PAST-BP
Prevention After Stroke—Blood Pressure
Year of Publication: 2016
Authors: Mant J, McManus RJ, Roalfe A, ..., Hobbs FDR
Journal: BMJ
Citation: Mant J, McManus RJ, Roalfe A, et al. Different systolic blood pressure targets for people with history of stroke or transient ischaemic attack: PAST-BP (Prevention After Stroke—Blood Pressure) randomised controlled trial. BMJ. 2016;352:i708.
PDF: Clinical Question
Does an intensive systolic blood pressure (SBP) target (<130 mm Hg) result in greater BP reduction than a standard target (<140 mm Hg) in patients with a history of stroke or TIA?
Study Overview
Objective
Assess whether an intensive systolic blood pressure (SBP) target (<130 mm Hg or ≥10 mm Hg reduction) reduces SBP more than a standard target (<140 mm Hg) in patients with prior stroke or TIA in primary care.
Study Summary
In a primary care population with prior stroke or TIA, setting an intensive SBP target (<130 mm Hg or 10 mm Hg reduction) led to a small additional reduction in SBP (≈3 mm Hg) compared to a standard <140 mm Hg target. Both groups saw clinically meaningful reductions, suggesting that active BP management is more impactful than target selection.
Intervention
Open-label randomized controlled trial in 99 UK general practices. Patients were randomized to intensive SBP target (<130 mm Hg or ≥10 mm Hg drop if baseline <140) vs. standard SBP target (<140 mm Hg). Follow-up: 12 months.
Bottom Line
Targeting SBP <130 vs <140 mmHg in post-stroke/TIA primary care patients produced only 2.9 mmHg additional reduction at 12 months (P=0.03). Both arms achieved large reductions (~13-16 mmHg). Only 51% achieved the individualised intensive target. Active management matters more than the specific target. 529 patients, 99 UK practices, open-label.
Major Points
- Small but significant BP difference: intensive target reduced SBP by additional 2.9 mmHg (95% CI 0.2-5.7; P=0.03) at 12 months.
- Both arms achieved large reductions: -16.1 mmHg (intensive) vs -12.8 mmHg (standard). >80% in both achieved SBP <140 mmHg.
- Only 51% achieved the individualised intensive target (<130 mmHg or 10 mmHg reduction). Clinician/patient reluctance common near target.
- Intensive target increased workload: more GP visits (median 2 vs 1; P<0.001), more nurse visits, more treatment intensifications (458 vs 278; P<0.001).
- Higher withdrawal in intensive arm: 20% vs 12% (P=0.02) — despite no objective increase in side effects.
- Only 6 cardiovascular events total (1 intensive, 5 standard) — grossly underpowered for clinical endpoints.
- Pragmatic primary care trial: 529 patients, 99 UK practices. Prevalent population including 51-54% TIA-only.
- Authors conclude a full pragmatic trial of intensive targets in primary care is not warranted.
Design
Study Type: Randomized, open-label, primary care-based controlled trial
Randomization: 1
Blinding: Open-label
Enrollment Period: 2009–2011
Follow-up Duration: 12 months
Centers: 99
Countries: United Kingdom
Sample Size: 529
Analysis: Mixed models adjusting for baseline BP, age group (<80, ≥80), sex, diabetes, atrial fibrillation, and general practice (random effect); principal analysis was complete case, with multiple imputation as sensitivity analysis
Inclusion Criteria
- History of stroke or TIA (on general practice stroke/TIA register)
- Systolic BP ≥125 mm Hg
- Registered at participating UK general practices
- Able to provide informed consent
Exclusion Criteria
- Already taking ≥3 antihypertensive agents
- Postural drop in SBP >20 mm Hg on standing
- Already being treated to a 130 mm Hg SBP target
- Unable to provide informed consent
- Insufficient corroborative evidence of stroke or TIA
Baseline Characteristics
| Characteristic | Control | Active |
|---|---|---|
| Age (mean) | 71.7 | 71.9 |
| Female (%) | 41 | 41 |
| Systolic BP (mean ± SD) | 142.2 ± 13.4 | 142.9 ± 14.0 |
| Diabetes (%) | 10 | 10 |
| Previous stroke (%) | 46 | 49 |
| Previous TIA (%) | 54 | 51 |
Arms
| Field | Intensive BP Target | Control |
|---|---|---|
| Intervention | Target SBP <130 mm Hg (or 10 mm Hg reduction if baseline <140 mm Hg) | Target SBP <140 mm Hg |
| Duration | 12 months | 12 months |
Outcomes
| Outcome | Type | Control | Intervention | HR / OR / RR | P-value |
|---|---|---|---|---|---|
| Change in systolic blood pressure from baseline to 12 months | Primary | −12.8 mm Hg | −16.1 mm Hg | 0.03 | |
| SBP <140 mm Hg achieved at 12 months | Secondary | 82% (161/197) | 82% (150/182) | 0.59 | |
| SBP <130 mm Hg achieved at 12 months | Secondary | 54% (107/197) | 57% (103/182) | 0.36 | |
| Major cardiovascular events (composite) | Secondary | 5 events | 1 event | HR 0.19 (95% CI 0.02–1.87) | 0.16 |
| Emergency hospital admissions | Secondary | 7.8% per year | 12.8% per year | HR 1.56 (95% CI 0.84–2.93) | 0.16 |
| Fall-related admissions | Secondary | 2 admissions | 2 admissions | ||
| Fall-related admissions | Adverse | 2 admissions | 2 admissions | ||
| Reported symptoms at 12 months | Adverse | No significant difference | No significant difference across 16 symptoms in Table 4 | All NS | |
| Treatment changes due to side effects | Adverse | 30 changes | 77 changes | <0.001 |
Subgroup Analysis
No significant interaction by baseline SBP (<140, ≥140), age group (<80, ≥80), diabetes, or atrial fibrillation
Criticisms
- Open-label design introduces potential bias
- Relatively short follow-up (12 months)
- Underpowered for clinical outcomes such as recurrent stroke or cardiovascular events
- 28% missing primary outcome data with differential loss to follow-up in intensive arm
- Trial population younger and less disabled than typical prevalent cerebrovascular disease population; over-represented TIA-only patients
Funding
UK National Institute for Health Research (NIHR; Stroke Prevention in Primary Care, Programme Grant for Applied Research, RP-PG-0606-1153) and an NIHR Professorship (RJMcM).
Based on: PAST-BP (BMJ, 2016)
Authors: Mant J, McManus RJ, Roalfe A, ..., Hobbs FDR
Citation: Mant J, McManus RJ, Roalfe A, et al. Different systolic blood pressure targets for people with history of stroke or transient ischaemic attack: PAST-BP (Prevention After Stroke—Blood Pressure) randomised controlled trial. BMJ. 2016;352:i708.
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