Persistent proteinuria is associated with the occurrence of cardiovascular disease: a nationwide population-based cohort study

Proteinuria is an important risk factor for cardiovascular disease (CVD) and acts as a surrogate marker of renal damage. This study aimed to determine the association between changes in proteinuria and the occurrence of CVD. In our study, 1,708,712 participants who consecutively underwent national health examinations from 2003-2004 (first period) to 2005-2006 (second period) were included. They were classified into four groups based on the presence of proteinuria at the two consecutive health examinations: (1) normal (0 → 0), (2) proteinuria-improved (participants who had improved proteinuria (+ 1 → 0, + 2 → ≤ +1 [0 or + 1], ≥ +3 → ≤ +2 [0, + 1 or + 2]), (3) proteinuria-progressed (0 → ≥ +1, + 1 → ≥ +2, + 2 → ≥ +3), and (4) proteinuria-persistent (+ 1 → +1, + 2 → +2, ≥ +3 → ≥ +3). We used a multivariate Cox proportional hazards model to assess the occurrence of CVD according to changes of presence and severity of proteinuria. During a median of 14.2 years of follow-up, 143,041 participants (event rate, 8.37%) with composite CVD were observed. Compared with the normal group, the risk of incident risk of CVD was increased according to the severity of proteinuria in each of the persistent, progressed, and improved groups (p for trend < 0.001). In a pairwise comparison, the risk of composite CVD in the improved (hazard ratio [HR]: 1.32, 95% confidence interval [CI]: 1.27-1.37), progressed (HR: 1.49, 95% CI: 1.44-1.54), and persistent groups (HR: 1.78, 95% CI: 1.64-1.94) were higher than that of the normal group. Furthermore, the improved group had a relatively lower risk of composite CVD compared to the persistent group (HR: 0.75, 95% CI: 0.69-0.83, p < 0.001). The incidence risk of composite CVD was associated with changes of presence and severity of proteinuria. Persistent proteinuria may be associated with increased risk of CVD, even compared with improved or progressed proteinuria status.