Proteinuria and metabolic syndrome as predictors of cardiovascular death in non-diabetic and type 2 diabetic men and women

Aims/hypothesis: Proteinuria predicts cardiovascular disease (CVD), but it is unclear whether this is explained by the association of the metabolic syndrome with proteinuria. Therefore, we investigated proteinuria and the metabolic syndrome as independent predictors of CVD death in men and women. Methods: The cohort comprised 574 non-diabetic men, 707 non-diabetic women, 371 diabetic men and 349 diabetic women, all free of CVD at baseline. Modified World Health Organization criteria were used to define the metabolic syndrome, and a urinary protein concentration of >= 0.1 g/l (or >= 0.2 g/l) to define proteinuria. The endpoint was CVD mortality during the 18-year follow-up. Results: Among non-diabetic men, CVD mortality per 1,000 person-years was as follows: no metabolic syndrome, no urinary protein group: 5.3; no metabolic syndrome, positive for urinary protein: 8.9; positive for metabolic syndrome, no urinary protein: 13.3; and positive for metabolic syndrome and urinary protein: 14.9. For non-diabetic women the corresponding values were: 0.9, 2.3, 4.9 and 7.9, respectively. Among diabetic men, CVD mortality per 1,000 person-years was 15.2, 32.5, 23.6 and 42.0 for the respective groups. Among diabetic women it was 25.3, 38.0, 26.3 and 40.3 (urinary protein in all cases defined as >= 0.1 g/l). In multivariate Cox models including both urinary protein and metabolic syndrome, the hazard ratios (HRs, 95% CI) of proteinuria for CVD mortality were 1.5 (0.9-2.4) in non-diabetic men, 1.8 (0.8-4.2) in non-diabetic women, 1.6 (1.0-2.6) in diabetic men and 1.6 (1.1-2.3) in diabetic women. Urinary protein as a continuous variable was associated with CVD mortality in all groups. The corresponding HRs for metabolic syndrome were: 1.6 (0.9-2.7), 4.0 (1.7-9.7), 1.5 (1.1-2.0) and 1.1 (0.8-1.5). Conclusions/interpretation: Proteinuria predicted CVD mortality independently of the presence of metabolic syndrome in non-diabetic and diabetic subjects. Metabolic syndrome predicted CVD mortality in non-diabetic women and in diabetic men, independently of the presence of proteinuria.