Value of a negative aeroallergen skin-prick test result in the diagnosis of asthma in young adults: correlative study with methacholine challenge testing.
Chest
; 122(3): 821-5, 2002 Sep.
Article
em En
| MEDLINE
| ID: mdl-12226019
ABSTRACT
BACKGROUND:
None of the existing tests for the diagnosis of asthma are considered to be definitive. Certain circumstances require prompt diagnosis, and a test able to predict the absence of asthma would be very useful.OBJECTIVE:
To evaluate the contribution of a skin-prick test (SPT) to the diagnostic workup of subjects with suspected asthma. PATIENTS ANDMETHODS:
The study included three groups of subjects aged 18 to 24 years group A, asthmatic patients (n = 175); group B, control subjects (n = 100); and group C, subjects with suspected asthma (n = 150) with normal spirometry findings and a negative exercise challenge test result. All underwent an SPT to a battery of common aeroallergens, and group C underwent a methacholine challenge test (MCT) in addition. The sensitivity, specificity, positive predictive value, and negative predictive values (NPV) of the SPT were calculated using provocative concentrations of methacholine causing a 20% fall in FEV(1) (PC(20)) of < 4 mg/mL and < 8 mg/mL as diagnostic cutoff values for asthma in the MCT. Bayes' formula was used to determine posttest probabilities of having asthma, both for positive and negative SPT results.RESULTS:
A positive SPT result to at least one allergen was found in 95.5%, 54%, and 69% of patients in the three groups, respectively. The sensitivity, specificity, and NPV of the SPT were 90.7%, 52.0%, and 84.8%, respectively, with a cutoff value of PC(20) < 8 mg/mL. The lower cutoff, PC(20) < 4 mg/mL, increased the sensitivity and NPV to 98.2% and 97.8%, respectively. A negative SPT result decreased the probability of having asthma by 10-fold to 20-fold in subjects whose pretest probability was low to moderate.CONCLUSIONS:
Incorporating an SPT into the workup of subjects with suspected asthma can reduce the cost of this process significantly. The SPT may be used as a simple, fast, safe, inexpensive, and reliable method to predict the absence of asthma in young adults.
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Base de dados:
MEDLINE
Assunto principal:
Hipersensibilidade Respiratória
/
Asma
/
Testes de Provocação Brônquica
/
Testes Intradérmicos
/
Alérgenos
Idioma:
En
Ano de publicação:
2002
Tipo de documento:
Article