Premorbid blood pressure control of incident transient ischaemic attacks and strokes; prevalence and determinants; Analysis of individual patient data over 10 Years

Abstract

BACKGROUND: Uncontrolled blood pressure is the most important modifiable risk factor for strokes. AIMS AND METHODS: We determined the prevalence and determinants of blood pressure control in patients with incident transient ischaemic attacks(TIA) and strokes from 2002-2012 in a population-based cohort(Oxford Vascular Study). Controlled blood pressure(BP) was defined as having BP<140/90mmHg and was studied in different cardiovascular risk groups according to the Framingham 10-year general cardiovascular risk(CV-Risk) predicted at time of event and 10years pre-event; low(≤ 10%), moderate(11-19%) and high(≥ 20%) risk. We also studied the associations of controlled BP adjusted for age and sex. RESULTS: Among 1741 patients with incident TIA/strokes, 1051 (60.4%) had known hypertension, of which 891 (84.8%) were on anti-hypertensive treatment. However, only 698 (40.1%) of all and 306 (29.1%) of treated patients had controlled BP. On predicted 10-year CV-Risk at event, 861 (72.5%) of 1188 (77.0%) in high risk group had known hypertension, of which 758 (88.0%) were on treatment. However, only 346 (29.1%) of all in high-risk group and 190 (25.1%) of treated high risk patients had controlled BP. In contrast, 120 (88.2%) of 136 (8.8%) in low risk group had controlled BP. Risk stratification without scoring for BP showed consistent results except the number in high-risk group dropped to 863 (55.9%). Analysis with CV-risk 10years pre-event also showed similar trends. Age(adjusted OR=0.97, 95%CI=0.97-0.98, p<0.001), high CV-risk at event/10years pre-event (0.97, 0.95-0.99, p<0.013, 0.95-0.99, p=0.008), being treated for hypertension(0.43, 0.35-0.52, p<0.001), BMI≥ 30Kg/m2(0.72, 0.55-0.92, p=0.010) and high total cholesterol(0.91, 0.84-0.99, p<0.026) were negatively associated with controlled BP. However history of atrial fibrillation(1.35, 1.03-1.77, p=0.030) and physical dependency(modified-Rankin-Scale>2; 1.54, 1.15-2.06, p<0.001) were positively associated with controlled BP. CONCLUSIONS: Premorbid blood pressure control in patients with incident TIA/strokes was inadequate especially in high-risk patients. Controlling BP to targets in elderly and high CV-risk patients would be important in reducing incident TIA/strokes.