Association between asthma, asthma symptoms and C-reactive protein in US adults: data from the National Health and Nutrition Examination Survey, 1999-2002.

BACKGROUND AND

OBJECTIVES

CRP is elevated in several inflammatory diseases; however, little is known about its association with asthma.

METHODS

The study evaluated the associations between CRP, asthma and asthma symptoms using data on 8020 adults >or=20 years of age from the latest US National Health and Nutrition Examination Survey.

RESULTS

The prevalence estimates of current asthma, wheezing and nocturnal cough were 3.6% (95% CI: 2.9-4.4), 14.7% (95% CI: 13.7-15.8) and 4.6% (95% CI: 3.8-5.3), respectively. Geometric mean of CRP was 0.20 mg/dL (95% CI: 0.19-0.21). The majority of female (69.5%) respondents were in the fourth (highest) quartile of CRP. Mean CRP levels were significantly higher in non-Hispanic blacks as compared with non-Hispanic whites. The adjusted odds of current asthma and past asthma (as compared with no asthma) were 1.60 (95% CI: 1.02-2.53) and 1.43 (95% CI: 1.07-1.91), respectively, greater in the fourth quartile of CRP. The adjusted odds of presence of both wheezing and nocturnal cough were 2.18 and 3.40 in the third and fourth quartile of CRP, respectively.

CONCLUSIONS

This study shows that adults with asthma and asthma symptoms have higher levels of CRP. The potential use of CRP as a clinically useful marker for asthma severity and control should be further explored.