8/9/13

by Nancy Walsh
Staff Writer, MedPage Today

Children and adolescents with coexisting asthma and depression tended to have high levels of the inflammatory marker C-reactive protein (CRP), researchers found.

After controlling for variables including other illnesses and socioeconomic status, the presence of both asthma and depression was associated with a sevenfold greater risk of having levels of CRP above 2 mg/L (OR 7.02, 95% CI 1.13-43.48, P<0.05), according to Lilly Shanahan, PhD, of the University of North Carolina in Chapel Hill, and colleagues.

And for children with both conditions, the likelihood of having CRP levels above 3 mg/L rose tenfold (OR 10.04, 95% CI 1.42-70.96, P<0.05), the researchers reported online in the Journal of Pediatrics.

Measurement of CRP is a common way of estimating risk for chronic inflammatory disease in adults, with levels above 3 mg/L often being used as a cutoff.

CRP also is “a promising biomarker” for identifying children at risk “because it is detectable during childhood, when it is already associated with precursors of chronic disease, including obesity and vascular changes,” the researchers observed.

Other studies have demonstrated the presence ofinflammation in children with asthma who experience stressful events and poverty — experiences that have in turn been linked with depression, which also is associated with low-grade inflammation.

But whether asthma and depression together influence the inflammatory process in youth has not previously been examined, so Shanahan’s group analyzed data from 1,420 participants in the Great Smoky Mountains Study of psychiatric illness in children and teens.

Study participants and their parents were interviewed annually between ages 10 and 16. Blood was drawn for high-sensitivity CRP measurement at each visit, and depression evaluated with the Child and Adolescent Psychiatric Assessment.

Other variables adjusted for included age, sex, recent infections and injuries, as well as medication and substance use.

On bivariate analysis with a total of 3,664 CRP samples available, factors associated with levels above 2 mg/L included age, body mass index, asthma, Native American ethnicity, nicotine use, and being on medication.

In a longitudinal analysis, the researchers then determined that elevated CRP also predicted high levels at the next year’s assessment:

• CRP >1 mg/L, OR 6.64 (95% CI 4.34-10.16,P<0.001)
• CRP >2 mg/L, OR 6.94 (95% CI 4.22-11.43,P<0.001)
• CRP >3 mg/L, OR 9.16 (95% CI 4.64-18.07,P<0.001)

In addition, the coexistence of asthma and depression also predicted the risk of reaching the 2 mg/L and 3 mg/L levels at the next annual visit, with odds ratios of 13.85 (95% CI 1.15-166, P=0.04) and 19.18 (95% CI 1.49-246, P=0.02), respectively.

To see if specific components of depression were more associated with high inflammation, the researchers then separately analyzed the emotional/cognitive subset of symptoms and the somatic/physiologic subset, and found that only the emotion/cognitive aspects were associated with CRP levels above 3 mg/L (OR 4.73, 95% CI 1.29-17.21,P<0.05).

They offered several possible explanations for their findings, such as that children with asthma who are depressed may be less adherent to treatment for their airway disease, which could increase systemic inflammation.

That might be particularly pertinent for children with emotional/cognitive symptoms such as sadness and hopelessness, they noted.

Another explanation involved the inflammatory overlap in asthma and depression.

“Research on other chronic illnesses with an inflammatory basis also shows exacerbation of inflammation in the presence of depression. Neuroendocrine processes involving glucocorticoid hormones that regulate the body’s immune response may, in part, be responsible for these exacerbations,” wrote Shanahan and colleagues.

Moreover, the presence of depression with asthma could heighten children’s susceptibility to pollutants and infections, they suggested.

They advised healthcare providers to be aware of the potential long-term health consequences of coexisting asthma and depression in young patients, especially those exhibiting emotional/cognitive symptoms.

“Aggressive treatments and monitoring for compliance with treatments may be particularly important for this subgroup,” they noted.

Limitations of the study included its reliance on parental report of asthma and a lack of information about asthma severity, as well as the measurement of only a single inflammatory marker.

• Reviewed by Robert Jasmer, MD Associate Clinical Professor of Medicine, University of California, San Francisco and Dorothy Caputo, MA, BSN, RN, Nurse Planner

last updated 08.09.2013