Asthma Prevalence Three Times Higher in MS

Nancy A. Melville

March 07, 2019

DALLAS — Asthma occurs in people with multiple sclerosis (MS) with a prevalence that is nearly three times greater than the general population, suggest new findings from population-based data on more than 56 million Americans — the largest study to date on the prevalence of asthma in MS.

"These results add to the growing and timely MS comorbidity literature and they emphasize the need for comorbidity management as an integral part of comprehensive MS patient care," senior author Farren B. Briggs, PhD, an assistant professor at Case Western Reserve University and University Hospitals Cleveland Medical Center, in Cleveland, Ohio, told Medscape Medical News.

Treatment of MS can be complicated by an array of comorbidities, ranging from depression and anxiety to fatigue and hypertension, but data on the prevalence of chronic lung disease and asthma in MS has been conflicting.

In research presented here at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2019, Briggs and colleagues reported on findings from a cross-sectional study of electronic health record information available in the IBM Explorys EPM: Explore database on 141,880 people with MS and 56,416,790 without MS.

After controlling for factors including age and gender, they found an adjusted asthma prevalence in those with MS of 19.6% compared to 6.6% in controls, for a prevalence ratio (PR) of asthma in MS that is 2.97-times higher than is seen in those without MS (95% confidence interval [CI], 2.96, 2.97, P < .0001).

While the rate of asthma in those without MS was generally uniform when considering age and gender, the prevalence is seen in a U-shaped pattern in those with MS, with the highest prevalence in young and elderly patients. Among those with MS under 30, the asthma rates were above 20%, and among those age 80 years or older, the asthma prevalence rates ranged from 15% to 30%.

Significant differences were seen in asthma prevalence between those with and without MS within subgroups: Among females, asthma prevalence among those with MS was 17.4% compared to 8.6% without MS (age-adjusted PR 2.38); in males, the corresponding rates were 13.4% vs 6.3% (age-adjusted PR, 2.80).

Among African Americans, asthma prevalence was 18.5% in those with MS and 10.9% without MS (age and gender adjusted PR, 1.48).

"We were very surprised (by the results), particularly by the U-shaped distribution, with the greatest asthma prevalence among the young and elderly with MS," Briggs told Medscape Medical News. 

He noted that the reasons for the higher rates in asthma are not well understood.

"It is unknown why there is this increase," Briggs explained. "We do know that MS and asthma share several common risk factors, including tobacco smoke, vitamin D insufficiency, and obesity. There is also evidence for some overlap in their genetic risk factors."

In the study, which was also published last month in the journal Multiple Sclerosis and Related Disorders, Briggs and his colleagues further note evidence of a shared genetic susceptibility between MS and asthma.

Several studies show genetic variation in BACH2 gene, which encodes an immunomodulatory transcription factor that regulates effector-memory T-cells, has been associated with increased risk for asthma, MS, and several other autoimmune diseases," the authors write.

While those associations remain to be understood, other links between asthma and MS in terms of their effects on lifestyle are clearer, the authors added.

"It is important to evaluate the burden of asthma in MS as both diseases are disruptive to daily living, are associated with decreased quality of life, and are costly; thus, together these negative influences may be compounded in those with both diseases."

While the study is the largest of its kind to investigate asthma prevalence in MS, additional studies are needed to better understand the relationship, Briggs told Medscape Medical News.

"The seemingly complex relationship between MS and asthma warrants further research, particularly efforts to understand the possible shared biological processes mediating both diseases," he said.

"We also need to evaluate the extent to which the co-occurrence of these chronic conditions may impact daily functioning, quality of life, and prognosis, which will allow us to develop effective interventions to improve patient outcomes."

Neurologist Mark Gudesblatt, MD, medical director of the Comprehensive MS Care Center at South Shore Neurologic Associates in Patchogue, New York, noted that symptoms in asthma may mimic those seen in MS.

"I believe that neurogenic generation of bronchospasm or tissue relaxation/compliance is also impacted in people with MS," said Gudesblatt, who was not associated with the current study.

"An underappreciated aspect in MS is autonomic dysfunction," he explained. "Orthostatic hypotension or intolerance or postural orthostatic tachycardia syndrome (POTS) causes fatigue as well and likely contributes to generation of bronchospasm as well."

Comorbidities in general that can occur with MS are known to have negative effects, including a decreased likelihood of initiating treatment with a disease-modifying therapy (DMT), and while the research is not conclusive, that may extend to asthma.

According to one study of more than 10,000 people in three Canadian provinces who have MS plus one or more comorbidities, chronic lung diseases — including asthma — were associated with reduced DMT initiation, as were hyperlipidemia and, to a greater extent, ischemic heart disease and anxiety.

While the association with chronic lung disease did not reach statistical significance, possibly due to smaller numbers of affected individuals, the authors speculated that the reduced DMT initiation may result from patients already being overwhelmed with medications.

"A possible reason for this association in patients with ischemic heart disease, one also likely to be present for patients with hyperlipidemia and chronic lung diseases, is that they are already burdened with multidrug regimens," the authors of the Canadian study note.

"This greater number of concurrent drug therapies is likely to affect patients' and physicians' decisions regarding initiating another treatment. Perceived benefits of therapy may also be less when multiple chronic conditions affect health status," they say.

Ruth Ann Marrie, MD, PhD, coauthor of the Canadian study and a professor of medicine and community health sciences at the University of Manitoba, in Winnipeg, Canada, spoke on comorbidities in MS at the ACTRIMS Forum and underscored the need for awareness in treating patients.

"Comorbidity is common in MS; (conditions) may confound diagnosis and are associated with multiple adverse outcomes," she said.

"They should be considered when selecting treatment regimens and may affect treatment outcomes," Marrie said. "There are many gaps in knowledge regarding comorbidity and management of MS which require further research."

Briggs and coauthors, Gudesblatt, and Marrie have disclosed no relevant financial relationships.

Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2019: Abstract 083. Presented March 1, 2019.

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