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Table 1 Characteristics of clinical trials of aspirin therapy included in meta-analysis

From: Aspirin has potential benefits for primary prevention of cardiovascular outcomes in diabetes: updated literature-based and individual participant data meta-analyses of randomized controlled trials

Lead Author, publication date

Name of study or source of participants

Study design

Patient population

Location

Baseline year of study

Age group

Males (%)

Allocation concealment

Blinding to subjects

Blinding to carers

Aspirin dose

Medication compliance (%)

Duration of therapy (years)

Completeness of follow-up

Trial participants with diabetes

Peto, 1988

BMD

Randomised, open label with no placebo

Healthy male doctors

UK

1978–1979

19–90

100.0

No

No

No

500 mg daily

NR

5.6

Unclear

101

PHS Steering Committee, 1989

PHS

RCT, double blinded

Healthy male doctors

USA

1982

40–84

100.0

Unclear

Yes

Yes

325 mg every other day

NR

5.0

99.7

533

ETDRS Investigators, 1992

ETDRS

RCT, double blinded

Participants with type 1 and 2 diabetes

USA

1980–1985

18–70

56.5

Unclear

Yes

Yes

650 mg daily

91.8

5.0

94.7

3711

MRC, 1998

TPT

Randomized, placebo controlled. Factorial with initial parallel group phase

Patients at high risk for IHD

UK

1989–1994

45–69

100.0

Adequate

Yes

Yes

75 mg daily

NR

6.7

98.9

68

Hansson, 1998

HOT

RCT, double blinded

Participants with hypertension

Multiple countries

1992–1994

50–80

NR

Adequate

Yes

Yes

75 mg daily

NR

3.8

97.4

1501

Sacco, 2003

PPP

Randomised open trial with 2 × 2 factorial design

Participants > 50 years with one or more CV risk factors

Italy

NR

64.3*

48.2

Adequate

No

No

100 mg daily

71.8

3.6

99.3

1031

Ridker, 2005

WHS

RCT, double blinded, 2 x 2 factorial

Healthy female health professionals

USA

1993

≥ 45

0.0

Unclear

Yes

Yes

100 mg on alternate days

NR

10.1

99.4

1027

Belch, 2008

POPADAD

RCT, double blinded, 2 x 2 factorial

Patients ≥ 40 years with type 1 and 2 diabetes, ABP <=0.99

Scotland

NR

≥ 40

44.1

Adequate

Yes

Yes

100 mg daily

50.0

6.7

99.5

1276

Ogawa, 2008

JPAD

Randomised open label with blinded end point assessment

Patients with type 2 diabetes

Japan

2002

65.0*

55.0

Adequate

No

No

81 or 100 mg daily

90.0

4.4

92.4

2539

Ikeda, 2014

JPPP

Randomised open label, parallel group

Elderly with multiple atherosclerotic risk factors

Japan

2005–2007

60–85

NR

Adequate

No

No

100 mg daily

76.0

5.0

~ 98.7

4903

McNeil, 2018

ASPREE

RCT, double blind

Community dwelling free of CVD, disability, dementia

USA, Australia

2010–2014

≥ 65

74.0

Adequate

Yes

Yes

100 mg daily

70.0

4.7

98.5

2057

ASCEND Study Group, 2018

ASCEND

RCT, double blind

Patients identified from diabetes registers or general practices

UK

2005–2017

≥ 40

63.0

Adequate

Yes

Yes

100 mg daily

70.0

7.4

99.1

15,480

  1. ASCEND, A Study of Cardiovascular Events in Diabetes; ASPREE, Aspirin to Reduce Risk of Initial Vascular Events; BMD, British male doctors; ETDRS, Early Treatment Diabetic Retinopathy Study; HOT, Hypertension Optimal Treatment; IHD, ischaemic heart disease; JPAD, Japanese Primary Prevention of Atherosclerosis with Aspirin for Diabetes; JPPP, Japanese Primary Prevention Project; MRC, Medical Research Council; NR, not reported; PHS, Physicians’ Health Study; POPADAD, Prevention Of Progression of Arterial Disease And Diabetes; PPP, Primary Prevention Project; RCT, randomised controlled trial; UK, United Kingdom; USA, United States of America; WHS, Women’s Health Study
  2. * Average age