[Discriminative properties and validity of a health status questionnaire in obstructive airway disease patients: the Airway Questionnaire 20].
OBJECTIVE
To evaluate the discriminative properties and validity of the Airways Questionnaire 20 (AQ20) in a sample of patients with airway obstruction and to compare its properties with those of the St George's Respiratory Questionnaire (SGRQ) and the Short Form 36 (SF-36).


METHODS
A convenience sample of 47 subjects was recruited from among 61 consecutive patients referred to an outpatient clinic specialized in obstructive airway diseases. All subjects completed the AQ20, SGRQ, and SF-36. Other measures were the baseline dyspnea index (BDI), 6-minute walk test (6MWT) distance, spirometry, results of arterial blood gas analysis, and body mass index.


RESULTS
The AQ20 showed very good correlation with the SGRQ total score (rho=0.84, P< .001) and moderate correlation with all SF-36 domains (physical capacity, rho=-0.53; physical functioning, rho=-0.61; bodily pain, rho=-0.55; general health, rho=-0.59; vitality, rho=-0.55; social functioning, rho=-0.57; emotional role functioning, rho=-0.51; mental health, rho=-0.61; all P< .001). The BDI and the 6MWT distance were the best predictors of AQ20 score (r2=0.31) in the regression model. An area under the receiver operating characteristic curve of 0.91 (P< .001) indicated a high level of accuracy for the AQ20, using the SGRQ as the gold standard.


CONCLUSIONS
This study shows that the AQ20 is an accurate health status questionnaire in patients with moderate-to-severe airway obstruction. It could be an alternative to longer, traditional questionnaires such as the SGRQ.
Respiratory Division, Faculdade de Tecnologia e Ciências (FTC), Universidade Federal da Bahia, Salvador, Bahia, Brazil. aquilescamelier@yahoo.com.br
Aquiles
A
Camelier
Fernanda W
FW
Rosa
Oliver A
OA
Nascimento
Ana Luiza G
AL
Fernandes
Jose R
JR
Jardim
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006304:Health Status; D006801:Humans; D008297:Male; D008875:Middle Aged; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis*; D011795:Surveys and Questionnaires