

Airway remodeling may play a role, they speculate. "A potential reason for a decreased response to [inhaled corticosteroids] could be explained by differences in type of airway inflammation in older patients," they further propose, with less Th2-driven, eosinophilic inflammation (thought to be more responsive to steroids) and more Th1-driven neutrophilic inflammation.

The authors have disclosed no relevant financial relationships.

Am J Respir Crit Care Med. Published online June 11, 2015. Abstract

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