Sample size estimation for randomised controlled trials with repeated assessment of patient-reported outcomes: what correlation between baseline and follow-up outcomes should we assume?

Table 3 Baseline to post-randomisation follow-up correlations by trial

Trial name	Pearson baseline to post-randomisation follow-up correlation
Trial name	Mean	Median	No. of correlations	SD	Minimum	Maximum
Leg Ulcer	0.48	0.5	N = 18	0.13	0.23	0.71
NAMEIT	0.46	0.46	N = 54	0.1	0.21	0.63
Homeopathy for CFS	0.5	0.53	N = 5	0.19	0.18	0.65
Acupuncture	0.44	0.45	N = 24	0.12	0.2	0.62
Knee Replacement	0.45	0.48	N = 14	0.16	0.09	0.65
FED	0.5	0.56	N = 18	0.12	0.32	0.7
AIM-High	0.46	0.49	N = 60	0.14	0.16	0.74
PoNDER	0.44	0.47	N = 26	0.11	0.19	0.58
COPD	0.53	0.54	N = 48	0.08	0.37	0.68
Corn Plaster	0.45	0.45	N = 12	0.06	0.33	0.53
PLINY	0.67	0.74	N = 15	0.15	0.41	0.87
3Mg	0.39	0.39	N = 1	-	0.39	0.39
SELF	0.44	0.44	N = 9	0.07	0.31	0.54
BEADS	0.46	0.53	N = 3	0.3	0.14	0.71
DiPALS	0.54	0.57	N = 65	0.18	0.01	0.91
Lifestyle Matters	0.66	0.64	N = 28	0.11	0.45	0.88
IPSU	0.57	0.63	N = 15	0.13	0.34	0.73
POLAR	0.32	0.36	N = 15	0.14	0.04	0.53
PRACTICE	0.36	0.38	N = 6	0.36	−0.13	0.79
STEPWISE	0.53	0.56	N = 28	0.13	0.24	0.72
Total^a	0.5	0.51	N = 464	0.15	−0.13	0.91

ISSN: 1745-6215