Abstract
OBJECTIVES: Interstitial lung disease in systemic sclerosis has a significant impact in the quality of life. This prospective study was designed to determine the correlation between quality of life in systemic sclerosis-interstitial lung disease patients using patient-reported outcome measures and the lung function test parameters, with assessment done at baseline and 1 year. METHODS: In total, 63 consecutive systemic sclerosis-interstitial lung disease patients underwent lung function test, 6-minute walk distance, and quality of life-validated questionnaires (King's Brief Interstitial Lung Disease and Functional Assessment of Chronic Illness Therapy dyspnea). King's Brief Interstitial Lung Disease covers three components, namely chest, breathlessness, and psychological symptoms. The Functional Assessment of Chronic Illness Therapy dyspnea score has Part I (breathlessness symptoms) and Part II (physical limitation due to breathlessness). All assessments except for 6-minute walk distance were done both at baseline and at 12 months. RESULTS: Both forced vital capacity predicted percentage at baseline and 12 months had significant negative correlation with the Functional Assessment of Chronic Illness Therapy dyspnea score Part I (p values: 0.038 and <0.001, respectively). Both forced vital capacity and diffuse capacity for carbon monoxide predicted percentage at 12 months were also negatively correlated with Functional Assessment of Chronic Illness Therapy dyspnea score Part II (p values: 0.001 and 0.010, respectively). There was no significant correlation between King's Brief Interstitial Lung Disease score and the lung function parameters, at both baseline and at 1-year interval. Positive significant correlation was observed between forced vital capacity predicted percentage at baseline and 6-minute walk distance (p = 0.001). CONCLUSION: Systemic sclerosis-interstitial lung disease affects quality of life, which is best assessed using the Functional Assessment of Chronic Illness Therapy dyspnea score as it correlates significantly with the lung function test parameters.