Daily home spirometry: an effective tool for detecting progression in idiopathic pulmonary fibrosis

Abstract

Rationale: Recent clinical trial successes have created an urgent need for earlier and more sensitive endpoints of disease progression in idiopathic pulmonary fibrosis (IPF). Domiciliary spirometry permits more frequent measurement of FVC than does hospital-based assessment, which therefore affords the opportunity for a more granular insight into changes in IPF progression. Objectives: To determine the feasibility and reliability of measuring daily FVC in individuals with IPF. Methods: Subjects with IPF were given handheld spirometers and instruction on how to self-administer spirometry. Subjects recorded daily FEV1 and FVC for up to 490 days. Clinical assessment and hospital-based spirometry was undertaken at 6 and 12 months, and outcome data were collected for 3 years. Measurements and Main Results: Daily spirometry was recorded by 50 subjects for a median period of 279 days (range, 13–490 d). There were 18 deaths during the active study period. Home spirometry showed excellent correlation with hospital-obtained readings. The rate of decline in FVC was highly predictive of outcome and subsequent mortality when measured at 3 months (hazard ratio [HR], 1.040; 95% confidence interval [CI], 1.021–1.062; P ≤ 0.001), 6 months (HR, 1.024; 95% CI, 1.014–1.033; P < 0.001), and 12 months (HR, 1.012; 95% CI, 1.007–1.016; P = 0.001). Conclusions: Measurement of daily home spirometry in patients with IPF is highly clinically informative and is feasible to perform for most of these patients. The relationship between mortality and rate of change of FVC at 3 months suggests that daily FVC may be of value as a primary endpoint in short proof-of-concept IPF studies.