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Purpose: To examine the extent to which individual- and neighborhood-level differences in socioeconomic status (SES) contribute to SLE activity and organ system involvement.
Methods: Data derive from the first three waves of interviews of the Lupus Outcomes Study (LOS), a national longitudinal study of 982 persons with SLE interviewed annually, augmented with data from their census block group (600-3000 residents). After multiple imputation, 2,840 observations were available for analysis. We use 2 measures of individual SES: annual household income (<$40,000, $40-80,000, or ≥$80,000) and education (high school diploma or less, some college, or college degree). Neighborhood SES is based on the proportion of households in the block group at or below 125% of the Federal poverty threshold. Poverty areas have >30% of households in poverty. Outcome measures include the Systemic Lupus Activity Questionnaire (SLAQ), a self-report proxy for current disease activity; self-reported vascular events (myocardial infarction, stroke, venous thromboembolism); self-reported renal involvement; and medical chart documentation of ACR renal criterion (i.e., persistent proteinuria or cellular casts). From regression models controlling for gender, race, age, marital status, disease duration, smoking, body mass index, and recruitment source (academic, community, or non-clinical source), we estimate adjusted means or rates of each outcome for the individual and neighborhood SES measures separately and in combination.
Results: Of 982 subjects, 91% are female, 66% are white non-Hispanic, with mean age 34±13 at diagnosis and 47±13 at interview. Mean SLAQ score is 12.4±8 (range 0-42; higher scores=more activity), 27% reported vascular events, 40% reported renal involvement, and 27% met ACR renal criterion. The table shows results from multivariate models:
*adjusting for household income
After adjustment for covariates, lower individual SES -- measured by education or income -- predicts higher SLAQ scores and higher rates of vascular events. Renal involvement is more commonly reported by those of middle or low income, but does not vary by education or poverty area. Documentation of ACR renal criterion is more common among patients with higher education. In models containing both individual and neighborhood SES measures, poverty area is not independently associated with any of these outcomes.
Conclusion: In a large, diverse cohort drawn from clinical and non-clinical sources, disease activity and vascular manifestations of SLE are associated with SES, independent of race and other covariates. Further research is needed to explore reasons for the divergent results in SLE renal manifestations.
Methods: Data derive from the first three waves of interviews of the Lupus Outcomes Study (LOS), a national longitudinal study of 982 persons with SLE interviewed annually, augmented with data from their census block group (600-3000 residents). After multiple imputation, 2,840 observations were available for analysis. We use 2 measures of individual SES: annual household income (<$40,000, $40-80,000, or ≥$80,000) and education (high school diploma or less, some college, or college degree). Neighborhood SES is based on the proportion of households in the block group at or below 125% of the Federal poverty threshold. Poverty areas have >30% of households in poverty. Outcome measures include the Systemic Lupus Activity Questionnaire (SLAQ), a self-report proxy for current disease activity; self-reported vascular events (myocardial infarction, stroke, venous thromboembolism); self-reported renal involvement; and medical chart documentation of ACR renal criterion (i.e., persistent proteinuria or cellular casts). From regression models controlling for gender, race, age, marital status, disease duration, smoking, body mass index, and recruitment source (academic, community, or non-clinical source), we estimate adjusted means or rates of each outcome for the individual and neighborhood SES measures separately and in combination.
Results: Of 982 subjects, 91% are female, 66% are white non-Hispanic, with mean age 34±13 at diagnosis and 47±13 at interview. Mean SLAQ score is 12.4±8 (range 0-42; higher scores=more activity), 27% reported vascular events, 40% reported renal involvement, and 27% met ACR renal criterion. The table shows results from multivariate models:
| SES measure | SLAQ (mean, CI) | Vascular events (%, CI) | Renal involvement (%, CI) | ACR Renal criterion (%, CI) |
| Education | ||||
| ≤High school | 15 (14,16) | 33 (27,39) | 39 (32,45) | 24 (19,30) |
| Some college/AA | 14 (13,15) | 29 (25,33) | 44 (39,48) | 23 (19,27) |
| BA or above | 11 (10,12) | 25 (21,29) | 42 (37,47) | 32 (27,36) |
| Household income | ||||
| <$40,000 | 15 (14,16) | 35 (30,40) | 46 (41,51) | 27 (22,31) |
| $40-80,000 | 12 (11,13) | 24 (20,28) | 44 (39,49) | 27 (23,32) |
| ≥$80,000 | 10 (9,11) | 24 (19,29) | 34 (29,40) | 26 (20,31) |
| High poverty area* | ||||
| Yes | 14 (12,16) | 26 (17,35) | 40 (31,50) | 25 (17,33) |
| No | 13 (12,13) | 29 (26,32) | 42 (39,46) | 27 (24,30) |
After adjustment for covariates, lower individual SES -- measured by education or income -- predicts higher SLAQ scores and higher rates of vascular events. Renal involvement is more commonly reported by those of middle or low income, but does not vary by education or poverty area. Documentation of ACR renal criterion is more common among patients with higher education. In models containing both individual and neighborhood SES measures, poverty area is not independently associated with any of these outcomes.
Conclusion: In a large, diverse cohort drawn from clinical and non-clinical sources, disease activity and vascular manifestations of SLE are associated with SES, independent of race and other covariates. Further research is needed to explore reasons for the divergent results in SLE renal manifestations.
L. Trupin, None.