Health-related qualtiy of life development of IPF in comparison to other interstitial lung diseases

Background Interstitial lung diseases (ILD) are associated with an impaired generic and disease-specific health related quality of life (HRQL). Idiopathic pulmonary fibrosis (IPF) is one of the most severe ILD with a high burden of disease. However, the longitudinal development of HRQL (i.e. EQ-5D-5L experience based value (EBVS), Visual analog scale (VAS) and Kingʼs Brief Interstitial Lung Disease questionnaire (K-BILD)) in patients with IPF compared to other ILDs is not yet fully examined. Methods We measured HRQL for 162 patients from the HILDA study at two time points 1 year apart. We calculated mean change scores of EBVS, VAS and K-BILD total score and K-BILD domain specific scores (breathlessness and activities, chest symptoms, psychological impact). Using the minimal clinical important difference (MCID) of 8 points for VAS and K-BILD, we looked at clinically important HRQL development. We adjusted the HRQL change in a second step for age, sex, education, clinic location, smoking status, FVC % predicted, baseline HRQL, and comorbidity burden. Results The mean age was 62.6 (SD 12.4), 68.5% were male, mean FVC% pred was 71.2 (SD: 20.0), mean DLCO % pred was 44.8 (SD 16.5). 41 (25.3%) of the patients had IPF. The mean HRQL-change for patients with IPF compared to other ILD patients was −3.0 vs. −0.6 for K-BILD, −3.1 vs. −2.3 for the VAS and −0.04 vs. −0.03 for the EBVS. Decrease of HRQL was highest in the chest domain (−9.0 vs. −3.4) followed by (the only significant difference) breathlessness (−7.8 vs. −0.3, p = 0.0119) and psychological domain (−1.5 vs. −0.2). According to MCID 24.4% of IPF and 14.1% of the other ILDs showed decreased HRQL measured on K-BILD, 39.0% vs. 32.2% on VAS. Only 4.9% of the IPF showed better HRQL vs. 13.2% according to disease-specific HRQL, 26.8% vs. 21.5% on VAS (no significant differences). After adjusting for the above listed variables there are no significant differences in the HRQL-change between the two groups. Discussion HRQL deteriorates on average in all ILD patients over time. During one year there were no significant differences between IPF and other ILDs. However, the trend shows a stronger deterioration for IPF, especially in the breathlessness and activity domain. A bigger cohort and longer time period is necessary for further research.