The data were collected from a randomized , placebo-controlled trial underway at @ tertiary-care medical centers to determine whether the combination of an angiotensin I-converting enzyme inhibitor and angiotensin II-receptor blocker was superior to the inhibitor alone , and whether low blood pressure ( < @/@ mm Hg ) was superior to standard blood pressure ( @-@/@ -@ mm Hg ) , in delaying renal cystic progression in @ patients with ADPKD , stages @ and @ chronic kidney disease , and hypertension ( age , @-@ y ) .