Abstract
OBJECTIVE: The Nijmegen Questionnaire (NQ) enables the assessment and identification of symptoms related to respiratory dysfunction and hyperventilation syndrome. The aim was to investigate the validity of the Turkish version of the NQ in asthmatics. MATERIAL AND METHODS: Fifty-four individuals with asthma were included. Spirometry was performed. Dyspnea was assessed using the modified Borg and modified Medical Research Council scales. Breath-holding time was recorded. End-tidal carbon dioxide was measured using a portable capnograph. Oxygen saturation and heart rate were recorded. Asthma Control Test was used to evaluate the asthma control level. Quality of life was assessed using the Asthma Quality of Life Questionnaire and Nottingham Health Profile. Beck Depression Inventory was used to determine depression. RESULTS: Bartlett's test of sphericity (360.749, df 105, P < .001) and Kaiser-Meyer-Olkin criterion (0.752) for 15-item NQ supported a single-factor model with 36.38% of explained variability through principal component analysis and explanatory factor analysis. For 15-item NQ with this single-factor model, Cronbach's alpha was 0.872, and the test-retest reliability was 0.628. There was a significant negative correlation between NQ and Asthma Control Test (r = -0.448), and Asthma Quality of Life Questionnaire (r = -0.743) and a significant positive association with Beck Depression Inventory (r = 0.477), Nottingham Health Profile-energy (r = 0.370), Nottingham Health Profile-pain (r = 0.313), Nottingham Health Profile-sleep (r = 0.294), and Nottingham Health Profile-physical activity scores (r = 0.406) (P < .05). CONCLUSIONS: The 15-item Turkish version of the NQ is valid and reliable in asthmatics. Individuals with uncontrolled asthma have higher NQ scores than those with well-controlled asthma. NQ is associated with asthma control level, asthma-related quality of life, health profile, and depression.