Table 1. Odds ratios, 95% confidence intervals and P-values for logistic regression models.

Dependent variable	Independent variable	OR (95% CI)	P-value
EOI	Number of previous studies	1.98 (1.57–2.51)	<0.001
	Number of individual RCTs	2.51 (1.71–3.78)	<0.001
	Number of cluster RCTs	2.16 (1.57–2.99)	<0.001
	Practice size (1,000's)	1.03 (0.99–1.08)	0.160
Randomised	Number of previous studies	1.91 (1.52–2.42)	<0.001
	Number of individual RCTs	2.42 (1.65–3.61)	<0.001
	Number of cluster RCTs	2.07 (1.51–2.86)	<0.001
	Practice size (1,000's)	1.04 (0.99–1.08)	0.137

Abbreviations: CI, confidence interval; EOI, expression of interest; OR, odds ratio; RCT, randomised controlled trial.