Self-report daily life activity as a prognostic marker of idiopathic pulmonary fibrosis

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is a progressive disease, leading to substantial physical impairment. The distance walked in 6 min (6MWD) is a measure of exercise tolerance and is of prognostic relevance in IPF. While 6MWD is a punctual measurement which may not be representative, self-reported daily life activity may represent the patients' functional capacity more globally even in less severe affected patients. Objectives: We evaluated and characterized a simple classification system based on the patients' self-reported daily activity and analyzed if this would add significantly to the prognostic information of the 6MWD alone in IPF patients. Methods: Daily life activity was assessed in IPF (n = 156) patients with standardized questions and categorized in activity classes (AC I-IV), comprising the less severe impaired in AC I and II. The 6MWD was also assessed. Results: ACs were related to the lung functional impairment and inversely correlated to the 6MWD. Thirty-two patients were in AC I/II, 98 in AC III and 26 patients in AC IV. Thirty-seven (23.7%) patients died during a median follow-up of 14.9 months, comprising 1 patient in AC I/II. In addition, a 6MWD <470 m predicted mortality. Combining AC I/II and a 6MWD >470 m identified a subgroup of patients with favorable outcome. Conclusions: AC is a novel scoring system which can easily be obtained and correlates with lung functional and physical impairments as well as mortality. Moreover, AC adds prognostic information to the 6MWD.