Translation to Spanish and Validation of the Specific Saint George's Questionnaire for Idiopathic Pulmonary Fibrosis

Introduction

Interstitial lung disease (ILD) is associated with low exercise tolerance, dyspnea, and decreased health-related quality of life (HRQL). Idiopathic pulmonary fibrosis (IPF) is one of the most prevalent in the group. A specific version of the Saint George's questionnaire (SGRQ-I) has been developed to quantify the HRQL of IPF patients. However, this tool is not currently validated in the Spanish language. The objective was to translate into Spanish and validate the specific Saint George's Respiratory Questionnaire for idiopathic pulmonary fibrosis (SGRQ-I).

Methods

The repeatability, internal consistency and construct validity of the SGRQ-I in Spanish were analyzed after a backtranslation process.

Results

In total, 23 outpatients with IPF completed the translated SGRQ-I twice, 7 days apart. Repeatability was studied, revealing good concordance in test–retest with an ICC (interclass correlation coefficient) of 0.96 (P<.001). Internal consistency was good for different questionnaire items (Cronbach's alpha of 0.9 including and 0.81 excluding the total value) (P<.001).The total score of the questionnaire showed good correlation with forced vital capacity FVC% (r=?0.44; P=.033), diffusing capacity of the lungs for carbon monoxide (DL_CO%) (r=?0.55; P=.011), partial pressure of oxygen in arterial blood PaO₂ (r=?0.44; P=.036), Medical Research Council Dyspnea scale (r=?0.65; P<.001), and number of steps taken in 24 h (r=?0.47; P=.024).

Conclusions

The Spanish version of SGRQ-Ideveloped by our group shows good internal consistency, reproducibility and validity, so it can be used for the evaluation of quality of life (QOL) in IPF patients.