A critical review of the psychometric properties of the Nijmegen Questionnaire for hyperventilation syndrome.

The Nijmegen Questionnaire is commonly used by physiotherapists and other health professionals in clinical and research settings. This outcome measure was developed by researchers at the Nijmegen University in the Netherlands as a screening tool for the hyperventilation syndrome in the 1980s. However, the literature that supports the efficacy of its use is scarce. This paper examines the evidence in relation to the conceptual basis, validity, and reliability of the Nijmegen Questionnaire. A systematic review of the literature was carried out to identify studies that are related to the above measurement properties for the questionnaire. Studies identified were evaluated for their methodological qualities using the COSMIN checklist. The clinical utility of this instrument is also discussed. Issues associated with the development and validating process of this outcome measure are identified. There is also a lack of evidence in cultural validation given that the Nijmegen Questionnaire was developed in the Netherlands. While this is the only questionnaire currently available that is designed specifically for the screening of hyperventilation syndrome, administrators need to be aware of the issues identified in relation to validity and reliability when interpreting the results. Applying more robust validating processes to establish the efficacy of the Nijmegen Questionnaire appears to be a priority for researchers to improve the quality of health services for individuals suffering from hyperventilation syndrome.