Medical insurance, socioeconomic status, and age of onset of endstage renal disease in patients with lupus nephritis.

OBJECTIVE: Limited access to care may hasten progression to endstage renal disease (ESRD) in patients with lupus nephritis. We examined associations between type of medical insurance, socioeconomic status (SES), and age at onset of ESRD in a national, population-based cohort.
METHODS: Using the United States Renal Data System, incident cases of ESRD due to lupus nephritis in the US from January 1, 1996, to June 30, 2004, were examined in this cross-sectional study (n = 7971). Age at onset of ESRD was compared among patients with different types of medical insurance and by SES.
RESULTS: In each ethnic group, patients with private insurance were older at the onset of ESRD than those with no insurance or Medicaid. For example, whites with private insurance were on average 7.5 years older than those with no insurance and 8.2 years older than those with Medicaid. There were no differences in age at onset of ESRD between those with no insurance and those with Medicaid. SES, based on the socioeconomic characteristics of the patient's area of residence, was associated with age of onset of ESRD only in whites.
CONCLUSION: Among patients with lupus nephritis who develop ESRD, those with private medical insurance are older when they begin ESRD treatment than those with Medicaid or no insurance. Given that medical insurance is unrelated to the age at onset of lupus nephritis, these findings suggest that progression to ESRD varies with medical insurance status, possibly because of differences in quality of care or access to care.