Differing environmental risk factors for membranous versus proliferative lupus nephritis
© Dooley et al.; licensee BioMed Central Ltd. 2012
Published: 27 September 2012
Nephritis is a frequent and severe organ involvement in patients with systemic lupus erythematosus. This study examined hormonal and environmental risk factors for biopsy-proven lupus nephritis (LN), comparing exposures of lupus patients with LN with patients without LN; additional analyses were conducted specifically for the subsets of those with membranous versus proliferative nephritis.
The Carolina Lupus Study (CLU) is a population-based, case-control study of hormonal, environmental, and genetic risk factors for SLE in the southeastern US (n = 265 incident cases). Diagnosis of LN was determined at the time of enrollment up to 2001 by ACR criteria, with 63 nephritis cases confirmed based on renal biopsy records. An additional 100 biopsy-confirmed LN patients from the CLU study area and time period were identified through disease registries, comprising the nephritis CLU (CLN) cohort. Data collection for both cohorts was a structured 60-minute interview including female reproductive history, lifetime job history, smoking history, use of moonshine and family history of kidney disease, dialysis, hypertension and diabetes. We estimated the association between exposures and risk of developing LN, and LN subtypes (proliferative vs. membranous LN) using logistic regression models, with OR and 95% CI adjusted for age, state, race and education. Analyses were limited to exposures before diagnosis of lupus or LN.
Reproductive history among LN cases and lupus cases without nephritis stratified by current age (females only)
Ages 18 to 34 (n= 127)
Age at menarche
All LN cases ( n = 64)
Lupus cases without nephritis ( n = 63)
OR (95% CI)
8 to 9
1.84 (0.35 to 9.62)
0.54 (0.11 to 2.65)
0.58 (0.15 to 2.29)
0.76 (0.27 to 2.18)
1.54 (0.34 to 6.93)
4.94 (0.88 to 27.92)
3.57 (0.56 to 22.73)
17 to 18
Trend test (P value)
Our findings provide evidence of an increase risk of LN associated with past use of moonshine, family history of kidney disease, and later age at menarche. Null associations were seen for most other exposures and risk factors examined. Although not previously studied in relation to LN, moonshine use has been associated with chronic kidney disease in other studies as it contains lead and other heavy metals, and is thought to damage the kidney through a variety of mechanisms. The negative association of solvent exposure with membranous nephritis suggests that different pathophysiologic mechanisms may be involved in membranous versus proliferative LN.
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