Education, zip code-based annualized household income, and health outcomes in patients with systemic lupus erythematosus.

Abstract

To determine the association of socioeconomic status [SES; education and zip code-based annual household income (Z-AHI)] and ethnicity with health-related quality of life (HRQOL) among patients with systemic lupus erythematosus (SLE). Data on 211 subjects from a cross-sectional study (LupusPRO) using the Medical Outcomes Study Short Form-36 questionnaire to evaluate physical health scores (PCS) and mental health scores were used to obtain education and zip code. The 2000 US Census was used to obtain each zip code's median annual household income. Education and Z-AHI correlated with PCS (education standardized beta = 0.17, 95% CI 0.47, 3.65, p = 0.01, r(2) = 0.03; Z-AHI standardized beta = 0.15, 95% CI 0.57, 8.30, p = 0.02, r(2) = 0.02) on regression analysis. Z-AHI was linked to PCS, independent of education. Ethnicity was associated with PCS through disease activity and SES. SES is associated with HRQOL in SLE. Z-AHI and education are equally predictive surrogates of SES; however, Z-AHI, independent of education, was predictive of HRQOL. Z-AHI has less subject bias and is easily obtainable, therefore its use for future HRQOL studies is suggested.