Strengths and weaknesses of renal markers as risk factors and surrogate markers.

The reports of associations between albuminuria and estimated glomerular filtration rate and mortality are a major advance in understanding the progression of renal disease and its sequelae. These findings reinforce the importance of population risk profiling. However, application is limited by validity concerns due to substantial unexplained heterogeneity in many meta-analyses. Application to treatment decisions is premature given insufficient analysis of randomized trials of the association of by-arm differences in laboratory measures and by-arm differences in patient-relevant outcomes.