Vascular diseases and their risk factors in IgA nephropathy

Many studies have focused on risk factors for renal insufficiency in IgA nephropathy (IgAN). We recently found metabolic factors, especially uric acid, to predict progression and marked histopathological lesions in IgAN. Since vascular diseases (VDs), in addition to renal insufficiency, affect the overall survival of IgAN patients, we studied the occurrence of and risk factors underlying VDs in IgAN.

In this study, VDs here comprised the presence of coronary heart disease (CHD) and/or cerebrovascular disease (CeVD). We correlated clinical, metabolic and histopathological findings with the occurrence of VDs in 221 adult patients with IgAN. Seven histopathological parameters were semiquantitatively graded. Logistic regression analysis was used to evaluate independent predictors of VDs in these patients. The occurrence of VDs in IgAN patients > or = 30 years of age was studied and compared with that in the general population drawn from the same area.

VDs were notably common in IgAN patients. Patients with IgAN had significantly more frequent VDs, CHD and CeVD than the general population (P < 0.01 to < 0.001). Of > or = 30 years of age IgAN patients, 25% had some VD at the end of follow-up, while only 9% of the general population had VDs [odds ratio, OR 4.6 (2.2-9.4)]. Old age, male gender, hypertension, proteinuria, renal insufficiency, hyperuricaemia, hypertriglyceridaemia, diabetes, smoking and high body mass index correlated with the occurrence of VDs in univariate analysis. In all patients initial renal insufficiency and smoking were independently associated with some VD, male gender with CHD and hypertension with CeVD. In the multivariate analysis model including patients with initially normal renal function, male gender was independently associated with some VD, and hypertriglyceridaemia with CHD.

VDs, especially CeVD, would seem to be particularly common in patients with IgAN. Patients with progressive renal disease run a significantly elevated risk of developing VD. Many previously known risk factors for VD were also associated with the occurrence of some VD in the present study. Vascular changes seen in renal biopsy in patients with IgAN signify an elevated risk of VDs.