British Doctors Trial - British Doctors Trial


Aspirin vs placebo for primary prevention


To determine if prophylactic daily aspirin would reduce the incidence of major cardiovascular events.

Study Design

Study Design:

Patients Screened: ~20,000
Patients Enrolled: 5139
NYHA Class: Not reported
Mean Follow Up: 6 year
Mean Patient Age: <60: 47%, 60-69: 39%, 70-79: 14%
Female: 0
Mean Ejection Fraction: Not evaluated

Patient Populations:

Male physicians <80 years old who were listed in UK Medical Directory


Aspirin use or contraindications to its use History of peptic, ulcer, stroke, or MI

Primary Endpoints:

Fatal or nonfatal MI

Secondary Endpoints:

Total mortality, nonfatal MI or stroke

Drug/Procedures Used:

Randomized in 2:1 fashion to aspirin 500 mg/day (or 300 mg/day enteric formulation) or no therapy (instructed to avoid aspirin). By 1 year, 19% allocated to aspirin stopped taking it, and during the next 5 years an additional 5% discontinued therapy. In the group allocated to avoid aspirin, ~2%/year began to use it, usually because vascular disease had developed.

Concomitant Medications:

Not reported.

Principal Findings:

There were no significant differences in the rates of fatal or nonfatal MI between the two groups (10.2/1000 pt years [aspirin] vs 9.7/1000 pt years). Daily aspirin was associated with a significant reduction in the frequency of confirmed transient cerebral attacks (1.6/1000 pt years vs 2.8/1000 pt years, p<0.05). However, the aspirin group had a small, nonsignificant excess of fatal and nonfatal strokes (4.8/1000 pt years vs 4.1/1000 pt years). Strokes defined as "probably hemorrhagic" also occurred at similar rates (0.16/1000 pt yrs [aspirin] vs 0.21/1000 pt years [controls]). All-cause and vascular mortality rates were 10% and 6%lower, respectively, in the aspirin group than in the control group (3.6% vs 4.2%, 4.3% vs 4.6%) but these differences were not statistically significant.


The use of aspirin for primary prevention was not associated with a significant reduction in major cardiovascular events. In particular, there was no reduction in nonfatal MI associated with aspirin use, a finding seen in the larger US Physicians Health Study (see N Engl J Med 1989;321:129–135).


BMJ 1988; 296: 313-6.

Keywords: Coronary Artery Disease, Stroke, Platelet Aggregation Inhibitors, Vascular Diseases, Primary Prevention

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