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

BACKGROUND

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.

OBJECTIVE

This study aimed to prepare a JNQ, verify its reliability and validity, and demonstrate its clinical benefits in asthma treatment.

METHODS

The JNQ was prepared by back-translating the NQ with the author's consent. The answers to self-administered questionnaires, including the JNQ, Asthma Control Test (ACT), Asthma Control Questionnaire (ACQ), Mini Asthma Quality of Life Questionnaire (Mini-AQLQ), and Patient Health Questionnaire 9 (PHQ-9), were obtained with the consent of 68 people with asthma (average age ± SD, 52.04 ± 12.43 years) who visited Nihon University Itabashi Hospital. The reliability of the JNQ was analyzed by the Cronbach alpha coefficient. A comparative test was conducted for each questionnaire (ACT, ACQ, Mini-AQLQ, PHQ-9), considering a JNQ score of 23 as the cutoff value. Patients with a score of 23 or more were assigned to the DB group, whereas patients with a score of less than 23 were assigned to the non-DB group. We analyzed the correlation between the JNQ and each questionnaire.

RESULTS

The JNQ showed sufficient reliability (Cronbach alpha = 0.875). Correlation analysis between the JNQ score and each questionnaire revealed negative correlations with the ACT score ( = 0.262) and Mini-AQLQ score ( = -0.453) and positive correlations with the ACQ score ( = 0.337) and PHQ-9 score ( = 0.539). All of these correlations were statistically significant. As a result of the comparative test, the DB and non-DB groups showed a significant difference in Mini-AQLQ ( = .023) and PHQ-9 ( = .003) scores. No significant difference was observed between ACT ( = .294) and ACQ ( = .177) scores.

CONCLUSIONS

The JNQ validates DB in Japanese people with asthma and reflects the deterioration of asthma control, decreased quality of life, and depression. Using the JNQ, early diagnosis and therapeutic intervention (eg, breathing exercises and a psychosomatic approach) for DB in people with asthma may help suppress the severity of asthma in Japan.