Blood Pressure in Early Autosomal Dominant Polycystic Kidney Disease

To the Editor: In the Halt Progression of Polycystic Kidney Disease (HALT-PKD) study, Schrier et al. (Dec.11 issue) 1 randomly assigned patients with early-stage autosomal dominant polycystic kidney disease (ADPKD) to either a standard blood-pressure target or a low blood-pressure target.The low blood-pressure target was associated with a slower increase in total kidney volume, but not with an overall change in the estimated glomerular filtration rate (GFR).The latter finding might be viewed as being disappointing.However, we would caution that the institution of strict blood-pressure control will result in an acute, hemodynamic, but reversible decrease in the estimated GFR.A recent scientific workshop sponsored by the U.S. National Kidney Foundation and the Food and Drug Administration concluded that this acute effect is not indicative of irreversible loss of nephrons. 2Accordingly, rather than using the baseline estimated GFR, we would suggest comparing only on-treatment slopes of the estimated GFR.Such an analysis does show a benefit associated with the low blood-pressure target (P = 0.05). 1 Since a decrease in the estimated GFR is a late phenomenon in many patients with ADPKD, 3 a subgroup analysis of on-treatment estimated GFR slopes with the use of forest plots would be of interest, since it might hint at whether certain subgroups of patients with earlystage disease might benefit from a low bloodpressure target.