Background: Patients with interstitial lung disease (ILD) have poor health-related quality of life (HRQL). However, whether HRQL differs among different subtypes of ILD is unclear. The aim of this study was to determine whether HRQL was different among patients with idiopathic pulmonary fibrosis (IPF) and chronic hypersensitivity pneumonitis (CHP).
Methods: We identified patients from an ongoing longitudinal cohort of patients with ILD. HRQL was assessed using the Short Form (SF)-36 medical outcomes form (version 2.0). Regression analysis was used to determine the association between clinical covariates and HRQL, primarily the physical component summary (PCS) and mental component summary (MCS) score. A multivariate regression model was created to identify potential covariates that could help explain the association between the ILD subtype and HRQL.
Results: Patients with IPF (n = 102) were older, more likely to be men, and more likely to have smoked. Pulmonary function was similar between the groups. The patients with CHP (n = 69) had worse HRQL across all eight domains of the SF-36, as well as the PCS and MCS, compared with patients with IPF (P < .01-.09). This pattern remained after controlling for age and pulmonary function (P < .01-.02). Covariates explaining part of the relationship between disease subtype and PCS score included severity of dyspnea (P < .01) and fatigue (P < .01). Covariates explaining part of the relationship between disease subtype and MCS score included severity of dyspnea (P < .01), female sex (P = .02), and fatigue (P = .02).
Conclusions: HRQL is worse in CHP compared with IPF. HRQL differences between ILD subtypes are explained in part by differences in sex, dyspnea, and fatigue.