Table 3

Regression model predicting variability in response rates in placebo groups of clinical trials; n = 153 studies/comparisons; formal and diagnostic variables (ICD coding)


Beta
t (DFs = 142)
p-value

Constant

2.07
0.04
Duration in months
0.31
6.17
<0.000001
Multicenter trial
0.13
3.04
0.003
Quality Index
0.18
3.44
0.0008
Neoplasms (C)
-0.21
-5.48
<0.000001
Organical psychological disorders (F0)
-0.12
-3.24
0.001
Disorders due to substance abuse (F1)
-0.14
-2.97
0.003
Nervous diseases (G)
-0.10
-2.55
0.01
Prevention trial
0.44
7.94
<0.000001
Quality rating: Additional treatment described?
-0.21
-4.34
0.00003
Quality rating: Dropouts described?
-0.16
-3.33
0.001

Walach et al. BMC Medical Research Methodology 2005 5:26   doi:10.1186/1471-2288-5-26