Table 1

Study design and size

% (n = 47) articles


Study design

RCT*

11 (5)

Prospective cohort study

21 (10)

Database or other retrospective cohort

68 (32)


Reason for sample size

No reason given

77 (36)

Justified time interval (clinical or technology)

4 (2)

Trial size (RCT or cohort)

19 (9)


Power calculation reported

0 (0)


Median (IQR) [range]


Eligible for study:

Number of patients (n = 35)

403 (148 to 833)

Number of events (n = 20)

112 (62 to 289)

Included in analysis:

Number of patients (n = 45)

342 (130 to 684)

Number of events (n = 33)

110 (61 to 230)


Number of events per candidate variable (n = 28)

10 (5 to 33) [2 to 95]


*RCT randomised controlled trial

Mallett et al. BMC Medicine 2010 8:20   doi:10.1186/1741-7015-8-20

Open Data