Low socioeconomic status (measured by education) and outcomes in systemic sclerosis: Data from the Canadian Scleroderma Research Group

Abstract

Objective. In systemic lupus erythematosus, socioeconomic status (SES) affects outcomes. SES can modify outcomes by altering timing of access to care and adherence. It is unknown whether SES affects systemic sclerosis (SSc) outcomes. Disease can affect income and cause work disability, thus education (completed long before SSc onset) may be a proxy for SES. Methods. The Canadian Scleroderma Research Group collects annual data on patients with SSc. Baseline data were used from a prevalent cohort. Education was stratified by whether participants completed high school. Regression models assessed effects of education on organ complications and survival. Results. In our study, 1145 patients with SSc had 11.0 ± 9.5 years' disease duration; 86% were women, with a mean age of 55.4 ± 12.1 years. About one-quarter did not complete high school; this was more common in older patients (p < 0.0001), men (p = 0.017), those with lower income (p < 0.0001), the unemployed (p < 0.054), smokers (p < 0.001), where DLCO was < 70% predicted (p = 0.009), in those with arthritis (p = 0.047), higher Health Assessment Questionnaire-Disability Index (p = 0.017), elevated erythrocyte sedimentation rate (p = 0.019), median C-reactive protein (p = 0.002), proteinuria (p = 0.016), steroid use ever (p = 0.039), and those more likely to have died in followup (12.7% vs 8.0%; p = 0.024). However, adjusting for confounders, there was no effect of education on mortality; whereas mortality was related to age, diffuse cutaneous SSc (dcSSc) subset, elevated pulmonary arterial (PA) pressure on echocardiography, low forced vital capacity expressed as percentage of predicted, and proteinuria (similar in the dcSSc subset and in limited cutaneous SSc), mortality was increased in older patients, those with elevated PA pressure, and those with low DLCO. Conclusion. Completing less education than high school was not associated with a worse prognosis in SSc after adjustment for confounding characteristics. The Journal of Rheumatology Copyright © 2013. All rights reserved.