FENO and AHR mannitol in patients referred to an out-of-hospital asthma clinic: a real-life study

TY - JOUR

T1 - FENO and AHR mannitol in patients referred to an out-of-hospital asthma clinic

T2 - a real-life study

AU - Backer, Vibeke

AU - Sverrild, Asger

AU - Porsbjerg, Celeste

PY - 2014/5

Y1 - 2014/5

N2 - Objective: Ongoing airway inflammation measured by fractional exhaled nitric oxide (FENO) and airway hyperresponsiveness (AHR) to mannitol are associated in selected asthma patients, but no evidence exists of this association in unselected asthma patients. The aim was to investigate the association between FENO and AHR to mannitol in unselected individuals with possible asthma. Methods: A real-life study on patients with possible asthma referred to a specialized asthma clinic. Data on asthma history, FEV1, FENO, atopy, smoking, treatment and AHR to mannitol were collected. Results: In 217 unselected patients with symptoms suggestive of asthma, FENO and response to mannitol were tested. Of the 141 who underwent both tests, 32 (23%) had FENO >25ppb, and 58 (41%) had AHR to mannitol. A significant association between high FENO and AHR was found (p<0.001); 26% responded to mannitol despite a normal NO, and 8% had a high FENO but no AHR. Additionally, a weak association was found between log FENO and log response to mannitol (r=0.32, p<0.01). The area under the ROC curve for FENO as a predictor of AHR was 0.66 (95% CI 0.6-0.8) and for mannitol for having high FENO was 0.73 (95%CI 0.6-0.9). Conclusion: In a large sample of patients referred to an asthma clinic, an association was found between FENO and AHR to mannitol. However, a significant proportion of asthma patients had a normal FENO despite having AHR, suggesting that in some patients, AHR to mannitol is not driven by eosinophilic airway inflammation.

AB - Objective: Ongoing airway inflammation measured by fractional exhaled nitric oxide (FENO) and airway hyperresponsiveness (AHR) to mannitol are associated in selected asthma patients, but no evidence exists of this association in unselected asthma patients. The aim was to investigate the association between FENO and AHR to mannitol in unselected individuals with possible asthma. Methods: A real-life study on patients with possible asthma referred to a specialized asthma clinic. Data on asthma history, FEV1, FENO, atopy, smoking, treatment and AHR to mannitol were collected. Results: In 217 unselected patients with symptoms suggestive of asthma, FENO and response to mannitol were tested. Of the 141 who underwent both tests, 32 (23%) had FENO >25ppb, and 58 (41%) had AHR to mannitol. A significant association between high FENO and AHR was found (p<0.001); 26% responded to mannitol despite a normal NO, and 8% had a high FENO but no AHR. Additionally, a weak association was found between log FENO and log response to mannitol (r=0.32, p<0.01). The area under the ROC curve for FENO as a predictor of AHR was 0.66 (95% CI 0.6-0.8) and for mannitol for having high FENO was 0.73 (95%CI 0.6-0.9). Conclusion: In a large sample of patients referred to an asthma clinic, an association was found between FENO and AHR to mannitol. However, a significant proportion of asthma patients had a normal FENO despite having AHR, suggesting that in some patients, AHR to mannitol is not driven by eosinophilic airway inflammation.

KW - Adolescent

KW - Adult

KW - Age Factors

KW - Ambulatory Care

KW - Ambulatory Care Facilities

KW - Analysis of Variance

KW - Asthma

KW - Bronchial Hyperreactivity

KW - Bronchial Provocation Tests

KW - Child

KW - Cohort Studies

KW - Exhalation

KW - Female

KW - Forced Expiratory Flow Rates

KW - Humans

KW - Male

KW - Mannitol

KW - Middle Aged

KW - Nitric Oxide

KW - Prognosis

KW - Respiratory Function Tests

KW - Risk Assessment

KW - Severity of Illness Index

KW - Skin Tests

U2 - 10.3109/02770903.2013.878953

DO - 10.3109/02770903.2013.878953

M3 - Journal article

C2 - 24450977

SN - 0277-0903

VL - 51

SP - 411

EP - 416

JO - Journal of Asthma

JF - Journal of Asthma

IS - 4

ER -