Evaluation of the short-form 36-item questionnaire to measure health-related quality of life in patients with idiopathic pulmonary fibrosis

Objective: To validate the use of the 36-item short-form questionnaire (SF-36) for measuring health-related quality of life (HRQL) in patients with idiopathic pulmonary fibrosis (IPF). Design: Observational data at a single point in time, Setting: A specialized outpatient respiratory clinic. Participants: Thirty-four patients (mean +/- SE age, 58.29 +/- 1.87 years) with IPF and no significant comorbidity. A matched control group for HRQL measurements was composed of 34 normal subjects (mean age, 58.00 +/- 1.89 years). Measurements and results: Dyspnea was measured by the baseline dyspnea index (BDI). Respiratory function evaluation included FVC, FEV1, and resting; arterial blood gases. IPF patients showed a mean BDI score of 5.21 +/- 0.46. The mean FVC and FEV1 values were 62.41 +/- 2.96% and 66.41 +/- 3.33%, respectively. The mean Pao(2) was 67 +/- 2.51 mm Hg, and the mean Paco(2) was 37 +/- 1.05 mm Hg. Patients scored significantly worse than control subjects with respect to the SF-36 domains of physical functioning, physical role, general health perceptions, vitality, social functioning, emotional role, and mental health index. BDI scores were significantly correlated with five SF-36 components, and FVC and FEV1 were significantly correlated with two SF-36 components. Significant negative correllations were found between arterial pH and four SF-36 domains. Conclusions: Patients with IPF have a significant impairment of HRQL in both physical and psychological functioning. Dyspnea is the most important factor influencing the quality of life in these subjects. The SF-36 questionnaire is a valid instrument to evaluate HRQL in IPF patients.