Asthma and lower airway disease
Diagnostic properties of inhaled mannitol in the diagnosis of asthma: A population study

https://doi.org/10.1016/j.jaci.2009.06.028Get rights and content

Background

A new indirect bronchial provocation test measuring airway responsiveness by using inhaled mannitol was recently introduced.

Objective

The aim of this study was to examine the diagnostic properties of airway responsiveness to inhaled mannitol in the assessment of asthma in an unselected sample of young adults.

Methods

Two hundred thirty-eight young adults randomly drawn from the nationwide civil registration list were challenged with inhaled, dry-powder mannitol. A respiratory specialist, blind to the test results, classified all 238 subjects with respect to the presence of asthma. The classification was based on respiratory symptoms, spirometric results, atopy, and fraction of exhaled nitric oxide values and response to inhaled β2-agonists. On this basis, sensitivity, specificity, and predictive values were assessed to different cutoff values of the test. A receiver operating characteristic curve was constructed, and the accuracy of the test, defined as the area under the curve, was computed.

Results

Fifty-one (21.4%) subjects had current asthma. Of 33 subjects with airway hyperresponsiveness to mannitol, 30 had current asthma. The specificity and sensitivity were 98.4% (95% CI, 96.2% to 99.4%) and 58.8% (95% CI, 50.7% to 62.6%), respectively. The positive predictive value (PPV) and negative predictive value (NPV) were 90.9% (95% CI, 78.4% to 96.8%) and 89.8 (95% CI, 87.7% to 90.7%), respectively. The area under the receiver operating characteristic curve was 0.89 (95% CI, 0.83-0.95).

Conclusions

In an unselected sample of young adults, bronchial provocation with inhaled dry-powder mannitol had a high diagnostic specificity for the diagnosis of asthma.

Section snippets

Study design

The study is a cross-sectional population study performed at the Respiratory Research Unit, Copenhagen University Hospital Bispebjerg, Copenhagen, Denmark. An unselected sample of 1000 young adults between the ages of 14 and 24 years was randomly drawn from the civil registration list. All subjects received a validated self-administered asthma and rhinitis screening questionnaire, with 20 questions adopted from the American College of Allergy, Asthma & Immunology screening program extended with

Population characteristics

Of the 978 subjects possible to contact, 448 (45.8%) responded by returning the screening questionnaire. Among these, 238 (24.3%) volunteered to participate in the study and completed the examination.

There were no differences between participants and nonparticipants regarding the prevalence of self-reported asthma; age; familial predisposition to asthma, allergic disease, or both; and smoking habits. The ratio between male and female subjects, however, was different in the 2 groups (Table I).

Response to mannitol

Discussion

Recently, a new BPT for asthma with inhalation of mannitol powder was introduced. Unlike the current tests available, the mannitol test has only 1 operating standard and protocol. The inconveniencies of comparing test results from one study with those from another because of differences in protocols have remained a major weak spot in AHR research. One operating standard is therefore an absolute advantage.

It was the objective of this study to uncover the distinctive qualities of the mannitol

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    The Danish Agency for Science, Technology and Innovation, an institution under the Danish Ministry of Science, Technology and Innovation, granted a 1-year scholarship. Pharmaxis provided the research team with an unrestricted grant, with which one of the research assistants was employed. Moreover, parts of the Mannitol kits were delivered at no cost by Pharmaxis.

    Disclosure of potential conflict of interest: V. Backer has received research support from Pharmaxis. The rest of the authors have declared that they have no conflict of interest.

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