Sociodemographic determinants in the evolution of pain in inflammatory rheumatic diseases: results from ESPOIR and DESIR cohorts

Objective: To determine whether sociodemographic factors are associated with heterogeneity in pain evolution in inflammatory rheumatic diseases (IRDs) after accounting for disease-specific characteristics in a system with universal health care. Methods: This analysis included the data from two prospective observational cohorts of early IRDs (ESPOIR for early rheumatoid arthritis (RA) and DESIR for early spondyloarthritis (SpA)). Data on pain was measured respectively at 13 and 9 occasions spanning 10 and 6 years of follow-up using Short-Form 36 bodily pain amongst 810 participants of ESPOIR, and 679 participants of DESIR. Linear mixed models were used to characterise differences in pain evolution as a function of age (tertiles), sex, ethnicity, education, marital, and professional status after accounting for disease-related, treatment, lifestyle, and health factors. Results: While transitioning from early (disease duration ≤6 months for RA and ≤3 years for SpA) to longstanding disease, differences in pain evolution emerged as a function of age (p<0.001), sex (p=0.050), and ethnicity (p=0.001) in RA, and as a function of age (p=0.048) in SpA; younger age, males, and Caucasians exhibited lower pain in the latter phases of both diseases. Highly educated (RA, β=-3.8, p=0.007; SpA, β=-6.0, p<0.001) in both diseases, and Caucasians (β=-5.6, p=0.021) in SpA presented with low pain early in the disease, with no changes throughout disease course. Conclusion: Those older, females, non-Caucasians and lowly educated have worse pain in early and/or long-standing IRDs despite universally accessible health-care. Early identification of at-risk population and implementation of multidisciplinary strategies may reduce patient-reported health outcome disparities.