Effect of control of systolic blood pressure on survival in cats with systemic hypertension.

BACKGROUND: Systemic hypertension is a common clinical problem, often occurring in association with renal disease in cats. Limited information is available to assess the effect of blood pressure and the treatment of hypertension on survival. HYPOTHESIS: That adequacy of blood pressure control is associated with the duration of survival in cats with systolic hypertension. ANIMALS: One hundred and forty-one client-owned cats with systolic hypertension.
METHODS: Hypertensive cats were treated with amlodipine besylate and were followed until death or the study end point. Time-averaged systolic blood pressure (SBPOT) after implementation of antihypertensive medication and stabilization of systolic blood pressure (SBP) was calculated by using the equation (area under the curve/survival [days]). Cats were divided into quartiles based on their SBPOT, representing varying levels of blood pressure control (median [25th, 75th percentile]: Q1 = 137 [132, 141] mm Hg, Q2 = 148 [145, 151] mm Hg, Q3 = 157 [155, 158] mm Hg, Q4 = 170 [164, 175] mm Hg). Survival and clinical variables were compared between the quartiles. Cox proportional hazard regression analysis was used to determine the association of age, renal function, proteinuria, SBPOT, and the presence of hyperthyroidism on survival. Urine protein to creatinine ratio (UP:C) was compared at diagnosis of hypertension and after initiating treatment.
RESULTS: Only UP:C and SBP at diagnosis differed significantly between SBPOT quartiles. Proteinuria was the only variable significantly related to survival in hypertensive cats. A significant decline in UP:C was found in cats treated with amlodipine besylate. CONCLUSIONS AND CLINICAL IMPORTANCE: Proteinuria before and after treatment of hypertension is strongly associated with survival in cats with systolic hypertension. Treatment with amlodipine besylate can result in a significant reduction in UP: C.