Despite renin-angiotensin-aldosterone system blockade, which retards progression of CKD by reducing proteinuria, many patients with CKD have residual proteinuria, an independent risk factor for disease progression. We aimed to address whether active vitamin D analogs reduce residual proteinuria. We systematically searched for trials published between 1950 and September of 2012 in the Medline, Embase, and Cochrane Library databases. All randomized controlled trials of vitamin D analogs in patients with CKD that reported an effect on proteinuria with sample size$50 were selected. Mean differences of proteinuria change over time and odds ratios for reaching $15% proteinuria decrease from baseline to last measurement were synthesized under a random effects model. From 907 citations retrieved, six studies (four studies with paricalcitol and two studies with calcitriol) providing data for 688 patients were included in the meta-analysis. Most patients (84%) used an angiotensin-converting enzyme inhibitor or angiotensin receptor blocker throughout the study. Active vitamin D analogs reduced proteinuria (weighted mean difference from baseline to last measurement was 216% [95% CI, 213% to 218%]) compared with controls (16% [95% CI, 0% to 112%]; P,0.001). Proteinuria reduction was achieved more commonly in patients treated with an active vitamin D analog (204/390 patients) than control patients (86/298 patients; OR, 2.72 [95% CI, 1.82 to 4.07]; P,0.001). Thus, active vitamin D analogs may further reduce proteinuria in CKD patients in addition to current regimens. Future studies should address whether vitamin D therapy also retards progressive renal functional decline. 24: 186324: -187124: , 201324: . doi: 10.1681 CKD is a worldwide health burden, affecting about 15% of the Western adult population. 1 CKD is associated with premature death, cardiovascular disease, infection, and cancer, and it consumes disproportionate health care resources. [2][3][4] The mainstay of current CKD treatment is pharmacological blockade of the renin-angiotensin-aldosterone system (RAAS) by angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). Although these drugs may retard progression of both renal and cardiovascular disease 5-9 partly through their capacity to reduce proteinuria, 10,11 progression to ESRD and cardiovascular complications cannot be prevented in many CKD patients.
J Am Soc NephrolA recent single-level meta-analysis including over 2 million participants showed that albuminuria is independently associated with mortality and ESRD, regardless of age. 12 The amount of residual albuminuria/proteinuria under RAAS blockade is a strong predictor of both long-term renal disease progression 13,14 and cardiovascular complications, 15