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

OBJECTIVE: To determine whether socio-demographic 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 RA and DESIR for early SpA). Data on pain was measured, respectively, on 13 and 9 occasions spanning 10 and 6 years of follow-up using the Short-Form 36 bodily pain score for 810 participants of ESPOIR, and 679 participants of DESIR. Linear mixed models were used to characterize 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 long-standing 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 participants (RA, β = −3.8, P = 0.007; SpA, β = −6.0, P < 0.001) for both diseases, and Caucasians (β = −5.6, P = 0.021) for SpA presented with low pain early in the disease, with no changes throughout disease course. CONCLUSION: Being older, female, non-Caucasian and having lower education was found to be associated with worse pain in early and/or long-standing IRDs, despite universally accessible health-care. Early identification of at-risk populations and implementation of multidisciplinary strategies may reduce patient-reported health outcome disparities. TRIAL REGISTRATION REGISTRATIONS: ESPOIR: ClinicalTrials.gov, www.clinicaltrials.gov, NCT03666091. DESIR: ClinicalTrials.gov, www.clinicaltrials.gov, NCT01648907.