Risk association between hypocomplementemia and the development of lupus nephritis

A single-center, case-control observational study.

Abstract

Introduction: Systemic lupus erythematosus (SLE) activity is monitored by complement levels C3, C4, and CH50. The present study aimed to investigate the association between hypocomplementemia and the development of lupus nephropathy (LN) in patients with SLE, to determine whether hypocomplementemia is a predisposing factor.

Methods: The present observational, case-control study was conducted at the Eugenio Espejo Hospital in Quito, Ecuador, from 2009 to 2014. Records of patients diagnosed with SLE were included. Two groups were formed: the first with lupus nephropathy and the second without lupus nephropathy. The variables included demographic and clinical data, hypocomplementemia status, C3 and C4 levels, 24-hour proteinuria, serum creatinine, and serum urea. The strength of association between hypocomplementaemia and renal involvement in patients with SLE was summarized by odds ratios (ORs) and their 95% confidence intervals (CIs).

Results: A total of 134 patients were included. There were 52 cases and 82 controls. Hypocomplementemia is associated with the risk of developing lupus nephritis (OR=11.1; 95% CI 4.9-25.2, P <0.05). These results were maintained with sex-adjusted models (OR=11.2; 95% CI 4.9-25.7, P <0.05), and by age and sex (OR=11.5; 95% CI 5.0-26.7; P <0.05). Patients with extremely low C3 values had a 4-fold increased risk of developing LN, while those with extremely low C4 values had an 8-fold increased risk.

Conclusions: There is a strong risk association between hypocomplementemia and the development of lupus nephritis in patients with SLE.