Table 4 Estimates of correlations between early and primary outcomes (\(\rho _{s,t}\)) and standard deviations (\(\sigma\)), at each interim analysis and the study end, for each RCT; the expected correlations were \(\rho ^{*}_{s,s^{\prime }}=0.5\) for all pairs of outcomes for all RCTs and the primary outcome time-point t and expected standard deviation (\(\sigma ^{*}_{t}\)) are shown for each RCT

WAT (FU at 6w, 3m, 6m and \(t=12m\) and \(\sigma ^{*}_{t}=9\))

 1

0.60

0.71

0.50

9.9

10.4

9.7

5.6

 End

0.59

0.72

0.80

10.1

9.8

8.9

10.4

DRAFFT (FU at 3m, 6m and \(t=12m\) and \(\sigma ^{*}_{t}=20\))

 1

0.78

0.72

-

22.3

17.5

-

13.5

 End

0.61

0.73

-

22.6

18.2

-

16.6

WOLLF (FU at 3m, 6m, 9m and \(t=12m\) and \(\sigma ^{*}_{t}=25\))

 1

0.59

0.77

0.88

22.6

23.5

26.7

25.7

 2

0.58

0.78

0.89

22.1

23.9

24.7

24.7

 3

0.48

0.71

0.82

21.1

23.6

25.2

26.4

 End

0.58

0.73

0.74

21.3

23.9

25.6

26.2

FASHION (FU at 6m and \(t=12m\) and \(\sigma ^{*}_{t}=20\))

 1

0.56

-

-

22.9

-

-

25.8

 2

0.56

-

-

23.9

-

-

27.3

 End

0.57

-

-

24.1

-

-

26.3

CSAW (FU at \(t=6m\) and \(\sigma ^{*}_{t}=9\))

 1

-

-

-

-

-

-

12.2

 2

-

-

-

-

-

-

11.7

 End

-

-

-

-

-

-

11.8

FIXDT (FU at 3m and \(t=6m\) and \(\sigma ^{*}_{t}=20\))

 1

0.61

-

-

20.1

-

-

24.6

 2

0.65

-

-

20.1

-

-

23.7

 End

0.65

-

-

20.0

-

-

24.1