Table 3 Estimates of the treatment effects (\(\beta _{t}\) and \(\beta 0_{t}\)) on the primary outcome at time t, test statistics (Z and Z0) and information accrual (I), at each interim analysis and the study end, for each RCT; where \(Z=\beta _{t}/\mathrm {sd}(\beta _{t})\), \(Z0=\beta 0_{t}/\mathrm {sd}(\beta 0_{t})\) and \(I=1/\text {var}(\beta _{t})\) and \(I0=1/\text {var}(\beta 0_{t})\). The primary outcome time-point t and the expected information \(I^{*}\), to trigger each interim analysis, are shown for each RCT

WAT (\(t=12m\) and \(I^{*}=\) 0.150 and 0.321)

 1

4.30

1.68

0.152

6.80

1.78

0.068

 End

2.18

1.16

0.283

2.23

1.18

0.278

DRAFFT (\(t=12m\) and \(I^{*}=\) 0.073 and 0.219)

 1

1.41

0.40

0.080

4.39

0.89

0.041

 End

1.51

0.94

0.387

1.37

0.85

0.384

WOLLF (\(t=12m\) and \(I^{*}=\) 0.025, 0.050, 0.075 and 0.165)

 1

-0.36

-0.06

0.025

-1.79

-0.22

0.016

 2

-2.76

-0.62

0.051

4.11

0.73

0.032

 3

0.19

0.05

0.075

2.16

0.51

0.056

 End

-3.65

-1.38

0.143

-3.14

-1.16

0.137

FASHION (\(t=12m\) and \(I^{*}=\) 0.025, 0.050 and 0.127)

 1

3.60

0.58

0.026

7.08

1.08

0.023

 2

6.50

1.50

0.053

6.77

1.48

0.048

 End

8.74

2.99

0.117

9.08

3.09

0.116

CSAW (\(t=6m\) and \(I^{*}=\) 0.123, 0.247 and 0.525)

 1

1.42

0.52

0.134

1.42

0.52

0.134

 2

2.17

1.08

0.249

2.17

1.08

0.249

 End

3.31

1.89

0.325

3.31

1.89

0.325

FIXDT (\(t=6m\) and \(I^{*}=\) 0.036, 0.071 and 0.165)

 1

1.14

0.22

0.037

2.29

0.41

0.033

 2

-2.85

-0.76

0.072

-0.52

-0.13

0.066

 End

-4.27

-1.51

0.125

-3.97

-1.39

0.124