The Thai version of the Nijmegen questionnaire.

Purpose: The Nijmegen questionnaire is a screening tool for detecting hyperventilation syndrome. The present study aimed to cross-culturally adapt the questionnaire to Thai language and test its psychometric properties for screening hyperventilation syndrome, in which the prevalence is increasing due to the impacts of the COVID-19 pandemic. The Thai version of the Nijmegen questionnaire (NQ-TH) was generated following a cross-cultural adaptation guideline including initial translation, synthesis of forward translation, back translation, expert committee review, and prefinal testing. Fifty control participants and one-hundred patients with symptoms related to hyperventilation syndrome were enrolled in this study for the determination of psychometric properties. Content validity, construct validity, internal consistency reliability, and test-retest reliability of the NQ-TH were assessed. Its discriminant ability and cutoff point for screening hyperventilation syndrome were also revealed.

Findings: The obtained IOC and disappeared floor and ceiling effects indicated excellent content validity of the questionnaire. There were significant correlations between the total scores of the NQ-TH and other questionnaires and recorded respiratory measurements obtained from the patients, i.e., SF-36-TH ( = -0.257), HADS-TH ( = 0.331), RR ( = 0.377), and BHT ( = -0.444). This supported the construct validity of the NQ-TH. An acceptable internal consistency was also observed (Cronbach's alpha = 0.789). Test-retest repeatability of the questionnaire was high (ICC = 0.90). Moreover, the NQ-TH reliability was also ensured by calculated MDC (2.68). The cutoff point of the NQ-TH was at 20 with 98% sensitivity and 94% specificity. The NQ-TH established by the present study is a valid and reliable tool for screening hyperventilation syndrome among Thais.