Validity study of the Japanese version of the Nijmegen Questionnaire for verifying dysfunctional breathing in Japanese asthma patients

Dysfunctional breathing (DB) is a clinical condition characterized by irregular breathing patterns presenting a sensation of dyspnea and a feeling of chest tightness. DB is a known comorbidity of asthma that is difficult to control, leading to poor quality of life, so early diagnosis and therapeutic intervention are essential to improve the clinical condition of asthma. The Nijmegen Questionnaire (NQ), developed to screen for DB and translated into various languages, is used worldwide. However, a Japanese NQ (JNQ) is unavailable, so DB has not been clinically verified in people with asthma in Japan.