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Abstract: Slide Presentations |

ROLE OF EXHALED NITRIC OXIDE AND SPIROMETRY IN PREDICTING ASTHMA EXACERBATIONS FREE TO VIEW

Arthur F. Gelb, MD*; Colleen Flynn Taylor, MA; Chris M. Shinar, PharmD; Carlos Gutierrez, MD; Noe Zamel, MD
Author and Funding Information

Lakewood Regional Medical Center, Lakewood, CA


Chest


Chest. 2005;128(4_MeetingAbstracts):146S. doi:10.1378/chest.128.4_MeetingAbstracts.146S-a
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Abstract

PURPOSE:  This study explores the complementary roles of spirometry and FENO to identify asthmatics at risk for exacerbations.

METHODS:  We prospectively studied 44 nonsmoking asthmatics (24 F) age 51 ± 21 yr (mean ± SD), clinically stable for 6 weeks and on fluticasone 250/salmeterol 50 ug or equivalent for 3 years. Over the next 18 months we documented asthma exacerbations requiring ≥ 1 tapering course of corticosteroids. Total exhaled nitric oxide (FENO), small airway/alveolar nitric oxide (CANO), large airway nitric oxide flux (J’awNO) and spirometry were measured.

RESULTS:  Baseline FEV1 was 2.1 ± 0.7L, 70 ± 20% predicted post 180 ug albuterol. When baseline FEV1 ≤ 76% predicted, exacerbations occurred in 20 of 30 (67%); whereas if > 76% predicted, only in 2 of 14 (14%), p = 0.003 chi-square. Using ROC curve for first exacerbation, with cutoff point of FEV1 76%, predicted the AUC = 67%, sensitivity = 0.91, specificity = 0.50, PPV = 0.65, NPV = 0.85, likelihood ratio = 1.8. When baseline FENO was abnormal (≥ 28 ppb), exacerbation occurred in 13 of 17 (76%); whereas when FENO < 28 ppb, in 9 of 27 (33%), p = 0.003 chi-square. Using ROC curve for first exacerbation, with cutoff point FENO = 28 ppb, the AUC = 71%, sensitivity = 0.59, specificity = 0.82, PPV = 0.77, NPV = 0.87, likelihood ratio = 3.3. Controlling baseline FEV1, an abnormal FENO increased the relative risk (RR) for exacerbation by 2.4 (95% CI, 1.1 - 4.5) Mantel-Haenszel, p = 0.011. Abnormal increase in CANO increased RR 3.0 (0.9 - 9.9) p = 0.036 and abnormal J’awNO increased RR 2.4 (1.0 - 5.6) p = 0.04. Controlling baseline FENO, FEV1 ≤ 76% predicted increased RR 1.7 (1.1-2.7) p = 0.02.

CONCLUSION:  Baseline FENO ≥ 28 ppb and FEV1 ≤ 76% predicted identifies stable asthmatics at risk for exacerbations requiring ≥ 1 tapering course of corticosteroids over 18 months.

CLINICAL IMPLICATIONS:  Asthma exacerbations can be more effectively predicted.

DISCLOSURE:  Arthur Gelb, None.

Monday, October 31, 2005

2:30 PM - 4:00 PM


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