Objectives: To compare physical and mental health-related quality of life (HRQoL) across four systemic autoimmune rheumatic diseases (SARD).
Methods: Incident subjects enrolled in four SARD cohorts, namely systemic lupus erythematosus (SLE), systemic sclerosis (SSc), rheumatoid arthritis (RA) and idiopathic inflammatory myopathies (IIM) were studied. The outcomes of interest were baseline Short Form Health Survey physical (PCS) and mental (MCS) component summary scores. Multivariate analysis was conducted to determine whether PCS and MCS scores differed across SARD type.
Results: The study included 118 SLE (93% women, mean age 36 years), 108 SSc (79% women, mean age 55), 64 RA (63% women, mean age 58) and 25 IIM (68% women, mean age 49) subjects. Mean PCS scores were 38.9 ± 12.2 in SLE, 37.1 ± 13.3 in RA, 35.0 ± 13.6 in SSc and 28.0 ± 15.4 in IIM. Mean MCS scores were 45.0 ± 13.3 in RA, 44.4 ± 14.7 in SSc, 40.1 ± 14.3 in SLE and 33.6 ± 18.7 in IIM. SARD type was an independent predictor of HRQoL with, in some cases, the magnitude of the differences reaching one standard deviation (IIM worse PCS scores compared to SLE (β -12.23 [95% CI -18.11, -6.36; p<0.001]); IIM worse MCS scores compared to SSc (β -11.05 [95% CI -17.53, -4.58; p = 0.001]) and RA (β -11.72 [95% CI -18.62, -4.81; p = 0.001]).
Conclusions: Cross-SARD research provides a novel approach to gain greater understanding of commonalities and differences across rheumatic diseases. The differences observed warrant further research into correlates and trajectories over time.