Aims: Studies have shown a non-linear relationship between systolic blood pressure (SBP) and diastolic blood pressure (DBP) and outcomes, with increased risk observed at both low and high blood pressure (BP) levels. We hypothesized that the BP-risk association is different in individuals with and without diabetes at high cardiovascular risk.
Methods and results: We identified patients with (N = 11 487) or without diabetes (N = 19 450), from 30 937 patients, from 133 centres in 44 countries with a median follow-up of 56 months in the ONTARGET/TRANSCEND studies. Patients had a prior history of stroke, myocardial infarction (MI), peripheral artery disease, or were high-risk diabetics. Patients in ONTARGET had been randomized to ramipril 10 mg daily, telmisartan 80 mg daily, or the combination of both. Patients in TRANSCEND were ACE intolerant and randomized to telmisartan 80 mg daily or matching placebo. We analysed the association of mean achieved in-trial SBP and DBP with the composite outcome of cardiovascular death, MI, stroke and hospitalization for congestive heart failure (CHF), the components of the composite, and all-cause death. Data were analysed by Cox regression and restricted cubic splines, adjusting for risk markers including treatment allocation and accompanying cardiovascular treatments. In patients with diabetes, event rates were higher across the whole spectrum of SBP and DBP compared with those without diabetes (P < 0.0001 for the primary composite outcome, P < 0.01 for all other endpoints). Mean achieved in-trial SBP ≥160 mmHg was associated with increased risk for the primary outcome [diabetes/no diabetes: adjusted hazard ratio (HR) 2.31 (1.93-2.76)/1.66 (1.36-2.02) compared with non-diabetics with SBP 120 to <140 mmHg], with similar findings for all other endpoints in patients with diabetes, and for MI and stroke in patients without diabetes. In-trial SBP <120 mmHg was associated with increased risk for the combined outcome in patients with diabetes [HR 1.53 (1.27-1.85)], and for cardiovascular death and all-cause death in all patients. In-trial DBP ≥90 mmHg was associated with increased risk for the primary outcome [diabetes/no diabetes: HR 2.32 (1.91-2.82)/1.61 (1.35-1.93) compared with non-diabetics with DBP 70 to <80 mmHg], with similar findings for all other endpoints, but not for CHF hospitalizations in patients without diabetes. In-trial DBP <70 mmHg was associated with increased risk for the combined outcome in all patients [diabetes/no diabetes: HR 1.77 (1.51-2.06)/1.30 (1.16-1.46)], and also for all other endpoints except stroke.
Conclusion: High on treatment BP levels (≥160 or ≥90 mmHg) are associated with increased risk of cardiovascular outcomes and death. Also low levels (<120 or <70 mmHg) are associated with increased cardiovascular outcomes (except stroke) and death. Patients with diabetes have consistently higher risks over the whole BP range, indicating that achieving optimal BP goals is most impactful in this group. These data favour guidelines taking lower BP boundaries into consideration, in particular in diabetes.
Clinical trial registration: http://clinicaltrials.gov.Unique identifier: NCT00153101.
Keywords: Blood pressure; Diabetes; High cardiovascular risk; Hypertension; Myocardial infarction; Stroke.
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