Table 4 Relationship between Number of patients Needed to Screen (NNS) to identify one participant and RCT characteristics

Total

103

Journal

0.78

BMJ

44

2.95 (1.42–9.30)

British Journal of General Practice

31

2.30 (1.38–4.42)

Family Practice

17

1.81 (1.23–3.46)

Journal of Family Practice

11

2.79 (1.95–7.92)

Number of enrolees

0.40

<100

40

3.15 (1.63–5.64)

110–260

31

2.19 (1.22–9.95)

260–650

15

1.66 (1.32–3.11)

>650

17

2.78 (1.38–5.16)

Multicentre

Multiple

83

2.79 (1.42–6.33)

Single

16

2.05 (1.18–7.83)

Unclear

3

1.66 (1.60–5.95)

Funding Source

0.09

Charity

10

2.61 (1.23–4.48)

Governing body

3

1.60(1.60–6.06)

Government

55

2.14 (1.34–6.33)

Pharma Industry

8

3.98 (2.10–15.59)

Other

9

5.33 (1.95–7.92)

Not Listed

18

2.62 (1.23–3.48)

Intervention Studied

0.47

Counselling/Lifestyle

8

4.75 (2.05–169.71)

Decision Support aids

6

2.89 (1.42–17.21)

Educational

21

2.05 (1.34–3.63)

Pharmaceutical therapy

9

1.89 (1.66–5.16)

Surgery/procedure

3

1.59 (1.11–9.95)

Other

55

2.79 (1.42–6.38)