Older Asthmatics More Likely to Die from Symptoms, Less Likely to Be Studied

While elderly patients with asthma are more likely than younger patients to succumb to their symptoms and to have symptoms that persist despite treatment, they are studied less frequently than younger asthmatics, according to a systematic review.

"There has been very little research done to date on asthma in the elderly, and we need to address whether current guidelines apply in this population or whether alternative strategies should be taken," said Michael Wechsler, MD (pictured), professor of medicine at National Jewish Health in Denver, in an interview with MD Magazine.

In his review, Wechsler and colleagues examined the effects of aging and illness on lung and cellular structure and function, and of differences in response to treatment. They also offered management strategies and recommended future research which could improve outcomes in the elderly asthmatic population.

"We need to get a better understanding of differences in the underlying pathophysiology of asthma in those who developed asthma at an early age, and who have since gotten older. What is the effect of aging on asthmatic airways?" Wechsler said. "We also need to better understand asthma that presented in adulthood. What mechanisms are causing this?"

Age-associated changes in lung structure include reduced chest wall compliance, decreased respiratory muscle strength as well as changes in lung parenchyma. Pulmonary function from such changes occur in many older patients who also have obstructive and mixed respiratory patterns with increased residual volume (RV) and reductions in forced expiratory volume in 1 second (FEV₁).

Wechsler and colleagues note that this age-related decline in FEV₁ is worsened with asthma even when controlling for smoking.

"Therefore, it is critical to use age-adjusted values when interpreting spirometry results in older patients to avoid over-diagnosis of respiratory impairment," they cautioned.

Researchers found that much of the research on "immunosenescence”, in which aging is associated with alterations in immune response, has focused on cancer and autoimmunity and not on elderly asthmatics — despite evidence that this process increases susceptibility to airway infections, which exacerbates asthma and could contribute to late onset asthma (LOA). Additionally, they noted that emerging data suggest that neutrophils in the airway and sputum increase with aging, along with increased levels of neutrophil mediators such as MMP-9, neutophil elastase and interleukin (IL)-8.

"Determining underlying airway inflammation in older adults with asthma is important as neutrophilic asthma is often less responsive to corticosteroid treatment, suggesting that alternative therapies may be indicated for older patients," the researchers indicated.

Pharmacologic management should be guided by aging processes as well as underlying pathologic factors, Wechsler and colleagues pointed out. Beta₂-agonist bronchodilators, for example, carry increased risk for adverse effects in elderly patients with cardiovascular disorders. Anti-cholinergic medications may be better tolerated in those patients, but can increase risk for cognitive impairment, falls, urinary outlet obstruction and closed angle glaucoma.

Leukotriene receptor antagonists (LTRAs) present advantages in the relative ease of use compared to hand held inhalers, and have been associated with improvement of asthma indices in the elderly, albeit less than in younger patients. The development of therapy targeted at interleukins also shows promise, and Wechsler and colleagues found data suggesting that the Anti-IL-5 agent mepolizumab (Nucala, GlaxoSmithKline) is effective in elderly asthmatics with eosinophilic inflammation.

"By doing more research in this patient population, we can gain insight into the different mechanisms at play, and then get a better understanding of which therapies we should use in which patients," Wechsler said.

The review of asthma in the elderly and late-onset adult asthma was posted on-line July 19 in Allergy.