Clinical relevance of visit-to-visit blood pressure variability: impact on renal outcomes

An impaired renal function has been found associated with very high cardiovascular (CV) risk, especially in subjects with type 2 diabetes. Microalbuminuria is a sensitive early marker of renal damage, often preceding the more advanced stages of diabetic nephropathy. Consistent evidence has been provided that any degree of quantifiable albuminuria, even in the range of normoalbuminuria, is a significant predictor of CV events and progression to end-stage renal disease. This is of particular relevance in subjects with type 2 diabetes in whom the prevalence of microalbuminuria may be as high as 50%. This has motivated the search for novel, yet modifiable risk factors the correction of which may contribute to prevention of albuminuria development and of renal impairment progression in patients with type 2 diabetes, aimed at further reducing the overall CV risk profile in these patients. One of these proposed novel risk factors is an increase in blood pressure variability (BPV). This suggestion is supported by a series of studies, carried out either in diabetic and in nondiabetic populations, which have provided evidence that an increased BPV, in addition to increased average BP levels, may be an independent predictor not only of CV events and mortality but also of development and progression of renal disease. The purpose of the present paper is to provide a critical review of the evidence exploring the relationship between BPV and renal dysfunction with particular emphasis on the relationship between visit-to-visit BPV and urinary albumin excretion variability.