The Influence of Income and Formal Education on Damage in Brazilian Patients With Systemic Lupus Erythematosus

Abstract

Objective: The aim of this study was to evaluate the association of socioeconomic status and American College of Rheumatology/Systemic Lupus International Collaborating Clinics Damage Index (SDI) score in Brazilian patients with systemic lupus erythematosus (SLE). Methods: Five hundred twenty-three patients (SLE ACR criteria) 18 years or older who were at 12 months or greater since diagnosis were included. Socioeconomic status was assessed by per-capita income and years of education. Race was categorized as white and nonwhite. The SDI and Mexican SLE Disease Activity Index were used. Statistical Analysis: Mean +/- SD and median were used for descriptive analysis. Student t test, Mann-Whitney U test, chi(2) test, and Spearman rank correlation coefficient and univariate and multivariate regression analyses were performed. The level of significance was set at 5% for all statistical tests. Results: Ninety-six percent were female, 51.2% were nonwhite, and the mean age was 37.8 +/- 1.4 years. Disease duration was 8.2 +/- 10.3 years and formal education was 10.2 +/- 3.5 years. Unemployment among patients was 63.7%, with median monthly per-capita income of US $276. Mean SDI score was 1.4 +/- 1.52, and 65.6% had some type of damage (SDI >= 1). Patients with SDI of 1 or greater had lower income (P = 0.039). Nonwhite patients had higher SDI than did white patients (P = 0.005). The SDI presented a positive correlation with disease duration (P < 0.001) and age (P < 0.001) and a negative correlation with years of education (P = 0.001). Working patients had lower SDI than did inactive ones (P = 0.001). In a multivariate analysis, older age, higher disease duration, nonwhite race, low income, and out-of-work profile were associated with damage. Conclusions: Besides nonmodifiable characteristics such as longer disease duration and older age, low income was also associated with damage. Therefore, interventions to give adequate socioeconomic support are necessary to improve outcome, mainly in poorer and nonwhite SLE patients.