Environmental factors predicting nephritis in systemic lupus erythematosus

To evaluate social class, ethnic origin, and various endocrine variables as potential risk factors in the development of nephritis in patients with systemic lupus erythematosus (SLE).

A cross-sectional survey was carried out of all outpatients with SLE attending the lupus Clinic of St Thomas's Hospital from March to October 1992 using retrospective survival data. The main outcome measure was the duration of SLE before the onset of nephritis.

Two hundred and ninety six women and 11 men were studied; the male patients were excluded from the analysis. Univariate analysis showed an increased risk of nephritis in patients with SLE of West Indian origin with 54 v 19% with nephritis at five years, in patients of lower social class, in patients who did not drink alcohol, and in those with a history of fetal loss after the onset of lupus. No significant effect of the age of onset of SLE, use of oral contraceptives, normal pregnancy, or smoking was seen. Multivariate analysis showed that ethnic origin did not influence the risk of nephritis independently of social class.

Factors associated with socioeconomic deprivation may increase disease severity in patients with SLE.