Cigarette smoking and socioeconomic status in disease outcomes of systemic lupus erythematosus: results from the 1000 Faces of Lupus cohort
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Date
2013-05-13
Authors
Nguyen, Mai
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Abstract
Part 1: The effect of smoking on the disease characteristics of systemic lupus erythematosus
(SLE) has not been extensively researched in large cohorts to date. Through this study, we aim
to examine the relationship between current smoking status, sociodemographic variables, disease
activity and organ damage in a large cohort of SLE patients. Methods: 1380 adult SLE patients
from the 1000 Faces of Lupus cohort were tested for differences in sociodemographic variables,
disease activity and organ damage between current smokers and non-smokers. Significant
variables from univariate analyses were included in linear regression models examining for
predictors of disease outcomes. Results: More Caucasians (19%) and Aboriginals (44%)
smoked compared to Asians (6%), and Africans (9%) (p<0.001). More smokers had low income
compared to non-smokers (27% vs. 11%, p<0.001). Less smokers completed high school (76%
vs. 87% of non-smokers, p<0.001). No difference in organ damage was found. Disease activity,
measured by the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) score,
trended higher in current smokers (5.5 ± 0.3 vs. 5.0 ± 0.1 in non-smokers). In linear regression,
smoking status was the only significant predictor of SLEDAI (p=0.024), other than current
treatment with prednisone when controlled for income, education, ethnicity, number of
diagnostic criteria met, and age at diagnosis of SLE. Conclusion: Current smoking is a predictor
of increased disease activity in SLE, and may account for the differences in disease activity seen
between ethnic and socioeconomic groups.
Part 2: The relationship between socioeconomic status (SES) and disease outcome is well
studied in SLE. Inflammation and immune dysfunction have been proposed as possible
mediators. We aim to examine the relationship between SES, autoantibody frequency, and
inflammation in SLE patients. Methods: A cohort of 273 Winnipeg SLE patients was tested for
associations between education, income, autoantibody frequency and inflammation as measured
by erythrocyte sedimentation rate (ESR). Linear regression models were developed for
predictors of total autoantibody frequency, elevated ESR, and organ damage. Results: No
associations were found between SES and autoantibody frequency. Less education and low
income were associated with increased maximum ESR scores (p<0.001, p=0.035 respectively).
Both income and education were predictors of increased mean ESR scores in linear regression
(p=0.025 and p=0.047). When total ACR score, age, and income were included in the regression
model, mean ESR score and high school completion were predictors of organ damage (p=0.032
and p=0.04). Conclusion: Low SES is associated with elevated inflammation, and inflamation.
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medicine