Lupus and IgA nephropathy: coexistence or coincident?

Background: Systemic lupus erythematosus is a multisystem autoimmune disease primarily manifesting as lupus nephritis. While lupus nephritis is the most common renal pathology in lupus, non-lupus nephropathies such as IgA nephropathy occasionally occur. This study aims to evaluate the clinical features and outcomes of lupus patients with IgA nephropathy, comparing them with those of primary IgA nephropathy and lupus nephritis.

Methods: A comprehensive literature review was conducted using the PubMed and Google Scholar databases to identify cases of systemic lupus erythematosus with IgA nephropathy reported between 1995 and December 2023. A total of 16 cases were identified and 2 additional cases from our clinic were included. These cases were compared with 47 lupus nephritis patients from our clinic and 215 primary IgA nephropathy patients from the literature. Data were collected on demographics, serology, renal biopsy findings, treatment, progression to renal failure and mortality.

Results: We identified 18 cases of lupus with IgA nephropathy with a median age of 41.6 years and a female predominance (72.2%). In comparison to the primary IgA nephropathy cohort, lupus with IgA nephropathy group exhibited a lower rate of renal failure (11.1% vs. 34%) and mortality (5.6% vs. 20%). Additionally, the lupus-IgA nephropathy group showed a slightly lower mortality rate compared to the lupus nephritis cohort (5.6% vs. 10.6%).

Conclusion: Lupus with predominantly IgA deposits often follows a more indolent course than primary IgA nephropathy but severe cases with crescentic glomerulonephritis can still progress to renal failure.