The characteristics of different diagnostic tests in adult mild asthmatic patients: comparison with patients with asthma-like symptoms by gastro-oesophageal reflux.
BACKGROUND
Diagnosing asthma cannot be always easy. It is important to consider the validity of the diagnostic tests, and/or how much more commonly they are positive in patients with asthma compared to healthy subjects and, particularly, to patients with asthma-like symptoms.


OBJECTIVE
To evaluate the validity of diagnostic tests for asthma, in terms of sensitivity, specificity, positive and negative predictive values, in patients with bronchial asthma compared to patients affected by gastro-oesophageal reflux disease (GERD) with asthma-like symptoms, and healthy control subjects without asthma and gastro-oesophageal reflux (GER).


METHODS
Single-center, cross-sectional, observational study.


METHODS
We studied 60 patients with mild asthma, 30 patients with GERD and asthma-like symptoms and 25 healthy control subjects.


METHODS
We measured provocative concentration of methacholine causing a 20% fall in the forced expiratory volume in 1s (MCh PC(20)/FEV(1)), the amplitude percent mean of peak expiratory flow (A%M of PEF), derived from twice-daily readings for >2 weeks, the FEV(1)/forced vital capacity (FEV(1)/FVC) ratio, the eosinophil count in blood and in induced sputum and the serum eosinophil cationic protein (ECP) levels.


RESULTS
FEV(1)/FVC ratio, A%M of PEF, blood eosinophils counts and serum ECP levels were less sensitive and specific when the reference population was composed of patients with asthma-like symptoms by GER. While, MCh PC(20)/FEV(1) and induced sputum eosinophils count were the most sensitive (both 90%) and specific (89% and 92%, respectively) tests.


CONCLUSIONS
Our findings demonstrate that MCh PC(20)/FEV(1) and the induced sputum eosinophil count are the most useful objective tests in patients with mild asthma. All patients with asthma presented both an MCh PC(20)/FEV(1) <1500 microg and eosinophils count in the induced sputum >1%.
Di Lorenzo
Gabriele
G
Dipartimento di Medicina Clinica e delle Patologie Emergenti, Università degli Studi di Palermo, Via del Vespro no. 141, 90127 Palermo, Italy. dilo601@unipa.it
Mansueto
Pasquale
P
Esposito-Pellitteri
Maria
M
Ditta
Vito
V
Castello
Francesco
F
Lo Bianco
Claudia
C
Leto-Barone
Maria Stefania
MS
Di Fede
Gaetana
G
Traverso
Marcello
M
Rotolo
Giuseppe
G
Vigneri
Sergio
S
Rini
Giovambattista
G
D000328:Adult; D001249:Asthma / Q000175:diagnosis* / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D001985:Bronchial Provocation Tests / Q000379:methods; D016085:Bronchoconstrictor Agents; D003937:Diagnosis, Differential; D047150:Eosinophil Cationic Protein / Q000097:blood; D004804:Eosinophils / Q000473:pathology; D004812:Epidemiologic Methods; D005260:Female; D005541:Forced Expiratory Volume; D005764:Gastroesophageal Reflux / Q000175:diagnosis* / Q000503:physiopathology; D006801:Humans; D007958:Leukocyte Count; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D013147:Spirometry / Q000379:methods; D013183:Sputum / Q000166:cytology; D014797:Vital Capacity
D015415:Biomarkers; D016085:Bronchoconstrictor Agents; D016210:Methacholine Chloride; D047150:Eosinophil Cationic Protein; C479220:RNASE3 protein, human