THE ASSOCIATION BETWEEN HEALTH-RELATED QUALITY OF LIFE AND DISEASE PROGRESSION IN IDIOPATHIC PULMONARY FIBROSIS: A PROSPECTIVE COHORT STUDY

Background and objective: Generally, a disease-specific health-related quality of life (HRQOL) measurement is more useful than generic measures in assessing perceived physical and mental health characteristic of a particular disease. The idiopathic pulmonary fibrosis (IPF)-specific version of St. George's Respiratory Questionnaire (SGRQ-I) has been recently developed for patients with IPF. We proposed to evaluate associations between the SGRQ-I and other clinical indices, as well as its prognostic value in patients with IPF. Methods: Fifty-two patients with IPF were recruited in this prospective cohort study. HRQOL was assessed using the SGRQ-I and the Medical Outcomes Study 36-item Short Form, dyspnea using the modified Medical Research Council (mMRC) dyspnea scale, and psychological status using the Hospital Anxiety and Depression Scale (HADS). We then evaluated the relationship between the SGRQ-I and other clinical measures, as well as oneyear clinical deterioration defined as a hospital admission due to respiratory exacerbation or all-cause death. Results: Stepwise multiple-regression analyses revealed that the mMRC dyspnea scale, the HADS anxiety or depression, and minimum oxygen saturation during a six-minute walk test significantly contributed to the Total and three components of the SGRQ-I. In multivariate Cox proportional-hazards analyses, the Total score of SGRQ-I predicted clinical deterioration independent of forced vital capacity, the six-minute walk distance, or partial pressure of arterial oxygen on room air. Conclusions: The SGRQ-I is a multidisciplinary instrument representing physical, functional and psychological impairments in patients with IPF. The SGRQ-I is a significant predictor of short-term disease progression independent of physiological measurements.