Cultural and linguistic validation of the NHQ-2 Questionnaire: a specific instrument for assessing patient's usability of inhalation devices.

Background: An increasing number of inhalation devices are presently available in the market. They are differently characterized in terms of their handling and usability, both factors which may affect the outcomes of respiratory treatment. The assessment of the preference and the usability rate of all devices can be carried out by means of specific questionnaires. Before their use, the identification of errors due to the incorrect wording of questions included in the questionnaires, together with the trans-cultural reliability represents the main issues of their cultural and linguistic validation.

Methods and results: The New Handling Questionnaire - NHQ-2 is a novel specific questionnaire aimed to measure both the preference and the usability of all kinds of inhalation devices. The method used for its validation has been summarized in the first section of the present paper, while the results of the specific validation and translation process have been described in the second section, together with the grading of improvement achieved over the process. The comprehensibility and the reproducibility rates achieved for both the Italian and the English final versions of the NHQ-2 questionnaire were very high, such as >90 % for each question included.

Conclusions: The novel NHQ-2 questionnaire proved very high comprehensibility and reproducibility in both its Italian and English final versions. It can be proposed for the trans-cultural clinical use when the usability, and not only the patients' preference of devices, should be assessed.