Validation of the Japanese Severe Respiratory Insufficiency Questionnaire in hypercapnic patients with noninvasive ventilation

Background The Severe Respiratory Insufficiency (SRI) Questionnaire was originally developed in German to assess health-related quality of life (HRQL) and was validated as a multidimensional instrument with high psychometric properties in chronic hypercapnic respiratory failure (CHRF) patients receiving noninvasive ventilation (NIV). We aimed to investigate the intercultural adaptation of the Japanese SRI Questionnaire and whether it is a reliable and valid HRQL questionnaire to administer to those patients. Methods The SRI Questionnaire was adapted to Japanese using a translation and back-translation procedure, followed by equivalency assessment. It was validated in 56 stable outpatients receiving NIV for CHRF, primarily due to chronic obstructive pulmonary disease (COPD) and/or pulmonary tuberculosis sequelae. Results Examination of the frequency distribution of the Japanese SRI Questionnaire showed that the subscales and summary were approximately normally distributed and well balanced. There were no significant differences in SRI scores between patients with COPD and pulmonary tuberculosis sequelae. Cronbach׳s α values representing internal consistency of seven SRI subscales ranged from 0.56 to 0.80; attendant symptoms and sleep had the lowest values. Cronbach׳s α value was 0.92 for the SRI summary. The SRI summary score was significantly related to all eight subscales of the Medical Outcomes Study 36-item short form, with correlation coefficients of 0.41–0.66. Conclusions The Japanese SRI Questionnaire was produced using a standardized procedure and an equivalency study. It has high psychometric properties with internal consistency and concurrent validity. The Japanese SRI Questionnaire can be used to assess HRQL in patients on NIV for CHRF.