Background Health-related quality of life (HRQoL) is an important outcome of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), and the Medical Outcomes Study Short Form-36 (SF-36) is usually used as a generic measure of HRQoL. However, there are only several published reports focusing on HRQoL among patients with AAV. In addition, another popular measure of HRQoL, the 5-level EuroQoL 5-Dimensions Questionnaire (EQ-5D-5L), which is often used for the calculation of quality-adjusted life years (QALYs) has received less attention in the field of AAV.
Objectives We aimed to cross-sectionally investigate the relationship between HRQoL assessed by the SF-36 and the EQ-5D-5L, and clinical background and indices among AAV patients.
Methods Patients with AAV were defined and classified according to the European Medicines Agency algorithm. Patients were approached during their outpatient attendance in our university clinic from July through December 2015. Some of the hospitalized patients during the study period were also eligible to the study. Patients were asked to complete the SF-36, the EQ-5D-5L, and other related demographic questionnaires. The SF-36 contains 36 items scored in 8 domains. Using the national norm score and its SD, the “0–100 score” of each domain of the SF-36 was transformed to the norm-based score (NBS) so that each had a mean of 50 and a SD of 10 in the national population sample. In addition, 2 summary scales were calculated based on NBS: physical (PCS) and mental (MCS) component summary scores. A lower score in SF-36 indicates poorer health or greater disability. The EQ-5D-5L comprises the 5 dimensions of HRQoL, and each dimension has 5 levels. An EQ-5D-5L health state was converted to a single summary index by applying the formula and ranges from 0 to 1; 0 meaning death and 1 complete health. Physicians were asked to complete the Birmingham Vasculitis Activity Score (BVAS) and the Vasculitis Damage Index (VDI) simultaneously and record other medical information.
Results A total of 34 Japanese patients with AAV (microscopic polyangiitis 23, granulomatosis with polyangiitis 8, and eosinophilic granulomatosis with polyangiitis 3) participated. In the study population, the mean age was 66, 29 were women, the mean disease duration was 7 years, the mean prednisolone dosage was 10.9 mg/day, the mean BVAS was 5.2, and the mean VDI was 2.7. The mean scores in 7 out of the 8 domains of the SF-36 were significantly lower than those of the age- and sex-matched national norms (p<0.05). The mean PCS and MCS scores of the SF-36, and the mean EQ-5D-5L index value were 29.4, 48.0, and 0.72, respectively. The mean PCS score and the mean EQ-5D-5L index value were significantly lower than those of the age- and sex-matched national norms (p<0.05), whereas the mean MCS score was not. The PCS score and the EQ-5D-5L index value had moderate inverse correlation with age, the prednisolone dosage, the BVAS, and the VDI (r= -0.41 to -0.62), whereas the MCS score did not. Sex and AAV classification were not significantly associated with the PCS and MCS scores or the EQ-5D-5L index value.
Conclusions In the study population, the PCS score and the EQ-5D-5L index value in patients with AAV were lower than the national norm and inversely correlated with age, the prednisolone dosage, the BVAS, and the VDI, whereas the MCS score was not.
Disclosure of Interest S. Hirahara: None declared, Y. Katsumata: None declared, M. Harigai Grant/research support from: Teijin Pharma Ltd. and Chugai Pharmaceutical Co., Consultant for: Teijin Pharma Ltd., Y. Kawaguchi: None declared, H. Yamanaka: None declared