Validation of the severe respiratory insufficiency questionnaire for Chile

Long-term home non-invasive ventilation (LTH-NIV) has an impact on the health-related quality of life of patients with chronic hypercapnic respiratory failure (CRF) of different causes. There are generic and specific questionnaires for respiratory diseases. In 2003 a specific questionnaire was developed for patients with CRF in LTH-NIV, called the Severe Respiratory Insufficiency (SRI) questionnaire, which has been shown to be reproducible and reliable and has been validated in several languages. The aim of the study was to translate and culturally adapt the SRI questionnaire for adult Chilean patients under LTH-NIV, and to assess its psychometric properties.

The Chilean version of the SRI was obtained using the translation-back translation method, which was then applied by cross-sectional study to a non-probabilistic convenience sample of stable patients from five regions of Chile. The validated Chilean version of the SRI questionnaire and SF-36 (gold standard) questionnaire were applied, demographic and ventilatory data were collected. Reliability was analysed using Cronbach's alpha and intraclass correlation (test-retest). Construct validity was tested using exploratory factor analysis (principal component extraction and equimax orthogonal rotation) and hypothesis testing (Mann-Whitney test). Convergent criterion validity was tested using Spearman's rho.

The sample comprised 248 patients, 132 women (53.2%), median age (IQR) was 62 years (51-75), 146 patients (58.9%) were 60 years or older, 40% had a low education level. The mean ± SD completion time of the questionnaire was 18.8 ± 9.1 min, and 100% of the items were answered. The questionnaire was self-applied by 46.8% of the sample. The validated Chilean version of the SRI questionnaire showed very good overall reliability (0.95) and by scales (> 0.7). It showed a good correlation with the SF-36, with equivalent scales, a rotated matrix with 8 factors and hypotheses that explain the underlying constructs.

The validated Chilean version of the SRI questionnaire has good psychometric properties. It is feasible, valid, and reliable for application to evaluate patients with CRF in LTH-NIV. It was found to be sensitive to assess the characteristics of the local population.