Interpret cautiously
Participants with persistent asthma were more likely to be female, have higher body mass index (BMI), and higher high-density lipoprotein (HDL) cholesterol levels, compared with those without asthma.
Participants with persistent asthma had the highest burden of carotid plaque (P ≤ .003 for comparison of proportions and .002 for comparison of means).
Moreover, participants with persistent asthma also had the highest systemic inflammatory marker levels – both CRP and IL-6 – compared with those without asthma. While participants with intermittent asthma also had higher average CRP, compared with those without asthma, their IL-6 levels were comparable.
In unadjusted models, persistent asthma was associated with higher odds of carotid plaque presence (odds ratio, 1.97; 95% confidence interval, 1.32-2.95) – an association that persisted even in models that adjusted for biologic confounders (both P < .01). There also was an association between persistent asthma and higher carotid TPS (P < .001).
In further adjusted models, IL-6 was independently associated with presence of carotid plaque (P = .0001 per 1-SD increment of 1.53), as well as TPS (P < .001). CRP was “slightly associated” with carotid TPS (P = .04) but not carotid plaque presence (P = .07).
There was no attenuation after the researchers evaluated the associations of asthma subtype and carotid plaque presence or TPS and fully adjusted for baseline IL-6 or CRP (P = .02 and P = .01, respectively).
“Since this study is observational, we cannot confirm causation, but the study adds to the growing literature exploring the systemic effects of asthma,” Dr. Tattersall commented.
“Our initial hypothesis was that it was driven by inflammation, as both asthma and CVD are inflammatory conditions,” he continued. “We did adjust for inflammatory biomarkers in this analysis, but there was no change in the association.”
Nevertheless, Dr. Tattersall and colleagues are “cautious in the interpretation,” since the inflammatory biomarkers “were only collected at one point, and these measures can be dynamic, thus adjustment may not tell the whole story.”
Heightened awareness
Robert Brook, MD, professor and director of cardiovascular disease prevention, Wayne State University, Detroit, said the “main contribution of this study is the novel demonstration of a significant association between persistent (but not intermittent) asthma with carotid atherosclerosis in the MESA cohort, a large multi-ethnic population.”
These findings “support the biological plausibility of the growing epidemiological evidence that asthma independently increases the risk for cardiovascular morbidity and mortality,” added Dr. Brook, who was not involved with the study.
“The main take-home message for clinicians is that, just like in COPD (which is well-established), asthma is often a systemic condition in that the inflammation and disease process can impact the whole body,” he said.
“Health care providers should have a heightened awareness of the potentially increased cardiovascular risk of their patients with asthma and pay special attention to controlling their heart disease risk factors (for example, hyperlipidemia, hypertension),” Dr. Brook stated.
Dr. Tattersall was supported by an American Heart Association Career Development Award. The Multi-Ethnic Study of Atherosclerosis was supported by the National Heart, Lung, and Blood Institute and the National Center for Research Resources. Dr. Tattersall and co-authors and Dr. Brook declare no relevant financial relationships.
A version of this article first appeared on Medscape.com.