Meta-analysis: the effect of statins on albuminuria.

BACKGROUND: Albuminuria is an independent risk factor for cardiovascular and renal disease with limited therapeutic options. Data on the effects of statins on albuminuria are conflicting.
PURPOSE: To determine whether and to what degree statins affect albuminuria. DATA SOURCES: English-language and non-English-language studies found in PubMed, MEDLINE, EMBASE, BIOSIS, SciSearch, PASCAL, and International Pharmaceutical Abstracts (IPA) databases and the Cochrane Central Register of Controlled Trials that were published between January 1974 and November 2005. STUDY SELECTION: Randomized, placebo-controlled trials of statins reporting baseline and follow-up measurements of albuminuria or proteinuria measured by 24-hour urine collection or the urinary albumin-to-creatinine ratio. DATA EXTRACTION: Two investigators independently abstracted study quality, characteristics, and outcomes. DATA SYNTHESIS: Fifteen studies involving a total of 1384 patients and averaging 24 weeks in duration were included. Meta-analysis of the proportional reduction in proteinuria showed that statins reduced albuminuria (11 studies) and proteinuria (4 studies) in 13 of 15 studies. The reduction in excretion was greater among studies with greater baseline albuminuria or proteinuria: change of 2% (95% CI, -32% to 35%) for those with excretion less than 30 mg/d, -48% (CI, -71% to -25%) for those with excretion of 30 to 300 mg/d, and -47% (CI, -67% to -26%) for those with excretion more than 300 mg/d. Statistical heterogeneity was evident only in the group with excretion greater than 300 mg/d (excretion < 30 mg/d, I2 = 23% [P = 0.27]; excretion of 30 to 299 mg/d, I2 = 0% [P = 0.64]; excretion > or = 300 mg/d, I2 = 63% [P = 0.020]). LIMITATIONS: Published studies were not of high quality on average and varied markedly in effect size, as well as in characteristics of the cohorts. Unpublished studies showing no effect could impact these results.
CONCLUSION: Statins may have a beneficial effect on pathologic albuminuria. The validity of this finding, and whether this effect translates into reduction of cardiovascular or end-stage renal disease, requires larger studies.