Multivariate analysis of prognostic factors and effect of treatment in patients with IgA nephropathy

Although the clinical and histological prognostic factors of IgA nephropathy have been investigated in detail, the value of treatment in terms of renal outcome is not well understood.

The authors examined data from 237 patients with IgA nephropathy (age 31.4+/-13.5 years, mean+/-SD) who had been followed-up for at least six months (follow-up periods, 62.3+/-45.5 months). The authors initially tested the significance of prognostic factors (age, sex, systolic blood pressure, proteinuria, serum creatinine, and histological severity) and treatment strategies (steroid therapy, renin-angiotensin system inhibitors and tonsillectomy) on renal outcome with univariate analysis, then evaluated the findings using the Cox proportional hazards model.

Univariate and multivariate analyses showed that among the prognostic variables, a high level of serum creatinine at renal biopsy, large amounts of proteinuria, and extensive histological injury were significant risk factors for end-stage renal failure. Kaplan-Meier analysis showed that the renal survival rates associated with these factors were significantly poorer depending on their severity. Univariate analysis revealed that tonsillectomy was the only significant treatment that contributes to the maintenance of renal survival. Moreover, urinary abnormalities disappeared at a significantly higher frequency when patients were treated by tonsillectomy. The Cox proportional hazards model showed that steroid therapy independently contributed to improve renal prognosis in addition to tonsillectomy, and the hazard ratios were 0.26 (95% CI, 0.07 to 0.93) and 0.37 (95% CI, 0.14 to 0.99), respectively.

Steroid therapy and tonsillectomy can independently improve renal outcome in patients with IgA nephropathy.