Hyperventilation in asthma: a validation study of the Nijmegen Questionnaire--NQ.
BACKGROUND
The Nijmegen questionnaire (NQ) has previously been used for screening the hyperventilation syndrome (HVS) in asthmatics. However, no validity study has been reported so far.


OBJECTIVE
To examine the validity and reliability of the NQ in asthma patients and identify the prevalence of HVS.


METHODS
The NQ (n = 162) was examined for translation, construct, cross-sectional and discriminant validity as well as for internal consistency and test-retest reliability.


RESULTS
Principal component analysis and exploratory factor analysis revealed a single factor solution with 11 items and 58.6% of explained variability. These 11 NQ items showed high internal consistency (Cronbach's alpha = 0.92) and test-retest reliability (IR = 0.98). Higher NQ scores were found in the following subgroups: women versus men (p < 0.01); participants with moderate versus mild asthma (p < 0.001) or uncontrolled versus controlled asthma (p < 0.001), and participants with breath-hold time (BHT) < 30 versus ≥ 30 s (p < 0.01) or end-tidal CO2 (ETCO2) ≤ 35 versus >35 mmHg (p < 0.001). A cut-off score of >17 discriminated the participants with regard to the presence of HVS. The NQ showed 92.73% sensitivity and 91.59% specificity. The total NQ score was found significantly correlated with ETCO2 (r = -0.68), RR (r = 0.66) and BHT (r = -0.65). The prevalence of HVS was found 34%.


CONCLUSIONS
The NQ is a valid and reliable questionnaire for screening HVS in patients with stable mild-to-moderate asthma.
Department of Physical Therapy, Technological and Educational Institution - TEI of Athens , Athens , Greece .
Eirini P
EP
Grammatopoulou
Emmanouil K
EK
Skordilis
Georgios
G
Georgoudis
Aikaterini
A
Haniotou
Afroditi
A
Evangelodimou
George
G
Fildissis
Theodoros
T
Katsoulas
Panagiotis
P
Kalagiakos
D000328:Adult; D000368:Aged; D001249:Asthma / Q000150:complications*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006985:Hyperventilation / Q000150:complications* / Q000175:diagnosis* / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D015203:Reproducibility of Results; D011795:Surveys and Questionnaires; D055815:Young Adult
Hyperventilation; Nijmegen questionnaire; reliability; validity