Table 2.

Spearman’s Rank Correlation Between Study Characteristics and Placebo Response Using the Endpoint Percent Days Abstinent.

	Naltrexone (n = 23)		Acamprosate (n = 15)
Characteristics	rs	p-value	rs	p-value
Duration of treatment (weeks)	−0.12	0.59	−0.37	0.17
Publication year	−0.18	0.41	0.57	0.03
Mean age of participants	−0.42	0.05	0.39	0.15
% Male	−0.04	0.85	−0.12	0.67
Number of sites	−0.22	0.31	0.35	0.20

Note: each of two trials involving both naltrexone and acamprosate treatment arms was treated as two separate trials in the analysis.